Gripping and Anchoring Effects on the Mechanical Strengths of Orthodontic Microimplants.

PURPOSE: The aim of this study was to evaluate the mechanical strengths in 5 different designs of orthodontic microimplants by analyzing their configuration of structure.

MATERIALS AND METHODS: Thirty microimplants of 5 types (diameter 1.5 mm: type A, B, and C; diameter 1.3 mm: type D and E) were assessed. All microimplants were manually driven into the artificial bones at a 7-mm depth. The anchor area (AA), gripping area (GA), insertion torque (IT), Periotest value (PTV), and pullout strength (PS) were measured. Intergroup and intragroup comparisons were used to detect their significant differences.

RESULTS: In the intergroup comparison, type D had a least IT (4.5 Ncm). In the PTV analysis, type B had the largest AA (7.76 mm) and its PTV (1.6) was significantly least than the others. In the PS test, type C had the largest GA (2.40 mm) and its PS was the largest. Intragroup comparisons (IT and PS), type A, and type E presented positively significant correlation. GA revealed positive with PS, and AA showed reverse tendency with PTV.

CONCLUSION: The more AA of microimplants, the more stable they are. The more GA of microimplants, the more PS they are. Therefore, type C was better than the others because it had the largest GA and second largest AA.