engleski

To what extent design of manual screwdriver modifies insertion torque of orthodontic mini-implants?

AIM: The study focused on the influence of screwdriver design in combination with and without predriling a pilot hole of inner implant diameter on insertion torque of orthodontic mini-implants, controlling for implant length, cortical thickness and vertical insertion force as co-factors. Materials and methods: A total of 120 mini-implants (Forestadent, Pforzheim, Germany) of 1.7mm in diameter and 6 and 8mm in length were manually inserted into 120 swine rib bone samples. Maximal insertion torque as a measure of primary stability and vertical force were measured. The study included procedures with and without pilot hole and different screwdriver handles and shaft length. RESULTS: Design of manual screwdriver does not modify insertion torque to a significant extent. In multiple linear regression model pilot hole width of inner mini-implant diameter is a statistically significant predictor of higher torque values of manually inserted cylindrical mini-implants (p=0.032). Other significant predictors of higher torque are: thicker cortical bone (p<0.001), implant length 6 mm (p=0.023) and higher vertical force at maximal torque (p<0.001). The model accounts for 43.6% of total variability of maximal insertion torque. By controlling the effect of all other factors the most independent contribution to the explanation of higher implant insertion torques are cortical thickness and vertical force at maximal torque accounting for 16.6% and 13.5% of variability respectively, while implant length and the presence of pilot hole account for 2.5% and 2.3% respectively. CONCLUSION: Handle type and shaft length of manual screwdriver do not significantly influence insertion torque, while predrilling a pilot hole of inner implant diameter has low impact on torque values of manually inserted self-drilling orthodontic mini-implants.

mini-implants; orthodontic; torque

Rad financiran potporom Sveučilišta u Rijeci 13.06.2.1.53 "Prediktivni čimbenici uspjeha ortodontske terapije u djece i adolescenata".