Biologic evaluation of a hollow-type miniscrew implant: an experimental study in beagles.

INTRODUCTION: The aims of this study were to assess the biologic stability of a newly designed hollow (H-type) miniscrew compared with conventional (C-type) miniscrews through histomorphometric and histologic analysis.

METHODS: Both types of miniscrews were placed into the maxillae and the mandibles of 12 beagles. Maximum insertion torque, Periotest (Siemens AG, Bensheim, Germany) value, bone-implant contact, and bone volume were measured.

RESULTS: The overall success rates of the H-type were 78.3% in the maxilla and 60.0% in the mandible. Mean maximum insertion torque values of the H-type were 14.2 N-cm in the maxilla and 20.9 N-cm in the mandible. The Periotest values of the H-type were -1.5 in the maxilla and -6.4 in the mandible. Mean maximum insertion torque and Periotest values of the H-type were higher than those of the C-type. In the maxilla, the bone-implant contact values of the H-type were 37.3% and 32.3% at 3 and 12 weeks, respectively. In the mandible, the bone-implant contact values were 31.4% and 18.5% at 3 and 12 weeks, respectively.

CONCLUSIONS: Considering the lower success rate and the insufficient bone-implant contact and bone volume of the H-type in the mandible, the clinician should choose a suitable combination of miniscrews depending on local bone quality and implantation site, such as an H-type in the maxilla and a C-type in the mandible.