Effects of wobbling angle on the stability measures of orthodontic mini-implants during insertion and removal procedures

Abstract

Objective: To investigate the effects of wobbling angle on the stability measures of orthodontic mini-implants (OMIs) during insertion and removal procedures in artificial bone blocks. Materials and Methods: A total of 36 OMIs (self-drilling type, cylindrical shape, 7 mm in length, 1.45 mm in diameter) were allocated into three groups according to the amount of wobbling angle (W-0u, W-2u, and W-4u groups; N512 per group). The OMIs were installed and subsequently removed from artificial bone blocks (Sawbone) using a driving torque tester with a uniform speed of 28 rpm. Insertion peak time (IPT), maximum insertion torque (MIT), total insertion energy (TIE), near-peak insertion energy (NPIE), maximum removal torque (MRT), and near-peak removal energy (NPRE) were measured. Results: The W-4u group showed the longest IPT and highest TIE and NPIE, followed by the W-2u and W-0u groups (W-0u , W-2u , W-4u, all P , .001). The W-2u and W-4u groups showed significant increase in MIT compared with the W-0u group (W-0u , [W-4u,W-2u]; P , .001). Although there was no significant difference in NPRE among the three groups, the W-4u group showed a decrease in MRT compared with the W-0u and W-2u groups (W-4u , {W-2u,W-0u]; P , .05). Although the W-4u group showed a 14.5% (2.9 Ncm) increase in MIT compared with the W-0u group, there was only a 6% (1.3 Ncm) decrease in MRT from the W-0u group to the W-4u group. Conclusion: Slight wobbling during the OMI insertion procedure may be acceptable in terms of the stability measures of OMIs during insertion and removal procedures. (Angle Orthod.

A comparative surface evaluation of orthodontic mini-implants before and after en masse retraction—A SEM study

“…Cho et al . [ 17 ] evaluated several parameters like active tip width, mini-implant external diameter, the minor diameter of the internal thread, percentage of the minor diameter of the internal thread to external diameter, number of threads, pitch, angle of thread, flank width, pitch width, and taper to check the mechanical retention of the metallic structures of implants on the cortical and dense bone. In the current study, there is a statistically significant difference in the pitch dimension of the Dentos group before insertion and post-retrieval which affects the primary stability of mini-implants.…”