Influence of Simulated Bone Quality and Cortical Bone Thickness on Implant Stability Detection Using Resonance Frequency and Damping Factor Analysis

Purpose: The aim of this study was to test whether damping factor is an adequate parameter for monitoring the status of the trabecular bone-implant interface. Materials and Methods: Implants were placed in epoxy resin with elastic moduli of 2,900, 210, and 1.4 MPa to simulate cortical bone, cancellous bone, and connective tissue, respectively. Resonance frequency and damping factor (DF) values of the tested implants were measured using vibration analysis. An impulse force was used to induce vibration within implants. The DF values of the tested implants were calculated from the obtained frequency spectrum using a half-power method. The resulting data were analyzed to test the statistical effects of the cortical height and trabecular status on the DF values of the sample implants. Results: When the simulated tissue at the implant-bone interface changed from connective tissue to bone, the detected DF value decreased markedly. In addition, the mean DF value of the tested implants increased significantly (P .05) from 0.043 ± 0.008 when the elastic modulus of the surrounding resins was 2,900 MPa to 0.114 ± 0.018 when the modulus was 1.4 MPa. Furthermore, when the tested implants were firmly fixed with 2 mm of simulated cortical bone, the alternation of healing tissue at the trabecular bone area could be detected by the DF method. Conclusion: DF is a sensitive measure for monitoring the status of oral implant osseointegration when implant boundary conditions are good at the cortical level but still weak at the trabecular bone area. Keywords: damping factor, ISQ, implant, osseointegration, vibration analysis