Loading of three unit implant-supported prosthesis: strain gauge measurements

Objectives: This study evaluated deformations occurring in a three-unit implant-supported prosthesis made linearly and offset.

Methods: We made 2 polyurethane blocks with an elasticity modulus similar to that of medullary bone, where 3 implants (4 x 13 mm; numbered 1, 2, and 3, right to left), parallel and 7 mm apart (center to center) were positioned linearly and offset, with the medium implant offset by 2 mm. Micro-unit abutments were positioned with 20 Ncm. On these blocks, 5 bars (n=5) were made, simulating three-element implant-supported prostheses. Measurements were performed by 4 strain gauges placed on the superior surface of the polyurethane block (Excel Sensores, Brazil). The measurements were carried through a load application of 100 N during 10 sec in 2 different positions: (A) implant 1, left side; and (B) between implants 1 and 2. The data in µe (micro strain) were subjected to statistical analysis by ANOVA and Tukey's test.

Results: The values in µe for the linear prosthesis at positions A and B were, respectively, 243.4 ± 166.82 and 167.9 ± 125.59, and for the offset prostheses were 99.8 ± 15.03 and 97.7 ± 9.57. We verified by ANOVA that the effects of interaction (p = 0.069 > 0.05) and position (p = 0.626 > 0.05) were not statistically significant, but that the configuration was significant (p = 0.010 < 0.05).

Conclusion: The linear pattern had higher values (in µe) than the offset, and there was no significant difference between positions in the linear and offset configurations.