The Efficacy of Convergence Angle on E-Max Restorations Retention Bonded with Adhesive Bioactive Cement Vs Adhesive Resin Cement : (An In Vitro Study) /

Abstract

Fixed prosthodontic dentistry have experienced great advances in numerous features like; preparation design, luting cements and dental materials. One of the most significant parameter influencing the success rate and life span of the fixed restoration is the preparation design. Where the convergence angle of the tooth play a major role for the success of the final restoration. Fundamental standards of crown retention were built up on the geometric principals of arrangements, for example, convergence angle, height, and surface area. By decreasing the convergence angle and increasing both the preparation height and the surface area, the retention is increased. The primary function of the luting cement in the success of the fixed restoration is to keep the crown retentive in its place; contingent upon either conventional, adhesive resin, or recently bioactive cements. Glass ionomer cement have been known for their ease of application, however their main disadvantage was the early inadequate strength and toughness as it takes 48 hours to reach its full strength. Lately, adhesive resin cements have gained popularity as they rely upon the concept of adhesion; adhesion to tooth structure (enamel and dentin), and to the indirect restoration. In spite of the advancement of various luting cements, there was lack of bioactivity property and sealing capacity against bacterial leakage that inhibits secondary caries and thus, causing failure of the restoration. As bioactivity is defined as: Materials forming a surface layer of an apatite-like structure in the presence of an inorganic phosphate solution. Numerous formulas of bioactive cements were presented like calcium aluminate and calcium silicate agents to form hydroxy-apatite, remineralize the tooth and seal the tooth/crown interface for a successful restoration. Nowadays, the type of the crown material is shifted to high esthetic option represented in ceramic restorations with variety of types and techniques of manufacturing. One of the most utilized ceramic restoration is the E-max crowns. It is a ceramic material that consolidates great mechanical properties and incredible esthetic outcomes. E-max is indicated for single crowns, veneers and inlays. It can be pressed or milled. Therefore, this study aimed to assess the efficacy of convergence angles on the retention of E-max crowns bonded with adhesive bioactive cement versus adhesive resin cements.