Endodontics The main clinical and anatomical concepts. Methods of endodontic treatment.
The science of Endodontics studies anatomy and physiology of root canals, pulp and periodontium, the matters of etiopathogenesis, their treatment and prevention from inflammations. The purposes of endodontic treatment are: 1. Elimination of the infection from the root canals by means of removing: а) pulp and its necrotized remains b) infected dentine 2. Preparation of the root canal for filling, i. е. giving the desired shape to it. 3. Complete obturation of the root canals Endodontium (pulpo-apical complex) - a complex of tissues including the apical periodontium, bone of periapical region, pulp and peripulpar dentin, which are interconnected morphologically, functionally and clinically
Fig. 1.Scheme of tooth structure and its surrounding tissue
Fig. 2.Endodontium (scheme)
There are several clinical-anatomical concepts (Fig. 3.):
Radiological apex of the root is the most remote from the crown portion of the tooth root by x-ray.
Anatomical apex (anatomical apical hole) is the place of exit of the root canal to the root surface.If the anatomical apical hole is at the tip of the root, then the anatomical and radiographic apex match. However, in most cases due to the curvature of the apical part of the root canal anatomical apex is on the lateral surface of the root at a distance of 0.5-1mm from radiographic apex.
Physiological apex (physiological apical hole) is the site of physiological narrowing of the root canal at a distance of 0.5-1 mm from the anatomical apex. The space between these two points is called the Kettler zone. Physiological apex is the boundary between the root pulp and periodontal tissues.
Fig. 3.Schematic representation of the apical part of the root and root canal
Important from a practical point of view is the presence of small branches of the root canal, often in the apex of the root (Fig. 4.). These brances form in the apical part of root an apical delta and are called the deltoid branches. They usually depart at an angle from the main canal and may end blindly or communicate with the periodontium.Additional channels located in the middle or cervical part of the root, called pulpo-periodontal anastomoses. Only 33% of the roots have unbranched root canal , 50% of roots have one branch, and the remaining 17% have the multiple branches.
Fig. 4.The deltoid branches of the root canal and pulpo-periodontal anastomoses (scheme).
The inability to delete the contents of the deltoid branches and additional channels leads to the preservation in them of necrotic areas of the pulp and pathogenic microorganisms.It may be a source of development and progression of periodontitis and requires adequate medicamental processing during endodontic treatment.
Hearths of acute and chronic inflammation in dental pulp and periodontium cause physical and mental discomfort to patient and be a source of development of odontogenic inflammatory processes of maxillofacial area and neck, can complicate the course of internal organs and systems diseases, induce the development of focal infections as well.Therefore, a pulpitis and periodontitis require timely, adequate and efficient endodontic treatment. Endodontic treatment is an important part of the dental treatment aimed at the preservation and restoration of the form and function of the tooth. It involves instrumental (mechanical) manipulations (processing) and medicamental therapeutic effects in root canals. Although it should be noted, that the concept of "endodontic treatment" is much broader and bigger.
After precise diagnosis, in case it is necessary, the oral cavity is prepared for endodontic treatment. The following procedures should be performed for this purpose: а) examination and correction of the degree of the mouth opening b) filling of other carious cavities, which do not serve as access into the tooth cavity (for example, percervical carious cavities) c) treatment of periodontal diseases (gingivotomy, gingivectomy etc.) d) temporary restoration of destroyed walls of a tooth with the purpose of temporary filling e) grinding of masticator tubercles to eliminate supra-contacts f) in case of abundant salivation 30 minutes before processing rinsing by solution of atropine is recomended Indications of endodontic treatment are: 1. Inflammation of the dental pulp – pulpitis. 2. Inflammation of apical periodontium tissues – periodontitis with absence or presence of destructive changes in the periapical tissues. 3. Pulp removal for prosthodontic, periodontal or orthodontic reasons. 4. Injury to the tooth resulting in irreversible damage to the pulp and the necessity of its removal and root canal filling. 5. Presence of the conditions for preservation of the tooth and carrying out an endodontic treatment. The criteria for maintaining the tooth and conducting the treatment are: ● functional value of the tooth in the future ● the possibility of restoration of the tooth crown ● sufficient stability of the tooth ● the effectiveness of medical procedures ● satisfactory general condition of the patient Main contraindications of endodontic treatment (including "retreatment") are: 1. Extensive destruction of tooth tissues, the inability to restore its shape and function after endodontic treatment. 2. The presence of inflammation in periodontium of affected tooth, which is linked with the diseases of the internal organs or which is a source of odontogenic inflammatory process (sinusitis/inflammation of maxillary sinus/, osteomyelitis, etc.). 3. Significant loss of periodontal tissues, tooth mobility of III grade. 4. Vertical root fracture. 5. The ineffectiveness of endodontic interventions. 6. Severe general condition of the patient. 7. Inappropriate behavior of the patient and unwillingness to cooperate with the doctor. It should be noted that many of these contraindications are facultative.Sometimes an endodontic treatment is possible if the special devices, tools and environment are present in clinic. In some cases, it is possible to use the conservative surgical methods of endodontic treatment to save the tooth. Methods of endodontic treatment Choice of endodontic treatment method depends on the degree of pathological changes in the pulp, involvement of periodontal tissues in the process, the condition of the dental hard tissues, level of reactivity and regenerative abilities of the patient`s organism, qualification and material-technical equipment of doctor-stomatologist. Methods of treatment of pulpitis Biological method treatment of pulpitis is а full preservation of vital pulp of the tooth.Biological method of pulpitis treatment allows with the help of medications to eliminate inflammation in the pulp and stimulate an origination of dentine.Biological method is used in cases when the pathological changes in the pulp of the tooth are reversible.Medicine effect on the pulp is carried out by application of the medicamental strips (Fig. 5.).
Fig. 5.Biological method of pulpitis treatment
The method of vital amputation of the pulp is a variation of the biological method.In case of this method the affected coronal pulp is removed, and more viable root pulp, which does not lost its barrier and regeneration function, is maintained in the root canals alive (vital). Medicamental effect on left part of pulp is carried out by application of curative liner on the root canals orifices(Fig. 6.). Removal only the coronal pulp is called an amputation, and the method of treatment is amputative.
Fig. 6.Treatment of pulpitis by the method of vital amputation Extirpation methods of treatment of pulpitis During these methods, the coronal and root pulp is completely removed (extirpation), the root canals are mechanically and medically processed, and then hermetically filled (Fig. 7.). Coronal part of the tooth is restored with a corresponding filling material or artificial crown. The method of vital extirpation is the removal of vital pulp under anesthesia. Method of nonvital extirpation of pulp means the necrotization (devitalization) of pulp using medicine or physiotherapeutic procedures, and then its removal. Anesthesia in this case is not required.
Fig. 7.Extirpation method of treatment of pulpitis Method of devital amputation is carried out in case of obstruction of the root canals for endodontic instruments.Only the coronal pulp should be removed and root pulp, which should be necrotized beforehand, impregnated with special agents that cause antiseptic effect and turning it into aseptic cord (Fig. 8.). This processing of the pulp is called an impregnation, and method is called impregnative.
Fig. 8.Treatment of pulpitis by devital amputation method (scheme) Combined treatment method is used if a tooth has both passable and impassable root canals.In this case coronal pulp is removed first of all.From the well-passable channels the pulp is completely removed, the channels are processed mechanically and medicamentaly, and then hermetically filled (extirpation method).In impassable channels a pulp should be necrotized, and then impregnated (method of devital amputation) (Fig. 9.).
Fig. 9.The combined method of pulpitis treatment The most effective and common are extirpation methods of pulpitis treatment. Application of these methods allows the doctor to figure out the following tasks: ● a maximum removal of infected and necrotized tissues from the root canals ● to reduce the number of pathogens in the root canal, periapical tissues and parietal dentin to the minimum pathogenic level ● to perform the hermetic sealing of the root canal. Methods of treatment of periodontitis Treatment of periodontitis is carried out by using of the same technologies and on the basis of the same principles as the treatment of pulpitis. Depending on the clinical situation there are two basic approaches to the conservative endodontic treatment of periodontitis. According to a first way of the medical tactics, to eliminate the source of chronic periapical inflammation processing and hermetically filling of the root canal is rather enough, eliminating it as a source of constant infection of the periodontium (Fig. 10.).
Fig. 10.Endodontic treatment of periodontitis without active influence on periapical hearth (figure) The second way of the medical tactics is periapical therapy means an active medicamental and/or physiotherapeutic effect on the periapical area via the root canal to eliminate this hearth (lesion) and subsequent hermetic filling of the root canal.The elimination of the hearth in this case is caused by the ongoing therapeutic effects and local and general protective “forces” of an organism (Fig. 11.).
Fig. 11.Endodontic treatment of periodontitis in combination with periapical therapy (scheme) The basic rule and the most important criterion of the quality of endodontic treatment: the root canal must be passed, mechanically and medicamentally processed (treated) and filled all over (entirely), i.e. up to the physiological apex.
Anatomical and topographical structure of tooth cavity Central incisor of the upper jaw The coronal part of the tooth cavity is formed by the labial, palatal and two lateral walls, has shape of triangular gap flattened in the vestibular palatal direction (Fig. 12.). The vault (upper border, wall) of the cavity is defined at the level of the middle third of the tooth crown. Towards the root a coronal cavity is being narrow and becoming a single root canal.Channel of central incisor of the upper jaw is broad, cross-section (transversal) is of round shape.
Fig. 12.Central incisor of the upper jaw Lateral incisor of the upper jaw The coronal part of the tooth cavity has a shape of a triangle (Fig. 13.). Its widest part is in the cervical area of the tooth. The vault of tooth cavity is determined along the line of the middle third of the crown, has three pits directed towards the cutting edge, according to its cusps.
Fig. 13.The lateral incisor of the upper jaw The canal is compressed laterally, narrower than in the central incisors.On cross-section (transversal) channel is elongated in vestibular palatal direction and has an oval shape.Often the tip of the root and root canal is slightly curved toward palate.In 1% of cases an additional channel is present. Canine of the upper jaw The tooth cavity has a spindle shape (Fig. 14.). At the middle of the crown the cavity expands, and at the level of the neck is it’s the biggest part. Then the tooth cavity without visible boundaries transfers into a wide root canal.On cross-section it has an oval form, is elongated in buccal palatal direction.Often the root and root canal in the apical part has a curvature in the lateral or palatal direction.
Fig. 14.canine of the upper jaw Central incisor of the lower jaw The tooth cavity resembles a triangle.The vault of tooth cavity is close to cutting edge (Fig. 15.). Coronal part of the cavity smoothly passes into the root canal. Since the tooth root is compressed in mediolateral direction, the cavity at the transverse cut has an oval or slit (gap)-like shape.The channel is narrow, often poorly passable.
Fig. 15.Central incisor of the lower jaw Lateral incisor of the lower jaw The tooth cavity is bigger than tooth cavity (Fig. 16.). Channel has oval shape, elongated in the vestibular-lingual direction. The main difference is the root canal of lateral incisor is wider than central incisor root canal, often there are two canals, the vestibular and lingual.
Fig. 16.The lateral incisor of the lower jaw Mandibular canine The cavity of the tooth, as the tooth, has a spindle shape (Fig. 17.). At the middle of the crown the cavity expands. Its largest size is in the cervical area of the tooth, smoothly passes into the root canal.On cross-section the channel has an oval shape, compressed in mediolateral direction.Often there are two canals, buccal and lingual.
Fig. 17. canine of the mandible First premolar of upper jaw The crown cavity of the tooth is compressed in the anteroposterior direction, has the shape of a slit elongated in the buccal palatal direction (Fig. 18.). There are the vault of tooth cavity, the bottom and 4 walls. The upper border (vault) of cavity is located at the level of the tooth neck.The bottom of the tooth cavity has a saddle shape and is located significantly above the neck of the tooth, under the gingiva.At the edges of the bottom of cavity there are the buccal and palatal canals funnel shaped orifices. Channels are hardly passable, however, the palatal canal is wider, straight, and buccal is narrower, curved. In 2 - 6 % of cases there are 3 channels: two buccal and one palatal.
Fig. 18.first premolar of upper jaw Second premolar of upper jaw The crown cavity of the tooth resembles the first premolar, is compressed in the anteroposterior direction, has the shape of a slit elongated in the buccal palatal direction (Fig. 19.). The upper border (vault) of cavity is located at the level of the tooth neck. Coronal cavity continues into a straight, well-passable root canal without sharp boundary, the orifice of which is located in the center of the cavity.In 24% of cases the second premolar of the upper jaw may have two channels (buccal and palatal) that can be joined and opened with one or two apical foramens.
Fig. 19.second premolar of upper jaw First premolar of lower jaw Coronal tooth cavity is oval, narrowed in the anteroposterior direction (Fig. 20.). The largest size of the cavity is observed below the neck of the tooth. Gradually narrowed, the cavity continues into one passable channel. Sometimes there are two canals (buccal and lingual) that can be connected and opened with one or two apical foramens.
Fig. 20. first premolar of lower jaw Second premolar of lower jaw The crown cavity of the tooth has round shape.Cavity of the tooth crown continues into one well- passable canal by gradually narrowing (Fig. 21.).
Fig. 21. second premolar of lower jaw First molar of the upper jaw In the coronal portion of the tooth cavity, which has shape of the crown, there are: the upper border (vault), the cavity bottom and 4 walls (buccal, palatal, anterior and posterior). In cross section the cavity has the shape of a rhombus.The vault of cavity is located on the border of upper and middle third of the tooth crown.The bottom of the cavity is slightly convex and is located in the neck of the tooth or slightly higher, under the gingiva. At the bottom of the cavity there are three orifices of the root canals: anterior buccal, posterior buccal and palatal, which when connecting form a triangle (Fig. 22.). The basis of the triangle is formed by a line connecting the orifices of the buccal canals, and the top - palatal. The longest channel is palatal, usually straight, well passable.
Fig. 22. first molar of the upper jaw The buccal canals are narrow, curved; usually the mechanical processing is difficult. Often in the anterior buccal root there is a fourth channel.Typically, it has a narrow orifice, is difficult to clean with instruments.In some cases it is isolated, and sometimes in the apex of the tooth merges with the main channel and ends with one apical foramen. Second molar of the upper jaw There are 4 version of the structure of the tooth cavity, respectively, four variants of the anatomical shapes of crown.The most frequent are first and fourth versions of the tooth cavity structure. First version: the structure of the cavity is similar to the shape of cavity of the upper first molar. Second and third variants are more rare.The cavity of the tooth has a diamond shape, elongated in the anteroposterior direction.The orifices of the channels converge and are located almost on the same straight line. Fourth version of the structure of the tooth cavity has a triangular shape, accordingly to tricuspid form of the chewing surface. The upper border (vault) of cavity of the upper second molar is projected at the level of the tooth neck.The bottom of the tooth cavity is above the level of the tooth neck. There are three root canals: two buccal (frontal and posterior), one palatal (Fig. 23.). The palatal canal is wide, well passable, buccal canals are narrow, curved, often have a side branches.
Fig. 23.second molar of the upper jaw Third molar of the upper jaw Structure of coronal cavity is variable as the tooth, often similar to the shape of tooth cavity of the upper first or second molar with three channels. Sometimes there are more than three root canals. Often, the channels merge into one channel.Because of the peculiarities of structure and poor access a third molar makes special challenges during endodontic treatment First mandibular molar The crown cavity has a upper border, bottom and 4 walls (buccal, lingual, anterior and posterior).The vault of cavity is located on the border of middle and lower thirds.The bottom of cavity has the shape of a rectangle elongated in the anteroposterior direction. Bottom is located at the level of the tooth neck or slightly lower and has a convex surface.At the bottom of the cavity there are 3 root canals orifices.There are 2 canals in the frontal root and 1 canal in the posterior root.The frontal buccal canal`s entrance is located directly under the same cusp. Entrances of the frontal lingual and posterior channels are located beneath the longitudinal fissure separating the buccal and lingual cusps.The orifices of the channels form a triangle with a top at the posterior canal orifice.Frontal channels are narrow, especially the frontal buccal. Posterior channel is broad, well passable. Often, the tooth has 4 channels; 2 of them are located in the frontal root, and 2 others- in the posterior root. The orifices of the channels form a quadrangle in this case (Fig. 24.).
Fig. 24.first mandibular molar Second mandibular molar The tooth cavity resembles the shape of the tooth cavity of the first mandibular molar.Compared to the first mandibular molar a tooth cavity has a smaller size and the distance between the orifices of the root channels is less due to the convergence of the frontal and posterior roots (Fig. 25.).
Fig. 25.second mandibular molar Third mandibular molar The tooth cavity structure is variable and similar to the form of the tooth itself, often resembles the structure of the tooth cavity of the lower first or second molars.However, the number of channels is not constant due to the diversity of number and location of the roots.Often the roots are fused to form one channel. Table 1.Options of the teeth Upper jaw Teeth tooth length, mm root length, mm Length of the crown, mm
1 22,2 ± 1,9 13,0 ± 1,7 9,2 ± 1,5
2 21,5 ± 1,8 12,9 ± 1,6 8,6 ± 1,2
3 25,6 ± 2,7 15,9 ± 2,4 9,7 ± 1,4
4 20,7 ± 2,0 13,6 ± 1,8 7,1 ± 1,0
5 20,8 ± 2,0 14,4 ± 1,9 6,7 ± 0,9
6 19,5 ± 1,8 13,3 ± 1,7 6,2 ± 0,6
7 19,6 ± 1,9 13,0 ± 1,8 6,6 ± 0,8
8 18,4 ± 2,0 12,2 ± 2,0 6,2 ± 0,9
Lower jaw 1 20,3 ± 1,8 12,8 ± 1,6 7,5 ± 1,3
2 21,8 ± 1,9 13,7 ± 1,6 8,2 ± 1,1
3 25,1 ± 2,8 15,3 ± 2,1 9,8 ± 1,4
4 21,5 ± 1,8 13,7 ± 1,7 7,8 ± 1,1
5 21,9 ± 1,9 15,2 ± 1,8 6,7 ± 1,1
6 20,2 ± 1,7 14,5 ± 1,7 5,8 ± 0,9
7 20,2 ± 1,7 14,1 ± 1,7 6,1 ± 0,9
8 18,9 ± 1,9 12,8 ± 1,9 6,1 ± 0,9
The topography of the orifices of the root canals
Numbering of the channels: 1 - palatal 2 – frontal (anterior )buccal 3 – posterior buccal 4 - buccal 5 - anterior lingual 6 - frontal (anterior )buccal 7 - posterior Fig. 26.The layout of the orifices of the root canals
Fig. 27.The topography of the orifices of the root canals Taking into account the topographical features of the teeth it is necessary to provide the most optimal access to the root canals of different teeth groups. The entrance to the cavity of the upper incisors and canines should be provided from palatal surface, cingulum. And on lower jaw access should be from the lingual surface, often including a cutting edge. Access to the tooth cavity in premolars is provided from the middle part of chewing surface, in molars- from the medial region of the chewing surface. To provide access to root canals means to reveal the tooth cavity. The requirements of the opening of tooth cavity: ●walls of the formed cavity should match with the walls of the tooth cavity ● must be an absence of vault of cavity and its overhanging edges ● there is wide instrumental access to the root canals (at the entrance to the root canal a tool does not bend) ●walls and bottom of the cavity should not be thinned In the opened tooth cavity the orifices of the canals can be seen and explored by probe.
Endodontic tools/instruments Endodontic instruments are designed to work in the tooth cavity and root canals. Endodontic instruments can be both for manual use and for handpieces. All endodontic instruments should meet the following requirements: 1. Provide the processing of dental canals for the whole length. 2. Allow a free working space in the oral cavity. 3. Be safe and well fixed from outside as much as possible. 4. The working part must correspond to its functional purpose. All over the world there are certain norms of standardization (based on size, purpose, color, signs)of endodontic tools, and manufacturers should follow these norms. The standardization is carried out by the International Organization of Standards (ISO). All endodontic tools consist of a handle and a pole where the working part is located. The working part is usually 16 mm , while the entire length of the tool can vary: а) 25 mm is the standard length, b) 31/28 mm –long tools, which are used for processing of roots of upper incisors and canines, c) 21 mm – short tools, which are used for the roots of masticatory teeth, as well as in case of limited mouth opening. The diameter of working parts of the tools evenly enlarges up to 0.32 mm which allows to form the canal in a cone shape.
The size of an endodontic tool is defined by the diameter of its tip (d1), which can be from 06 to 140 units. For example, the number 35 means diameter of the working part`s tip of the instrument is equal to 0,35 mm
Fig. 28. Manual endodontic instrument (basic parameters): L1 – length of working part; L2 is the total
length of the metal rod; D1 – the diameter of working part`s tip; D2 = D1 + 0,32mm.
To facilitate the definition of the tool size it is accepted to paint the handle of the tool, in the color corresponding to the size or to put a color mark on it.
Number Color
6 Pink 06 8 Grey 08 10 Violet 010 15 45 90 White 015, 045, 090 20 50 100 Yellow 020, 050, 100 25 55 110 Red 025, 055, 110 30 60 120 Dark blue 030, 060, 120 35 70 130 Green 035, 070, 130 40 80 140 Black 040, 080, 140
Taper (conicity) of standard tools is 2%, ie the diameter of these tools increases by 0.02 mm for every millimeter of length, respectively. Currently, the instruments has made with custom(non standart) taper, 04, 06, 08.10, 12 (Fig.29.).
Fig. 29.Scheme of conicity of endodontic instruments Graphic symbols of instruments types are also regulated by the ISO standard. It should be taken into consideration that the symbols are not corresponding to cross-sectional shape of the working part (tab. 3.). Table 3.Common symbols of endodontic instruments
Classification of endodontic tools/ instruments according to usage/purpose
I. Endodontic tools/instruments to make an access to root canals
II. Endodontic tools/instruments and devices for diagnostic purposes, to examine and diagnose the root canals
III. Endodontic tools/instruments to remove dental soft tissues
IV. Endodontic tools/instruments to enlarge the orifices of canals
V. Endodontic tools/instruments to pass the canals
VI. Endodontic tools/instruments to enlarge and smoothen the root canal
VII. Endodontic handpieces
VIII. Endodontic tools/instruments to fill root canals
IX. Other endodontic instruments and devices
Endodontic tools/instruments to make an access to root canals
Different burs fixed in a high-speed handpiece are been using to open and disclosure of the tooth cavity. During working in deep tooth cavities so-called endoburs can be used (Fig. 35.).
Fig. 35. endoburs
These are carbide or diamond heads of various shapes with rounded top without cutting edges (threads) or diamond dust(particles). The tip of these tools is called the Batt-type. Burs of round shape in this case are not used to avoid a perforation of the bottom and walls of the cavity. It is better to use an endodontic excavators which have longer working part than conventional ones (Fig. 36.).
Fig. 36. Dual endodontic excavator
Endodontic tools/instruments and devices for diagnostic purposes, to examine and diagnose the root canals
Designed to determine a localization , working length and direction of root canals. Surveillance of orifices is carried out by using manual endodontic probes (explorers) of various shapes. In this group there are the root needles. They are of three types: round depth indicator, root needle for a cotton turunda (tamponage, bandage) and root needle of Miller (tab. 4.). A depth indicator is a smooth tool of a round cross-section form. There is a special rubber marker (stopper), which measures and fixes the length of the canal. Root needle for a cotton turunda in cross section has a rounded shape and staggered notches. Cotton is applied and twisted on the working part and thanks to threads is not shifted when immersing the tool in a root canal. A root needle can be either of a round or a ribbed cross-section form. It is used to define the passability and the direction of canals. Sometimes it is used medicinal processing of the tooth canals by wadded turunda, as well as for drying the canals. Faceted needle Miller has a square cross section. The tips of all the root needles are rounded. Table 4.Root needle
Verifiers are used to fill the root canals with Termafil, when it is necessary to define the length and size of the gutta-percha pin beforehand, so they can be conditionally related to diagnostic tools. They represent plastic or metal intracanal instruments, which are used usually for obstruction of channels by method of introducing hard gutta-percha pins (with Thermafil systems). Before obturation of the canal verifier is entered, the size of which corresponds to the selected obturator (filler) size, and thus determines the compliance of the prepared canal size to filler.
To determine the passability of the root canal, its length and shape x-rays should be used, including visiography, apex locator.
Endodontic tools/instruments to remove dental soft tissues
Most often to remove pulp, its remains and cotton turunda from the root canal Pulp extractor should be used . Pulp extractor is a metallic pole on which prong-like tines are located at sharp angle, giving to it a shape of Christmas-tree. It is used to remove the pulp and its remainders from the root canal. The rotation in the aperture of the canal should not exceed 360о, since further rotation can result in its breakage. The symbol is a star with 8 sharp corners (angles).
Pulp extractor
Removal of soft content from root canal, especially in narrow and curved root canals, you can also use root rasps, K-files and H-files. During working with these tools the removal of pulp, its remains from the root canal occurs in the process of expansion of the channel along with the layer of the dentin on wall.
Endodontic tools/instruments to enlarge the orifices of canals To facilitate the endodontic treatment, it is recommended to expand the orifice and the upper third of the channel, giving them a funnel-shaped form. The main instruments of this group are: Gates-Glidden has a short drop-like working part on a long rod. It is made only for mechanical handpieces. The recommended speed is 450-800 rev/min. It helps to make the best approach to the root canals. The tip of the working part it generally rounded, which makes it safe to use. It is produced from size 1 to 6, which correspond to following numbers by ISO: 50, 70, 90, 110, 130, 150 respectively.
Fig. 39. Gates-glidden.
Largo /Peeso-Reamer/ is an instrument, the working part of which is longer compared with Gates- Glidden. The recommended speed is 800-1200 rev/min. It is used to enlarge the root canal in the field of an orifice to fix the different pins. The tip can be blunted or rounded. It is produced from size 1 to 6, which correspond to following numbers by ISO: 70, 90, 110, 130, 150, 170.
Fig. 40. Peeso-Reamer.
Orifice opener has an evenly narrowing ribbed surface. It is used in the straight part of root canlas, for their enlargement. This instrument can be of 3 sizes; it is also produced with diamond dust Orifice opener-МВ.
Fig. 41. Orifice opener.
Beutelroсk reamеr 1 /B1/ is meant to work with a mechanical handpiece. It has 11 mm-flame-like working surface with 4 sharp edges. It is manufactured from size 1 to 6. The recommended speed is 800-1200 rot/min.
а б
Fig. 42.Beutelroсk reamеr 1 (а); Beutelroсk reamеr 2 (б).
Beutelroсk reamеr 2 /B2/ has 18 mm-cylindrical working surface. It is made by method of twisting a flat metal plate, having sharp edges, around its axis. The recommended speed is 450-800 rot/min., and it is a very dangerous (aggressive) tool to work with. It is produced from size 0 to 6, which correspond to the following numbers on ISO: 30, 35, 45, 60, 75, 90, 105. Preparations for antiseptic dressings
For imposing an antiseptic bandage a small cotton ball moistened with drug (without excess) and placed in a tooth cavity on the orifices of the root canals. Then the cavity is hermetically sealed, with temporary material without pressure.
Fig. 72. The imposition of antiseptic dressings.
When applying the antiseptic bandage is diffusion of drugs into root canal dentinal tubules, deltoid branch and periapical tissue with obtaining a therapeutic effect. After 5-6 days. antiseptics diffuse into the surrounding tissue and the therapeutic action antiseptic bandage is weakened and then stopped.
The optimal duration of the imposition of antiseptic dressings – 2-3 days., the maximum duration of blending is not more than 5 days. For the imposition of antiseptic dressings use a ready-made combination of drugs, provides comprehensive therapeutic effect.
Part of the preparations for antiseptic dressings usually include:
●1-3 potent antiseptic
●1-2 corticosteroid hormone for fast relief of inflammation and reduce the irritation of antiseptics
●analgetics to relieve pain.
Most often as an antiseptic component in the products for medical dressings include derivatives of phenol, eugenol and chlorhexidine.
Derivatives of phenol (formocresol, thymol, camporota, carbolic acid, etc.) have a pronounced disinfectant effect. They combine well with each other and with other drugs (corticosteroids, anesthetics, etc.).
Eugenol has antimicrobial, anti-inflammatory, analgesic and deodorizing effect. The disadvantage of drugs on the basis of eugenol and phenol derivatives is their strong irritant and a toxic effect on the periapical tissue if used incorrectly. In addition, they can inhibit the polymerization of composite materials in the subsequent restoration of the tooth. Chlorhexidine is one of the most active local antiseptic It has high activity against microflora of root canals, retains activity in the presence of blood, pus, various secrets and organic substances. In dentistry for the imposition of antiseptic dressings used in the form of 0.2 % alcohol solution. In comparison with eugenol and derivatives of phenol chlorhexidine has a more soft and physiological effect on the periapical tissue, so there is no need to include in the drug anti- inflammatory drugs and corticosteroid hormones. An important property of chlorhexidine is that it does not disturb the polymerization of composite materials.
The imposition of antiseptic dressings allows to solve the following tasks:
- reduction of pain
- destruction of pathogenic microflora, located in the root canal, dentinal tubules and deltoid branches
- relief of inflammation in the periodontium
-stimulation of reparative processes in the bone tissue periapical region. Indications for the imposition of antiseptic dressings:
-the hermetic seal the tooth between visits in the process of endodontic treatment
-prolonged antiseptic effect on the root canal system, dentinal tubules and deltoid branches
-conservative treatment of acute and exacerbation of chronic forms of periodontitis "closed" way
-"check the teeth on Hermeticism" before the permanent filling of root canals.
Drugs for chemical enlargement of root canals. Gels-Endolubricants
Root canals, especially narrow and obliterated, is not always possible to pass and to expand using only endodontic instruments. In such cases resort to chemical expansion. The method is based on the introduction into the lumen of the canal of a solution of any acid, which, interacting with the mineral components of dentin, decalcified and softens it, turning in a loose structure, which facilitates the process of subsequent tooling of the channel. Chemical enlargement of root canals does not replace the mechanical (instrumental) extensions, but complements and facilitates it. For chemical expansion of channels, there are two types of drugs: liquids and gels.
Liquid for chemical enlargement of root canals
For chemical enlargement of root canals using ready-made liquid preparations on the basis of a 10-20% solution of ethylenediaminetetraacetic acid (EDTA) or its disodium salt (Trilon B). The composition of the liquids for chemical expansion of root channels also include antiseptics, stabilizers and other components. Liquid for chemical expansion of root channels can be used directly in the process of instrumental treatment of root-canals, and for chemical enlargement impassable channels between visits. Technique of chemical channel expansion directly in the process or tooling. After drying of the tooth cavity on orifices of the channels using a pipette or tweezers cheeks causing a small amount of the drug solution for chemical enlargement of root canals and pump it into the channels orifices using a thin K-Riemer or K- file for 2-3 min. Then start to pass and mechanical processing with endodontic instruments. Chemical and mechanical effects alternate to obtain the desired result. After tooling, the channel is washed with antiseptic solution, and then distilled water.
Technique of chemical expansion of the channels during the period between visits is used when hyper calcified and and obliterated root canals when they are unable to pass in the first visit. For this, a cotton swab soaked in the liquid for chemical expansion of channels, is placed on the orifices of the root canals and sealed shut with a bandage for 2-7 days. When you visit the dressing is removed and conduct instrumental treatment of the channel, alternating chemical and mechanical extension. After tooling, the channel is washed with antiseptic solution, and then distilled water.
Gels-Endolubricants
Drugs in this group are liquid, gel-like consistency. In addition to EDTA, antiseptic agents and floating agents that help remove particles of dentin, these preparations contain a lubricant, facilitating the movement of instruments in the canal. The most important characteristic of these gels is not so much the ability to chemical expansion of the root canal, how much lubrication, the ability to slide the tool into the root canal, reducing the risk of jamming. Therefore, drugs in this group called endo-lubricants (endodontic lubricant).
Methodology for clinical application of gel-endolubricants. A small amount of gel is applied to the endodontic instrument or is injected into the orifice of the root canal. Immediately after that start machining. The procedure is repeated several times, making sure that the channel walls and the working part of the file constantly to cover: a small amount of gel. After instrumental treatment of channel is washed thoroughly with sodium hypochlorite solution and then with distilled water, dried and sealed. You should pay attention to the fact that the gel cannot be left in the canal until the next visit. With the passage and instrumental treatment of root canal tools for the chemical extensions - gels and liquids must be necessary. Gels-endolubricants apply in all cases of instrumental treatment of root canals. Liquid should be used for chemical expansion of channels that failed to go to the top in the first visit.
Means to stop bleeding from root canals
Quite often in the process of endodontic treatment there is bleeding from the root canal. It hampers the mechanical and drug treatment, does not allow quality fill the channel, can lead to crown discoloration and creates the risk formation of hematoma in apex, which can cause pain after treatment, of inflammatory complications. The most common causes of bleeding:
• traumatic separation of the pulp when removing pulp extraction:
• trauma to the periodontal tool in the wrong determination of the working length.
• perforation of wall of root canal.
To stop bleeding from the root canal using various tools and methods:
1. Drugs with vasoconstrictor and astringent properties.
Substances in this group are used most often. It is a complex preparations containing vasoconstrictors - epinephrine and its analogs, astringent and styptic substances. These drugs have a mild, physiological effects, but sometimes ineffective.
2. Cauterizing drugs This group includes 10% solution of hydrogen peroxide, the liquid phosphate-cement, phenol-formalin. These drugs are highly effective, but have strong time - irritating effect, so use them rarely.
3. 3% water solution of hydrogen peroxide. The hydrogen peroxide in contact with tissue, decomposes into water and atomic oxygen. This provides a bactericidal effect, the formation of foam and mechanical cleaning of the channel. Hemostatic effect of hydrogen peroxide due to the fact that foam accelerates the transition of fibrinogen to fibrin, leading to blood clotting and the formation of a blood clot on the wound surface.
4. Diathermocoagulation of pulp in the root canal. Used for therapeutic purposes of heat energy, which is released at the site of contact of the electrode with the tissue when passing through them an alternating electric current. When conducting diathermocoagulation in the area of contact of the electrode with tissue by converting electrical energy into heat occurs raising the temperature to 60-80°C. This causes denaturation of proteins, destruction of nerve endings, coagulation of capillaries, venules and arterioles. The blood coagulates and the vessel lumen is closed. Surgical diathermy are shown first if the vital methods of treatment of pulpitis with the aim of stopping and preventing bleeding from the root canal. In addition, it allows you to influence the microflora of the root canals, to produce a complete and high-quality extermination pulp, turning it into a dense aseptic cord that facilitates its removal from the channel. In dental practice for conducting diathermocoagulation use special devices - diathermocoagulator (Fig. 73.).
The methodology of the diathermocoagulation of the vital pulp in the root canals:
1. The procedure is performed under anaesthesia and is the stage of endodontic treatment.
2. Tooth exposed, pass root channels, determine the working length.
3. Diathermocoagulator ready to work.
4. The tooth is isolated from saliva, dried.
5. In the root canal to the working length of the endodontic instrument is administered, for example, K- file. Its thickness should correspond to the width of the root canal.
6. Electrode of diathermocoagulator touching the metal rod of the tool, and then completing the electrical circuit for 2-3 c.
7. After diathermocoagulation proceed to the instrumental treatment of canals and removal of the root pulp.
Fig. 73. Diathermocoagulator "DKS-3M".
The coagulation of the pulp occurs only in the place of direct contact with the electrode, i.e. an electrode is introduced into the channel 2/3, and coagulation of the pulp will occur to a depth 2/3 of the channel length.
Do not conduct diathermocoagulation in patients with insufficiency of the cardiovascular system and individual intolerance of electric current. It is not recommended to use the diathermocoagulation of the endodontic treatment of teeth with absorbable or non-developed roots.
The principles of processing and filling of carious cavities
Caries is a pathological process, which characterized by demineralization and soften of tooth hard tissue further occurrence of cavity.
The classification of caries:
1. According to localization ( Bleck’s classification)
I class –the carious cavities are located in the area of natural fissures and holes of all groups of teeth (the vestibular and lingual grooves of molars, blind holes(cingulum) of molars on vestibular surface and palatal surface of upper incisors).
Class II- the cavities are located on aproximal(contact) surfaces of molars and premolars.
Class III- the cavities are located on the contact surfaces of incisors and canines without damaging their cutting edges and angles.
Class IV- the cavities are located on the contact surfaces of incisors and canines involving their cutting edges and angles.
Class V – the cavities are located in precervical area of all group of teeth.
Nowadays the American scientists at the head of Yevgeni Ioffe distinguish one more class- 6th class
Class VI-the cavities , which located on cutting edges of frontal teeth, on the tubers (cusps) of posterior teeth, and on the equator area of all group of teeth.
2. According to depth of process (clinical-morphological):
• Caries in spot stage (macula cariosa)
• Superficial caries (caries superficialis)
• Intermediate caries (caries media)
• Deep caries (caries profunda)
3. According to affected tissue (anatomical):
• Enamel caries
• Dentine caries
• Cement caries 4. According to the clinical course of caries process:
• Chronic or typical, slowly proceeded caries (the process proceeds slowly, the walls and bottom are hard, but pigmented).
• Acute or fast proceeded caries (the process proceeds fast, the walls and bottom of caries cavity are soft, but non-pigmented, often several teeth are affected.
• Peracute caries (the process proceeds extremely fast, the walls and bottom of caries cavity are very soft and non-pigmented, several teeth are affected, moreover, on one tooth can be observed several cavities).
• Stopped caries (the process stops due to elimination of caries causing factors).
5. According to intensivity:
• Compensated (till 5 teeth are affected)
• Subcompensated (from 5-8 teeth are affected)
• Decompensated (more than 8 teeth are affected)
6. According to WHO:
• Enamel caries including chalky spot
• Dentine caries
• Cement caries
• Stopped caries
• Odontoclasia (children melanodetia, melanodontoclasia)
• Tooth another caries
• Unspecified caries
The development and advancement of caries process
The development and advancement of caries process of tooth hard tissue depends on its localization and thickness of enamel in that area. The advancement of caries process is not the same in enamel and dentine as they have different chemical composition and different histological structure. The caries process, developing in enamel, for I class has triangle form, which top is directed to the enamel surface, and bottom to the dentine-enamel border. In dentine the process advance not only in deeper layers but also to peripheral parts, so the cavity has triangle form, which top is directed to the pulp and bottom to the enamel. That’s why there are softened dentine layers under the enamel, and the hanged enamel edges can be broken under influence of masticatory(chewing) pressure.
The carious processes on contact and precervical surfaces also have triangle form, which top is directed to dentine, and in dentine it’s directed to the pulp. Due to enamel prisms arrangement the entrance of cavity is wider than those of I class(pic.10).
Pic.1 The advancement of carious process in various class cavities.
General principles of preparation of carious cavities
Tooth preparation is preparation of hard tissue, which main aim is to remove damaged (affected) tissue and create maximal convenient (favorable) conditions for filling, restoring anatomical shape and functions.
The preparation and formation of caries cavity depends on its shape, localization and sizes.
As tooth hard tissue preparation is very thorough and painful process, we should keep the following rules:
Tooth preparation should be done under anesthesia
The procedure should be performed under maximal good natural and artificial lightening
The preparation should be performed with cooling by water in order to avoid of thermal traumas
It should be kept the all rules of safety and ergonomics
Work only with sterile instruments
The all using instruments should be sharp, non-warn, well-fixed, and rotating instruments should be centralized and without vibration.
While preparing the tooth it should be taken into consideration the tooth anatomo - topographic features
There are several methods of carious cavity preparation.
The “preventive preparation method” by Black- Carious cavity should be prepared till tooth immune zone ( the less caries affected areas of teeth: the cusps(tuberculum), cutting edges, equator, convex surfaces of teeth), thus remove pathoanatomically healthy tissue (pic.2).
Pic.2. Preventive expansion of I class cavities.
The positive features of this method are:
1. It prevents origination of secondary caries.
2. Provides good adhesion of filling material to tooth tissue.
The negative features are:
1. Removal of big volume of healthy tissue.
2. Weakening of durability of the crown.
3. Time consumption.
The second method was suggested by Lukomsky and is called method of “biological expediency”. According to this method only visible damaged tissue should be removed (pic.3).
Pic.3. I class cavities preparation by the method of biological expediency.
The positive features of this method are:
1. Saving visible healthy tissue of tooth
2. Less time consumption
The negative features are:
1. High probability of secondary caries
2. Non-longevity (fall-out) of fillings
The stages of preparation of carious cavities
1. Opening of carious cavity. It’s a removal of hanging edges of enamel in order to provide good access to the carious cavity. Opening of the cavity is made by ball- shaped or fissure burs, the diameter of which is smaller than the entrance of the cavity (pic.4,5). Saving(keeping) hanging enamel is permitted only
a b
pic.4. opening of carious cavity: a-with ball-shaped bur, b- with fissure bur
Pic.5. the choice of bur for opening the carious cavity: a- correct, b,c –incorrect
2.The preventive expansion of carious cavity. The aim of this stage is to prevent the origination of secondary caries. The carious cavity nearby, intact areas , which are susceptible to caries, are also prepared, but in a way that the border “filling- tooth” will located in immune zone. In case of preparation is made by Lukomsky method , the above mentioned stage can be missed.
3. Necrectomy. It’s a removal of softened and pigmented dentine, as well as food remains. The volume of necrectomy depends on clinical course, localization and depth of carious process. Necrectomy is made by hatchets or hard alloy rounded burs at low speed. In case of working with hatchets the preparation starts not from the walls of carious cavity but from the center of the bottom in order to avoid accidental opening of the pulp cavity (pic.6).
Pic.6. removal of softened dentine by hatchets from the bottom: a-correct, b-incorrect It’s not allowed to leave softened and pigmented dentine on the bottom, except several cases when we can keep pigmented but hard dentine. During acute course of caries in pediatric dentistry it can be left softened layer of dentine in condition to perform remineralization therapy. While doing necrectomy it’s important to take into consideration the topographic anatomy of tooth.
For the distinction softened and demineralized dentine in carious cavity we use many coloring substances-0,5% solution of fuchsine (the softened dentine is colored into red ) or we use 1-2% hydrate solution of methyle blue (the softened dentine is colored into blue). The bandage of coloring substanceis placed into the cavity and after 15 seconds it’s colored. The following are the representatives: “Caries Detector”, “Caries Marker”, “Sic” (pic.7).
Pic.7. The application of coloring substance in carious cavity for distinction the demineralized remains of dentine.
Nowadays there are special devices for distinction pathological tissues. (ex. The device DIAGNOdent).4. Formation of carious cavity. The aim of this stage is to provide comfortable conditions for longevity and well-fixation of filling material. For this purpose the cavity should be formed box-shaped in superficial and middle caries, i. e. the angle between the bottom and walls should be 90 degrees , angles-sharp, bottom- flat. (pic.8).
Pic.8. The position of the conic bur:1-during the formation of bottom, 2-during the formation of the walls. In case of deep caries, the bottom of the carious cavity is formed taking into consideration the topography of tooth cavity. The creation of retention grooves is possible on dentine –enamel border.
However, these rules are used when filling the cavity by materials which do not have adhesions to firm tissues of the tooth (amalgam, silicate, and silicophosphate cements). Using of the composites and glassionomer cements allows to form the cavity with spherical (rounded) outlines, without well-defined right angles.
5. Processing of the enamel edges. In some cases, depending on the choice of the filling material, it should be created folder while processing the enamel edge. An angle of 45 degree should be created - falc. This (folder) enlarges the adhesion surface of the filling and enamel , has aesthetic meaning, as it makes invisible the border between filling and enamel (pic.9). When filling by amalgam the fold is processed through all the thickness of enamel, and in case of composites – only half way through. When filing by cements the folder of enamel is not made, as the thin layer of this filling quickly blasted under the chewing pressure (pic.10). This is the last stage of mechanical processing of the cavity.
Pic.9. the processing of enamel edges.
Cement amalgam composite
Pic.10. formation of the enamel edges depending on choice of filling.
After the mechanical processing the washing and drying of the carious cavity should be done. It’s performed by steam of water and air gun. The usage of antiseptics is not preferable as they can weaken the adhesion of filling. So the cavity is ready for filling.
Peculiarities of preparation of the 1th class cavities
These are cavities, located in natural fissures of molars and premolars, as well as in blind holes (cingulum) of the frontal teeth. 1th class cavities can be processed like box-shape, oval, fissure – shape etc.. The external outlines of formed cavity depends on the structure of fissures, as well as the advancement of carious process and its depth (pic. 11).
Pic.11. the 1th class cavity formation in premolars: 1th class cavity of upper premolar: a- before the formation, b- after the formation; c- already formed cavity in second premolar of lower jaw.
The opening of 1th class is usually made by rounded (ball-shaped) or fissure burs. The 1th class cavity, which is already formed on the occlusal surface of the tooth, has the following elements; walls (4), bottom ( the surface which is directed to the tooth cavity), edges, angles (pic. 12).
Pic.12. the elements of the carious cavity: 1-edges, 2-walls, 3-angles, 4-bottom.
The preparation of 1th class cavities mainly is performed by the above-mentioned steps. If two carious cavities are located on a chewing surface of molar teeth and integrity of enamel platens is preserved, then two isolated cavities are formed. In case of considerable thinning of enamel platens it is recommended to form a whole cavity on the chewing surface. During preparation of a cavity on a chewing surface of molar and premolar teeth it is necessary to take into account, that the border “seal-tooth” should not be in the area of contact of antagonist teeth (pic.13).
Pic.13. 1th class cavities formation depending on degree of damage of fissures: a-two isolated formed cavities, separated by firm enamel platens, b- connection of two cavities, c- formation of the cavity by fissure complete preparation .
Among the surface of the first molars of mandible, the longitudinal groove (non-intersected) passes.The second molars of the mandible have cross-shape groove. In these two cases the 1th class cavities should be formed by preparing the whole fissures (pic.14).
Pic.14. the cavity formation on the surfaces of lower molars: a-before preparation of carious cavity, b,c,d- different types of cavity formation.
The fissures , which pass between mesial and distal cusps of upper molars , are intersect by well-expressed enamel platen. And if this platen is not damaged, it should be preserved during cavity formation. So 1th class cavities are formed in the area of damaged fissures. On the chewing surface of upper premolars one non-intersected groove passes between the cusps, and it should be completely prepared while forming 1th class cavity.
On the occlusal surface of lower first premolar, there is a well-expressed enamel platen, which intersect the groove into two parts. If this platen isn’t caries affected, it should be preserved, and only the carious affected part is prepared.
On the occlusal surface of second premolar of mandible the groove isn’t intersected by enamel platen, that’s why it completely prepared during cavity formation.
The 1th class includes also carious cavities in natural pits on the vestibular or oral surfaces of the molars. When the cavity is very small and the tissues on the occlusal surface is preserved (there is no changes) , so the cavity is formed in oval shape, in limits of natural pits (pic.15).
Pic.15. The cavity formation on the buccal surface of lower molar: a- before preparation, b- after preparation.
In case when the cavity is big (in natural pits) , and after necrectomy the thin layer of enamel separates it from occlusal surface, the cavity should be opened on occlusal surface.
In case when the carious cavities are located both on occlusal surface and buccal surface and separated only by thin wall, they (two cavities) should be connected together by additional platform (pic.16).
Pic.16. 1th class cavity formation in case of simultaneous affection of occlusal and buccal surfaces of lower molar: a- before preparation, b-after preparation, c- the shape of formed cavity from occlusal surface.
The 1th class cavities also can located on the palatal surfaces of frontal teeth , in natural pits ( mainly it happens in lateral incisors). Preparation of these cavities should be done very carefully because the above-mentioned cavities are very close to the pulp (pic.17).
Pic.17. Formation of the 1th class cavity in the area of cingulum (blind hole) of upper incisor: a- before preparation, b- after preparation.
Peculiarities of preparation of II class cavities
II class cavities are located on the contact surface of posterior teeth. There are 3 basic types of preparation of 2nd class cavities: without additional platform, with additional platform and mesio-occlusial-distal (MOD-cavity).
The cavity is prepared without additional platform , when it is located very close to occlusal surface. In case of necessity this type of cavities can be prolonged to occlusal surface (pic. 18).
Pic.18. Formation of 2nd class cavity on the molar without additional platform.
The cavity is formed without additional platform as well as when neighboring tooth is absent, and the cavity is located in the precervical area of contact surface. In this case the cavity is prepared in oval shape.
When the neighboring tooth is present, the 2nd class cavity is formed with additional platform ( pic.19).
Pic.19. The elements of 2nd class cavity with additional platform: 1-the bottom of main cavity; 2- the bottom of additional cavity; 3-the walls of additional walls; 4- the wall of main cavity; 5- the precervical wall of main cavity.
The following are the preparation stages: a) Opening of the cavity from occlusal surface. This means that access for clarification and formation of the cavity is formed from the chewing surface, which eases the necrectomy and creates favorable conditions for filling. b) Creation of additional platform on the chewing surface.
The purpose of creation of this platform is to provide additional steadiness of the filling and to redistribute the masticatory stress on it. The additional platform is prepared within the limits of fissures without infringement of integrity of hills. The sizes of additional platform depends on location, width, and depth of cavity, as well as the choice of filling material. When filling is performed by cements and amalgam the length of the additional platform should be twice longer than the main cavity and the depth should be 1mm lower of the dentine-enamel border, and the width should be 1/3 of the chewing surface of the tooth. When filling is done by composites the additional platform can be prepared with the limits of enamel, since the adhesion of composites to enamel is stronger. c) Creation of inclination of perigingival wall. Perigingival wall is prepared with a small inclination to the bottom of the cavity in order to provide better fixation of the filling (pic.20.,21).
Pic.20. the formation of 2nd class cavity: a- before preparation, b-after preparation.
Pic.21. the formation of the 2nd class cavity with combined defects of contact and occlusal surfaces: a-before preparation, b- during preparation, c- after preparation.
The MOD cavities are formed when simultaneously affected two contact surfaces. The additional platform here is formed into the fissure, and the cusps is obligatory prepared to avoid its fracture (pic.22).
Pic.22 MOD formation of 2nd class: a-before preparation; b-after preparation; c- the shape of the formed cavity from occlusal surface.
In case when simultaneously two neighboring teeth’s contact surfaces are affected, their preparation is performed together.
Nowadays the usage of GIS allows to prepare 2nd class cavities by tunnel technique (pic.23).
Pic.23. 2nd class cavities preparation by tunnel technique: a- before preparation, b- during preparation.
This method is made when the cavity is located in the area of equator or below it. The aim of this method is to preserve the contact wall and marginal crest of occlusal surface. The entrance to the cavity is made from fissure of chewing surface.
The possible complications of this method are: accidental opening of tooth cavity and incomplete removal of infected tissue.
Peculiarities of preparation of III class cavities
These cavities are located on the contact surfaces of frontal teeth without including the cutting edge. The cavity formation depends on its sizes and presence of neighboring tooth. In case of absence of the neighboring tooth the cavity is formed in triangular shape with the top directed to cutting edge and the basis directed to gingiva. Pregingival wall is recommended to prepare with sharp angle to the bottom of the cavity (pic.24).
Pic.24. 3rd class cavity preparation in absence of neighboring tooth: a- before preparation; b- after preparation.
When the cavity is very small and is located in precervical area, and in case of absence of neighboring tooth, it’s formed in oval shape.
There is no necessity to create additional platform when the cavity is very deep and involves the oral wall of the tooth (pic.25).
Pic.25.Formation of deep cavity of 3rd class: a- before preparation, b-after preparation.
In case of presence of neighboring tooth, the cavity is prepared from the oral side by creating additional platform and with maximal preservation of a vestibular wall.
The basic demands for additional platform are:
• the width of additional platform of oral surface should be equal the width of main cavity and in case of huge defect of contact surface it should be smaller than the width of main cavity.
• the length of additional platform should be no shorter than 1/3 of oral surface of tooth; the depth- 1mm below dentine –enamel border.
• It should be 2,5-3mm space between cutting edge and its neighboring wall (pic.26).
Pic.26. the formation of additional platform of 3rd class cavities : a-before preparation; b- after preparation.
All pigmented dentine , irrespective of the degree of hardness, is removed. The fold on the edge of the cavity is made more acute so that the border between the filling and the tooth is imperceptible. Often, the hypertrophy of the gum papilla can become an obstacle to the preparation and formation of the cavity. It is recommended to remove the hypertrophy papilla before starting the treatment.
Peculiarities of 4th class cavities preparation
These are cavities located on contact surfaces of frontal teeth, including the cutting edge. The main purpose of preparation and treatment is creation of the best conditions for the restoration of the angle of the crown part of the tooth.
Preparation of the 4th class cavities is very similar to 3rd class cavities preparation. When the neighboring tooth is absent and the vestibular and oral walls are hard enough , the cavity is prepared without additional platform. The shape of formed cavity repeats the shape of decayed cavity (pic.27).
Pic.27. the preparation of the 4th class cavity without additional platform: a-before preparation, b- after preparation.
In presence of neighboring tooth , the additional platform should be created from palatal surface, which formation is the same in 3rd class cavities (pic.28).
Pic.28. preparation of 4th class cavities with additional platform: a- before preparation, b- after preparation.
The cavity is prepared from the oral side, with the maximal preservation of vestibular wall. All pigmented dentine, irrespective of the degree of hardness, is removed.
Formation of additional platform on the lingual surface or along the cutting edge (in case if it is wide enough). In this case the topographical anatomy of the tooth has to be considered. For the best fixation of filling it can be created retention grooves (points).
Peculiarities of preparation of 5th class cavities
These cavities are located on precervical parts of all teeth. Mostly vestibular surfaces of the teeth are affected. Often the lower end of the carious cavity is located lower than the gum end, which is the reason for local catarrhal or hypertrophic gingivitis. This disturbs the preparation and formation of the carious cavity, therefore the gingivitis should be cured or the gum papilla should be removed in advance. Taking into account that this area of the tooth is very sensitive to pain irritants the preparation of the cavity, irrespective of its depth, has to be done under anesthesia. The cavity is formed in oval shape, the angles between the walls and the bottom of the cavity should be slightly acute, not right; i.e. the entrance should be narrower than the bottom of carious cavity, which insures better adhesion of filling material. The bottom of the cavity should be convex, considering the location of the pulp chamber of the tooth. Perigingival wall should be inclined towards the bottom of the cavity (pic.29. 30).
Pic.29. the formation of 5th class cavities: a-before preparation, b- after preparation.
Pic.30. formation of 5th class cavities of molars: a- before preparation, b- after preparation.
Mistakes and complications during carious cavity preparation
Conductive anesthesia
During conductive anesthesia the anesthetic is inserted far from the operative area near the nerve trunk.
The following types of conductive anesthesia are used for the mandible:
1. Mandibular anesthesia – n. alveolaris inferior and n. lingualis are blocked during this anesthesia. All the teeth, the half of the lower lip, tongue, mucous membrane of the mouth bottom and lingual part of gingiva are blocked.
Mandibular anesthesia can be carried out inter-orally and extra-orally.
Inter-oral mandibular anesthesia by palpation:
а) with the wide open mouth of the patient the doctor must palpate the anterior edge of the mandible ramus near the distal edge of the third molar (if it misses, then right after the second molar, fig.7).
Fig. 7. Palpation of the anterior edge of the mandible ramus. b) bone landmarks must be palpated by left forefinger, if the anesthesia is done on the right side and by right thumb if it is done on the left side. c) doctor must find the anterior edge of the ramus by finger and take it a little bit medial, in order to reach postmolar pit. The finger must be fixed in the pit so the doctor can feel the temporal crest. d) syringe must be placed on the level of premolars of the opposite side (fig. 8).
Fig. 8. The position of the syringe during mandibular anesthesia. e) the needle prick must be done 7-10mm above the occlusial surface of the third molar, near the temporal crest, where the finger is positioned (fig. 9).
Fig. 9. The mandible ramus on side projection (а) and straight projection (б): 1 – condylar process, 2 – coronoid process, 3 – anterior edge of ramus, 4 – temporal crest, 5 – postmolar pit, 6 – mandibular foramen, 7 – uvula of the mandible, 8 – postmolar triangle. f) the needle must be taken outside, backwards and on the depth of 5-8mm it reaches the bone, where 0,5-1,0ml anesthetic must be inserted to block the lingual nerve. g) without losing the contact with bone the needle must be taken above, backwards and out (parallel to mandible ramus) on the depth of 2mm up to bone groove, where the n. alveolaris inferior is located. h) aspiration probe must be carried out and the rest part of anesthetic must be inserted. Inter-oral apodactyl method of mandibular anesthesia (without palpation)
This method is less accurate, as it is based on plica pterigomandibularis, which is located near temporal crest. It can be wide, middle and narrow.
Extra-oral mandibular anesthesia
Extra-oral mandibular anesthesia is done when the mouth opening is limited. The patient’s head must be taken to back and opposite to the side of anesthesia. The mandible angle must be palpated by forefinger and thumb. The needle prick is done near the base of mandible, 1.5cm anteriorly to the angle. The needle must be taken upper for 3.5-4cm by the internal surface of the mandible ramus, strictly parallel to its back edge. The contact between the needle and the bone must be kept all the time. It can be comfortable to insert the needle without the syringe and then fix the syringe before anesthetic insert. 3ml of anesthetic must be inserted to block n. alveolaris inferior. Lingual nerve can be blocked by taking the needle upper for 1cm. Filling of carious cavities The choice of filling material for fillings depends on the localization of cavities, group affiliation of teeth, the depth of the lesion, and positive and negative properties of materials. Currently, it is important that the cost of the filling material, the superimposed filling.
Pecularities of filling carious cavities depending on their depth
When filling a deep carious cavity, it is necessary to put a medical (containing calcium hydroxide) and isolating linings on its bottom. Depending on the choice of the constant filling material to be used for filling of the cavity, the medical and isolating linings are placed by following way: - If a composite of chemical hardening, cement or amalgam are to be used, than the medical lining is placed on the bottom of the carious cavity, on the spot closest to the pulp, and the isolating lining is placed on the bottom and walls of the cavity up to the dentine-enamel border. - If a composite of light hardening is to be used, than the medical lining is placed on the bottom of the carious cavity, on the spot closest to the pulp, and the isolating one is placed only on the medical lining, since the role of the isolating lining of closing the dentin canals, will be performed by dentin protector (primer). In case of middle caries there is no need to use a medical lining, so only isolating one is placed; and that is only in case of filling by amalgam, cement or chemical composite. When filling by composite of light hardening, isolating lining is not used. In case of caries in the stage of pigmented spot on the permanent teeth and superficial caries the medical and isolating linings are not used; the cavity is directly filled by filling material.
Filling of carious cavities of different classes 1. FILLING OF CARIOUS CAVITIES OF I CLASS ● Cavity of considerable size with a large occlusal loads. - amalgam Cavity of a small size with a small occlusal loading: - silicophosphate cements -glass ionomer cements restoration chemical curing and light-curing -compomers Cavity of considerable size with a large occlusal loads. - amalgamCavity of considerable size with a large occlusal loads. – amalgam - composites self-curing and light-curing, hybrid, microhybrid, nano- composites, condensable. -ormocers Currently amalgam is used for treatment of molar teeth of the upper jaw, i.e. where it is not noticeable when smiling. Composites can be both of light, and chemical hardening, it is only important for them to be macrofilled, macro-hybrid, or totally made hybrid, i.e. strong enough. When filling deep cavities with difficult access for polymerization it is necessary to use composites of chemical hardening. It is very convenient to use packed (condensed) composites which have denser consistence and small shrinkage. For the first, lowermost layer of the filling it is desirable to use flowing composites, and it is preferable to pass the polymerization light through the enamel, and the thickness of the composite should not be more than 2mm. Compomers and glass-ionomer cements are used when filling small cavities and also when it is necessary to fluorination of tooth tissues. For filling of cavities of I class it is possible to use “layered” or "sandwich technique" restoration methods. 2. FILLING OF CARIOUS CAVITIES OF II CLASS ●Cavity of small size without departing from the occlusal surface: - silicophosphate cements -glass ionomer cements restoration chemical curing and light-curing -compomers ●Cavity of a large size with access to the occlusal surface, with an additional site in MOD cavities: - amalgam - composites self-curing and light-curing, macrophill, hybrid, micro hybrid, nano-composites, condensable. -ormocers The general principles of filling of carious cavities of II class are similar to those for I class. However, the peculiarity of filling of these cavities is restoration of contact surfaces of teeth, which is located in the area of tooth equator. Various matrices and interdental wedges are used for that purpose. Matrix holders are used to fix a matrix on the tooth. Interdental wedges press the matrix to the edge of the tooth, providing its tight leaning to the tooth and preventing formation of hanging edge of filling material in the interdental space. Besides the wooden wedges become wet in the oral cavity, they inflate, and slightly move apart the teeth, providing more tight contact after removal of the wedge. After the filling occlusion and contact surfaces of the tooth should be smooth and shiny. Contact surfaces are polished by stripes - special strips with different degree of abrasiveness. Stripes can be metallic and plastic. The quality of restoration of contact surface is checked with the help of floss. 3. FILLING OF CARIOUS CAVITIES OF III CLASS For filling of carious cavities of III class the following are used: ●for cavities of small size without going on the vestibular surface: - silicate cements -glass ionomer cements restoration chemical curing and light-curing -compomers - flowable composites. ● Cavity of considerable size with exit to the vestibular surface, with the added facility: - composites self-curing and light-curing, microphill, hybrid, micro hybrid, nano-composites, condensable. -ormocers When filling cavities of III class it is also necessary to use matrixes and wedges for correct restoration of contact point. 4. FILLING OF CARIOUS CAVITIES OF IV CLASS For filling of carious cavities of IV class the following are used: ● cavity of small size: -compomers - flowable composites. ●Cavity of big size with the additional platform on the oral surface and the cutting edge: - light-curing composites, hybrid, microhybrid, nano-composites - the combination of glass ionomer cements, composites microfillic, hybrid, microhybrid (layer restoration technique) -ormocers.
The main difficulty of filling cavities of this class is the restoration of the crown angle and ensuring the aesthetic effect. The combination of strong compomers, ormokers and hybrid composites with very aesthetic micorfiles – that are placed as last superficial layer, also ensures a very good result of restoration of tooth angle and achievement of maximal aesthetic appearance. To achieve strong fixation of filling materials it is necessary to use parapulpar (in case of vital pulp) or intraroot pins.
5. SEALING CARIOUS CAVITIES OF THE V CLASS For sealing carious cavities of V class the following are used: ● cavity of small size: - silicate cements, silicophosphate -glass ionomer cements restoration chemical curing and light-curing -compomers - flowable composites. ●Cavity of big size: - composites self-curing and light-curing, macrophill, hybrid, microhybrid, nano-composites - the combination of glass-ionomer cements, flowable, hybrid, microhybrid composites, nanocomposites - glass ionomer cements for restoration, chemical curing and light-curing -compomers The filling of carious cavities of V class is sometimes made in two visits, since during the development of carious process in pericervical area the marginal gingiva is almost always inflated: - In the first visit the carious cavity is prepared; inflamed gums are cured or hypertrophied gum papillae is removed; temporary filling is placed on the tooth - In the second visit the temporary filling is replaced by a permanent one. When filling carious cavities of V class it is necessary to perform retraction of gingiva with the help of retraction cord or cofferdam.
The filling of carious cavities of different filling materials The stages of filling with an amalgam 1. Anesthesia (when it is needed) 2. Preparation of the carious cavity. The carious cavity is prepared according to the classical rules, i.e. there is formed a box-shaped cavity with right angles between the bottom and the walls. It is possible to create retentive grooves along the dentine– enamel boundary of tooth for improvement of fixation of the filling. It is also necessary to make skewing of enamel (fold) at the angle of 45 degrees. 3. Isolation of the cavity from saliva by cotton swabs or cofferdam, washing and drying of the cavity by water and air. 4. Placement of isolating, and if necessary medical linings. The isolating lining is placed on the whole bottom and walls of cavity up to the dentine–enamel border; basic lining having thickness 1-1,5 mm is placed, to protect the pulp from thermal irritation. The walls of cavity can be additionally covered by a special adhesive system that improves the adhesion and marginal attachment of filling. 5. Placing of amalgam into the cavity and its condensation. The first portion of amalgam is placed into the cavity immediately after mixing (within 1 minute); then it is thoroughly compacted by plugger or amalgam-trigger (fig.31).
Fig. 31. Stopper for condensation of amalgam: a – General view of the tools
Herewith, mercury excess is excreted on the surface of amalgam, and it has to be removed. Then, the next portions of amalgam are placed; each one is processed the same way as the first one. The cavity is filled up with amalgam with a slight excess. 6. Modeling of filling. First of all the rough modeling is performed with help of the dense, moistened in alcohol and wrung out cotton tampon. Then, the excess of filling is removed by sharp hatchet from the tooth surface along the filling margins. After that, the fissures are shaped on the surface of filling using smoothers. The hardening time of amalgams is 60 minutes, and final crystallization of the alloy happens in 6-8 hours. Therefore the patient should not eat for 1-1,5 hours and should not chew on the side of filling during 24 hours. 7. Grinding and polishing of a filling. This stage is performed in 24 hours after the filling. The filling is polished and grounded by feneers, polishers, herewith the polishers must be moved from the center of filling to the periphery (fig,32,33).
Fig. 32. Polishing of amalgam fillings. Fig. 8.33. Finishing of amalgam fillings.
There are various kits for finishing of amalgam fillings. Thus, the set of elastic head is coded by colors: blue head is used for pre-finished seals, pink, for final (Fig. 34.).
Fig. 34. A series of elastic heads for finishing of amalgam fillings.
After polishing the filling should: - restore the anatomical shape of the tooth crown - have a mirror shine - the probe should not be detained during the movement along the border of the filling and tooth tissues.
THE STAGES OF FILLING BY GLASS-IONOMERIC CEMENTS
Basic rules of working with glass-ionomeric cements: 1. Dissection of the cavity. - no need to prophylactically excise healthy tissue - there is no need to form a classic cavity - no need to create retention points - no need to create the bevel of the enamel (fold) - wedge-shaped defects and erosions not processed, cleaned of plaque with abrasive toothpaste -in deep cavities, apply imposition of medical paste based on calcium hydroxide. 2. Choice of color of filling: when choosing the color of filling it is necessary to take into consideration that after hardening the cement becomes slightly dark in 2-3 weeks, i.e. the color of the filling has to be chosen slightly lighter than the original one. 3. Conditioning. A hybrid glass-ionomeric chemical adhesion to dentin and enamel worse than the "classic" sits, so before applying them, the cavity is treated with conditioner 10-15seconds (10-25% solution of polyacrylic acid) to remove the smear layer. 4. Washing and drying of the cavity. It is necessary to avoid excessive drying of the cavity, as the GIC is hydrophilic material. 5. Cement mixing. Mixing of glass ionomeric cement cannot break the ratio of "powder- liquid". If there is little of the powder, the seal is fragile. If there be a little fluid, then the seal will take away the remaining moisture from the pulp, causing hypersensitivity of the tooth. Before collecting the powder in a jar need a good shake to loosen the powder measure spoons without slides. The jar should be immediately closed, because powder sits very hydroscopic and picks up moisture from the air. The cement is mixed for 30-60sec with a plastic spatula on a smooth glass surface or on a special paper. In the liquid entered the powder in two portions, each portion is mixed for 20 s. After mixing the cement mixture should have a shiny and smooth surface. 6. The introduction of the material into the cavity. Preferably plastic tools. Curing seal shall be performed in conditions of absolute absence of moisture, preferably under pressure. During curing, the material cannot be touched. Time curing of fixing cements is 4-7min, recovery - 3-4min, isolating cement - 4-5min. 7. Isolation of the seal from the oral fluid. It is done with special hermetic, because within 24 hours the cement is sensitive to the effects of saliva. 8. Final processing and polishing fillings made in 24 hours.
Filling cavities with composites The methods for filling cavities with composites can be divided into 4 groups: 1. Adhesive technique 2. Bonding-technique 3. Sandwich technique 4. Layer restoration technique
The technique of adhesive restorations
Adhesive technique (Fig. 35.) provides for the restoration of one tooth, usually micro-hybrid or nano-composite with the use of adhesive system, which provides communication with the enamel and dentin. The imposition of an isolating liner in this case is not required, except for deep cavities requiring imposition of medical and isolating liner.
Fig. 35. Adhesive restoration technique (scheme).
The adhesive technique is shown in filling all classes by black.
Stages overlay composite fillings using the adhesive technique restoration . cleaning the tooth surface This manipulation is a common and mandatory for filling any materials. Is the removal of the sealable surface of the tooth hard and soft dental deposits, pigmentation etc. With this purpose, manual and mechanical tools for the removal of dental deposits, polishing head, cleaning brush with abrasive toothpastes do not contain fluoride. Finally, the teeth are thoroughly washed with water. More appropriate prior to beginning rehabilitation of the mouth to hold the patient complete a professional dental cleaning.
Planning for building restoration selection of restoration material shade At this stage drawn up a common plan for the construction of restoration, a plan for preparation of the hard tissues of the tooth are selected restorative materials.
When planning the restoration are evaluated: - the size of the tooth - assessment of external contours of the tooth, the topography of contact points, forms the cutting edge - morphological characteristics of the tooth - occlusal relationship of the tooth, etc.
There are special color tables to define tooth color. “Vita shade” is considered universal. According to this table teeth can have 4 color shades (Fig.36): -red-brownish- A1; A2; A3; A3,5 ; A4; - red-yellowish- B1; B2; B3; B4 -grey- C1; C2; C3; C4; -red-grayish- D2; D3; D4.
Fig. 36. The color scale "Vita".
It is better to choose the color at day-light, and the tooth has to be humid. When choosing the color, it has to be taken into consideration, that the tooth crown can be divided in 3 color parts (fig.37): -cervical part- more yellowish - body -cutting edge or chewing surface- more transparent. The choice of the main color of the tooth is defined based on the color of the body part. Once the main color is defined, it is possible to choose the required shades for cervical and cutting edge (chewing surface) parts. Beside shades, these filling materials also have deferent degrees of transparency to imitate the tooth layers, i.e. opaque dentine shades, transparent enamel shade and more transparent incisal (for cutting edge and superficial layers of the enamel).
Fig. 37. Color zones in the coronal portion of the tooth.
● Preparation of carious cavity When aesthetic restorations with composites preparation of the cavity is carried out with maximum preservation of unaffected tissues of the tooth. ● Isolation of the tooth Sealed for isolation of tooth from saliva, the oral and gingival fluid using cotton swabs, retraction of the filament, saliva ejectors, "vacuum cleaner". The best isolation of the tooth and retraction of the soft tissues can be achieved using rubber dam.
● medicamental treatment and drying of the cavity medicamental treatment of a cavity is carried out as follows: in the beginning spend abundant lavage of the cavity with distilled water, water-air spray and the drying air stream from the "gun" dental unit, then the bottom and the cavity walls are treated with 2% solution of chlorhexidine digluconate for 30-60 sec, followed by drying the drug with a blower.
● placement of linings With the use of modern adhesive systems covered with a thin layer at middle caries can not be applied, since the hybrid layer provides a reliable insulation of the pulp from the toxic effects of the components of the filling material. With deep carious cavities in the area closest to the pulp of the tooth is overlaid with the minimum number of medicated pads and covered with an isolating material. An isolating liner covers only a bottom of the cavity without going to the wall.
● Application of adhesive systems When the adhesive restoration techniques is done processing the adhesive system and enamel, and dentine, and the isolating liner. The adhesive system is applied in accordance with the instructions of the manufacturer.
. Filling of carious cavity As you know, all composites shrink during curing, and the shrinkage direction is in the direction of heat. In the case of chemical composites is the shrinkage in the direction of the bottom and sides of the cavity, and the layers of the composite chemical curing are superimposed horizontally. Composites light-cured made in the cavity layers. The thickness of each layer should not exceed 2mm, and the thickness of the first layer should be even less. The heat source for light-cured composites is a light bulb that is shrinking them towards the light. Therefore, the layers of the composite material should be applied more vertically, in the first 10-20 seconds polymerizing them through the layer of enamel, and then from the nearest to the seal distance (Fig. 38.).
Fig. 38. Layer-by-layer depositing and directed polymerization of light- curing composite.
After applying and curing the seal on the contact surface and removing the metal matrix, it is recommended to conduct additional lighting of interdental area to the buccal and lingual (palatal) side at 20 C. (Fig. 39.).
Fig. 39. Additional polymerization of composite restoration in class II cavities after removing the metal matrix.
An important point in the technique of filling by light hardening composites is the layer inhibited by oxygen. It is the superficial layer of the hardened composite, where the polymerization process is inhibited by air oxygen. It consists of free radicals and polymer matrix. It looks like a shiny, sticky film on the hardened surface of the material, and it is easily removed by the instrument. When using the lamp in the no- oxygen conditions the film becomes hard. The inhibited layer creates conditions for quality bonding of the new portion of the material with the earlier polymerized one. But the inhibited layer left on the surface of the filling after the process is completed, has high penetrability for food colorants, is prone to abrasion, is easily damaged by the instrument, therefore it has to be removed. For this purpose the filling surface is grinded and polished. When the composite is hardened under the matrix, it is fully polymerized and has a smooth surface, which does not required additional processing. If blood, oral or gum liquid get into the cavity during the filling the characteristics of the inhibited layer get impaired, even after through drying its surface loses its capacity to connect with the next layer of composite. In this case it is needed to perform 10 second etching and repeated placement of adhesive system.
● Final processing of the restoration Grinding and polishing of fillings is an important step in the restoration of the tooth. The quality of their conduct largely depends not only the final result, but also the duration of the conservation properties of the restoration. This procedure consists of several stages: 1. Macrocentrinae - correction form of restoration taking into account the anatomical shape of the tooth and occlusion. At this stage removed the "extra" areas of restorative material are identified and eliminated areas of the seal, the inflated occlusion. Macrocentrinae is turbine diamond burs with air-to-water cooling. Control of the occlusion is carried out using an occlusive (copy) paper. 2. Mikrogeterogennye - create smooth surfaces of the restoration. This manipulation is done 10-12-sided finirai carbide or diamond burs with fine grain and turbine handpiece under air-water cooling. 3. Grinding and polishing are carried out with the aim of creating a perfectly smooth and shiny surface of the restoration, mimic the Shine and smoothness of natural tooth enamel. For grinding and polishing of composite restorations using a polishing head and discs of different degrees of abrasiveness. Sometimes used do not contain abrasive silicone polishing cups in combination with polishing pastes. The contact surface of restorations polished special abrasive strips - strips. For the treatment of fissures, cervical area of the teeth and other areas with difficult terrain, the use of special polishing brushes made of abrasive synthetic fibers. 4. Rebonding. On the surface of the seal apply surface sealant to close the cracks. 5. Recommendations to the patient After performing aesthetic restoration of the tooth composite material of the patient is recommended not to eat within 2 h and within a day to discourage chewing hard, tough foods. If the treatment was carried out under anesthesia, the patient should refrain from chewing hard food or chewing gum until the full restoration of the sensitivity of soft tissues to avoid biting. In the case of the restoration of the front teeth of the patient is recommended during the day to refrain from Smoking and consuming staining foods - strong tea, coffee, colored juices and berries, red wine. Women should not use lipstick in a period of 24 hours after restoration.
Bonding- technique of filling teeth. Bonding-technique (Fig. 40.) used when working with composite materials having hydrophobic adhesive systems that provide only communication with the enamel of the tooth. In this case, the bottom wall of the cavity overlaps with the insulating liner strip from the zinc- phosphate or glass-ionomeric cement is strictly up to the enamel- dentinal border.
Fig. 40. Bonding-technique (scheme).
Sandwich technique of tooth filling
Sandwich technique is filling of the tooth by 2-layer filling, i.e. combination of 2 permanent filling materials. - Glass ionomer cement+composite - Compomer+composite The sandwich-technique of tooth filling was suggested to reduce the negative features of composites: polymerization shrinkage, insufficient biocompatibility of composites, and lack of caries-static effect. There are 2 variations of filling by this method: 1. Closed sandwich- the cement is covered by composite from all the sides and does not have any contact with the oral cavity 2. Open sandwich – the cement is not covered from any side by composite and contacts with the oral cavity.
Fig. 41. Closed "sandwich". Fig. 42. Open "sandwich".
Stages of filling by sandwich-technique method
1. Anaesthesia 2. Cleaning the teeth from deposits. 3. Choice of the filling material color 4. Preparation of carious cavity 5. Isolation of the tooth from saliva 6. Washing and drying of carious cavity 7. Placement of linings
In case of deep caries medical lining is placed. If “classical” GIC is used, filling is done in two visits. During the first visit the whole cavity is filled by GIC. During the second visit a 2mm filling layer is removed for subsequent filling by composite. This is explained by the fact that the “ripening” of classic GIC takes about 24 hours. When etching, washing and drying the surface of none “ripened” glass ionomer, the flow of chemical reaction of cement hardening changes, the formation of chemical bond with enamel and dentine is impaired. Besides that, the composite shrinks when polymerized, and it separates the non “ripened” GIC from the bottom of the cavity, which later can result in pulpitis and periodontitis. When GIC of double or triple hardening is used, only base lining covering the whole dentine is places, and the tooth is filled during the same visit. 8. Etching- 30sec. for enamel, 15-sec for dentin, washing and drying of the cavity. 9. Placement and polymerizations of adhesive system 10. Placement of composite into the cavity, and its hardening. 11. Polishing of the filling 12. Rebonding 13. Recommendations to the patient
Technique of layered restoration
The layered restoration technique is used when filling big cavities on chewing teeth to get strong and aesthetic filling. For this purpose different composites can be used: flow and condensable, hybrids and micorfilles.
Technique of layered restoration method is carried out in accordance with the rules and principles of the adhesive technique. Differences exist only at the stage of blending of the restorative material.
Stages of filling by layered restoration technique 1. Cleaning the teeth from deposits. 2. Planning of restoration and shade selection of the restorative material. 3. Preparation of carious cavity 4. Isolation of the tooth from saliva 5. Medicamental processing and drying of carious cavity 6. Placement of medical or isolating linings
At middle caries in the case of adhesive systems 5-th or 6-th generation the isolating liner is not placed. At deep caries on the bottom of the cavity nearest the pulp of the tooth, apply a minimal amount of calcium- salicylates cement and covered with an isolating material, better - hybrid glass- ionomeric cement. The isolating liner can be placed only on the bottom, without going to the wall.
7. The application of the adhesive system. When this technique is usually used more easy to use adhesive systems of the 5th and 6th generations (Fig. 43.). Methodology and features of the adhesive system in accordance with the instructions of the manufacturer.
Fig. 43. Layer restoration: application of adhesive system.
8. The creation of the initial adaptive (superadditive) layer. At this stage, all the walls of the cavity covered by a thin layer of flowable composite (0.3-0.5 mm). Due to the high fluidity of liquid composite easily fills all the micro-roughness and irregularities, providing a tight marginal seal of the filling. In addition, the liquid layer of the composite absorbs the chewing pressure on the tooth (Fig. 44.).
Fig. 44. Layer restoration: the creation of adaptive (superadditive) layer.
9. Filling the cavity of condensed composite. The cavity is filled with a condensable composite is carried out by horizontal layers with a thickness of 2-2,5 mm (Fig. 45.). Each layer polymerized separately. Due to the low polymerization shrinkage of the material and the presence underneath of the adaptive elastic layer of flowable composite is directed polymerization when the filling is to use optional. Condensable composite provides strength and spatial stability of the restoration. When the filling of cavities class II at this stage, recover the points of contact. The cavity "is not fiiled" on 1 - 1,5 mm to the occlusal contact of teeth-antagonists.
Fig. 45. Layer restoration, sealing with condensable composite.
10. Modeling the outer layer of the restoration. The remaining 1-1. 5 mm are filled with a universal micro-hybrid or nano-composite (Fig. 46.). This layer gives the restoration of smoothness and aesthetics.
Fig. 46. Layer restoration: sealing or micro-hybrid nano-filled composite.
11. Final processing and polishing of the filling 12. Rebonding 13.Recommendations to the patient.
Mistakes and the complications during tooth filling. 1. Wrong choice of filling material. Complications - premature deterioration, fall out or fracture of the filling, impairment of the aesthetics. When there are other metals in the oral cavity of the patient it is probable to observe the phenomena of galvanism when filling by an amalgam. 2. The lack of contact points. Observed at filling of carious cavities on contact surfaces when not in use matrix or it is placed incorrectly. In interdental area accumulated food residues that may occur with pain, bleeding, or gingival papilla leads to the development of inflammation. 3. The overhanging edges of fillings. This complication is due to inadequate overlay of the matrix, where the wedge does not contribute to the tight fit of the matrix to the tooth surface and also in the case where for fixation of the matrix wedge is not used. 4. Violation of the methods and stages of sealing: the use of thick layers of light-curing composite, improper curing, failure to follow the instructions of the manufacturer when mixing the filling material. All this leads to loss of the seal. 5. Getting saliva or blood in the sealable cavity leads to loss of the seal or change its color. 6. Incorrect replacement, or the lack of medical and isolating linings in deep cavities, which contributes to the development of pulpitis and periodontitis. Lining must overlap the point on the bottom of carious cavity in the projection of pulp horns, and the technique of imposition of isolating liners depends on the type of core filling material. 7. Excess or insufficient restoration of occlusal surface of the tooth by filling material. It results in increased or on the contrary, insufficient functional load. Complications - development of a traumatic periodontitis, atrophic changes in the alveolar bone or vertical move of the antagonist tooth. 8.Fiiling of molars and premolars without cusps and fissures. In that case there are occlusion changes. 9. Poor-quality finishing of the filling - results in retention of food remainders, pigments on the surface of the filling and changes its color. Filling of root canals
Depending on the clinical situation and of the chosen treatment root canal therapy can be permanent and temporary. Temporary filling of root channels is carried out with non-hardening pastes with curative intent. Permanent root canal filling is the final and most important phase of endodontic treatment and is carried out with hardening pastsin combination with primary hard materials. The composition filling in the lumen of the root canal at permanent filling methodis calledroot filling. Root canal filling must undergoto following requirements: ● fill the entire lumen of the root canal of any configuration, without reaching the radiographic apex of the tooth by 1-1,5 mm ● tight all the way against the walls of the channel, an airtight seal is on the border of the material/tooth ● to provide sealing of apical opening in the physiological apex ● to be homogeneous, do not have pores and defects in the filling of the lumen of the root canal ● to be radiopaque ● to be sterile ● do not dissolve in the channel over time. Objective confirmation of the quality of the instrumental-medicament treatment and filling of root canals is a control radiograph. With its help check the degree of expansion and the preservation of the natural geometry of the root canals, the quality of filling with a filling material, the tightness of the material to the walls of the root canals, no inclusions of air bubbles in the thickness of the root fillings. 1. Root canal filling with pastes The advantages of this method are ease of implementation and relative low cost. At the same time, this method has some negative sides: it is difficult to achieve homogeneous filling and hermetic sealing of the channel even when removing it at the periapical tissue after curing almost all the paste shrinks and dissolves in the tissue fluid. Method is mostly used for temporary filling of root canals with non- hardening medicinal pastes. At permanent filling of canals, it is used in the application of phosphate-cement, resorcinol-formalin paste, sometimes endohermetics based on zinc-eugenol paste. To ensure maximum effectiveness of sealing paste should have the consistency of thick cream. Filling the canals with pastes can be performed both manually and with the help of Rotary paste filler. A. Method of "manual" filling of the root canal with paste (Fig. 95.) 1. The walls of the canal with a paper pin and smeared the substance on which the kneaded paste (eugenol, resorcinol-formalin liquid) (Fig. 95.,a). 2. With the help of K-file, K-reamer or root needle fill the apical part of the root channel with small amount of paste (Fig. 95.,b). 3. Condense the paste with a cotton, wounded on the working part of endodontic instrument (Fig. 95.,in). 4. Enter the next portion of paste at a shallower depth (Fig. 95.,g). 5. Pasta condensed with the help of the tool with a wound on it with a cotton pellet also introducing the tool to a shallower depth (Fig. 95.,d). 6. Continue to the introduction and subsequent condensation of portions of the paste, gradually reducing the insertion depth of the instruments, until the complete obturation of the canal. 7. The excess paste that had accumulated over the canal orifice, forced into the canal with a cotton ball (Fig. 95.,e). 8. x-ray for control of sealing quality.
Fig. 95. The method of "manual" fillingwith paste. (Scheme). B. Method of filling of the root canal paste using Rotary paste filler(Fig. 96.) 1. select one size smaller Rotary paste filler then master file. 2. Rotary paste filler fixed on headpiece and mark the working length with endostopper. The working part of Rotary paste filler immersed in filling material so that a small amount of material was delayed in the spiral (Fig. 96., a). 3. Rotary paste filler gently immerse into the canal at the working length, making sure that it moved freely in the channel without jamming. After that, the drill is activated at a small speed (100-120 rpm./min) 2-3 sec,. Then, without stopping the rotating tool is slowly removed from the canal. After that, the headpiece switched off (Fig. 96., b). 4. Rotary paste filler again immerse in filling material, and introducing into the channel on 2/3 of the working length, switched on the headpiece and injected material into the channel (Fig. 96.,c ). 5. Repeat the procedure by entering Rotary paste filler in the canal at 1/3 the working length (Fig. 96., g). 6. The excess paste that had accumulated over the canal orifice, condensed into the canal with a cotton ball (Fig. 96., d). 7. x-ray control of sealing quality. If apical hole is wide or expanded it in the process of instrumental processing, the first portion of paste immersed and condensed by the manual method, and only then applies Rotary paste filler. This is due to the fact that the open apical hole in the case of Rotary paste filler there is a very high risk of removing endosealers in the periapical tissues with the development of complications (post filling pain, traumatic neuritis of the region innervated by inferior alveolar nerve etc.).
Fig. 96. The method of filling the root canal with paste using Rotary paste filler.
2. Filling of root channels with the use of primary hard materials A mandatory condition for filling when using primary hard materials is their use in combination with hardening paste - endohermetics (sealers). This ensures the hermetic filling of apical hole, the homogeneity of root fillings, as well as hermetic filling on the border of the root fillings with the tooth. A. One pinmethod. The essence of the method is - thepin immersed in to the root canal together with hardening paste which (the pin) evenly distributes the filling material into the lumen of the channel, fills the apical hole mechanically. Method of one pin is also used when filling canals with GIC to facilitate theremoving of filling material from the root canal if necessary. During this method channel should have a conical shape with a circular cross section. The positive sides of this method are easy of implementation, relatively low cost and greater tightness of root fillings than when filling the canals with only pastes. The negative side of this method is not sufficiently reliable obturation of the canal, as between the pin and the wall of the channel remains thick layer of paste which is a "weak link" in the root filling and may eventually disappear. The technique of root canal filling by one pin method (Fig. 97.) 1. Selection and adjustment of the pin (Fig. 97., a). Takes a standard gutta-percha pins of the same size as the last endodontic instrument that is used apical part of the canal (the master file). The pin is inserted into the canal at working length; the tip of the pin should be slightly wedged in the apex. The pin is marked, fixing the working length. In doubtful cases, is carried out radiological control of the pin position in the channel. 2. Introduction of endosealer in the channel (Fig. 97., b). The paste is filled into the channel with K-file, K-reamer or rotary paste filler to the level of apical foramen. Densely to fill channel treatment does not recommended: when using rotary paste filler one portion is enough, when using "hand tools" - two or three portion. 3. Preparation of channel for pin (Fig. 97., in). It is performed to facilitate insertion of the pin into the root canal. To this end, slowly enter to the apex and slowly take out K-reamer diameter smaller than the chosen pin. 4. The introduction of the pin into the root canal (Fig. 97., g). The pin is covered with a filling material injected into the canal at working length. The movement of the pin should be slow to displace from the channel air bubbles. With the same purpose, it is recommended to make several reciprocating movements of the pin in the channel. The excess of filling material is removed by excavator or a cotton ball. 5. Removal of the protruding part of the pin (Fig. 97., d). The protruding portion of the gutta-percha pin is cut with a heated tool. 6. X-ray quality control of sealing. 7. The imposition of a temporary filling. The imposition of a permanent filling of carious cavity, it is expedient to postpone for 1-3 days to fully cure the paste in the root canal.
Fig. 97. The method of filling the root canal using one pin (the scheme).
B. The method lateral condensation of gutta-percha This method of cold condensation of gutta-percha is shown in channels with an oval cross-section. Methods of canal filling method of cold lateral condensation of gutta-percha (Fig. 98.)
Fig. 98. The method of sealing the root canal by the method of lateral condensation of cold gutta-percha (scheme). 1. Selection of the main gutta-percha pins (Master point) (Fig. 98., a). This step is about the same as using one pin. Takes a standard gutta-percha pin of the same size as the last endodontic instrument that is treated apical part of the canal (Master-file), and fitting in the channel. The difference in this method is- it is necessary to ensure that the pin doesn’t reach to the physiological apex 1 mm. a "reserve" to avoid output pin to the periapical tissue during condensation of gutta-percha in the canal. There are several methods of fitting of the main pin in the root canal. A. Visual test. The pin is marked at 1 mm less than working length. Then the pin is introduced into the root canal until this point. If the pin can be pushed deeper, takes the larger pin, or first pin is shortened (the diameter of the tip increases). The fitting of the pin continued until it entered into the desired position. B. Tactile test. Gutta-percha pin of the same size as the master file is introduced into the root canal 1 mm less than working length. If pin is chosen correctly, at a distance of 3-4 mm from the physiological apex have to make some effort to further advance the pin. In deriving the pin from the channel should be felt by him "jamming". This criterion in the dental literature termed "tug back" (pulling). If the pin freely, without resistance moves in the channel, should be taken the larger or shorter pin than the previous one. C. Radiographic test. Radiographic test is conducted after tentative selection of primary pin visual and tactile methods. In doing this, contact intraoral radiograph with the pins inserted in the channels. Radiographic evaluation of the position of the pin in the root canal is the most accurate and reliable method. After rearrangement the core pin it is marked, retaining the length that it needs to be introduced into the root canal. Then the pin is removed from the channel and begin filling. 2. The selection of spreader (Fig. 98.,b). The spreader is chosen of the same size as the Master file, or one size bigger, so as not to exceed the apical hole. Working length of the spreader should be 1-2 mm below the working length of the channel. 3. Introduction to channel endosealers (Fig. 98.,in). The material is inserted into the channel with K-file, K-Reamer or with rotary paste filler to the level of the apical hole and spread evenly over the channel walls. It is not necessary to fill the root canal with paste tightly, when using rotary paste fillerone portion is enough, when using the "manual" tools – two or three portions. 4. The introduction of the main pin into the channel (Fig. 98.,g). In advance chosen pincovered with endohermetics slowly inserted into the canal at working length. To prevent air embolism of the channel making a few reciprocating movements of the pin in the channel is necessary. 5. Lateral condensation of gutta-percha (Fig. 98.,d). Beforehand chosen spreader entered in the root canal. The movement of this tool should be clockwise. The depth of insertion is 1-2 mm less than working length. The gutta-percha is pushed to the wall of the channel. Leave the spreader in the canal for 1 min for adaptation of the pin to the applied pressure. 6. The removal of the spreader and the introduction of an additional pin (Fig. 98.,e). The spreader slowly removed from the canal with rotary movements and immediately replaced by an additional pin. Additional pin is selected of the same size or one size smaller than the spreader. Before the introduction of the channel the pin is pre- lubricated with endohermetics. 7. Lateral condensation of gutta-percha, removal of the spreader and the introduction of a second pin (Fig. 98.,W). The spreader is introduced into the root canal for 1-2mm smaller than at the previous stage. If the introduction of the spreader to the required depth is difficult, it is necessary to take tool of smaller size. Lateral condensation of gutta-percha and the introduction of the following additional pin are carried out. The operation is repeated to achieve complete obturation of the canal (Fig. 98.,z), i.e. until then, until the spreader does not enter into the channel. Usually to fill a single channel requires 4-6 pins. 8. Removing excess gutta-percha and pastes (Fig. 98.,and). Excess parts of the pins from the orifices of the channel are cut with a heated tool. Root canal filling is condensed on orifice of the channel. The excess of endosealers is removed with a cotton ball. 9. X-ray quality control of sealing. 10. Temporary filling of carious cavity (Fig. 98.,K). The imposition of a permanent filling, it is expedient to postpone for 1-3 days to fully hardening of paste in the root canal. Especially important to observe this when usingintracanal pins. When cold lateral condensation of gutta-percha pins never merge into a canal in a homogeneous mass and the intervals between them fills the hardened paste. Gutta- percha pins at the same time as sealed in the mass of endosealers. The apical hole, when the filling is carried out properly, should be filled by only one pin, which tight to the walls of the channel in the field of physiological apical constriction (Fig. 99.). The presence of more pins in apical part increases the risk losing hermetismin the channel due to additional layers of endosealers in the apical part of the root fillings.
Fig. 99. Lateral condensation of cold gutta-percha.Diagram of cross section of middle and apical parts of the canal.
C.The method of vertical condensation of gutta-percha.
To implement this method it is necessary to have: standard or non-standard guttapercha pins, pluggers of 3 sizes, sealer and heated pluger (heat carrier) 1. Washing and drying of the canal 2. Choosing and fitting of the main pin in the canal The size of the pin should be one size bigger than master-file. The sharp tip of a pin should be cut and fit in the canal, so that it becomes 2-3 mm shorter than the working length of the canal. Then, the pin can be taken out from the canal. 3. Inserting the sealer in the canal. 4. Preparation of the plugger – the first one should be big and enter into the canal and not reach the apex by 15 mm, second one by 10mm, the third one by 3-4mm. 5. Inserting and condensation of a gutta-percha pin in the canal. The pin is inserted in the canal and is cut at the orifice of the canal by a hot tool. Gutta-percha becomes soft and it can be condensed in the apical direction by a big size cold plugger. Then, the gutta-percha is warmed up again by a heated tool and condensed for another 5mm by medium size plugger. The procedure is repeated until 5-6 mm of apical part of the canal is filled. 6. An x-ray to control the quality of the filling . 7. The remaining part of the canal is filled by another pin and condensed by method of vertical or lateral condensation. 8. Temporary filling of cavity 9. Permanent filling after 1-2 days Anesthesia in dentistry. Premedication.
Since most dental procedures are enough painful, anesthesias is a prerequisite for effective treatment of dental diseases. Sometimes before anesthesia it is necessary to do premedication, i.e. medical preparing the patient for anesthesia. Indications for conducting sedation are: - fear and tension of patient, manifested by anxiety, hindering the work of the doctor
- fear and tension of patient, causing increased heart rate more than 90 beats per minute.
- fear and tension of patients with cardiovascular diseases, respiratory diseases, epilepsy etc. Premedication can be once or coursework. In case of single procedure the drug is taken 30-60 minutes before the treatment. In case of course premedication the drug (medication) is taken before sleep, in the morning and an hour before the treatment. Benzodiazepine tranquilizers are mainly used for sedation:
- phenazepam – 0,0005 – 0,001 g
- diazepam (seduksen) – 0.005 – 0.01 g
- tazepam (oxazepam) – 0.01 g
- elenium – 0.01 g
- phenibut – 0.25 g
Solution of Valerian can be also used.
Types of anesthesia Anesthesia is a complex of psycho preventive and medical treatment aimed to reduce or complete relief of pain during the treatment. Anesthesia ( Greco. anaestesio) – complete loss of sensation. There are three basic types of anesthesia: general, local and combined.
General anesthesia
General anesthesia is a state of reversible inhibition of Central nervous system, achieved by a pharmacological means, the effects of physical or mental factors. General anesthesia includes narcosis, neuroleptanalgesia, ataralgesia, central analgesia, audioanesthesia and hypnosis. Narcosis (gr. narcosis is lulling) is the methods of general anesthesia in which the feeling of pain is suppressed by narcotic substances. Medications for anesthesia affects sensory, emotional, autonomic(vegetative) and motor components of pain response. There are inhalation and non-inhalation anesthesia. The basis of inhalation methods is the method of administration of general anesthetics in the form of steam or gas through the respiratory tract. The introduction of narcotic substances (medications) into the body by any other way (intravenous, intramuscular, rectal), called the non-inhalation anesthesia.
Neuroleptanalgesia is method of general anesthesia without the use of drugs, which is achieved by intravenous administration of strong analgesic, ensuring the loss of pain sensitivity (analgesia), and the neuroleptic, causing mental indifference (apathy), muscle relaxation and neurovegetative inhibition, but without turning off consciousness. This anesthesia is widely used in combination with other types of anesthesia (narcosis, local anesthesia).
Ataralgesia is a kind of neuroleptanalgesia with use of sedatives and analgesics. Audioanalgesia and hypnosis. Sound anesthesia is achieved by creating the center of excitation in the cerebral cortex by means of an audio signal of a certain frequency range, which causes diffuse inhibition in other parts of the brain. Hypnosis as a form of psychotherapy is often used in combination with other types of anesthesia. Obligate indications for general anesthesia: 1) psycho labile and mental retarded patients, 2) diseases of the central nervous system, including organic disorders, accompanied with impaired intellectual and adaptive functioning when adequate contact with the patient is impossible (oligophrenia, down syndrome), 3) severe allergic reaction to local anesthetics. Other indications can be considered as a facultative, namely: - Extensive intervention in the oral cavity when the required amount of anesthetics needed for local anesthesia, is extremely high - The ineffectiveness of local anaesthesia or impossibility of its implementation (inflammatory or cicatricial changes in the tissues). Contraindications of general anesthesia: - acute diseases of the parenchymatous organs -cardiovascular disease in decompensative stage - myocardial infarction and post-infarction period up to 6 months -severe anemia - a severe form of bronchial asthma - acute alcohol or drug intoxication - diseases of the adrenal glands - acute inflammatory diseases of the upper respiratory tract, etc For general anesthesia the following are mainly used in dental clinics: nitrous oxide, halothane, trichloroethylene, cyclopropane, pentran, geksenal, sombrevin, ketamine etc.
Local anesthesia
Local anesthesia is anesthesia of the tissues of the surgical field by acting on the peripheral nervous system. There are 2 types of local anesthesia - injection and non-injection. 10% solutions of lidocaine in the form of gels and sprays, 10% solution of xylocaine in the form of applications are used for non- injection anesthesia. This method usually anesthetize the mucosal membrane and gingiva for painless removal of dental calculus, to anesthetize the place of needle piercing , for incision of the abscess, etc. Cryoanaesthesia (chloroethyl) means freezing of the mucous membrane; anesthesia with a laser or electromagnetic waves, acupuncture, electrophoresis are non-injection methods of anesthesia as well. Injection anesthesia is carried out with a syringe, injecting anesthetic into the deeper layers of the mucosal membrane. The following types of injection anesthesia:
- conductive (block) - infiltration
Infiltration anesthesia There are direct infiltration anesthesia, when the anesthetic is injected directly into the tissue of the surgical field, and indirect, when the depot of the anesthetic solution is created in a certain place and it diffuses into the deeper located tissues. According to the introduction place the following types of infiltration anesthesia are distinguished: 1. Submucosal: anesthetic is inserted into the region of the transition fold, where the submucosal layer is present; in case of the upper jaw it is slightly above the projection of the root apexes and for the lower jaw, a little below the projection of the root apexes (Fig. 1.).
Fig.1. Submucosal anesthesia
The place of injection can be treated with 1% iodine tincture or by application of anesthetic. Syringe should be hold with three fingers of the right hand (I,II,III) in the form of "writing pen", but I finger should freely reach the distal end of the piston. (Fig. 2.).
Needle is injected under an angle of 40-450 , and the bevel of the needle should face the bone. Anesthetic is injected slowly, since rapid injection lead to separation of tissues and damage of small blood vessels and nerve fibers that can cause pain. During anesthesia the needle should be moved parallel to the surface of the bone, with the constant injection of anesthetic solution, thus there is a depot of the drug not in a single point, but in the form of a strip which is formed during the injection of anesthetic substance (Fig. 3.).
Fig. 3. The position of the needle relative to the alveolar bone and transitional fold when moving it in the horizontal direction From palatal side a needle piercing is carried out in the angle formed by the palatal and alveolar processes of the upper jaw. With the exception of the incisors, which have such a place coincides with the incisive foramen, and the second and third molars in place of palatal major foramen. On the lingual side anesthetic solution is injected in the border of the mucous membrane on the alveolar bone and the sublingual region. 2. Subperiosteal anesthesia: the anesthetic is injected directly under the periosteum of the apical region of the tooth to be anesthetized. Subperiosteal anesthesia is carried out with a short needle. Needle piercing is performed in mucosa of the transitive fold in root apex area of the anesthetizing tooth. 0.5 ml of anesthetic should be injected. After 1-2 min the periosteum should be pierced and the needle should be moved towards root apex to a small distance at an angle of 450 to the axis of the root, than a depot of the anesthetic solution is formed. Subperiosteal anesthesia is performed in the case when the submucosal anesthesia is ineffective. 3. Intraligamentar anesthesia: the anesthetic is injected directly into the circular ligament of anesthetizing tooth and is used as a additional to the submucosal and subperiosteal anesthesia. Intraligamentar anesthesia is best done by a special injector and needles (Fig. 4.).
Fig. 4. Injector and needle for intraligamentar anesthesia
The injector has a corner nozzle or rotary head for changing the degree of tilt relative to the tooth, furthermore, during injection it provides high pressure and dosage of anesthetic. Needle for intraligamentar anesthesia should be thin and flexible, length 8-12mm, with a diameter of not more than 0.3 mm. During piercing the bevel of the needle should be turned to the root surface. The needle is placed in a circular ligament to a depth of 1-3mm. Anesthesia is carried out both from the mesial and distal sides of the root (Fig. 5.).
Fig. 5. The place of piercing by needle in case of intraligamentar anesthesia in different groups of teeth 4. Intraosseal anesthesia: the anesthetic is injected directly into the bone of the area of surgical intervention. Under applicative or infiltrative anesthesia an outer cortical plate of bone is cut by thin spherical bur. Through the formed channel a needle is entered into the spongy marrow of the alveolar bone, and 1-2 ml of 2% anesthetic solution is injected. It leads to immediate deep anesthesia of 2 adjacent teeth between which roots the anesthesia has been done. Anesthesia lasts approximately 1 hour. Intraosseoal anesthesia is rarely used because it is highly traumatic. 5. Intraseptal anesthesia : a method of introduction of the anesthetic into the bone septum (partition) between the alveoli of adjacent teeth (Fig. 6.). This anesthesia is a type of intraosseal anesthesia. Nerve fibers of bone and soft tissues are anesthetized due to the diffusion of anesthetic solution through the bone marrow spaces surrounding the alveoli, and also through the blood vessels of the periodontium and bone. Before anesthesia, it is necessary to remove dental plaque and calculus. The point of needle puncture is mostly at mid-distance between adjacent teeth; however, in case of pathological processes in the periodontium the place of puncture is changed. Therefore, before anesthesia, it is necessary to clarify location of partition by intraoral radiogram (x-ray).
Fig. 6. Intraseptal anesthesia Intraseptal anesthesia is carried out with a short needle. Needle is intruded at an angle of 900 to the surface of the gingiva above intraalveolar partition, a small amount of anesthetic is injected and push the needle into the bone tissue of the septum to a depth of 1-2mm, where 0.2-0.4 mm of anesthetic should be injected. 6. Intrapulpar anesthesia: the anesthetic is injected directly into the pulp of the tooth, when the pulp is exposed, and other types of anesthesia do not provide complete pain relief. In case of injection type of anesthesia many clinicians find it necessary to conduct suction trials to prevent the injury of the vessel and the ingress of anesthetic directly into the blood stream. After the needle puncture the syringe plunger should be pulled back to ensure no blood in it. In the presence of blood the direction of the needle should be changed. Often, to achieve complete pain relief several types of anesthesia are combined, for example, for analgesia of the lower molars the mandibular and infiltration anesthesia in the area of anesthetizing tooth are carried out to disable the terminal branches of the buccal nerve. Anesthesia efficacy also depends on the anatomical and histological structure of the jaws. Maxillary infiltration anaesthesia is more effective than lower jaw infiltration, as its periosteum and bone compact plate are more porous, and spongy substance is better developed.
Materials for temporary and permanent filling of the root canals
Classification of the material for the root canal filling
1. Plastic . non-hardening pastes . hardening pastes 2. Primary hard materials
Plastic non-hardening materials dissolve in the root canal during time. So they can be used only for root canal temporary filling or for primary teeth root canals filling.
Plastic hardening materials are also called endohermetics. They can be used separately or with primary hard materials (ex. gutta-percha pins).
I. Materials for root canal temporary filling
Non-hardening pastes are used for root canal temporary filling. They have medical effect. These materials are entered into the root canals by rotary paste filler (lentulo). After the material is entered, the root canal is closed hermetically by temporary filling material. After the treatment the root canal temporary filling materials are removed from the root canal.
The following materials are used for root canal temporary filling:
1. Pastes containing antibiotics and corticosteroids
These materials are used for acute inflammatory processes. They contain 2-3 antibacterial and antifungal medicaments of wide spectrum, corticosteroid medicament (for removing inflammatory and allergic processes) and x-ray contrast material. These pastes have strong but short-time effect. They are left in the root canal for 1-7 days.
2. Pastes containing metronidazole
These pastes are for the root canals in which the non-aerobic microflora is prevalent (gangrenous pulpitis, acute and exacerbated apical periodontitis). These pastes should be replaced every day until the acute inflammation is over.
3. Pastes containing long-term effect antiseptics
These materials contain strong antiseptics like thymol, cresol, iodoform, menthol etc.
These pastes are x-ray contrast. They don’t become hard and dissolve in the root canal very slowly. Pastes are used during the treatment of pulpitis and apical periodontitis for temporary filling of the root canals. Besides, they are used for primary teeth endodontic treatment (in this case they are used as permanent filling materials). 4. Pastes containing calcium hydroxide
These material are 50-55% calcium hydroxide containing water suspensions. Due to high pH (pH is about 12) these materials have bactericidal effect, they dissolve the necrotic tissues, activates osteogenesis, dentinogenesis, cementogenesis.
Pastes containing calcium hydroxide are used as root canal temporary filling materials during treatment of destructive apical periodontitis, cystic granulomas and radicular cysts.
After the mechanical and medical preparation of the root canal calcium hydroxide containing paste is entered into the root canal by rotary paste filler. The paste should come out from the canal during destructive apical periodontitis. After this the tooth is closed hermetically with temporary filling material. After 4-6 weeks the paste is replaced by another portion. And after, the paste should be replaced every 2 months until the positive result (bone destruction area decrease, absence of exacerbations). In case of positive result the root canal should be cleaned and filled by permanent filling materials.
Calcium hydroxide is also used for antiseptic preparation of the root canals. In this case the root canal should be prepared by tools and be washed with natrium hypochlorite. After this the root canal is filled by calcium hydroxide paste and the tooth is filled hermetically for 2-3 days. During next visit the root canal should be cleaned up and filled with permanent filling material.
It is important to know, that calcium hydroxide becomes inactive after contact with the air
CO2. That’s why the material container should be kept hermetically closed (pic. 74).
Pic. 74. Calcium hydroxide water suspension in hermetic syringe.
5. Pastes containing calcium hydroxide and iodoform
These pastes are used widely nowadays, because the calcium hydroxide has osteotrop effect and the iodoform has long-term antiseptic effect. These pastes are used during treatment of destructive forms of apical periodontitis, cystic granulomas and radicular cysts. It is not recommended to use these materials for permanent filling, because they don’t get hard.
II. Materials for root canal permanent filling
The aim of root canal permanent filling (obturation) is providing hermetic closure of apical foramen and dentin surface. This procedure separates the apical tissues from root canal microflora and blocks the entrance of exudate from periapical tissues, thus it blocks bacteria reinvasion.
Materials for root canal permanent filling should correspond to the following points:
. They should be easily entered into the root canal
. They should get hard slowly
. They should attach to the root canal walls and provide hermetic closure of it
. After hardening they should become a homogeny substance without pores
. They shouldn’t dissolve in the root canal but should dissolve out of it (in the apical tissues)
. They should be easily removed from the root canal
. They should be x-ray contrast
. They should have antiseptic and anti-inflammatory effect and should provide regeneration of the affected periapical tissues
. They shouldn’t irritate the periapical tissues
. They shouldn’t have toxic, allergic, mutagenic and cancerogenic effect
. They shouldn’t color the tooth tissues
. They shouldn’t disturb the adhesion and hardening of the permanent filling material
Materials for root canal permanent filling are divided into 2 groups: 1. Fillers – provide the root canal filling volume, hermetic filling of the whole canal decrease the shrinkage of the pastes. Primary hard filling materials (pins and some hardening pastes) are used as fillers.
2. Sealers (endohermetics) – are used to fill space between the pins and the root canal walls. Sealers provide hermetic filling and are used together with the fillers.
Some hardening pastes can be used as sealers and also as fillers (root canal filling only by pastes).
A. Plastic hardening pastes for root canal permanent filling
Classification:
1. Zinc-phosphate cements
2. Zinc oxide and eugenol containing materials
3. Epoxide pitches containing materials
4. Calcium hydroxide containing materials
5. Glass-ionomer cements
6. Resorcin-formalin containing materials
7. Calcium phosphate containing materials
1. Zinc-phosphate cements
During a long time these cements were used in dentistry as the best materials for root canal filling. The advantages of zinc-phosphate cement are:
. Can be easily entered into the root canal
. Dissolving properties are low
. Good adhesion
. It is x-ray contrast
. Has antibacterial effect during first 2 days
This material also has some disadvantages:
. Fast hardening (4-6min), thus the additional root filling is impossible
. In case of overfilling this cement doesn’t dissolve in periodontal tissues . The refilling is also impossible if it is necessary
Because of these disadvantages the zinc-phosphate cements are nor used nowadays.
2. Zinc oxide and eugenol containing materials
A chemical reaction appears when zinc oxide and eugenol are mixed with each other. As a result non-solving salt is originated, which is called zinc eugenolate. The paste becomes hard during 12-24 hours. To improve the therapeutic properties of these pastes some materials are also added into them (antiseptics, corticosteroids, x-ray contrast substances etc.).
Zinc oxide eugenol pastes and also the materials based on them (Endomethasone, Cortisomol, Sealite Ultra etc.) are effective endohermetics (pic. 75). They can be used separately ot together with gutta-percha pins.
Pic. 75. Endohermetics on zinc-eugenol cement base.
The advantages of zinc eugenol cements are:
. They can be easily entered into the root canal
. They have tong time of hardening
. After hardening they become into non-solving mass, which doesn’t have shrinkage and has good adhesion
. They are x-ray contrast
. They can be easily removed from the root canal if it is necessary . In case of overfilling these cements dissolve in the apical tissues
. Before hardening they have antiseptic and anti-inflammatory effects. After hardening they are biologically neutral
The disadvantages of zinc-eugenol cements are:
. Materials of these cements (eugenol, formaldehyde, paraformaldehyde etc.) have toxic and allergic effect on the organism tissues, especially in case of overfilling
. They can dissolve in the root canal
. They disturb the composite filling hardening
3. Epoxide pitches containing materials
These endohermetics contain epoxide pitches and x-ray contrast material. They are produced as “powder-paste” or “paste-paste” systems (pic. 76). After mixing the components these materials become hard during 8-36 hours.
a b
Pic. 76. Polymeric endohermetics of “paste-paste” system.
a – in syringe; b – in capsules (base and catalyst)
Epoxide pitches containing pastes can be used only with primary hard materials (gutta- percha pins, thermafils etc.).
The advantages of these materials are:
. They are plastic and can be easily entered into the root canal
. They have long time of hardening
. They are biologically neutral towards the apical tissues
. They don’t change in the root canal and are stable to humidity . They are thermostable, which allows to work with hot gutta-percha
. They are x-ray contrast
. They don’t disturb the composite polymerization
The disadvantages are:
. They have polymerization shrinkage of about 2%, so they can be used only with primary hard materials
. Bad adhesion if the root canal is not dried completely
. The retreatment is difficult
. They have high cost
4. Calcium hydroxide containing materials
These are polymeric materials, which contain calcium hydroxide. They are produced as “paste-paste” systems (base and catalyst pastes). Besides, they contain non steroid anti- inflammatory medicaments and x-ray contrast substance (pic. 77). The hardening time depends on root humidity and is approximately 16-24 hours. These materials also should be used together with primary hard materials.
Pic. 77 Calcium hydroxide containing polymeric endohermetic
Advantages and disadvantages of the calcium containing polymeric materials are almost the same with the epoxide endohermetics, but however they have some properties:
. Calcium hydroxide activates the regeneration processes in the apical tissues
. Due to non-steroid anti-inflammatory medicaments possibility of post-filling pains decrease . Due to absence of epoxide pitches the retreatment becomes easy
5. Glass-ionomer cements
GIC for the root canals differs from usual GIC by:
. Long hardening time (1.5-3 hours)
. More x-ray contrast
. More stability and biocompatibility
Root canal GIC makes chemical connections with root dentin, which provides good adhesion and hermetic filling. Besides, this material has good manipulation properties, lowest level of humidity adsorption, high biological neutrality and doesn’t have shrinkage.
The only disadvantage of the root GIC is the difficulty of retreatment if it is necessary. That’s why it is used only together with the gutta-percha pins.
6. Resorcin-formalin containing materials
Resorcin-formalin paste was made ex tempore: 2-3 drops of formalin (40% formaldehyde water solution) were added to crystal resorcin and 2-3 crystals of chloramine (as a catalyst). The solution was mixed with zinc oxide. After the polymerization of resorcin-formalin phenol-formaldehyde plastics appear. Such chemical reaction goes during root canal impregnation by resorcin-formalin.
Nowadays resorcin-formalin containing materials are produced in factories (“powder + 2 solutions” system). To improve the advantages of these materials some substances are also added into them: glycerin for increase of plastic properties, barium sulfate for x-ray contrast, hormonal substances for preventing pains after the filling (pic. 78).
Pic. 78. Resorcin-formalin containing material The advantages of resorcin-formalin pastes are:
. Strong anti-necrotizing effect
. Antiseptics of dentinal tubules and delta-branches
. Easy working
. X-ray contrast
. Biocompatibility after hardening
The disadvantages of resorcin-formalin pastes are:
. High toxicity of the components
. Irritation effect on the apical tissues
. Coloring of the tooth crown into pink color
7. Calcium phosphate containing materials
These materials are in elaborating process yet. Chemically they consist of 2 calcium phosphate substances: acidic and basic. During mixing these components reaction og neutralization happens and hydroxyapatite is originated.
The properties of these materials are:
. Good adhesion with root canal
. Low solvation in the water, tissues and blood
. X-ray contrast similar to dentin and bone tissue
. High solvation in the acids (if retreatment is necessary)
. High biocompatibility
Microbiology, biochemistry and physiology of oral cavity
The microflora of oral cavity is generally mainly constant, however it can greatly change due to the different reasons, such as: disorder of salivation, essence and consistency of the food, hygiene condition of the mouth cavity, different local diseases as well as various somatic illnesses. For example, the disorders of salivation, chewing and swallowing functions always result in increase of microflora in oral cavity. Same thing occurs in case of carious lesion, poor-quality fillings, and poorly made fixed prostheses, i. e. in all those cases, when there are prerequisites for accumulation of dental deposit and food residue, and their natural washing-out by the saliva flow becomes problematic.
The personal hygiene of the oral cavity prevents the increase of microflora and it supports preservation of the immunological status of the oral cavity. This takes place due to the preservation of structure and characteristics of the saliva and oral fluid, which in turn makes a powerful barrier against penetration of microbes and viruses through the oral cavity, which can cause acute and chronic diseases of the whole body.
The microflora of the oral cavity is very diverse, and is divided into two groups:
1) saprophilous or resident, i. е. permanent microflora of oral cavity, which is necessary for normal and natural functioning of all organs and tissues of the oral cavity as well as the whole body. This microflora also affects local immunity, it enhances bacterial balance, participates in digestive function by ensuring the quality of the formed food lump.
2) pathogenic microflora, i. e. microflora that causes, develops and progresses different diseases of oral cavity and of the whole body. It is preferable that there is no pathogenic microflora in oral cavity or it is in very limited quantity, so that it does not affect the oral cavity in any way.
However, this segregation of microflora is conditional, because in case of decrease of the local and general immunity the saprophilous microflora can become pathogenic.
It has to be noted that almost the whole microflora of the oral cavity comes from outside, and the first mass microbial invasion occurs in the first hours of a person’s life, and this process goes on during the whole life. Though, in the first years of life this process is especially enabled by certain negative external factors, such as parents’ kisses, licking the pacifier before giving it to a child, trying the food from baby’s spoon etc. These and similar factors are the cause of penetration of even larger amount of microflora, especially the pathogenic one, in the oral cavity of the child, whose grwoing body is not yet ready to fight against those germs. This becomes the reason for different thrushes, aphthaes and fungus.
Streptococcus salivarius, Streptococcus mitis, Streptococcus sanguis, Actinomyces, fusobacteria, lactobacilli and others are included in the first group.
Coccs make up the major part of oral cavity microflora (85-90%). They are very active biochemically: they decompose carbohydrates, split the proteins and form hydrogen sulfide. By decomposing the carbohydrates, streptococci promote the formation of lactic acid and other organic acids. These acids suppress the growing of some putrefactive microorganisms that get into the oral cavity from the external environment.
Amongst streptococci Streptococcus mutans, sorbinus, anginosus are considered to be pathogenic and are the main cause of dental caries. Besides streptococci, staphylococci: Staf epidermidi, Staf aureus also populate the oral cavity. All cocci of the oral cavity are mainly anaerobes.
certain amount of Lactobacteria also exists in the oral cavity of a healthy person. Like streptococci, they also produce the lactic acid, which has bacteriocyd effect on some pathogenic microorganisms, such as staphylococci, intestinal, typhoid and dysenteric bacilli. The amount of lactobacteria increases sharply in case of the carious lesions of teeth. There is even offered a special "lactobacilliar-test" (determination of lactobacteria quantity) for evaluation of the progress of carious process. Lactobacilli reproduce much better in anaerobic conditions, than in aerobic ones.
Leptotrichia also belong to the type of lactic acid bacteria. They are extremely anaerobe.
Actinomicetes always exist in the oral cavity of a healthy person. They look like fungi, some of them even reproduce by spore parity. But nevertheless, the main way of the reproduction of actinomicetes is a simple division.
The Fungi: the oral cavity of 50-60% of healthy people is populated with the yeast-like fungi of the genus Candida (C.albicans, tropicalis, crusei). Normally their quantity is limited. However, sometimes, for instance, in case of wrong use of antibiotics, fungi of the genus Candida, particularly C.albicans, become pathogenic and cause development of candidiases. In this case their quantity increases and they actively reproduce. Therefore in smears, taken for bacterial analysis, we see not just one or two but plenty of fungi, that actively reproduce via mycelia.
Spirochetes appear in an oral cavity from the teething moment of the first baby tooth. They are strict anaerobes. Sometimes, together with fusobacteria, spirochetes become the reason for different necrotic processes, such as ulceronecrotic gingivitis, stomatites and anginas, chronic gangrenous pulpits etc, in an oral cavity.
Protozoa: 50% of healthy people can have protozoa in their oral cavity, such as Entamotba gingivalis, Trichomonas. Mostly, they are localized in dental deposit, in parodontal pockets, and grow fast if there is poor hygiene of the mouth cavity.
Saliva and its functions
Saliva is a secretion of the salivary glands.
There are 3 pairs of major salivary glands in the oral cavity: a) parotid – glandula parotidea b) submandibular – glandula submandibularis c) sublinguale – glandula sublingualis.
Besides, there are also a lot of minor salivary glands in the oral cavity.
In the oral cavity there is so-called oral fluid, which contains not only saliva, but also microflora and products of its vital activity, gingival fluid, desquamated epithelium, the residues of food etc. Relative density of the oral fluid ranges within 1,001–1,017. An adult excretes 1500-2000 ml of saliva during a day. However, the intensity of salivation is not the same at different hours of the day. For instance, the salivation is rich during the meal time, and is scarce during the sleep. The secretion speed varies also depending on age, nervous excitement excitation, fear etc.
The saliva has buffer capacity, i. e. it is capable to neutralize the acids and bases, maintaining a certain environment (рН) in the oral cavity. The buffer capacity of saliva is one of the factors, raising the resistance of teeth to caries. It is necessary to note that in-take of food rich in carbohydrates for a long time reduces the buffer capacity of the saliva, and in-take of food rich in protein, on the contrary, raises it.
Normally the рН of oral fluid is 6,5-7,5. Some fluctuations in рН are possible during the day, for example it reduces at nigh. рН reduces also during the meal in-take, particularly, if food is rich in carbohydrates. However this does not last long and the рН of the oral fluid is restored very soon. This does not refer to the local reduction of рН in the oral cavity, for instance, on the surface of teeth enamel under the dental deposit.
Composition of the saliva and oral fluid
The saliva consists of water (99,0-99,4%) and organic and inorganic substances (0,6-1%).
Inorganic substances are calcic salts, phosphates, potassic and sodic compounds, chlorides, hydrocarbonates, fluorides etc.
The ionic activity of Ca and P in the oral fluid is an indicator of solubility of hydroxy- and fluoroapatites. The saliva in normal physiological conditions is supersaturated with hydroxy- and fluoroapatites which enables their penetration into the enamel. When рН of the oral fluid reduces, the amount of hydroxy- and fluoroapatites in saliva also decreases sharply, and the solubility of enamel apatites increases. The рН equal to 4,5-5,5 is considered to be critical. In case of even lower value of pH the apatites of external layer of enamel start to dissolve and are washed-out into the oral fluid
The organic substances are various enzymes, immunoglobulins, specific antigens and antibodies, which correspond to the blood group of the given person.
There are more than 60 enzymes and they are divided into 5 main groups:
1) carboanhydrases
2) esterases
3) proteolytic enzymes
4) transferring enzymes
5) mixed group.
By their origin enzymes are divided into 3 groups:
1) produced by salivary glands
2) produced in process of the fermentative activity of bacteria
3) produced as a result of leucolysis in the oral cavity.
The enzymes participate in phosphoric-calcium and carbohydrate metabolism, providing mineralization of teeth and bones, and adjusting transparency of tissues etc. Certain enzymes enable the migration of leukocytes in an oral cavity. Some enzymes, like lysocyme, RNase, DNase have antibacterial features. The leukocytes, T- and В-lymphocytes, which penetrate into the oral cavity from circulatory and lymphatic systems, also have antibacterial features.
Functions of the saliva:
1) digestive function – due to the enzymes of the saliva.
2) protective function – saliva protects mucous membrane from drying-out, it washes out the microorganisms and the residues of food from the teeth and mucosa of the mouth. The protective function is also carried out due to bactericidal features and buffer capacity of the saliva.
3) mineralizating function –activated by the mineral substances contained in the saliva.
Root canal filling by primary hard materials D. Root filling by chemically softened cold gutta-percha This is one of the methods of the lateral condensation. In this method chloroform or eucalypt oil is used as a dissolvent. After checking in the root canal the main gutta-percha pin tip is immersed in the dissolvent for 1 sec. Then it should be covered by endohermetics and inserted into the root canal again. The softened tip easily processed during condensation. Due to this filling hermetically closes the apical part of the root canal and fills collateral canals. After the main pin should be condensed by spreader. Then additional gutta-percha pin with endohermetic is inserted into the root canal.
E. Root filling by injection system OBTURA This method is good for large root canals with resorptive defects and with hard anatomical structure. OBTURA II system is a high temperature method during which the gutta-percha pin is heated up to 2000C in special device. It is called OBTURA II. Gutta-percha is inserted into the root canal by special injective syringe. Stopper is set on the syringe on 1mm shorter than the working length. The passability of the material through the syringe should be checked by screw rotation. The syringe is inserted into the root canal up to stop. Some portion of material is inserted slowly into the apical part of the root canal. Then the syringe is brought out slowly with material extrusion into the freed space. After the syringe is brought out completely, the root canal is filled up to the orifice.
F. Root canal filling by thermafils This method was invented in 1978 by Johnson. Thermafil is a metallic (titanium or stainless steel) or plastic cone-shaped pin, which is covered by alfa gutta-percha. The sizes correspond to ISO. Thermafil is for filling of straight root canals. Thermafil filling stages (pic. 101):
. Anesthesia – is necessary, because hot gutta-percha filling may be painful. . Mechanical and medicamental processing of the root canal. The root canal should be of expressed cone-shape with apical ledge. The enlargement of the coronal part should be more expressed for plugger insert. . Root canal washing and drying. . Thermafil choose – thermafil size is chosen by verifiers. . Sealer insert into the root canal – root canal walls are slightly smeared by sealer. . Thermafil insert into the root canal – thermafil is heated in special device which is called Thermaprep (pic. 100). After it should be inserted into the root canal during 8-10sec. Gutta- percha surplus is condensed by plugger.
Pic. 100. Thermaprep device . X-ray for control. . Cutting the additional part of thermafil by bur. . Tooth temporary filling.
Pic. 101. Root canal Thermafil filling: 1 - conicity 4%; 2 - funnel-shaped enlargement; 3 - verifier; 4 - Endohermetic; 5 - gutta-percha and endohermetic surplus; 6 - plastic pin; 7 – gutta-percha; 8 – material insert into the collateral canals; 9 – cutting line; 10 – root canal orifice; 11 – plugger; 12 – root canal filling.
Endodontic treatment of impassable root canals. Impregnation. Depophoresis. In clinical practice sometimes it is impossible to pass and fill the root canals up to the apex. In such cases some methods are used, which allow to leave pulp or a part of it inside the root canal. These methods are impregnation and depophoresis. These methods don’t allow to do good antiseptic preparation of the root canals and apical tissues isolation from the root canal.
1. Impregnation of the impassable parts of the root canals Impregnation is preparation of the root canal by some substances, which transform the pulp remains into an aseptic bundle. In this form it can remain for a long time without necrosis. a. Impregnation of the root canal by resorcin-formalin Resorcin-formalin transforms the pulp into an aseptic bundle, which is like plastic. This bundle doesn’t dissolve and change due to microflora or tissue liquid. Resorcin-formalin impregnation method
Before impregnation devitalization of the pulp should be done, otherwise “residual pulpitis” will occur. The patient’s position for lower jaw should be sitting, for upper jaw should be lying with head back. This is necessary for material insert into the root canal. First of all the tooth cavity must be opened. Then the passability of the root canals is defined. Mechanical and medicamental processing of the passable canals are prepared mechanically and is done. Impassable canals must be prepared as much as possible. The orifices must be enlarged. After pulp necrotizing must be done (devitalization or electric necrosis). After impregnation is done during 3-4 visits (not less). During first visit the root canal is prepared by resorcin-formalin liquid without catalyst. 5-6 drops of formalin is mixed with resorcin on the glass up to saturation. They are mixed with metallic spatula. Saturation is defined when the resorcin stops to dissolve in the liquid. Some crystals remain non- dissolved. After the tooth should be isolated from saliva and dried. 1-2 drops of the resorcin-formalin solution are applied on the canal orifice. It should be inserted into the passable part of the root canal by files during 3 min. The additional liquid must be removed by cotton. A new portion of liquid is applied on the orifice and again it is inserted into the root canal during 3 min. This should be done 3 times. After a small piece of cotton with resorcin-formalin liquid is put on the orifice. The tooth should be hermetically closed by powder (artificial) dentin. The second visit must be done after 1-2 days. During second visit the temporary filling must be removed and all the procedure of the first visit must be repeated. The third visit should be done after 1-2 days. During third visit the temporary filling is removed and the root canal impregnation is done by resorcin-formalin liquid with catalyst. For this purpose resorcin-formalin liquid is prepared like in the previous visits, then 2-3 crystals of Chloramine (catalyst) are added. After it must be mixed thoroughly. The mixture must have yellow shade. This solution must be inserted into the root canal again 3 times for 3 min. The additional liquid is removed with cotton. After the passable part of the root canal is filled with resorcin-formalin paste (resorcin-formalin liquid with catalyst should be mixed with zinc oxide until it become a paste). The additional parts of the paste must be removed from the tooth cavity and the orifices should be covered by isolative lining (ex. phosphate-cement). The crown is filled by permanent filling. Sometimes when the dentist is not sure that 3 visits are enough, impregnation can be done during 4 visits. This can be when the root canals are too narrow or too infected. But catalyst must be used only during last visit. During resorcin-formalin impregnation the pulp remains are saturated by resorcin-formalin mixture, and after the catalyst apply they transform into phenol-formaldehyde plastic. As a result the pulp with the microorganisms is embedded inside this glass-like substance. It can’t be dissolved. At the same time this substance has shrinkage and after polymerization (becoming hard) it moves away from root canal walls and apical foramen. So this method can’t guarantee hermetic filling of the root canal. That’s why it is important to fill the passable part of the root canal by resorcin-formalin paste. Teeth with resorcin-formalin impregnation become pink after some time. If the resorcin-formalin mixture comes out from the apical foramen, it irritates the apical tissues. Besides, these teeth become fragile, they attach to the surrounding bone tissue, which makes problems when it is necessary to remove them. b. Impregnation of the root canal with silver Impregnation with silver is a method during which the impassable parts of the root canal are filled by silver nitrate and further metallic silver particles origination. As a result a thin layer of metallic silver is originated on the walls of macro- and micro-canals, which embeds microflora inside the dentin. Silver reacts with the pulp proteins and silver albuminates appear, which transform the pulp into an aseptic bundle. Besides, silver has long-lasting antiseptic effect, which stops the microflora increase and the apical inflammations. The negative feature of the silver impregnation is the insufficient antiseptic effect, because the silver generally accumulates on the pulp surface, but not in the deeper layers. In the deeper layers microflora still remains active and this can lead to apical periodontitis. Other disadvantages of this method are the discoloration of the tooth into dark grey color and irritation of the apical tissues in case when it comes out from the apical foramen. Silver impregnation method
Before impregnation the pulp must be devitalized. The patient’s position for lower jaw should be sitting, for upper jaw should be lying with head back. This is necessary for material insert into the root canal. Mechanical and medicamental processing of the passable canals are prepared mechanically and is done. Impassable canals must be prepared as much as possible. The orifices must be enlarged. After pulp necrotizing must be done (devitalization or electric necrosis). After impregnation is done during 3-4 visits (not less). During first visit the impassable part of the root canal is prepared by silver nitrate 30% water solution. The tooth should be isolated from saliva and dried. 1-2 drops of the silver nitrate solution are applied on the canal orifice. It should be inserted into the passable part of the root canal by files during 3 min. The additional liquid must be removed by cotton. A new portion of liquid is applied on the orifice and again it is inserted into the root canal during 3 min. This should be done 3 times. After 1-2 drops of reducing agent (4% hydroquinone solution or mixture of 30% liquid ammonia and 10% formalin 1:1, prepared ex tempore) are applied on the orifice. The reducing agent should be inserted into the canal during 3min. The tooth cavity is colored into dark grey color. A piece of cotton with silver nitrate 30% water solution is put on the orifice. The tooth should be hermetically closed by powder (artificial) dentin. The second visit must be done after 1-2 days. During second visit the temporary filling must be removed and all the procedure of the first visit must be repeated. The third visit should be done after 1-2 days. During third visit the temporary filling is removed and the root canal impregnation is done by the same method as during the previous visits. This solution must be inserted into the root canal again 3 times for 3 min. The additional liquid is removed with cotton. After the passable part of the root canal is filled with any plastic hardening material. The additional parts of the paste must be removed from the tooth cavity and the orifices should be covered by isolative lining. The crown is filled by permanent filling. Sometimes when the dentist is not sure that 3 visits are enough, impregnation can be done during 4 visits. This can be when the root canals are too narrow or too infected. c. Combination of resorcin-formalin and silver impregnations Combination of these methods of impregnation increases the effectivity of the root canal impregnation. In this case silver impregnation is done at first. Silver covers all the macro- and micro- canals. Then resorcin-formalin impregnation is done. As a result the pulp transforms into plastic aseptic bundle. Combinative impregnation method
During first visit after tooth preparation the impassable part of the root canal is prepared by silver nitrate 30% water solution. The tooth should be isolated from saliva and dried. 1-2 drops of the silver nitrate solution are applied on the canal orifice. It should be inserted into the passable part of the root canal by files during 3 min. The additional liquid must be removed by cotton. A new portion of liquid is applied on the orifice and again it is inserted into the root canal during 3 min. This should be done 3 times. After 1-2 drops of reducing agent are applied on the orifice. The reducing agent should be inserted into the canal during 3min. A piece of cotton with silver nitrate 30% water solution is put on the orifice. The tooth should be hermetically closed by powder (artificial) dentin. The second visit must be done after 1-2 days. During second visit the temporary filling must be removed and all the procedure of the first visit must be repeated. The third visit should be done after 1-2 days. During third visit the temporary filling is removed and the root canal impregnation is done by the same method as during the previous visits. This solution must be inserted into the root canal again 3 times for 3 min. The additional liquid is removed with cotton. After impregnation by resorcin- formalin method is done. 1-2 drops of the resorcin-formalin solution without catalyst are applied on the canal orifice. It should be inserted into the passable part of the root canal by files during 3 min. This should be done 3 times. After a small piece of cotton with resorcin-formalin solution without catalyst is placed on the orifice and the tooth is filled by artificial dentin. Next visit must be done after 1-2 days. During fourth visit the temporary filling is removed and impregnation with resorcin-formalin solution with catalyst is done (3times, 3min.). The additional parts of the liquid must be removed by cotton. And the passable part of the root canal must be filled by resorcin-formalin paste. The additional parts of the paste must be removed from the tooth cavity and the orifices should be covered by isolative lining. The crown is filled by permanent filling.
2. Depophoresis with Cu-Ca hydroxide Depophoresis with Cu-Ca hydroxide is done by the following method. Root canals must be passed and enlarged up to 1/3-2/3 of the length. After Cu-Ca hydroxide water suspension is inserted into one of the canals. After this an electrode (cathode “–“) must be inserted into the root canal. The other electrode (anode “+”) is placed on the cheeks’ mucosa. Electrodes are connected to the depophoresis device, which provide constant electric current. During this procedure the current force is increased until slightly pricking or hot sense near the tooth. Then the force must be decreased. After it is increased again up to 1-2mA very slowly, with intervals. The procedure time is defined according to the electric dosage norm for one canal, which is 5mA/min. After finishing the procedure for one canal, the canal must be prepared with the same way. For maximum effect the depophoresis must be done 3 times with 8-14 days interval. After depophoresis the root canals must be filled by special acidic cement which contain copper (Cu). Before depophoresis the tooth must be devitalized. Depophoresis should be done by dentist, not by physiotherapeutist.
- 2 Mechanism of therapeutic effect of depophoresis is based on OH and [Cu(OH)4] ions penetration into the macro- and micro-canals under the influence of electric current. Due to this all the canals and apical foramen become closed by Cu-Ca hydroxide (“copper stoppers”). As a result the following happens inside the root canal and apical tissues:
1. Soft tissues destruction, which are inside the canal and apical delta. All these destruction products go into the apical tissues and are neutralized by the organism. 2. Antibacterial preparation of the canals due to bactericidal effects of the Cu-Ca hydroxide 3. Canals closure and Cu-Ca hydroxide depo origination in the non-filled parts of the root canal 4. Copper stoppers origination, which close all the apical delta canals. This provides hermeticity and long-lasting sterility of the apical part. 5. Osteoblasts’ function and bone regeneration activity due to therapeutic effect of Cu-Ca hydroxide The disadvantages of depophoresis are:
1. No treatment control, as X-ray doesn’t show the obturation 2. Technically hard method, as for 4-10min the tooth must be absolutely dry, and the dentist has to do a lot of manipulations at the same time 3. Tooth discoloration (yellow shade) 4. Long lasting treatment 5. Expensive device and materials Indications:
• Impassable root canals • Tool breakage inside the root canal • Traditional methods of treatment are not effective • Root canal retreatment is impossible Contra-indications:
• Cancers • Hard forms of auto-immune diseases • Pregnancy • Electric current intolerance • Allergies from copper • Exacerbation of chronic apical periodontitis • Suppurated cyst of jaw • Silver pin presence inside the root canal Depophoresis can’t replace the traditional methods of endodontic treatment. This is a method for impassable root canals as an alternative method for impregnation. 2.Torusal anaesthesia - performed in the field of torus mandibulae, the inferior alveolar (n.alveolaris inferior), the lingual (n.lingualis) and buccal (n.buccalis) nerves are blocked. The region of anesthesia includes all the teeth of the corresponding side, the mucous membrane of the alveolar process, half of the lower lip, tongue, mucosa of the cheeks.
The anesthetic solution is injected into the area of the mandibular torus , which is located on the inner surface of the mandible, anteriorly and upward from the uvula of the lower jaw. Inferior alveolar nerve lies posterior to the mandibular torus, buccal nerve – anterior to the mandibular torus, and the lingual nerve medially. They are separated from each other by loose connective tissue.
During torusal anesthesia syringe should be at the level of the molars of the opposite side. The patient's mouth should be open maximally. Place of puncture is the point formed by the intersection of a horizontal line drawn 0.5 cm below the chewing surface of the upper third molar and the grooves formed by the lateral pterygoid- mandibular plica and the cheeks. If the molars of the upper jaw are absent, an imaginary horizontal line must be 1.5 cm below the alveolar process of the maxilla (Fig. 10.):
Fig. 10. The position of the syringe and needle during torusal anesthesia.
In the area of the mandibular torus injected 1-3 ml of anesthetic, and then, withdrawing the needle back a few millimeters, injected 0.5-1 ml of anesthetic to turn off the lingual nerve.
3. Mental anesthesia - is carried out in the region of the mental foramen (foramen mentale), this switches off the mental nerve (n. mentalis). The region of anesthesia includes the canine, incisors and premolars, the mucous membrane of the alveolar process of the corresponding side and lower lip.
Mental anesthesia can be performed by intra –oral and extra-oral ways.
Intraoral technique of mental anesthesia The patient's teeth should be closed. Withdrawn the cheek, prick should be done at the middle of the crown of the first molar, retreating a few millimeters outward from the lower vault of the vestibule of the mouth. The needle is advanced to a depth of 0.75-1 cm downwards, anteriorly and inward to the mental foramen, where it is injected 0.5 ml of the anesthetic solution. Anesthesia occurs within 5 minutes.
Extraoral technique of mental anesthesia
Determine the projection of the mental foramen on the skin, and place the index finger presses the soft tissue to the bone (Fig. 11.).
Fig. 11. The location of the mental foramen on the skull.
The prick of needle should be done 0.5 cm above and posterior to this point, giving the direction of the needle corresponding the direction of the channel, inside and anterior till the contact with the bone. The 0.5 ml of the anesthetic solution is inserted. Anesthesia occurs within 5 minutes.
4. Anesthesia in the region of the buccal nerve. Anaesthesia is carried out with wide- open mouth of the patient. The syringe should be at the level of the molars of the opposite side. The prick of needle should be at the point of intersection of the horizontal line drawn at the level of the occlusal surfaces of the upper molars, and the vertical line- projection on the mucous membrane of the cheeks the front edge of the coronoid process (Fig. 12.). The needle is inserted 1.5 cm to the front edge of the coronoid process and injected 1-2 ml of anesthetic.
Fig. 12. Anesthesia in the region of the buccal nerve.
5. Anesthesia in the region of the lingual nerve.
With wide-open mouth , the tongue is removed in the opposite direction of(to) the anesthesia with spatula. The prick of needle is carried out on the level of middle of third molar, the deepest point of mandibular-lingual crest. Here the lingual nerve is placed superficially and 1-2ml anesthetic is inserted . Anesthesia occurs within 5 minutes.
The lingual nerve can be anesthetized also in the area of mandibular foramen.
Fig13. Anesthesia in the region of the lingual nerve.