Purpose: The aim of this study was to assess the effect of platform switching, using 3 different abutment sizes on the strain developed around implants supporting mandibular overdenture, using strain gages.
Materials: An implant-supported overdenture was constructed on an acrylic model with 2 implant fixtures placed at canine areas. Abutments of different sizes (5.5 mm, 4.5 mm, and 3.5 mm diameter) were screwed in the implant fixtures (platform switching). Anterior axial, anterior off-axis (lateral), and posterior load were applied on each abutment through a load applicator attached to the upper compartment of a universal testing machine until a load of 100 N, at which instant, the resultant strain on the implants was recorded using 4 strain gages connected to a 4-channel strain indicator. Data were analyzed by 1-way ANOVA at a significance level of 0.05, followed by Tukey-Kramer multiple comparisons test.
Results: Anterior axial load application and decreasing the abutment size lead to a decrease in the strain developed on the loaded abutment and to an increase in the strain developed on the unloaded abutment. Anterior off-axis load application and decreasing the abutment size lead to an increase in the strain developed on the loaded abutment and to a decrease on the unloaded abutment. On the other hand, posterior load application and decreasing the abutment size lead to an increase in the strain developed on the mesial side of the near abutment and a decrease in the strain developed on its distal side, where there was a significant increase in the strain developed on the mesial and distal sides of the far abutment.
Conclusion: The distribution of the strain developed because of decreasing the abutment size does not favor the use of platform switching in an implant-supported mandibular overdenture.