Effect of a Bilateral Cantilever Bridge Design as an Alternative to a Conventional Three-Unit Bridge on Peri-Implant Strain Distribution

Aim: This study aims to compare the biomechanical behavior of different implant-supported fixed dental prosthetic designs using strain-gauge analysis under varying loading conditions.

Materials and Methods: Polyurethane blocks (N = 4 ) were used as a bone simulator, while a 3D-printed resin served as the bridge material. The loading points included the first premolar, second premolar, and first molar individually, as well as combined at all three points. The first design was a standard three-unit bridge on two implants with a central pontic. The second used a single implant with a bilateral cantilever. The third was a three-unit bridge on two implants with a mesial cantilever, and the fourth was a similar bridge with a distal cantilever. Eight linear strain gauges were bonded to the polyurethane blocks adjacent to the implants. All designs were subjected to loading using a universal testing machine. Vertical (0°) loads ranging from 0 N to 100 N were applied to each design. Each specimen was tested 10 times per loading condition. The mean and standard deviation of the micro-strain values were compared using one-way ANOVA with post-hoc Tukey tests (p < .05).

Results: The results showed statistically significant differences (p < .05) in strain values among the prosthetic designs under different loading conditions. When subjected to loading at the first premolar, the bilateral cantilever generated the highest overall strain, measuring 973 (78) microstrain. The second-highest microstrain value was also observed in the bilateral cantilever during loading at the first molar, measuring 914 (63) microstrain. The lowest strain was recorded for the mesial cantilever bridge, with 78 (96) microstrain when loaded at the second premolar position.

Conclusions: Prosthetic design significantly affects how stress is transferred from implants to the surrounding bone simulator material. The bilateral cantilever generated the highest strain under first-premolar loading. Due to its less favorable biomechanical behavior, the bilateral cantilever design should be used with caution.