DENTAL ATTRITION Etiology and pathogenesis This nosology has multifactorial nature The causes which lead to dental attrition can divide into 3 groups  functional insufficiency of tooth hard tissues  High affection on tooth hard tissues  functional overloading of the teeth Functional insufficiency of tooth hard tissues can be caused by  endogen factors  exogen factors Endogen causes are  a)inherent eg. Capdepon’s displasia, disorders of amelogenesis and dentinogenesis  b) acquired – as a result of different endocrinopathyes such as functional disorders of hypophysis, sexual glands, thyroid gland etc. when mineral and protein metabolism is impaired. Exogen factors They can have  physical character  chemical character  alimentary character.  For example, radionecrosis, chemical necrosis, insufficiency of vitamins and mineral soles in the meal etc. High abrasion affection on tooth hard tissues  Very-solid food  non rational use of hygienic manipulation aimed for dental care  factory dust  occlusal disharmony caused by not correct work when making ceramic or metal-ceramic crowns and bridges, disturbances of technological process etc. Functional overloading of the teeth can be  local  generelized The causes of local overloading  pathological bites  anomalies of location and form of separate teeth  partial loss of teeth  not rational prosthesis  not correct choice of prosthesis- construction  occlusial disharmony during prosthesis-making etc. The causes of generelised dental attrition dysfunction of masticator muscles (bruxizm). Approximately 30 -40 % of patients suffering from bruxizm have pathological dental attrition. Early recognition of dental erosion is important to prevent serious irreversible damage to the dentition. Classification of dental attrition  According to the plane of affection  According to the extension  according to the depth of attrition According to the plane of affection  horizontal  vertical  complex According to the extension  local  generalized According to the depth of attrition  first degree – defect of tissues till 1/3 of crown height  second degree - defect of tooth tissues till 2/3 of crown height  third degree- defect of tooth tissues till the gingival edge Dental attrition can be also  Compensate - vertical extension doesn’t decrease  not compensative have a diminution of vertical extension Clinical image of dental attrition  Attrition of dental surfaces which can be flat or concave  hyper sensitivity regardless the depth of affection  diminution of interdental height. During the local form of dental attrition we can observe a diminution in crown’s sizes and interdental height. The changing of dental crown sizes is compensated by hypertrophy of alveolar bone. That’s why when we have saved molars occlusal height remains unchanged. Clinical image of dental attrition During the generelised form of dental attrition the occlusal height can diminish, but can be also saved owing to vacant (free) hypertrophy. Different variation in dental attrition is related to the following factors  Sex  Age  tooth position  in some cases, dental caries. The sex of the individual is found to be a major factor in and a higher degree of attrition is found among females. Tooth position is also an important variable in determining the degree of wear. The diminution of vertical dimension can lead to the  dysfunction of masticatory muscles and esthetic changing  dysfunction of temporo-mandibular joint  decompensation of dental attrition can lead to Costen’s syndrome developing which is characterized by pains of TMJ, face, temporal region, headaches, earaches PROSTHODONTIC TREATMENT OF DENTAL ATTRITION The goal of prosthodontic treatment of dental attrition  to make stable the attrition of tooth hard tissues  to restore the anatomical shape, esthetics and function  to restore the occlusial dimension if necessary The treatment plan depends on  degree of affection  form of the disease  popularity  conditions of the maxillo-facial system

The treatment of first degree dental attrition  The treatment is realized in one step using cast metal and metal-ceramic crowns and bridges. If the patient suffers from or other muscle dysfunctions the preparing of metal-ceramic constructions is contraindicated to avoid fractures of ceramic lays. During these nosologies we can make jacket crowns or bridges (not completely covered, the occlusal surface must be made from metal)

The treatment of second degree dental attrition The treatment is realized in 2 steps During the first step we must regulate myotatic reflexes (it lasts 3 months). The second step is the rational prostheses-making by stable construction, such as post-core covering by fused (cast) crowns or movable prosthesis (dentures).

The treatment of third degree dental attrition The treatment is also realized in 2steps. The first step is regulation of myotatic reflexes. The second step is also the rational prostheses- making by stable construction, such as post-core covering by fused (cast) crowns or movable prosthesis (dentures).  If we have dental attrition of second or third degree during the treatment it will be good to make post-core or crowns on antagonist teeth for saving vertical dimension and averting dental-wearing process. Acid Wear Acid wear is a form of tooth wear that is caused by acid softening the surface of the . When tooth enamel (the tooth’s hard surface) is exposed to acids (from food, juice of the stomach e.g. due to sickness or regurgitation), it temporarily softens and loses some of its mineral content. Saliva will help neutralise acidity, restore the mouth’s natural balance and slowly re-harden the tooth enamel. However, because the tooth recovery process is slow, if the acid attack happens frequently, the tooth does not have a chance to repair. When the enamel surface is soft and we brush our teeth, the enamel can be worn away more easily, become thinner over time, and lead to the following  reduced thickness of enamel,  surface texture changes  shape and appearance changes  may also cause teeth to become sensitive. The acid wear’s effects are:  Sensitivity - As tooth enamel is worn away, the underlying may be exposed. This is a softer part of the tooth and as it becomes exposed, teeth may be more sensitive. A slight twinge can be felt when consuming cold, hot or sweet foods or drinks.  Severe Sensitivity - As dentin continues to become exposed over time, patients can suffer from a severe case of sensitive teeth  Discolouration - Teeth can have a slight yellow appearance as enamel becomes thinner, the darker dentin shows through or may show a darker yellow appearance due to the exposed dentin showing through  Rounded Teeth - rounded ‘sandblasted’ look on the surface and edges of the teeth  Transparency - Front teeth may appear slightly transparent near their biting edges  Cracks Small cracks and roughness may be present at the edges of the teeth  Cupping - Small depressions may appear on the chewing surface of the teeth – at this stage any fillings may appear raised

You must protect your teeth because once tooth enamel is lost, it cannot be replaced. There are several steps that can be taken To help protect your teeth against the effects of dietary acids  Allow acidic foods and drinks to pass through your mouth quickly to reduce the time they are in contact with your teeth. Strong evidence suggests that the manner in which the acidic food or drink is consumed is more important than the overall quantity.  If possible, drink soft drinks through a straw directed into your mouth and not directly at your teeth.  Avoid brushing your teeth immediately after consuming acidic foods and/or drinks, as this is when enamel is at its softest and most likely to be damaged.  Dentists recommend you brush teeth gently, but thoroughly, with a medium or soft toothbrush. This will help to minimize the risks of abrasion and tooth wear. The difference between decay and acid wear is When foods containing sugar or starches are eaten, the bacteria in the mouth (in plaque) convert these products to acids that can lead to localized dissolving of the tooth enamel. Over time, this can cause the enamel to break down and a cavity to form, which may require filling by a dentist. While decay is a localized process (ie. it does not effect all of the teeth at one time), wear occurs across the whole tooth surface that has been exposed to acid. It does not involve bacteria or dietary sugars, but is the result of direct action of acids (either from food, drinks or the stomach juice e.g. due to sickness or regurgitation) on the tooth's enamel surface. Frequent consumption of food and drinks with a high acid content can cause enamel erosion. Some causes of acid wear Highly acidic  Grapefruit  Strawberry jam  Honey  Salad with vinegar dressing  Tomato salad with balsamic dressing  White or red wine  Fresh orange juice  Fresh grapefruit juice  Fresh apple juice  Soft drinks Slightly acidic  Bananas  Tomato soup  Hamburger  Chicken and fries  Beer Neutral  English Breakfast (bacon, sausage and egg)  Toast  Lobster and rice  Cheese  Chocolate cake  Milk  English tea  Fruit tea

Partial destruction of tooth hard tissues. Prosthetic treatment with inlays and onlays To repair damage involving over ½ of the tooth’s biting surface, rather than using a simple filling, or a crown, a dentist will often use an inlay, or an onlay. Inlay and onlay are the intracoronal restorations

. Intracoronal restorations are those that fit within the anatomical contours of the clinical crown of a tooth The causes of tooth partial destruction . carious

. noncarious Non carious causes . Increased attrition . Erosion . Trauma (acute and chronic) . Hypoplasia of enamel and dentin . Scratches of enamel and dentin The clinical picture of tooth partial destruction depends on sizes and localization of the defect. Complaints . can be absent or they can be: . pains caused by physical and chemical factors . inflammation of interdental papilla and food deposit in interdental space Symptoms of partial absence of the tooth crown . disorder of tooth anatomical form and as a result disorder of its function . increased sensitivity to physical and chemical factors ( if the tooth is vital) . loss of tooth contact point and affection of marginal parodont (if the cavity is on the contact surface of the tooth) . Injury of the mucous membrane of the oral cavity by acute borders of the defect . esthetic and speech disorders

An inlay is similar to a filling and lies inside the cusp tips of the tooth; an onlay is a more extensive reconstruction that covers one or more cusps of a tooth. Inlays and onlays, can be: . porcelain . gold or cast metal . composite resin . combined Minor to moderate lesions on teeth where the esthetic requirements are low can be restored with metal inlay. Ceramic inlay restoration is utilized to restore teeth with minor to moderate- sized lesions where the esthetic demand is high. Indications to inlay use : restoring of tooth structure when can’t restore by filling or other alternatives not accepted by patient. Contraindications – (better to do full crown) – Compromised retention – Tooth mobility second-degree and third-degree The advantages of inlay and onlay: 1.Esthetic (when used ceramic and composite) 2.Conservative of tooth structure removal (as compared with crown) 3. More precise control of contours and contacts ( especially proximal contours) 4. Exact border adhesion The disadvantages of inlay and onlay: 1.Increased cost and time ( most indirect techniques, excluding CAD/CAM methods, require two patient appointments. These factors, along with laboratory fees, contribute to the higher cost of indirect restorations relative to direct restorations. . Required properties to inlay materials biocompatibilty for the organism – (not allegic, not toxic)

. the material’s thermal extension coefficient must correspond to the same index of tooth hard tissues . firmness to attrition . little shrinkage

The methods of inlay preparation . direct . indirect . computed milling Steps of direct method . cavity formation . wax inlay modelling . removing of wax reproduction from the cavity . inlay casting . checking or correction of ready inlay in the oral cavity . extraoral polishing of inlay . fixation by fixing material and intraoral polishing Steps of indirect method . anesthesia . cavity formation . impression taking . cast model . wax inlay modelling . substitution of wax reproduction into the corresponding material . checking or correction of ready inlay on the cast model . checking or correction of ready inlay in the oral cavity . extraoral polishing of inlay . fixation by fixing material and intraoral polishing The main principles of cavity preparation in inlay preparing . to provide conditions for good inlay fixation . to provide possibilities to remove wax model and insert it into the cavity without deformation Special principles for cavity preparing for inlay . The cavity must have box form with smooth walls and flat floor . The wax model of inlay must be removed in one direction . For improving inlay retention additional cavities and undercuts can be formed . For good fixation of inlay the depth of cavity must be enough . The cavity ground and walls must successfully resist mastication pressure . To prevent fracture of thinned edges of the enamel as well as to increase exact adhesion of the inlay slant under 45 degree must be created along the margin preparing

Steps of inlay cavity preparation . Occlusal outline . Proximal box . Gingival bevel if indicated . Occlusal finishing bevel - if indicated Ceramic Onlay . Restoration is all ceramic with no metal . It is bonded to the tooth . Weaker than restorations with metal & can fracture during mastication Classification of Tooth Preparation by Black: Class І Class ІІ Class ІІІ Class ІV Class V

I class All pit and fissure restorations I I class Restorationsons on the proximal surfaces of posterior teeth Class ІІІ Restorationsons on the proximal surfaces of anterior teeth that do not involve the incisal angle Class ІV Restorationsons on the proximal surfaces of anterior teeth that do involve the incisal angle Class V Restorations on the gingival third of the facial or lingual surfaces of all teeth.

CAD/CAM technology: Computer Aided Design - computer-based tool that assist dental professionals in their design activities. Computer Aided Manufacturing - special-purpose processing hardware. The CAM system will work with a CAD design made in a 3D environment. This systems produces quicker and more efficient manufacturing processes. Laminate veneers Laminate veneer: thin layer of cast ceramic bonded to the facial surface of tooth with resin • Veneers are utilized in different thickness and dimensions depending on requirements of the given clinical situation In same cases they are thin coverings luted to the minimally prepared enamel. In other cases they are fairly thick, covering not only enamel but exposed portions of dentine Ceramic veneers are indicated . Cosmetic reason: – Cover stained teeth that can not be bleached, for teeth with moderate discoloration caused by tetracycline, fluoride, age, and . – Correct an aestetically unpleasing tooth shape . Restorative indications: – treat a traumatic anterior dental injury, traumatized, fractured, and worn dentition – Avoide new composite restoration . Functional corrections . Correction of poorly aligned teeth,diastema and malformed teeth

Ceramic veneers are contraindicated . Edge-to-edge and cross bite occlusal relationships because of excessive stress during function . Avoide in patients with heavy , poor oral hygiene, and severe dentinal demineralization. . Ceramic veneers should theoretically be exposed to minimal occlusal loads. – Potential complications of ceramic veneers: Delamination, inadvertent pulpal damage, periodontal irritation, and unnatural appearance. – Window preparation Preparation : • Only vestibular surface prepared • Nor incisal , neither oral! Standard veneer preparation Preparation : • Vestibular surface • 1mm incisal reduction • Oral surface unprepared!

Post and core. Dowel core A post and core is a dental restoration used to sufficiently build-up tooth structure for future restoration with a crown when there is not enough tooth structure to properly retain the crown, due to loss of tooth structure to either decay or fracture. Post and cores are therefor referred to as foundation restorations. Historical Perspectives During the eighteenth century, Pierre Fauchard inserted wooden dowels in root canals to retain a crown. The wood became wet and expanded, therefore, enhanced retention of the dowel. Unfortunately, it often split the root as well. At that time, additional efforts to develop crowns retained with dowels were limited by the failure of the endodontic therapy. One of the retentive devices developed by Dr. F.H. Clark in 1849 was very practical. It consisted of a metal tube in the canal and a split metal dowel which was inserted into it. This dowel was designed to allow drainage from the canal or apical areas. Classitication of the post by material 1. metal post (titan, gold, base metal) 2. ceramic 3. composite 4. fiberglass 5. carbonic ( C post) Indication for post use 1.When the destruction of the tooth crown structure is about 80-100% 2.As a bases for bridges 3.For reinforcing the pulpless tooth 4.Whith the other elements for splint when we have periodontal problems Contraindication for post use 1.Untreated pathological processes in periapical part of the root (unsuccessful endodontics) 2.Obstruction root canal 3.Short roots with thin walls 4.When we have ¾ and more alveolar bone atrophy near the root 5.Destruction of the root more than ¼ of it’s length 6.Caries on root or in canal Demands for roots of abutment teeth 1.The root canal must be well passable 2.Apical part of root canal must be good filled 3.The length of root must exceeds the height of future crown 4.The roots walls must be enough thick /not less than 2mm/ 5.Projectional part of root must be hard, isn’t affected by caries 6.Stump of root must be opened, if it’s covered with gingiva,we must do gingivectomy 7.The roots must be stable Types of metal dowels by method of fabrication 1.Cast dowel and cores 2. Prefabricated dowels Post Length Parameters 2/3 length of root Equal or exceeds to length of clinical crown 8 mm into canal Ideally 5 mm from apex Minimum 3 mm from apex

Types of Dowels The dowel design can be categorized by the surface configuration and the method of placement. There are basically 2 designs: 1.parallel-sided 2. tapered. The dowels may be retained within the root canal by a cement and/or they may utilize threads to actively engage the dentine. A variety of dowel systems exist for the restoration of endodontically treated teeth.

Types Prefabricated Dowels

When we use dowel core

1. Dowels were originally used to retain crowns when we have damage 80-100% 2. Use of dowels and cores was to reinforced endodontically treated teeth.

The methods of the cast post fabrication Direct Indirect

The direct method for fabrication of a dowel-core canal preparation resin pattern or wax post fabrication in oral cavity removing of pattern from the oral cavity casting of the dowel core checking or correction of ready post in the oral cavity cementation of the dowel core Steps of indirect method canal preparation impression taking (by double silicone material) cast model wax pattern modelling casting of the dowel core correction of ready post on the cast model correction of ready post in the oral cavity fixation by fixing material

The preparation for a dowel core is begun by preparing the coronal tooth structure for the crown that will be the final restoration for the tooth. Remove existing restoration, caries, bases, and thin or unsupported walls of tooth structure, preserving as much coronal tooth structure as possible. After the finishing the crown preparation the tooth is ready for preparation of the canal. The instruments of choice for removing the gutta-percha and enlarging the canal are Peeso-reamers. They are available in sets of six graduated sizes. Canal Preparation 1. Remove gutta percha with Peeso Reamer 2. Progress with Peeso Reamers until reamer is planing the walls of the canal 3. Verify length with periapical radiograph 4. Verify that there are no undercuts in canal

Remove gutta percha from canal with Peeso Reamers and progress with larger reamers until reamer is planing walls of canal Dowel Portion Of Pattern Recontour sides of plastic toothpick with acrylic bur so the toothpick fits passively into prepared canal. Place a thin coating of lubricant inside the canal so the resin can be removed and will not stick to the canal. Mix resin in dappen dish, load into composite syringe and inject resin into lubricated canal Immediately insert toothpick into resin and allow resin to begin setting When resin gets doughy, pump toothpick and resin in canal and then allow to set completely in the canal. After the resin has set, remove the toothpick and set resin and carefully inspect for completeness and lack of voids.If voids present, discard and make new pattern. Coronal Portion of Pattern 1. Place monomer and powder in dappen dishes 2. Place dowel portion of pattern back in canal with proper orientation 3. Verify that dowel portion of pattern is stable 4. Build up coronal pattern and allow to set. Buildup coronal portion of the pattern. Allow to set completely Evaluate final preparation from all aspects. Remove pattern and carefully inspect before sending to lab for casting.