A study on the correlation between implant stability values and initial insertion torque

Lee, Jong Hyuk; Yang, Jae Ho

Abstract

Statement of problem. Osseointegration is important mechanism of dental implant but it is not easy to evaluate. Indirect measurement is non-invasive and clinically applicable but they need more study about correlation between indirect values and degree of osseointegration. Purpose. The aims of this study were to evaluate the coefficient of correlation between indirect measurement and direct measurement under different healing time, and assessment of effect of initial insertion torque to the implant stability. Material and Methods. 20 rabbits received 3 implants on each side of tibia. Three kinds of implants (machined surface implant, Sandblasted with Large grit and Acid etched implant, Resorbable Blast Media treated implant) were used. During the surgery implant insertion torque were measured with OsseocareTM. After the 1, 4, 8, 12 weeks of healing time, animals were sacrificed and stability values (Implant Stability Quotient with OsstellTM, removal torque with torque gauge) were measured.
Results
. The Bone quality of rabbit tibia was classified into 2 groups according to the insertion torque. Resonance frequency analysis (ISQ) and removal torque showed positive correlation until 4th week (r=0.555, p=0.040). After 8th week (r=-0.011, p=0.970) the correlation became weak and it turned negative at 12th week (r=-0.074, p=0.801). Insertion torque and ISQ showed changing correlation upon the healing time (1st week: r=0.301, p=0.033, 4th week: r=-0.429, p=0.018, 8th week: r=0.032, p=0.865, 12th week: r=-0.398, p=0.029). Insertion torque and removal torque has positive correlation but it was not statistically significant (1st week: r=0.410, p=0.129, 4th week: r=-0.156, p=0.578, 8th week: r=0.236, p=0.398, 12th week: r=-0.260, p=0.350).
Conclusion
. In this study, bone quality may affect the degree of osseointegration positively during healing time and correlation between ISQ and degree of osseointegration can be different according to the healing time and bone quality.