Influence of Prosthesis Designs on Stress at Implant-bone Interface

Objectives:The aim of this study was to evaluate the influence on the stress distribution and the magnitude of stresses at implant-bone interface under different prosthesis design conditions of single molar implant restoration. Methods:MSC/NASTRAN finite element analysis software was used in the study. Six three-dimensional finite element models with different designs of single molar implant restoration were created and analyzed. Model 1: Replacing mandibular first molar with one standard-diameter (4mm×13mm) implant. Model 2: Replacing mandibular first molar with one wide-diameter (5.5mm×13mm) implant. Model 3: Replacing mandibular first molar with two implants (3.3mm×13mm), which parallel to each other. The two implants were placed on bucco-lingual midline of jaw and long axes were perpendicular to the occlusal plane. Model 4: Replacing mandibular first molar with two implants (3.3mm×13mm), which were 5-degree angled to each other. The two implants were placed on bucco-lingual midline of jaw. Model 5: Replacing mandibular first molar with two implants (3.3mm×13mm) that parallel to each other. One implant was placed on buccal site and the other was placed on lingual site. Model 6: Replacing mandibular first molar with one imaginary implant, which simulate furcation in bone as natural molar. Results:Von-Mises stress and maximum compressive stress at bone-implant interface of model 2~6 were much lower than that of model 1. Stress value of model 2 was the lowest, which showed 23.3~36.2% lower than that of model 1. Model 6 was the next, which showed 18.9~30.0% stress lower than model 1. In the other three models, stress value of model 3 was lower than that of model 4 and model 5, the difference between model 4 and model 5 was not obvious. Conclusions: Using wide-diameter implant or two-implant to restore single mandibular molar should be recommended in clinical practice. If adequate bone quantity is provided, using wide-diameter implant should be better.