Biomechanical Aspects Investigation of Endodontically Treated Tooth/Implant-Supported System by Using Fea, Reliability Fracture Probability Calculation and in vitro Ae Fatigue Testing (I)

Structure strength is a major complication for endodontically treated teeth that usually restored with post and core to recover its function. While endodontically treated tooth is splinted to an implant in edentulous region for some clinical situations, complex biomechanical aspects of a endodontically treated tooth/implant-supported system are derived from the dissimilar mobility between the osseointegrated implant and the tooth and the weak structure strength of endodontically abutment tooth. Many significant problems such as, loss of osseointegration, abutment screw loosening and prosthesis fracture arise due to the higher bending moment caused by the cantilever effect when chewing forces are applied on the system. Furthermore, remaining tooth fracture, adhesive interface debonding between tooth and post and post fracture might also induce by inappropriate ferrule design and compromised periodontal support (not enough post length in alveolar bone). Consequently, the aim of this study will focus on the biomechanical aspects investigation of endodontically treated tooth/implant-supported system under different ferrule designs, levels of periodontal support and designs of the implant-abutment connection (implant type); detail mechanical responses of those system will also compare to natural tooth/implant-supported system and free-standing endodontically treated tooth. Geometries and section contours of alveolar bone, abutment tooth and prosthesis are acquired from CT and Micro-CT to construct the solid models firstly and generate various solid models of endodontically treated tooth/implant-supported systems with two levels of periodontal support (distance from crown tip to alveolar bone: distance from alveolar bone to post base=1:1 and 2:1), three ferrule thickness designs (0.5mm, 1.0mm and 1.5mm) and three different implants (Frialit-2, ITI and Lifecore PrimaSolo) in CAD systems. Solid models are then imported to the finite element (FE) package to generate corresponding FE mesh models and carry out the convergence testing. Non-linear simulated approach by using contact element to simulate the interface adaptation within the implant system and setting visco-elastic material behavior of PDL are performed to calculate the detailed mechanical responses under system receiving various occlusal forces. ANOVA will be used to test for relative importance of the investigated factors and main effects for each level of the three investigated factors in terms of the stress values are performed. The simulated results are also incorporated into the Weibull function to calculate the failure probability for various endodontically treated tooth/implant-supported systems. In order to validate the rational results for biomechanical simulations and reliability analyses, a parallel dynamic fatigue testing will be performed for the cadaver and composite resin samples (fabricate by rapid prototyping and rapid tooling techniques). Strains and acoustic emissions (AE) signals are measured to understand the life time and fracture progress for influences of investigated parameters of endodontically treated tooth/implant-supported systems. Statistic analysis will be used to understand the interactions among numerical simulations (FEA), reliability analysis and dynamic fatigue testing. This study has been arranged for three-years, and the specific aims are as follows: First year: Constructing of various investigated finite element models of endodontically treated tooth/implant-supported systems and performing the pilot non-linear simulations. Second year: Performing the non-linear FE simulations for various endodontically treated tooth/implant-supported systems and reliability failure probability analysis. Three year: Dynamic fatigue testing for endodontically treated tooth/implant-supported systems and statistic analysis.

Project ID:PB9709-3576
External Project ID:NSC97-2221-E182-002