Effects of microgrooves on the success rate and soft tissue adaptation of orthodontic miniscrews

Objective: To evaluate the effect of microgrooves on orthodontic miniscrews in terms of success rate and soft tissue adaptation in animal experiments. Materials and Methods: The sample consisted of a non-microgroove (NMG) group and a microgroove group (MG; 50 μm pitch and 10 μm depth microgroove on the upper surface of the miniscrew). Miniscrews of 1.6 mm diameter and 6.0 mm length were placed into beagle dogs. Histomorphometric analysis in each group focused on bone-to-implant contact (BIC) and the bone area (BA) of pressure and tension sides. Independent and paired t-tests were completed for statistical analysis. Results: The success rate was found to be higher in the MG group than in the NMG group. The MG group showed significantly higher BIC on the pressure side when compared with the NMG group (P < .01). Although the NMG group showed significantly lower BIC on the pressure side than on the tension side at the upper side of the miniscrew (P < .01), the MG group revealed no significant differences between BIC on pressure and tension sides. The MG group generally exhibited erpendicular or circular alignment of the gingival connective tissue fiber with the miniscrew; the NMG group showed parallel alignment. Conclusions: The orthodontic load may affect bone remodeling on the pressure side of the miniscrew and may affect stability. The microgroove could exert some positive effects on soft tissue adaptation and bone healing. ⓒ 2008 by The EH Angle Education and Research Foundation, Inc.