Terminações marginais em coroas ocas de porcelanas e resinas especiais.

Abstract

Literature research demonstrates the importance of the marginal termination according to the type of material used in the restoration of a tooth, whether a hollow crown of porcelain or a special resin. Whether the treatment requires traditional feldspathic porcelain, melted glass porcelain, aluminized porcelains processed by computer, special resins with aesthetics and resistance similar to porcelain, the professional needs to know which type of marginal termination to prepare to be used for each case. The objective of this work is to verify possible differences in the characteristics of marginal terminations, regarding grinding and the type of cervical end used for porcelain and special resin hollow crowns, as well as their indications. I also make a comparison between the marginal terminations of the researched materials, the form of preparation, and the amount of grinding to achieve success in the clinical treatment. When a porcelain or special resin hollow crown is indicated, with or without internal reinforcement, the grinding of the cervical end in the preparation should have at least from 0.8 to 1.0mm. However, due to the natural convexity of the axial walls of the teeth, the grinding in the medium third will always be larger. The more convex the tooth is, the larger the grinding on its medium third. The difference will be in the type of recommended marginal termination, whether deep chamfer or shoulder. The end type recommended for aluminized porcelain hollow crown (In-Ceram, Procera) is deep chamfer. In the Procera system, these terminations facilitate the scanning of the preparation. For hollow crowns in feldspathic porcelain, ceramic glass and special resins the shoulder marginal termination with rounded internal angles is indicated, because it better dissipates the occlusals forces, decreasing the risk of crown fracture.