Rotational resistance of surface-treated mini-implants

Abstract

Objective: To test the hypothesis that there is no difference in the stability and resistance torotational moments of early loaded sandblasted and acid-etched (SLA) mini-implants and thoseof machined-surface implants of the same size and shape.Materials and Methods: A randomized complete block design was used in 12 skeletally maturemale beagle dogs. Ninety-six orthodontic mini-implants were tested. Two types of implants wereused: some had SLA surface treatment and some had machined surfaces without coating. After3 weeks of healing, rotational moments of 150 g were applied. The success rates, maximumtorque values, angular momentum, and total energy absorbed by the bone were compared. Allvalues were subjected to mixed-model analysis to evaluate the influence of surface treatment,rotational force direction, and site of implantation.Results: The maximum insertion torque and angular momentum of SLA implants were significantlylower than those of machined implants (P - .034, P - .039). The SLA implants had asignificantly higher value for total removal energy than the machined implants (P - .046). However,there were no significant differences in total insertion energy, maximum removal torque, andremoval angular momentum between the 2 groups. There was no significant difference betweenclockwise and counterclockwise rotation in all measurements.Conclusion: SLA mini-implants showed relatively lower insertion torque value and angular momentumand higher total energy during removal than the machined implants, suggesting osseointegrationof the SLA mini-implant after insertion. (Angle Orthod. 2009;79:899-907. © 2009 by The EH Angle Education and Research Foundation, Inc.