Relevance Of Torsional Vibration Resonance Frequency Analysis To Evaluate Degree Of Osseointegration:An Experimental Study In Rabbit Tibia

Background:In view of the impractical and crude methods to evaluate and determine implant stability and degree of osseointergration, Meredith introduced a non-invasive test method using resonance frequency analysis (RFA) to quantify the degree of implant stability. However, present RFA studies still focus attention on the resonance frequency of implant under a bending modal behaviour which is easy to be identified and obtained. With the progress of related research, the relation between resonance frequency value and the parameters of osseointegration is not yet clear, the utility of RFA based on bending modal behaviour to detect the early interfacial changes that occur during the process of osseointegration has to be questioned.Objective:Based on prophase research of torsional vibration resonance frequency, the objective of present experiment was to evaluate torsional vibration RFA values and bending vibration RFA values in relation to osseointegration and interfacial stability with animal models.Material and Methods:Six New Zealand rabbits were divided into three groups according to different sacrifice time. Two Straumann implants (8mm length,3.3mm diameter, regular neck) were placed in rabbit’s anteromedial tibia tuberosity near knee joint.RFA assessments of8weeks group were performed at the time of implant installation,1,2,3,4,6,8weeks. RFA assessments of2and4weeks group were performed on each implant both at the time of implant installation and animal sacrifice. At the end of the experiment, the rabbits were sacrificed and each implant site was processed for Micro-CT test and removal torque test. The results of Micro-CT test and removal torque test, i.e.3D-BIC%, removal torque and interfacial stiffness, were compared with corresponding Implant Stability Quotient (ISQ) values and torsional vibration RF values.Results:It was found that torsion.al vibration RF values correlate with interfacial stiffness, removal torque, and three dimensional bone-to-implant contact ratio, differences in3D-BIC%, removal torque, interfacial stiffness were reflected in the torsional vibration RF values during healing period. No correlations between parameters of osseointegration and ISQ values could be identified.Conclusion:Compared with the Osstell(?) ISQ, torsional vibration RFA is sensitive and direct enough to follow the early interfacial reactions the during healing period. The application of torsional vibration RFA indicts an advanced way to make quantitative measurements of the stability and the early changes of the implant-bone interface in vivo.