Abstract
The purpose of this study was to photoelastically compare the load transfer characteristics of a distal extension RPD of periodontally compromised abutments with and without implant assisted support in the posterior of a mandible. Two composite photoelastic models of a mandible that included reduced periodontal support of the connected canines and first premolars bilaterally were constructed with different simulants for teeth, bone and periodontal ligament. In one model threaded implants, 3.75mm diameter 7mm length, (Nobel Biocare) were embedded 20mm distal to the first premolars on the posterior edentulous ridges. I-bar partial dentures with mesial rests and distal guide planes were fabricated and physiologically adjusted to the models. The implant support conditions tested were support of 4mm healing abutments. Simulated vertical and lateral occlusal loads were applied at the first molar position and the stresses developed in the abutment teeth and surrounding bone were monitored photoelastically. Both vertical loads and lateral loads, applied to the denture base supported by implants with healing abutments generated high stress concentrations around the apices of ipsilateral implant and the abutment teeth. Posterior implants with healing abutment in the posterior of a mandible tended to assist support of periodontally compromised abutment teeth. of a distal extension RPD.
