Strain Gauge Analysis of Axial loading in External Hexagon Implants

Objective: The present study used strain gauge analysis to perform an in vitro evaluation of the effect of axial loading on 3 elements of implant-supported partial fixed prostheses, varying the type of implant placement and the loading points.

Method: Three external hexagon implants were straight and offset embedded in a polyurethane block. Microunit abutments were connected to the implants applying a torque of 20Ncm. Prefabricated Co-Cr copings  were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n=5). Four strain gauges (SG) were bonded onto the surface of the block tangentially to the implants, SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments with a 10Ncm torque and an axial load of 30kg was applied at three predetermined points (A, B, C). 

Result: The data obtained from the strain gauge analyses were analyzed statistically by repeated measures ANOVA and Tukey’s test, with a conventional level of significance of p<0.05. The results showed a statistically significant difference for the loading point (p=0.0001), with point A generating the smallest (137.2µε). A statistically significant difference was found for the implant placement (p=0.0001). 

Conclusion:

 It was concluded that the implant placement and the axial loading location did interfere in the magnitude of micro strain.