Biological Evaluation of Hollow Type Miniscrew Implant: an experimental study in the beagle dogs

Abstract

The aims of this study were to assess the biological stability of newly designed hollow type (H type) miniscrews, to confirm if H type miniscrew has enough stability as much as conventional (C type) miniscrew has, and to evaluate bone remodeling around the miniscrew through histomorphometric and histological analysis. Newly designed miniscrews and C type miniscrews were placed into the intraradicular spaces of the maxillary and mandibular first molars and mandibular fourth premolars of twelve beagle dogs. The maximum insertion torque and Periotest value were measured after placement. After tissue processing, bone implant contact and bone volume were measured. The results of the present study were as follows.1.Overall success rate of experimental group was about 78.3% in maxilla and 60.0% in mandible. Success rate of C type group was 100% in maxilla and mandible.2.Mean insertion torque (IT) values of H type miniscrews were 14.2 Ncm in maxilla and 20.9 Ncm in mandible, showing significant difference between maxilla and mandible.3.Periotest values (PTV) of H type miniscrews were -1.5 in maxilla and -6.4 in mandible. Mean PTV was significantly lower in H type compared to C type miniscrews in mandible (P < .0001).4.In maxilla, bone implant contact (BIC) of H type miniscrews was 37.3% and 32.3% at three and twelve weeks, respectively. In mandible, it was 31.4% and 18.5% at three and twelve weeks, respectively.5.At three weeks of H type miniscrews, BIC of the exterior part of the miniscrew (ExBIC) was 37.3% and 31.4% in maxilla and mandible, respectively, and BIC of the interior part of the miniscrew (InBIC) was 16.8% and 14.7%. At twelve weeks, ExBIC was 32.3% and 18.5%, and InBIC was 14.3% and 13.8% in maxilla and mandible, respectively. There was significant difference between ExBIC and InBIC (P < 0.05), except in mandible at twelve weeks.6.Mean bone volume was higher in exterior part of the miniscrew than in interior part in both jaws, and there was significant difference between exterior and interior part of the miniscrew in maxilla at three weeks with P < 0.01.