Multi-Factorial Investigation of a Cusp-Replacing Adhesive Premolar Restoration by CEREC System

A large field of compromised premolar, such as a remaining fractured tooth after extensive MOD restoration is a common and complicated clinical biomechanical problem. Generally traditional restorative methods (direct and indirect) are employed exhaustively to repair the compromised tooth. In recent years, CAD/CAM (CEREC) technology has added the new option of producing chairside ceramic restorations for repairing a large decimated tooth. However, the long-term success and retention of a ceramic restoration relates to the mechanical integrity arising from the restorative engineering design, especially for MODL cavity. The objective of this study was therefore to investigate the biomechanical interactions among restorative materials, cuspal preparation designs, and cement thickness in a cusp-replacing adhesive premolar restoration. Twenty Seven, 3D finite element (FE) models designed in a typical MODL restoration with three restorative materials (CAD/CAM ceramic block, indirect resin composite and glass-ceramic), four cavity preparation designs (without coverage design and buccal cuspal reduction of 1.0 mm, 1.5 mm and 2.0 mm in cuspal height) and three cement thicknesses (50 μm, 100 μm and 150 μm) will be constructed to perform the finite element (FE) simulations. The ANOVA test will be performed to determine the relative importance of the investigated factors and main effects for each of the three investigated factor levels (restorative material, preparation design and cement thickness) in terms of the principal stress values. A parallel fundamental tension-compression experiment will be performed and the strains and displacements measured to validate the intact premolar simulation results. In order to validate the rational results for biomechanical simulations, another dynamic fatigue testing will be conducted to estimate the fracture strength for all restorations. The results from this study are expected to clarify the biomechanical principles involved in traditional and CEREC restorations for compromised premolars and provide significant issues and design rules for clinical applications.

Project ID:PB9808-3424
External Project ID:NSC98-2622-E182-001-CC3