Laminate Veneers PDF

Laminate Veneers by Dr. Mai Salah Objectives 1) Definition 2) Advantages & Disadvantages 3) Indication & Contraindication 4) Factors affecting the bond interface 5) Diagnosis and Treatment Planning 6) Teeth Preparation 7) Impression 8) Provisional Restoration 9) Try-in 10...

Laminate Veneers by Dr. Mai Salah Objectives 1) Definition 2) Advantages & Disadvantages 3) Indication & Contraindication 4) Factors affecting the bond interface 5) Diagnosis and Treatment Planning 6) Teeth Preparation 7) Impression 8) Provisional Restoration 9) Try-in 10) Cementation 11) Porcelain Materials for Veneers Definition § Laminate veneering is a conservative method of restoring the appearance of discolored, pitted, or fractured anterior teeth. § They are thin-bonded ceramic prosthetics that restore the facial surface and part of the proximal surfaces of anterior teeth that require esthetic treatment. § A critical issue for the long-term success of these restorations is the adhesive cementation.  Advantages Disadvantages 1. Esthetic >>> allow light transmission (natural appearance) 2. Effective color change when bleaching is ineffective 1. Technique sensitive 3. Durability (biological, mechanical and chemical) 2. Irreversibile 4. Tooth conservation (confined to enamel layer). 3. High Cost 5. Shape, position and surface appearance can be modified 4. Preparation requires great skills 6. Preserves periodontal health due to supragingival finish line 5. Lack of repairability (minor tissue damage during preparation and impression) 6. Difficult provisionalization and color 7. Speed and simplicity matching 8. No anaesthesia and temporary restoration needed  Indications 1) Discolored nonvital teeth. 2) Front teeth with extensive cervical restorations. 3) Stains not removed by bleaching or micro abrasion. 4) Color defects and abnormalities: a) Amelogenisis imperfecta. b) Tetracycline discoloration. c) Physiological aging. d) Trauma. 5) Shape abnormalities: Microdontia and Malformation.  Indications 6) Alteration in tooth color. 7) Closing a diastema. 8) Correct minor malpositioing: Rotation & Angulation 9) Tooth lengthening 10) Anterior guide rehabilitation 11) Psychological needs of the patient 12) Structural and texture abnormalities: a) Fracture (incisal third). b) Abrasion. c) Erosion. d) Attrition Amelogenesis Imperfecta restored with Porcelain Laminate Veneer  Veneers instead of Orthodontics § Slightly malpositioned teeth can alternatively be treated with veneers. § After wax build-up, it was clear that teeth could be reconstructed with veneers very well.  Reconstruction of Reconstruction of Lower Fractured Front Teeth Incisor  Contraindications 1. Bruxism or parafunctional habits (success rates for veneers drop to 60% with bruxism) 2. Short teeth due to severe attrition 3. Teeth with inadequate enamel for sufficient retention (e.g., severe abrasion or erosion) 4. Existing large restorations. 5. Endodontically treated teeth with little remaining tooth structure. 6. Severe malignment (Needs ortho or full coverage restoration) 7. Severe Discoloration. 8. Bad oral habits causing excessive stress on restorations (e.g., nail/pencil biting) 9. Poor oral hygiene Factors Affecting Bond Interface  1) Dental Substrate Tooth preparation should always be as minimal as possible because this will preserve a larger amount of remaining enamel providing greater strength, as flexion of teeth may be related to veneer fractures and debonding. There is an increased risk of failure when veneers are bonded to large amounts of exposed dentin or on an existing restoration. Supragingival preparations also had a positive effect on the survival rate of porcelain veneers. 2) Ceramic Material Ceramics that contain a high percentage of vitreous glassy phases, which can be acid etched and silanized, have the best bonding behavior. Glazed ceramic improved color stability, abrasion resistance and tolerated by gingiva. Etching with hydrofluoric acid improve the bond strength between luting materials and the veneer. 13 3) Resin Cement Total etch adhesives is highly recommended. The polymerization and the hardness values of cements are the result of the nature of the cement (dual, chemical, or light-polymerizable types). A light-polymerized luting composite resin is preferred for cementation of ceramic veneers, because it provides longer working time and greater color stability. Dual-cure composite might be preferable in certain cases, especially in ceramics with the use of more opaque substructures. 14  3) Resin Cement § Adhesive cementation technique is sensitive and associated with a high incidence of postoperative sensitivity.. § Self-polymerized and dual-polymerized resin cements can darken with time, leading to undesirable changes in the color of the veneer. § Viscosity to allow for the suitable thickness of the cementation line and the complete settlement of the restoration  Proper diagnosis of causes for color changes of the Diagnosis and teeth. Treatment Planning Rubber index for evaluation Proper Oral hygiene adaptation. of the preparation. Diagnostic wax-up. Thorough professional tooth cleaning. Study models are prepared. Teeth Shades are recorded. Complete set of intraoral Intraoral radiographs and panorama. photographs. § A diagnostic wax-up is recommended to evaluate the need for orthodontic treatment, crown lengthening, gingival recontouring, and occlusal scheme evaluation and adjustments. § Tooth whitening and orthodontics should be included in the treatment plan discussion. § Completing veneer restorations following orthodontics is an excellent way to conserve tooth structure while enhancing esthetics. Veneer Preparation  Goals of Preparation 1. To generate sufficient space for the veneer, luting cement and opaque material 2. To remove convexities and provide a path of insertion without undercuts 3. Marginal integrity (definite chamfer seat to guide veneer placement) 4. To prepare a receptive enamel surface for etching and bonding to the laminate by removal of outer fluoride rich layer 5. To allow sulcular margin placement in severely discolored teeth A putty index (reduction guide) is essential for ensuring adequate and uniform porcelain thickness for veneers if the labial contours require modification.  1) Labial Preparation § There are several methods to gauge the amount of enamel removed, one of the most effective being the LVS depth cutter diamond. § This diamond stone will create horizontal striation or depth-cut groove on the labial aspect of the tooth. § The depth of the cut is limited by the shank which comes to rest on the surface of the uncut enamel between striation. § The LVS has two dimension (0.5 and 0.3mm).  1) Labial Preparation § Alternative method for gauging amount of enamel reduction >>> use no. 1 round bur. § The depth from the peripheral aspect of the bur to the shank is 0.4mm. § Hold the bur at a slight angle so that indentation can be made into the enamel to the depth limited by the base of the shank. § 0.3-0.5 mm of the entire labial surface is to be removed. § In case of deep discoloration labial preparation might extend to 0.8 mm.  1) Labial Preparation Remove the remaining enamel to the depth of the original grooves. The preparation should remain within the enamel especially at all peripheral marginal areas to ensure adequate seal. Sometimes, to facilitate cosmetic alignment, some dentin is exposed but margins remain on enamel. Therefore, a good general rule >>> ensure that over 50% of preparation is on enamel. 1) Labial Preparation Bulk reduction is done with coarse diamond in order to facilitate added retention and better refraction of the light. At the marginal area >>> use a fine-grit diamond to create a definite, smooth finish line to enhance the deal at the periphery. Done with LVS two grit diamond bur which has two different grit diamond. Chamfer finish line will be created (0.3 – 0.5 mm.) 27  2) Proximal Preparation § Margin of the laminate should be hidden within the embrasure area by extending the preparation about halfway into the interproximal contact areas. § This should be done without cutting through the contact point. § It also ensures the wrap around effect with etched resin bonds to increase bond strength. Management of contact areas depends on the technique used for producing the laminate and on the shape of the contact.  2) Proximal Preparation § Proximal reduction is achieved with the same LVS two-grit diamond-moving the margin into this embrasure area and just lingual to the buccal surface of the interproximal papillae. § Proximal margin >>> Smooth chamfer (0.5 mm deep). § N.B. Proximal contact areas adjacent to diastemata should be opened. Why??  2) Proximal Preparation § With minimal shade difference between the tooth (after preparation) and the desired final restoration is minimal, proximal chamfer finish lines are placed slightly labial (approximately 0.2 mm) to the contact areas of the adjacent tooth. 1. Ease in evaluating marginal fit during the try-in stage 2. Access for performing and evaluating finishing procedures 3. Access for home care (margins in "self-cleansing" area) 4. Ease in evaluating marginal integrity during follow-up and maintenance visits If multiple adjacent teeth are to be prepared....the contact should be opened to facilitate separation of the die without affecting interproximal finish line.  3) Incisal Preparation a. Window Preparation (recommended for most direct & indirect composite veneers) b. Incisal preparation c. Incisal wrap around (1.0-1.5 mm) Variations of Incisal Preparation  3) Incisal Preparation § Incisal reduction should ideally provide for 1 mm of porcelain thickness if it is desired to restore the original length.. § If inciso-gingival height of the final restoration is to be 0.5 mm longer than the existing tooth, only 0.5 mm of incisal reduction is required. § If preoperative teeth are to be lengthened by 1 mm, only rounding of the incisal edge and placement of a finish line are required.  3) Incisal Preparation § Never end the incisal edge where excursive movements of the mandible will cause shearing stress across the junction of porcelain.  Incisal Wrap Around Design § Indicated when tooth lengthening is needed or an incisal defect warrants restorations. § This design has many advantages: 1. Increasing strength (restrict angle of fractured) 2. Placing porcelain in compression rather than in tension. 3. Better esthetics. 4. Act as vertical stops. 5. Increase area for bonding.  4) Sulcular Extension § It is desirable to place the finishing margin just within the sulcus. § The maximum extension needed is 0.5 - 1 mm into the sulcus. § Finish line Configuration >>> Modified chamfer or chamfer (0.3 – 0.5 mm) created by the LVS two-grit diamond. § Tetracycline Stained teeth necessitates placing the finish line subgingivally, since the stain is darkest in the cervical area where the enamel is thin to be reduced.  5) Lingual Preparation § Any reduction of the incisal edge may need some lingual enamel modification so that there is no butt joint at the incisal/lingual junction but rather a rounded chamfer. § In case of overlapping design: 1. Creating 0.5 mm lingual chamfer 2. Extending ¼ the way down the lingual surface.  To Summarize § The amount of tooth reduction should be: a) Labial: Ø Gingival >>> 0.3 – 0.5 mm. Ø Middle and incisal >>> 0.5 – 0.8 mm. a) Incisal >>> 1 – 1.5 mm. a) Lingual >>> 0.5 – 0.7 mm.  Evaluation of Laminate Preparation 1. Even and Adequate Overall reduction 2. Definite Smooth Finish Line-Modified Chamfer 3. Simple Path of Insertion With No Undercut 4. Rounded Line Angle 5. Modification of the Contact Areas Case Scenario Tooth 22 has been discolored after endodontic treatment and will therefore be treated with a veneer. A retraction cord is placed that retracts the gingiva by approx. 1 mm, slightly subgingival preparation is possible. Preparation of depth cuts § Depth cuts which are 0.5 mm deep are prepared with the help of a tapered diamond bur with rounded tip (diameter at the center approx. 1 mm) Preparation of the facial surface § The facial surface is reduced by approx. 0.5–0.7 mm along the depth cuts. § A deep chamfer proceeds around the entire preparation. § The incisal edge is reduced by approx. 1 mm. § If lost front tooth length is to be restored, it is sufficient to level the incisal edge and place the lingual chamfer. Placing a lingual chamfer § After some smoothening of the labial surface, the rounded chamfer has been placed and the incisal edge has been sufficiently shortened. § A lingual, deep chamfer is created. § Chamfer facilitates cementation and increases the strength of the ceramic. Special Situations  1) Pre-existing Class III § Wrapping of preexisting composite restoration is indicated to minimize thermal stresses. § The bulk of the composite restoration creates a contraction pole and induce bending of the veneer  2) Masking Discoloration a) Mechanical removal of discolored areas then treated with application of composite to reestablish the contour of the preparation. b) OR the discolored area is maintained and incorporate a degree of opacity in the ceramic. c) OR use an opaque luting resin for cementation (the result is unpredictable)  3) Thin Teeth § Subjected to more bending stresses compared to thick teeth. § The incisal edge must be reduced more than 1.5 mm to create an optimal thickness of incisal porcelain Impression A vinyl poly-siloxane-based impression material is typically used in a custom or stock tray for veneer impression preparation. The retraction cord is positioned to expose the finish line. For CAD/CAM veneers, a digital impression is made with an appropriate scanner. Provisional Restoration Crystal-clear celluloid crowns are suitable as ready-made crowns or transparent plastic mold made on the waxed up model.  Cementation of Provisional Restoration § Provisional restorations should be made as one piece, with no attempt to separate individual provisional veneers. § Spot-etching at the center of the facial surface, followed by applying a bonding resin at the etched point only and using a small amount of a resin cement for attachment. Tryin  Tryin § Place a water soluble viscus paste or glycerin to hold the laminate and seat it with pulsating movement, then check: 1) Thickness and contour 2)Shade 3)Marginal accuracy § Determine the color of the composite cement  Tryin § Occlusion should be neither checked nor adjusted before the laminates have been bonded. § Occlusion should first be checked in the centric position, and any contacts on the lingual aspects of the newly-cemented veneers must be removed. § Occlusion must be checked in the protrusive mandibular excursion.  Tryin § As porcelain veneers are very thin, they must be handled carefully during the try-in and subsequent cementation. § Excessive finger pressure may cause the veneer to fracture, particularly when a high-viscosity resin cement is used. § Low film thickness is desirable for optimum adaptation to the tooth substrate. Bonding Steps  A. Treating the Interior Veneer Surface § For optimal ceramic–cement bond: a) sandblasting the ceramic surface with aluminum oxide particles b) acid-etching with hydrofluoric acid  Silane Coupling Agent § Silane is a bifunctional molecule that chemically bonds to the hydrolyzed silicon dioxide of the ceramic surface on one side and to the methacrylate group of the resin cement on the other side. § Applied to internal etched surface to increase the shear bond strength. § Facilitate adhesion between inorganic substrate (porcelain) and organic polymers (resin cement) by increasing porcelain wettability (hydrophobic).  B. Treating the Tooth Surface § Rubber dam § Clean the surface § Phosphoric acid etch § Rinse and dry § Apply the bonding agent § Light cure Laminate Placement Instruments  Holding Laminate with Light curing of Light-cured Translucent Tweeer and Plastic Resin Cement Cup Finishing  Failure of Laminate Veneer 1. Chipping & Fracture 2. Poor esthetics 3. Decreased marginal integrity and discoloration 4. Incomplete fit of the laminate 5. Debonding 6. Caries 7. Hypersensitivity and Patient discomfort  Choice of Ceramic Material for Laminate Veneers by Dr. Mai Salah § A material designed to resolve slight alterations in color will be of little help in case of anterior guide restoration in a parafunctional patient. § In order to resolve this problem, a classification of ceramics (based on material composition) is used to define the best option for each case.  Classification of Ceramics According to Material Composition Silicate Ceramics Oxide Ceramics 1. Feldspates 1. Aluminium oxide ceramics a) Conventional feldspates a) Inceram Alumina b) Reinforced with leucite crystals b) Inceram Spinelle c) Reinforced with lithium oxide c) Inceram Zirconia 2. Alumina porcelains 2. Zirconium oxide ceramics  Silicate Ceramics ü Characteried by presence of quartz, feldspate and kaolin – the basic component being silica dioxide. ü Heterogeneous materials composed of crystals surrounded by vitreous phase  1) Feldspates Porcelain § Predominant element is silica oxide or quartz § Subclassified as follows: Conventional Reinforced with leucite Reinforced with lithium oxide o Flexion resistance (320-450 MPa) o Reduced porosity due to interlocking between densely o Very good esthetics o Reproducible fit precision distributed elongated crystals + o Low fracture resistance o Flexion resistance (160-300 increase in crystal size (56.5 MPa) MPa) o Used for inner coping of restorations o Example: IPS Empress I o Example: IPS Empress II  2) Alumina Porcelain o They are the same as the conventional alumina porcelains. o However, proportion of aluminum oxide does not exceed 50%. o These materials are indicated for complete crowns.  Oxide Ceramics ü Polycrystalline materials with little or no vitreous phase ü Due to their great opacity, they are used as internal copings in ceramic restorations.  1) Aluminium Oxide Ceramics 1) In-Ceram Alumina >>> resistance to flexion 400-600 MPa. 2) In-Ceram Zirconium >>> resistance to flexion up to 600-800 MPa. 3) In-Ceram Spinelle >>> has isotropicoptic properties + low refraction index 4) Procera All-Ceram >>> fracture resistance of 680 MPa,  2) Zirconium Oxide Ceramics o Polycrystalline material with a tetragonal structure partially stabilized with yttrium oxide o Indicated for internal copings characterized by absence of porosities o Fracture modulus of 900MPa o Hardness of 1200 Vickers units o Examples: Lava and DC-Zircon oCeramic laminate veneers can be fabricated using glass-based ceramics, aluminium oxide or zirconium oxide ceramics. oSuccessful laminate veneers depend upon clinician ability to select the appropriate material to match ontraoral conditions and esthetic demands.  Fabrication of Veneers 1. Feldspathic porcelain baked in traditional water-slurry method. 2. Castable glass ceramics. 3. Heat pressed ceramics. 4. CAD/CAM processed “factory produced ingots”.  References 1. Color Atlas of Dental Medicine , Aesthetic Dentistry. Josef Schmidseder. 2005 2. Contemporary fixed prosthodontics, Stephen F. Rosenstiel, Martin F. Land, Junhei Fujimoto. Fifth Edition 3. High-Strength Ceramics Interdisciplinary Perspectives , Jonathan L. Ferencz, Nelson R.F.A. Silva, 2014 4. The Science and Art of Porcelain Laminate Veneers, Galip Gurel, 2003 5. Porcelain veneers: An update. Omar El-Mowafy. Nihal El-Aawar. Nora El-Mowafy. Dent Med Probl. 2018;55(2):207–211 6. Fons-Font, A., Solá-Ruíz, M. F., Granell-Ruíz, M., Labaig-Rueda, C., & Martínez-González, A. (2006). Choice of ceramic for use in treatments with porcelain laminate veneers. Medicina oral, patologia oral y cirugia bucal, 11(3), E297–E302.