Stress Distribution Around Dental Protheses Supported by 2 or 3 Implants

Objectives: The present study used photoelastic and strain gauge analysis to compare stress and microstrain perform an in vitro evaluation of the effect of the numbers of support in implant-supported fixed partial denture (FPD) with three elements.
Methods: Two polyurethane blocks: model 1 contain three implants and the second block (model 2) two of them, all implants have a external hexagon (3,75X 13mm). Then, the master models were duplicated in photoelastic resin. Microunit abutments were connected to the implants and received a 20 Ncm torque. Over the master model plastic prosthetic cylinders were screwed the abutments that received standard patterns cast in Ni-Cr alloy (n=10). Four strain gauges (SG) were bonded in the surface of the block, tangentially to the lateral implants. On the master model and photoelastic model, each metallic structure were screwed onto the abutments with a 10 Ncm torque. The data obtained from the strain gauge were analyzed statistically by RM ANOVA and Tukey's test, with a 5% conventional level of significance. The isochromatic fringes obtained in the photoelastic models after each load condition were recorded with a digital camera
Results: There was statistically significant differences in support of FPD( p=0,001).The results demonstrated that 3 implants has higher stress distribution and in the pontic of FPD we found higher difference 2326,950µε in 2 implants and 1006,574 in 3 implants).
Conclusions: Both methods found similar results. This study suggests that FPD can be supported by two or three implants.