Histologic and Biomechanical Evaluation of the Effects of Implant Insertion Torque on Peri-Implant Bone Healing

The aim of this study was to evaluate histologically and biomechanically the peri-implant bone healing around implants placed with high torque after a follow-up of 8 and 12 weeks. A total of 12 implants were placed in the lower edge of the mandible of 2 sheep. In each sheep, 3 implants were placed with a low torque (<25 N center dot cm, LT group) as a control, and 3 implants were placed with a high insertion torque (maximum torque, HT group). The sheep were killed after 8 and 12 weeks of healing, and the implants were examined for removal torque, resonance frequency analysis, and histologic analysis. The mean insertion torque in the LT group was 24 N center dot cm, whereas it was 105.6 N center dot cm in HT. All the implants osseointegrated and histologic analysis showed similar aspects of the peri-implant bone tissue for both groups and both healing times. Mean removal torque values for LT implants were 159.5 and 131.5 N center dot cm after 8 and 12 weeks, respectively, whereas those for the HT were 140 and 120 N center dot cm at 8 and 12 weeks, respectively. Implant stability quotient values were 26.6 and 76 for the LT group and 74 and 76 for the HT group at 8 and 12 weeks, respectively. It could be concluded that high implant insertion torque does not induce adverse reaction in cortical bone and does not lead to implant failure.