Biomechanical and Histometric Effects of Modified Surgical Drilling of Dental Implant Sites

Objectives: The purpose of this study was to evaluate implant insertion torque and osseointegration when utilizing clockwise and counterclockwise densification burs relative to its regular implant system drill counterpart.
Methods: Experimental healing chamber implants were surgically placed in sheep hip through one of the following instrumentation techniques: R (regular as recommended by manufacturer), CW (Versah drill clockwise), and CCW (Versah drill counterclockwise). Implant insertion torque was recorded at the time of implant placement. The implants remained in vivo for a period of 3 and 12 weeks, and following sacrifice were referred to non-decalcified histological processing. Statistical analyses were performed by a mixed model ANOVA (at an alpha=0.05) where instrumentation technique was the independent variable and insertion torque, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were the dependent variables.
Results: Insertion torque data showed significant differences between CCW and CW (highest), and R (lowest) instrumentation techniques (p<0.01). No substantial increase in BIC was observed as a function of time in vivo, and statistical evaluation of BIC depicted a significant effect of surgical technique, where CCW and CW presented significantly higher levels relative to the regular drilling technique (p<0.001). A more pronounced increase in BAFO over time was observed (non-significant) relative to BIC, and CCW and CW presented significantly higher BAFO levels relative to the regular drilling technique (p<0.001). Histomorphological evaluation depicted new bone formation in proximity (between threads) and in direct contact implants placed under all instrumentation techniques. A different morphology was observed around CW and CCW instrumented implants as instrumentation bone fragments acted as nucleating sites for new bone apposition.
Conclusions: Osseodensification technique proved to be beneficial for increasing implant insertion torque and osseointegration indicator values such as bone-to-implant contact and bone area fraction occupancy.