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Porcelain Laminate Veneers 2 Tariq Alghazzawi, BDS, MS, MSMtE, PhD Assistant Professor and Materials Engineer Departme

Advantages of Preparation vs. Non-Preparation. Achieve long-term successMaximize estheticsImprove fracture resistanceMaintain soft tissue health. Advantages of Tooth Preparation Design with an Incisal Overlap. It improves distribution of incisal load into wide surface area, reducing the stress co

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Porcelain Laminate Veneers 2 Tariq Alghazzawi, BDS, MS, MSMtE, PhD Assistant Professor and Materials Engineer Departme

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    1. Porcelain Laminate Veneers (2) Tariq Alghazzawi, BDS, MS, MSMtE, PhD Assistant Professor and Materials Engineer Department of Prosthetic Dental Sciences  College of Dentistry Taibah University

    2. Advantages of Preparation vs. Non-Preparation Achieve long-term success Maximize esthetics Improve fracture resistance Maintain soft tissue health

    3. Advantages of Tooth Preparation Design with an Incisal Overlap It improves distribution of incisal load into wide surface area, reducing the stress concentration of the laminate veneer as well as increasing adhesive surface area Highton R, Caputo AA, Matyas J. A photoelastic study of stresses on porcelain laminate preparations. J Prosthet Dent 1987;58:157-61. It improves the translucency of the restoration Weinberg LA. Tooth preparation for porcelain laminates. NY State Dent J 1989;55:25–8.  It makes the seating of the veneer easier during cementation Calamia JR. The etched porcelain veneer technique. NY State Dent J 1988;54:48–50. It increases adhesion and the retention surface of the restoration Friedman M. Multiple potential of etched porcelain laminate veneers. J Am Dent Assoc 1987;115(Spec Iss): 83E–87.

    4. Advantages of Window Preparation It allows for the achievement of a restorative strength that is comparable to that of unprepared teeth Hahn P, Gustav M, Hellwig E. An in vitro assessment of the strength of porcelain veneers dependent on tooth preparation. J Oral Rehabil 2000;27:1024–9. It allows a structural resistance to fracture similar to that of unrestored teeth Castelnuovo J, Tjan AH, Phillips K, Nicholls JI, Kois JC. Fracture load and mode of failure of ceramic veneers with different preparations. J Prosthet Dent 2000;83:171-80 Minimally affect the elastic behavior of teeth Better sustaining high dynamic stresses. Hui KK, Williams B, Davis EH, Holt RD. A comparative assessment on the strengths of porcelain veneers for incisor teeth dependent on their design characteristics. Br Dent J 1991;171:51–5.

    5. Disadvantages of Palatal Overlap Preparation design with a long chamfer extending into the palatal concavity is not recommended, since it creates a thin extension of ceramic in an area of maximum tensile stress. Excessive invasion of the palatal surface in the form of a long chamfer has been shown to be a possible cause of failure

    6. Disadvantages of Palatal Overlap Palatal chamfer did not provide increased strength for ceramic veneers; at the same time, however, they stated that the poor performance of this geometry preparation in their experimental study did not imply that such design does not meet the standards for clinical longevity and predictability.

    7. Disadvantages of Palatal Overlap Palatal chamfer appeared to be the weak element which displayed cracks extending to the facial surface of the veneer Castelnuovo J, Tjan AH, Phillips K, Nicholls JI, Kois JC. Fracture load and mode of failure of ceramic veneers with different preparations. J Prosthet Dent. 2000;83:171– 180. Finite element study that extensive chamfering into the palatal concavity must be avoided, due to the accumulation of functional stresses in this area Magne P, Douglas WH. Design optimization and evolution of bonded ceramics for the anterior dentition: a finite-element analysis. Quintessence Int. 1999;30:661–672.

    8. Dual Masticatory Simulator Stappert C , Ozden U, Gerds T, Strub JR. Longevity and failure load of ceramic veneers with different preparation designs after exposure to masticatory simulation. J Prosthet Dent 2005;94:132-9.) Stappert CFJ, Stathopoulou N, Gerds T, Strub JR. Survival rate and fracture strength of maxillary incisors, restored with different kinds of full veneers. Journal of Oral Rehabilitation 2005 32; 266–272Stappert C , Ozden U, Gerds T, Strub JR. Longevity and failure load of ceramic veneers with different preparation designs after exposure to masticatory simulation. J Prosthet Dent 2005;94:132-9.) Stappert CFJ, Stathopoulou N, Gerds T, Strub JR. Survival rate and fracture strength of maxillary incisors, restored with different kinds of full veneers. Journal of Oral Rehabilitation 2005 32; 266–272

    9. Stress Concentration

    10. Stress Concentration

    11. Stress Concentration

    12. Stress Concentration

    13. Stress Concentration Considering the three layers represented in the restorative system analyzed (i.e. porcelain veneer/resin cement/tooth structure): The stress was always concentrated at the level of the incisal margin when using the window preparation It was distributed from the middle third of the buccal surface or from the middle region of the incisal area to the load application area on the palatal surface, when the overlapped chamfer was performed The incisal area is a critical zone in teeth restored by means of porcelain veneers, so the chamfer with palatal overlap preparation provided a more favorable geometry for stress distribution than the window technique.

    14. Feldspathic Porcelain Laminate Veneers Advantages Similar modulus of elasticity (82GPa) to enamel (84.1 GPa) and dentin (18.6 GPa) so better stress distribution (deformation) to the root structure Excellent bonding to resin cement Disadvantages It can not be used for lost tooth structure for more than 2 mm Low marginal integrity Low mechanical properties Difficult to handle Bruxer/clenching patients Translucent so it can not mask severely discolored teeth

    15. Alumina Laminate Veneers Advantages Good mechanical properties Easier to handle It gives support for lost tooth structure more than 2 mm It mask severely discolored teeth Marginal integrity is improved Disadvantages It has much higher modulus of elasticity (418GPa) to enamel (84.1 GPa) and dentin (18.6 GPa) so poor stress distribution and may end up with root fracture Poor bonding to resin cement It is not strong enough to withstand bruxism and unfavorable occlusion

    16. Zirconia Laminate Veneers Advantages Superior mechanical properties Easier to handle Bruxer/clenching patients It gives support for lost tooth structure more than 2 mm Opaque so it mask severely discolored teeth Bright teeth Marginal integrity is improved Disadvantages It has higher modulus of elasticity (210 GPa) to enamel (84.1 GPa) and dentin (18.6 GPa) so poor stress distribution to the root structure Poor bonding to resin cement Opaque material

    17. Zirconia vs. Alumina laminate Veneers Zirconia has lower modulus of elasticity than alumina Alumina is more translucent than zirconia

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