Influence of implant diameter on the osseointegration of implants; an experimental study in rabbits

Lee, Jun Ho; Shin, Sang Wan; Kwon, Sang Ho

Abstract

STATEMENT OF PROBLEM: The survival rate of wide diameter implants was lower than of 3.75-mm implants in some clinical researches. PURPOSE: The purpose of this study was to investigate the influence of implant diameter on the osseointegration of implants in the rabbit femoral condyle and tibial metaphyses by means of removal torque measurements and histomorphometric analysis. MATERIAL AND METHOD: Ten adult New Zealand White rabbits were used in this study. Two 3.75-mm diameter implants were inserted through one cortical layer in the tibial metaphyses and one 3.75-mm diameter implant was inserted in the femoral condyle. 5.0-mm diameter implants were inserted in the other leg in the same manner. A total of 60 implants (3.75-mm diameter implants:30 ; 5.0-mm diameter implants:30) were installed. After a healing time of 4 and 12 weeks, the peak removal torque values required to shear off the implants were recorded. From the removal torque values (Ncm) obtained, the mean shear stress (N/mm2) was calculated. And the percentage of direct bone-to-implant contact and the percentage of bone area inside the thread were measured by Kappa Image Base-metreo. The Student's t-test was undertaken for statistical analysis (p<0.05). RESULTS: The removal torque value of 5.0-mm diameter implants was higher than of 3.75-mm diameter implants (p<0.05). The difference of shear stress value between 3.75-mm and 5.0-mm diameter implants was not statistically significant (p>0.05). The percentage direct bone-to-implant contact had no statistical difference between two groups (p>0.05). The percentage of bone area inside the thread had no statistical difference between two groups (p>0.05). CONCLUSION: It is concluded that the quality of osseointegration is not influenced by increasing implant diameter.