A comparative study of removal torque of endosseous implants in the fibula, iliac crest and scapula of cadavers: Preliminary report

Abstract

This study was undertaken to compare removal torque of endosseous implants in the fibula, iliac crest and scapula of cadavers. The fibulae, iliac crests and scapulae were harvested from the right side of 5 formalin-preserved cadavers. Endosseous implants (Brånemark System) were placed at 3 points of each bone. The removal torque of the implant was measured by a torque gauge manometer (Tohnichi 15 BTG-N). After measurement of the removal torque, the bone was cut at each implant site. The thicknesses of cortical and total bone were measured. The mean removal torques were 46.3 N cm in the fibulae, 15.2 N cm in the iliac crests and 21.4 N cm in the scapulae. There was a statistically significant difference in mean removal torque between the three bones. The total bone thicknesses were 11.7 mm in the fibulae, 9.9 mm in the iliac crests and 8.2 mm in the scapulae. The cortical bone thicknesses were 5.0 mm in the fibulae, 1.6 mm in the iliac crests and 1.8 mm in the scapulae. Significant correlation between the removal torque and the cortical bone thickness was found. However there was no significant correlation between the removal torque and the total bone thickness. In conclusion, the implants inserted in the fibulae showed the highest removal torques as compared to the ones inserted in the iliac crests and the scapulae. Moreover the removal torque was related to the thickness of the cortical bone in the implant sites.