Photoelastic Analysis of Morse Taper Implants Positioned Equicrestal and Subcrestal

Objectives: This study aimed to evaluate, by photoelastic analysis, the stresses generated by loads applied to the posterior implant supported crowns with teeth adjacent to the implant or not.
Methods: Morse taper implants (Ankylos®Dentsply Implants) with 3.5mm x 9.5mm were used. The teeth were made with Luxatemp resin and ceramic crowns were fabricated for implants. Three models containing tooth – implant – tooth were built, where each model had the implant in different heights from the marginal bone crestal level (equicrestal, 1.5 mm and 3.0 mm from the crest). Subsequently, other three models were made with the same characteristics, but the second molar was absent. Another three models presenting only the implant in position were obtained.
Results: Models with three elements under axial loading (balanced occlusion) presented stress in direction to the apical region as the implants were more subcrestal. The same behavior was noted for other models: models with two elements under axial loading (balanced occlusion), models with single implants under axial loading (central point or distal point) , and models with single implant without axial loading (buccal - lingual). The difference among models was only observed for the intensity of the stresses in some regions.
Conclusions: Thus, it can be concluded that the positioning of the implant in a subcrestal region decreases the stress in the crestal region regardless of the presence or absence of adjacent teeth. In addition, the presence of adjacent teeth influences on the stress intensity generated around the implants, but the direction of these stresses is not affected.