Effect of Torque on Narrow Diameter Dental Implants

Objectives: Treatment using dental implants has increased markedly over the years as outcomes are proving extremely predictable. However a small but significant number fail with fracture being a rare, but known complication. An aggravating factor may involve the use of smaller diameter implants which may be used to try and avoid bone grafting/augmentation along with its associated morbidity and cost. Often new implant designs are introduced without rigorous appraisal and thus limit the information available about potential complications. Nobel Active Implants were launched in 2008 with key differences in its design and surgical protocol including self tapping thread, internal hex connector and higher insertion torque. The aim of this project was to understand the effects of higher torque values on the internal connection and surface treatment of narrow platform Nobel Active (NA) compared with existing Nobel Replace Straight Groovy (NRSG) implants. Methods: Ten implants were used for each group and these were glued passively into perspex blocks using an epoxy resin based adhesive. The blocks were then held in a bench vice and torque applied using the appropriate implant driver held in a digital torque wrench. The implants were studied under light microscopy. Results: The results showed damage to the implant surface and prosthetic connection when torque was used in excess of recommended values. This appeared to happen eve after minimal increases in torque. Conclusions: Increased torque values appeared to alter the surface texture and fixture head connection. These changes could lead to bone resorption and prosthetic failure. Clinicians should strictly adhere to recommended torque values.

This research was supported by Nobel Biocare.