Preparation Design Selection For Porcelain Veneers Manufacturing: A Review

Due to high aesthetic qualities, proven biocompatibility and prognosis for long term durability, porcelain veneers have become a routine restorative procedure for frontal teeth treatment. From a mechanical point of view, porcelain veneers are fragile and brittle before cementing. After fixation they gain the necessary pressure strength, and become more tensile and resistant to bending, which guarantees their clinical longevity. Besides the strength of the material, the mechanical resistance of the veneers will also depend on the preparation design, which altogether will withstand the occlusal and lateral forces during mastication. An important decision that has to be made before starting preparation is to choose one of the four types of preparations. The actuality of the issue and more frequent use of veneers in everyday clinical practice, require vindicating and clearly define the type of preparations that will give better performance on fixed-prosthetic works. Reviewing the literature, we recognize that there are many ambiguities and controversies about the preparation designs, especially for incisal overlap. All of the described types of preparations have their strengths and weaknesses, but the latest studies promote incisal overlap preparation as the best. Long-term clinical trials and in vitro tests are required in order to clarify the dilemma.