Monitoring the Changes of Material Properties at Bone-Implant Interface during the Healing Process in Vivo: A Viscoelastic Investigation

The aim of this study was to monitor the changes of viscoelastic properties at bone-implant interface via resonance frequency analysis (RFA) and the Periotest device during the healing process in an experimental rabbit model. Twenty-four dental implants were inserted into the femoral condyles of rabbits. The animals were sacrificed immediately after implant installation or on day 14, 28, or 56 after surgery. Viscoelastic properties at bone-implant interface were evaluated by measuring the implant stability quotient (ISQ) using RFA and by measuring the Periotest values (PTVs) using the Periotest device. The bone/implant specimens were evaluated histopathologically and histomorphometrically to determine the degree of osseointegration (BIC%). The BIC% values at different time points were then compared with the corresponding ISQ values and PTVs. The mean ISQ value increased gradually and reached 81±1.7 on day 56, whereas the mean PTV decreased over time, finally reaching -0.7±0.5 on day 56. Significant correlations were found between ISQ and BIC% (r=0.701, p<0.001), PTV and BIC% (r=-0.637, p<0.05), and ISQ and PTV (r=-0.68, p<0.05). These results show that there is a positive correlation between implant stability parameters and peri-implant-bone healing, indicating that the RFA and Periotest are useful for measuring changes of viscoelastic properties at bone-implant interface and are reliable for indirectly predicting the degree of osseointegration.