9.1. Preventive Measures in Dental Caries Treatment

9. Prevention in preservation dentistry

9.1. Preventive measures in dental caries treatment

9.1.1 Introduction 9.1.2. Preventive measures at the stage of cavity preparation The main task of preservation dentistry In preservation dentistry, the preparation is to prevent dental caries and its of dental hard tissues is based on the consequences. removal of carious lesions in dental tissue Primary prevention in preservation and on the ensuring of retention of the filling dentistry is aimed at the prevention with regard to the prevention of dental of diseases of dental hard tissue. This caries. Residues of a carious lesion left on prevention is intended not only to fight the cavity walls and the pulp wall result against dental caries but it is also closely in secondary or recurrent caries formation connected with the prevention of periodontic with its consequences. pathologies. The identification of recurrent caries, Primary prevention in endodontics particularly in the fillings with a good relies on procedures to prevent caries near marginal closure is a diagnostic problem the pulp and acute or chronic diseases of the which cannot sometimes be solved even pulp. by using dental radiography. Secondary prevention is The main aim of dental caries the prevention of complications during treatment is to preserve healthy dental pulp. caries treatment and secondary (recurrent) The current choice of preparation tools caries formation. Secondary prevention is considering effectiveness and the used filling based on lege artis dental caries treatment, material is a basis for the prevention of pain focussing particularly on the extent of sensation during the preparation procedure. a carious lesion, remaining dental tissue, the When manual preparation relationship to the pulp cavity and the filling instruments are used, the patient feels the material used. instrument’s pressure. If low-speed rotating Secondary prevention in endodontics preparation tools are used, painful sensations consists of a system of consecutive are distributed evenly between pressure, procedures which are affected by anatomical temperature and vibration sensations (Tab. relations of root canals, disease diagnosis 9.1.). With high-speed rotating tools, the and a particular technique of root canal sensation of pain due to pressure preparation and filling. Early treatment and vibrations is decreased but temperature of dental caries and its consequences will irritation increases. With ultra-high-speed prevent serious complications. instruments, 80 – 90% of energy is The purpose of tertiary prevention converted into heat. is to avoid or diminish a negative effect of dental fillings, crown and root canal Table 9.1. The effect of the instrument’s speed on materials. This kind of prevention is based pain sensation on the offer of materials on dental market. Manual Pressure ///////// preparation However, it is also affected by the quality Low speed Pressure /// of the preparation of dental materials and Vibrations /// a particular working procedure used in the Heat /// treatment of dental caries or during High speed Pressure / endodontic therapy. Ultra-high speed Vibrations / Heat /////// Prevention in Preservation Dentistry

As a result, when the prepared area and the filling material used. Conventional of the tooth is not cooled properly, thermal preparation procedures follow basic damage to odontoblasts may occur together principles. with irreversible changes in the pulp. The main principle for dental caries Insufficient cooling may occur when treatment is to remove the matter changed the flow of water from the jet does not wash by carious lesion. Complications usually the prepared field due to the shape of the occur during the treatment of caries located cavity and the angle of a preparation tool. near the pulp when the dentist failed Unpleasant to painful sensation will to remove the carious dentin or when the arise due to the vibrations of rotating tools removal of carious matter was too radical which are not centred properly or have been irrespective of the anatomical size of the used for a longer period of time. Pain pulp cavity, increasing the risk of perforating increases particularly in patients with the the pulp cavity. damaged periodontium. When the principles of preventive Pain relief and reduction in the extension during cavity preparation is preparation time depend on the effectiveness maintained, this will ensure the extension of the preparation tools used (i.e. on the of cavity up to the point of self-cleaning. type, quality and the way of using the tools). Microbial plaque accumulates at a higher When sharp tools are used, approximately extent on irregularly positioned teeth. one half of kinetic energy delivered to the Treatment of dental caries for irregularly axis of a rotating tool during drilling positioned teeth depends not only on the and polishing will change into heat. This extent of loss of dental tissues, but also portion increases with blunt instruments; on a degree of seriousness of a particular almost all energy will change into heat when irregularity. In a large number of cases, the totally blunt tools are used. performance of a conventional treatment is The effectiveness of drilling and polishing not possible and it is necessary to apply strongly depends on the cross-section materials with adhesive bonds. At the of a chip and the cutting speed whose extensive loss of hard dental tissue, there magnitude depends on the tool’s diameter is a risk of subsequent fracture of a crown. and the number of revolutions. An increase In such cases it is therefore necessary to do in the cutting speed at an ultra-high number prosthetic treatment or extract the of revolutions enables one to make a chip abnormally positioned or markedly of a smaller diameter, with lower pressure destructed tooth. applied on the tool and thus lesser pain Through their attachment to dental during treatment. Reduction in the number hard tissues (mechanical, chemical), of revolutions during preparation depends composite materials are able to reduce on the pressure on the tool. The most preparation procedures and save dental hard significant reduction in the number tissues (preventive fillings), achieving the of revolutions is in turbine handpieces with best possible aesthetic effect at the same a direct drive where pressure causes the time. number of revolution to decrease by 25 - The prepared cavity must ensure the 30%. Improper and damaged rotating sufficient retention of a filling. components result in vibrations and the The preparation depends on the type of the overheating of the handpiece. This also material used (amalgam filling, cast fillings, increases the tool’s noise level. inlays made of different materials, Lege artis treatment is crucial when composite filling materials and glass dental caries is found. ionomer cements). Non-compliance The cavity preparation depends with retention principles for individual on the localization of dental caries, the materials will result either in the release extent of the loss of dental hard tissue of a filling or failure to achieve its mounting. Prevention in Preservation Dentistry

Fillings are exposed to chewing pressure. frequently an indication for the subsequent The respective kind of the material also extraction of a tooth. It is therefore specifies the need of sufficient depth necessary to consider the indications for the of preparation to ensure the resistance use of plastic or cast dental fillings. In the of individual filling materials. Shallow case of a large loss of dental hard tissue, it is prepared cavities fail to provide sufficient necessary to apply prosthetic treatment. firmness for the material and will break upon The extent of the preparation can be biting. Damage to the filling may also occur reduced in the case of small caries on the in high fillings during the adjustment occlusion surfaces of molars with huge of occlusion / articulation relations. The risk cusps. The use of molar composite materials of breaking the filling is highest in MOD is recommended. cavities and in Class IV cavities with the In order to prevent secondary caries, insufficient adjustment of articulation the enamel margin of the cavity, where the relations. The broken filling may irritate the amalgam filling will be placed, must be marginal periodontium causing acute treated properly. The enamel must be papillitis or periodontal abscess. underlain with dentin. The use of manual The strength of composite materials tools is recommended for the adjustment stems from mechanical binding to the of the enamel. bevelled and etched enamel, and increases The main aim of using composite with chemical binding to the enamel materials is to ensure the greatest possible and dentin depending on the used binding mechanical retention of a composite. The system. When composite filling materials insufficient angle of the enamel or errors are used, mechanical and chemical binding in subsequent phases of the procedure will shortens the preparation procedure. The lead to the failure to close the cavity, depth of the prepared cavity is not be resulting in secondary caries. governed only by the principle of the filling When caries treatment uses cast resistance. The extent of carious lesion dental fillings, the bevelling of enamel’s and the size of pulp cavity (age factor, edges is the main condition to ensure the anatomical relationship of individual teeth) cavity’s proper closure. are crucial factors. When the caries is located near the pulp, it is necessary 9.1.3. Preventive measures at the stage of to prepare in the close vicinity of the top cavity filling wall of the pulp cavity. Due to the risk of perforation, manual tools are required for Secondary caries or poor-quality fillings can performing gentle preparation also occur as a result of the working and completing the preparation. procedure used to fill the cavity with the When the preparation of the cavity is filling material. carried out, it is necessary to ensure not only Among the most common mistakes the sufficient stability of the filling against associated with amalgam fillings is the chewing pressure but also the proper incorrect selection of matrix and its resistance of the remaining dental hard insufficient fixation in Class II cavities tissues. With regard to the resistance (Figs. 9.1 and 9.2.). The injured of dental hard tissues, it is necessary dentogingival junction is painful and to comply with the “cusp rule” during the gingival bleeding will occur. Failure to preparation. The weakened cusps fail ensure the dry working field makes the lege to provide sufficient support to the artis completion of the definitive filling remaining dental tissue and the crown or impossible. root may fracture upon biting. The fractures expanding below the dentogingival junction and longitudinal fractures of the root are Prevention in Preservation Dentistry

The cavity has to be treated using closure. The presence of a fissure between a temporary filling and the definitive filling the filling and the enamel will always has to be made at a next visit. necessitate the formation of a new model. In the case of composite materials, it is necessary to comply with the working procedure for cavity filling. Shrinkage during polymerization arising due to the solidification of materials defines the suitability of using different forms Figure. nečitelné Incorrect application of matrices of composite filling materials. Large cavities and wedges and destructed crowns are treated using photopolymerizing materials. The quality of the filling made of photopolymerizing composite material is also affected by the quality of the lamp used, the type of material and the binding system used. Failure to comply with the working procedure Figure nečitelné application of matrices and wedges at each stage of the construction of a filling will result in the poor-quality filling. Damage to the marginal gingiva will also occur at the improper choice and attachment of sealing wedges in the interdental space. If the matrix is sealed 9.1.4. Preventive measures at the stage of insufficiently, amalgam during condensation the final treatment of fillings will penetrate across the cavity’s margin into the interdental space. The removal of non- The quality of the filling also depends on the solidified amalgam from the interdental filling’s final treatment. The correction space using manual tools is insufficient of occlusion and articulation relations will and will always result in injury to the prevent the elevated bite onto the filling marginal gingiva. It is therefore necessary to and the overloading of the periodontium. make a new filling. Solidified overhanging The insufficiently adjusted height of the fillings (of any material) will irritate the filling will result in the broken filling and its marginal gingiva and cause acute and release from the cavity. High fillings chronic pathological conditions of the after solidification may cause acute periodontium. or chronic damage to the periodontium. When the cavity is being filled, it is With regards to the prevention necessary to apply the amalgam into the of secondary caries, the treatment of the cavity in small portions and allow it filling’s surface is important. Amalgam to condensate properly. Insufficient fillings as well as cast dental fillings must be condensation is manifested by uneven polished thoroughly, particularly at the filling. The risk is greatest at the filling of filling’s margins. the gingival ledge in Class II cavities. Such There is currently a wide range fillings may break upon bite and irritate the of different polishing systems ensuring the marginal periodontium (pain upon perfect polishing of all kinds of fillings. The occlusion). polishing of the solidified filling’s surface is One important part of the working also important in composite fillings. After stage in the case of cast fillings is that the the adjustment of occlusion and articulation, cast in the cavity will be tested. Thorough the thorough polishing of the filling’s examination of the marginal closure of the surface is a prerequisite for good aesthetic cavity is the main prerequisite for a proper appearance. The polished surface of the Prevention in Preservation Dentistry filling will also ensure less accumulation indications for individual techniques with of microbial plaque. regard to the diagnosis of an endodontic disease, anatomical proportions of the root 9.2. Preventive aspects of canal and patient’s general state of health. endodontic therapy In practice, the decision-making is also influenced by the operation of a particular Pulp diseases usually result from dental surgery as the quality endodontic treatment caries or dental pulp trauma. Pathological is time-consuming. changes in the dental pulp also give rise to In order to avoid the most common vast abrasion and periodontal diseases. The mistakes in endodontic therapy, it is second group of pathological changes in the necessary: dental pulp is caused by dental treatment.  to ensure that the working field is Among the most common iatrogenic causes dry; resulting in damage to the pulp is tooth  to ensure a sterile working preparation performed at insufficient procedure; cooling, unsuitable underlying materials,  to determine the working length temporary and definitive filling materials. of endodontic tools, with regard Most cases of pulpitis can be treated to the diagnosis of a disease; using vital or mortal (devitalization)  to remove the contents of the root techniques. canal; With vital techniques, the treatment  to prepare the root canal respecting is completed within a single visit. If the the anatomy, root canal preparation working procedure is performed properly, techniques canal and the filling the patient will have no problems after the material used; treatment using the vital technique, the  to apply the root filling material. likelihood of complications due Failure to ensure the dry working field will to endodontic therapy decreases and the result in the entry of microflora from the procedure will save time of both patient mouth into the inner environment of the root and dentist. The main advantage of vital canal. At increased salivation and prolonged techniques is that devitalizing substances are endodontic treatment, the use of cellulose excluded and that the rate of potential swabs will not suffice to keep the field dry. complications is lowered. It is therefore necessary to work Failure to respect the with a dental dam or reduce salivation using contraindications of vital techniques for the a suitable premedication (atropine sulphate treatment of pulpitis (local, general) will 0.5 mg one hour before treatment). result in complications during treatment. The result of the endodontic Narrow, curved root canals with accessory treatment depends on the compliance canals and ramifications may result with a sterile procedure. Infection in insufficient pulp extirpation followed introduced in the root canal will be by residual pulpitis. manifested by acute complications during The main disadvantage of mortal therapy. techniques is the prolongation of the painful The preparation of the root canal is period associated with the effect possible with a technique using manual of devitalization substances on the pulp. The tools, the mechanical technique or ultrasonic perfect closure of the cavity with technique. For all techniques, two basic rules a temporary filling is to prevent arsenic must be followed: working with the tools papillitis. If the devitalizing substance is not with a preset working length, and using the removed in time, there is a risk that it may tools with an increasing size. spread into the periapical region. It is The tool’s working length depends therefore necessary to take into account all on the diagnosis of endodontic disease. If the Prevention in Preservation Dentistry tool is too long, it will penetrate into the periapical region, causing injury there. When infected root canals are treated, the use the instrument of an improper working length and not performing the mechanical preparation of the canal gradually will increase the risk of pushing the contents of the root canal through the apex. The root canal shaping procedures remove the canal’s contents using endodontic tools and root irrigating solutions that contain a disinfectant wich may also have a detergent effect. If the needle intended for irrigation is inserted only into the inlet of the root canal, the irrigation of the canal will be insufficient and the detritus will remain in the canal. The use of strong needles or the insertion of a needle up to the apical part Figure 9.3. Securing devices used with endodontic tools of the canal will not enable (particularly in thin canals) the irrigating solution to flow Every technique of the root canal out. This increases the risk of solution preparation has its risks. Nowadays, the penetrating into the periodontium causing combination of manual and ultrasonic possible allergic toxic reaction. technique appears to be the most suitable. In order to prevent swallowing or The manual technique used in root canal inhaling manual endodontic tools, it is shaping is associated with the risk of necessary to ensure their fixation using creating a ledge (Fig. 9.4.), weakening or different securing devices (chains, dental perforating the wall of the root canal (Fig. sutures, see Fig. 9.3.). All endodontic tools 9.5.). Cone preparation techniques for the have notches or openings on the handle root canal are therefore recommended (Fig. to attach the securing devices. This 9.6). Similar to manual techniques, with the minimizes the risk of swallowing or inhaling use of ultrasonic instruments one should also a released endodontic tool. This risk is take into account the angular straightening highest when a procedure is performed in the of the root canal where the wall of the new lateral section of the upper and lower jaws. It canal will get straight at the segment of also increases during painful procedures, in canal curvature after the endodontic shaping children, during the treatment of mentally (Fig. 9.7.). unstable patients. It is therefore necessary In order to suppress microbial to consider the indications of endodontic infection, different antiseptic substances are treatment and reduce the risk of endodontic inserted into the root canal. Basically, the complications, for example using more apical is the processing of the root premedication. canal, the lower amount of an irritating antiseptic substance is applied. Prevention in Preservation Dentistry

To prevent potential complications of Gutta-percha is one of the least irritating endodontic therapy, it is necessary to focus materials. Current condensation techniques on the occurrence of allergic reactions using combinations of gutta-percha and caused by different substances used such as suitable non-irritating filler enable the root irrigating solutions, antiseptic substances or canal to be filled at a minimum possible permanent filling materials. complication. Some root filling materials contain allergens or carcinogenic substances. Resorcinol-formaldehyde polycondensation resin is one of the endodontic materials most frequently used in the Czech Republic. Due to the presence of resorcinol and formaldehyde, it cannot be applied in patients with a history of allergic reactions to these substances. The levels of these two substances gradually decrease over time but in a number of patients they may induce acute complications after root canal filling. Serious problems occur with the overloading of the filling material into the periodontium.

Figure 9.4. The risk of ledge formation during the endodontic Figure 9.6. preparation Cone preparation

Figure 9.5. Perforation: A – above the alveolus, B – in the apical section of the root, C – in bifurcation, D – in the Figure 9.7. central section of the root Angular straightening of the root canal (the curvature of the canal before and after endodontic treatment)