THE ROLE OF PORCELAIN VENEERS IN PROSTHODONTICS

Advanced esthetic dental treatment procedures for correcting smiles

1. PORCELAIN VENEERS PRESENTED BY, Dr. ARUN THOMAS PHILIP ASST .PROFESSOR SREE ANJANEYA DENTAL COLLEGE

2. CONTENTS INTRODUCTION DEFINITION HISTORY INDICATION AND CONTRAINDICATIONS PREDETERMINING THE FACTORS TREATMENT PLANNING PRELIMINARY TOOTH MODIFICATION DIAGNOSTIC WAX-UP

3. TOOTH PREPARATION PROVISIONAL RESTORATION TRY IN LUTING CEMENTS MAINTENANCE FAILURES

4. INTRODUCTION The patients demand for treatment of unaesthetic anterior teeth is steadily growing. Accordingly, several treatment options have been proposed to restore the aesthetic appearance of the dentition. For many years, the most predictable and durable aesthetic correction of anterior teeth has been achieved by the preparation of full crowns. Laminate veneers is a conservative alternative to full coverage for improving the appearance of anterior teeth.

5. DEFINITIONS Veneer a thin sheet of material usually used as a finish; a protective or ornamental facing; a superficial or attractive display in multiple layers, frequently termed a laminate veneer. -(GPT-9) Porcelain laminate veneer - a thin, bonded ceramic restoration that restores the facial, incisal , and part of the proximal surfaces of teeth requiring esthetic restoration. -(GPT-9)

6. HISTORY In 1928, Dr. Charles Pincus developed a porcelain facing by baking a thin layer of porcelain onto a platinum foil. They were not bonded onto the teeth (suitable technology not yet having been invented); in fact, they were glued temporarily into place with denture powder. This changed dramatically in 1955 with the discovery of bonding. Buonocore ‐ introduced acid etch technique to increase adhesion of acrylic filling material to enamel

7. 1970s - Faunce and Myers described the bonding of prefabricated resin veneers, using adhesion of the resin cement to enamel after etching. 1970’s ‐ “ Mastique Veneer System” by Dentsply (preformed factory processed plastic laminates). Relatively easy to place on the tooth- kit with a moderate selection of different shapes and sizes that needed to be shaped to fit the selected teeth. They were technique sensitive, and there is high marginal discoloration.

8. Rochette in 1975 , first proposed the use of bonded ceramic restorations in the anterior dentition. Simonsen and Calamia provided the initial studies to demonstrate that porcelain etched with hydrofluoric acid could be bonded to composite, which in turn was bonded to etched enamel. As Porcelain veneers continued to evolve, a minimally invasive approach was used to provide a more esthetic and biologically compatible restoration. A minimal preparation of 0.5 mm was used to allow for room to place a 0.5 - to 0.7-mm-thick piece of porcelain over the tooth.

9. INDICATIONS In 2002, Magne and Belser presented the following classification for indications for Porcelain Veneers: Type I : Teeth resistant to bleaching Type IA : Tetracycline discoloration Type IB : Teeth that are unresponsive to bleaching Type II : Major morphologic modifications Type IIA : Peg laterals ( Conoid teeth) Type IIB : Diastema or interdental triangles to be closed Type IIC : Augmentation of incisal length or facial prominence (contour)

10. Type III : Extensive restorations Type IIIA : Extensive coronal fracture Type IIIB : Extensive loss of enamel by erosion and wear Type IIIC : Generalized congenital malformations. Partial veneer crowns can often be used to restore posterior teeth that have lost moderate amounts of tooth structure, if the buccal wall is intact and well supported by sound tooth structure. Anterior partial veneers are rarely suitable for restoring damaged teeth, but they can be used as retainers, offer a conservative approach to reestablish anterior guidance, and can be used to splint teeth

11. Situations that tend to having good long-term results are patients who have: A well-developed occlusal arch form A balanced occlusion Spacing between teeth ( diastema ) Discolored dentition Symmetric gingival architecture Minimal to no existing anterior restorations.

12. CONTRAINDICATIONS Teeth exposed to heavy occlusal forces, eg , moderate to severe wear owing to bruxism . Severely mal-positioned teeth. Presence of soft tissue disease. Highly fluoridated teeth: such teeth may resist acid demineralization and give rise to retention issues. Teeth in which color modification can be successfully achieved with various bleaching techniques. Teeth with extensive existing restorations.

13. PREDETERMINING FACTORS Various predetermining factors play important roles in the evaluation and decision-making process of the treatment planning of each case. These are :- Tooth Position - if the teeth are intact, their improper alignment, rotation, lingual or labial position will play an important role in treatment planning (aesthetic pre- recontouring ). Gingiva - to avoid gingival asymmetry and to maintain the height of the interdental papillae. If this is not carefully evaluated, the formation of black holes at the gingival embrasures will be unavoidable

14. 3. Gingival Margins – the laminate veneer's ideal margins are preferably located on the enamel and away from the gingiva . In the case of a high lip-line, may necessitate the overextension of the preparation margins. 4.Occlusion - Occlusal relations, heavy function or parafunction play vital roles. Severe parafunctional habits or unfavorable occlusal relations- full ceramic or porcelain-fused-to-metal crowns may be considered the preferred choice.

15. TREATMENT PLANNING Indications for veneers present ?? Absolute contra-indications present ?? Less than 50% enamel for bond, weak tooth or severe malposition Color/ contour abnormality slight?? Fixed or Removable Prosthetics, Orthodontics, Orthognathic surgery Bleaching, Cosmetic Contouring Esthetic fillings NO NO YES YES YES

16. Color/ contour abnormality slight?? Does the patient have conditions:- Bruxism Severe discoloration Single unit Limited finances? TREAT WITH PORCELAIN VENEER TREAT WITH DIRECT COMPOSITE VENEER NO NO YES

17. PRELIMINARY TOOTH MODIFICATION Shade selection A shade is selected from a porcelain system that is one half shade lighter than the desired shade. This allows for a slight darkening attributable to increased translucency with polymerization of the composite luting agent. Done when the tooth had not been dried out and this should be done in daylight.

18. Correction of pre-existing restorations, defects or contour abnormalities. Contouring deficiencies greater than 1 mm - resulted from caries, erosion or attrition - restored with glass ionomer cement. When class III is present - remove filling prior to bonding to expose margins that are then etched and sealed with the bonding composite. If incisal lengthening is desired- laminate incisal margins terminate at the facio-incisal angles.

19. DIAGNOSTIC WAX-UP With the mounted casts on the articulator, the teeth to be veneered are waxed up to ideal contour and occlusion. Serves as an evaluation of the potential esthetic and functional outcome. This wax-up also allows the dentist to show the patient a preview of the expected final outcome. Can be an excellent communication tool to ensure that the dentist and ceramist have a good understanding of the patient’s esthetic goals, and that the patient’s goals can be achieved.

20. TYPES OF VENEERS Direct Veneers Composite resin veneers which are free-hand placed. Indirect Veneers 1. Conventional powder-slurry ceramic ( feldspathic porcelain). 2. Heat-pressed ceramic. (e.g. IPS Empress 1 and 2,). 3. Machinable (CAD/CAM) ceramics (e.g. CEREC).

21. FELDSPATHIC VENEERS Feldspathic veneers are created by layering glass-based (silicon dioxide) powder and liquid materials. Silicon dioxide, also referred to as silica or quartz, contains various amounts of alumina. When these aluminum silicates are found naturally and contain various amounts of potassium and sodium, they are referred to as feldspars. GLASS-BASED CERAMICS Glass ceramics may be ideally suited for use as dental restorative materials. Their mechanical and physical properties have generally improved, including increased fracture resistance, improved thermal shock resistance, and resistance to erosion. They may be opaque or translucent, depending on the chemical composition and percent crystallinity

22. TOOTH PREPARATION Conventional and current popular practice for conservative veneer preparation is to remove 0.5 mm of tooth structure to create room for the placement of 0.5 mm of porcelain on the facial surface. PROCEDURE :- Labial Reduction Proximal Reduction Sulcular Extension Incisal Reduction Lingual Reduction

23. 1. Labial Reduction- Since the amount of enamel decreases at the cemento -enamel junction, some teeth permit less reduction at the gingival finish line to a standard of 0.3 mm and the reduction at the incisal half and incisal edge to a standard of 0.5 mm. The two diamond cutting burs of diameters 1.6 mm (depth cut 0.3mm) and 1.0 mm (depth cut 0.5mm) will create the exact depth orientation grooves and the remaining tooth structure is removed with round end tapered diamond. The tip of the diamond establishes a slight chamfer finish line at the gingiva .

24. The depth cutter can only penetrate until the non-cutting shaft is flush with the tooth surface The surface after the depth cutter is used in only one angle. Note that the only true depth is gained in the area of B (middle 1/3rd, black dots). To reach the necessary depth on points A (gingival 1/3rd, green dots) and C (incisal 1/3rd, red dots), the bur should be used in three different angulations

25. 2. Proximal reduction - Proximal extension is just a continuation of facial reduction with the round end tapered diamond. Adequate reduction is recommended at the line angle and uneven finish line is avoided by keeping the bur parallel with the long axis of the teeth .

26. 3. Sulcular Extension – The gingival margin is prepared using a chamfer diamond where the amount of reduction is slightly less, owing to the thinness of the enamel in this area. The gingival margin can be placed supragingival , at the height of tissue, or subgingival . This margin determination is dictated primarily by the esthetic goals. Ideally, subgingival margins should be avoided unless necessary because of the existing tooth color that needs to be blocked out and/or a dramatic change in the higher value of the porcelain shade requested.

27. 4. Incisal reduction - There are two techniques for the placement of incisal finish line. The one in which we are terminating our preparation at the incisal edge and the second technique in which the incisal edges slightly reduced and the porcelain overlaps the incisal edges. The multiwheel diamond burs are used to create 0.5-mm deep orientation grooves in the incisal edge and the remaining tooth structure is removed by round end tapered diamond.

28. It is better if the incisal overlap is incorporated into the preparation. It will not only improve the esthetic effects such as translucencies, but also improve the mechanical resistance of the veneer. (b) The bur is held 90 degrees to the incisal edge and the necessary preparation is done.

29. Lingual reduction- Lingual finish line is created by round end tapered diamond by holding the bur parallel to the lingual surface and forming a slight chamfer of 0.5-mm deep. Moreover, the lingual finish line depends on the thickness of the teeth and the patient’s occlusion. Finishing is done further.

30. There are four basic preparation designs that have been described for the incisal edge: • Window, in which the veneer is taken close to but not up to the incisal edge. This has the advantage of retaining natural enamel over the incisal edge, but has the disadvantage that the incisal edge enamel is weakened by the preparation. • Feather, in which the veneer is taken up to the height of the incisal edge of the tooth but the edge is not reduced. This has the advantage that once again guidance on natural tooth is maintained but the veneer is liable to be fragile at the incisal edge and may be subject to peel/sheer forces during protrusive guidance

31. • Bevel, in which a bucco -palatal bevel is prepared across the full width of the preparation and there is some reduction of the incisal length of the tooth. This gives more control over the incisal aesthetics and a positive seat during try in and luting of the veneer. • Incisal overlap, in which the incisal edge is reduced and then the veneer preparation extended onto the palatal aspect of the preparation. This also helps to provide a positive seat for luting whilst involving more extensive tooth preparation. This style of preparation will also modify the path of insertion of the veneer which will have to be seated from the buccal / incisal direction rather than the buccal alone.

32. PROVISIONAL RESTORATION Provisional restorations for laminates may not be essential as there is no exposure to the dentin and the proximal contacts are maintained. However, most often it may be necessary for the patient to maintain their social engagements and if the proximal contacts are broken. The two methods of provisionalization include - Direct method using composite resin with central spot etching and autopolymerizing acrylic resin and Indirect method after the cast fabrication

33. Direct method using composite resin with central spot etching or autopolymerizing acrylic resins

34. 2. Indirect method after the cast fabrication

35. TRY IN Major three steps in try-in procedure include: Dry try-in for marginal fit Wet try-in for proximal fit Resin cement try-in done for color matching

36. SUBSTRATE TREATMENT The enamel surface must be conditioned with phosphoric acid (37%). This procedure increases the surface energy of the structure, which leads to a perfect wetting of the surface with the bond. At this stage, care must be taken to avoid contamination with saliva, which can reduce the surface energy of the enamel. Therefore, isolation with a rubber dam is highly recommended, which lowers stress input during the clinical procedure

37. Steps for treating the inside of the veneer and the tooth surface just before bonding.

38. LUTING CEMENTS The clinical success of laminate veneers depends on the cementation of the indirect restorations, among other factors. Due to the inherent brittle nature of ceramics, adhesive cementation is used to improve fracture resistance by penetrating flaws and irregularities on internal surfaces, minimizing crack propagation, and allowing a more effective stress transfer from the restorative to the supporting tooth structure. Luting cements may be classified into two subgroups: cements associated with the use of conventional or self-etching adhesives, and self-adhesive cements, which do not require any prior conditioning of the tooth structure.

39. Technique When bonding the veneers one by one or as pairs, it is always better to place the luting resin inside the veneer to ease the control. A brush can be used to evenly distribute the composite inside the veneer After the inside of the veneer is loaded with the translucent luting resin, it is brought next to the tooth with the sticky pole, Once slightly seated from the incisal corner, it is then pushed apically and palatally with gentle finger pressure. The excess luting resin should be seen on all the margins, confirming that enough material is used

40. MAINTENANCE Success of any restoration depends on how the patient maintains it. Maintenance on the other hand should be a combined effort of dentist as well as the patient. Patient should be motivated: To avoid ultrasonic scaling and to undergo routine hand scaling. Abrasives and highly fluoridated toothpastes should be avoided. Excessive biting forces and nail biting and other habits should be under control. Soft acrylic mouth guards can be used during contact sports

41. FAILURES Three types of failures are reported :- Mechanical - Fracture - poor positioning of incisal margin, less incisal thickness, margins too subgingival . Debonding - use of expired cement, faulty veneer Biological - Postoperative Sensitivity - improper curing of cement, poor marginal adaptation Marginal Microleakage - poor fit and extension

42. Aesthetic - Improper Shade Selection Gingival Recession - improper subgingival placement and overcontouring .

43. CONCLUSION The clinical success of laminate veneers depends on both the suitable indications of the patient and the correct application of the materials and techniques available for that, in accordance with the necessity and goals of the aesthetic treatment. Evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case.

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