Comparative study of removal torque of 3 different hydroxyapatite coated implants in the femur of rabbits

ABSTRACT

INTRODUCTION: This study compared the strength of osseointegration as determined by the resistance to reverse torque rotation of three different hydroxyapatite coated implants in the rabbit femur model. MATERIALS AND METHODS: Three hydroxyapatite coated implants (HAPTITE), Tapered Screw-Vent (TSV) and BioTite-H - were used. A total of 40 implants were placed in the femur of 20 adult male rabbits. The animals were divided into two groups. In group A (n=10); one HAPTITE was placed into each right femur and one TSV was placed into each left femur. In group B (n=10); one HAPTITE was placed into each right femur and one BioTite-H was placed into each left femur. Five rabbits of each group were sacrificed at 4 and 8 weeks. The implants were removed by reverse torque rotation using a digital torque-measuring device. A total of 40 implants in 20 rabbits were used for the removal torque measurements. RESULTS: In the Group A, 4 weeks after implant placement, the mean removal torque for the HAPTITE and TSV was 70.7+/-31.6 N cm and 28.9+/-15.1 N cm, respectively. Eight weeks after implant placement, the mean removal torque for the HAPTITE and TSV was 87.9+/-26.2 N cm and 54.9+/-22.4 N cm, respectively. In the Group B, 4 weeks after implant placement, the mean removal torque for the HAPTITE and BioTite-H was 58.0+/-29.6 N cm and 37.7+/-14.1 N cm, respectively. Eight weeks after implant placement, the mean removal torque for the HAPTITE and BioTite-H was 91.4+/-47.1 N cm and 30.8+/-9.8 N cm. HAPTITE showed a higher removal torque than the other implants. CONCLUSION: These results suggest that HAPTITE increases the strength of osseointegration significantly as determined by the resistance to reverse torque rotation.