Bone Microstrain Values of 1-Piece and 2-Piece Implants Subjected to Mechanical Loading

Purpose: The purpose of this study was to measure and compare the strain levels in peri-implant bone as generated by 1-piece (1P) and 2-piece (2P) implant systems. Materials and Methods: The implants (1P and 2P) were placed into bovine bone according to the manufacturer's protocol. Four linear strain gauges were placed around each implant neck and apex. Each model was loaded in static loading by a material testing machine in ascending forces ranging from 20 to 120 N. Microstrains (mu epsilon) generated in the surrounding bone were measured by a strain gauge and recorded. Results: Recorded microstrains were significantly higher for 1P implants than for 2P implants. Average recorded microstrain values were significantly lower in the neck (71.6 and 17.3 mu s) compared with the apical (132 and 60 mu s) regions of 1P and 2P implants, respectively (P < 0.0001). Conclusions: Within the limitations of this study, highest microstrains were generated in apical regions regardless of implant design, but the 2P implant appeared to provide a stress-damping effect in both the cervical and apical regions compared with the 1P implant.