In-vitro investigation of primary stability of orthodontic mini implants with different lengths using resonance frequency analysis

Abstract

Out of various ways of gaining anchorage, mini implants are gaining attention due to its minimum compliance and maximum curative effects.Mini implants are considered successful if they have sufficient primary stability that comes from mechanical interlocking of mini implant with the bone.Factors which influence the implant stability are bone physiology, implant size, shape and surface characteristics. Considering all other factors within anatomic constraints, what may play a role in primary stability of mini implants is length. Literature search to correlate mini implant length with primary stability was found to be insufficient and hence this study was undertaken. In this study, two goat jaws were subjected to spiral 3D CT scan and the areas with D2 bone density were identified and marked. In these D2 density marked areas, 30 implants of 1.5 x 6mm (GROUP A) and 30 implants of 1.5 x8mm (GROUP B) were placed. Their stability was measured by Radio Frequency Analysis using Osstell ISQ device with its Smart Peg. A connector was fabricated to make the fit of smart peg compatible with the head of mini implant. Readings were made in 5 different directions for each implant and their average value was considered as final reading. It was noted that primary mini implant stability is significantly higher (p 0.034) with GROUP B implants than with GROUP A implants. The increased length of mini-implants positively affects its primary stability and should be taken into consideration when implants are used as anchorage devices.