Evaluation of Strain and Insertion Torque of Mini-implants at 90° and 45° Angulations on a Bone Model using...

Temporary anchorage devices or mini-implants have gained great attraction due to its capability to provide absolute anchorage, low cost, versatility, and can be loaded immediately after placement.

The aim of this study is to use FEA analysis to assess the strain and insertion torque of mini-implants on a bone model at two distinct angulations of 45° and 90°.

A computer-aided three-dimensional (3-D) model representing alveolar bone and mini-implants were developed using ANSYS software. Computed tomography scan images of the implant and the alveolar bone were taken and exported in DICOM format for 3-D image processing. The thickness of the bone model is 1 mm. Ti6Al4V orthodontic single and double threaded mini-implants (L = 7 mm, D = 1.5 mm) were inclined at 45° and 90° on to the bone surface to measure the insertion torque and strain produced.

Maximum insertion torque (MIT) for single-threaded mini implant at 45° and 90° angulations are 20.001 Nmm and 19.977 Nmm, respectively. MIT for double-threaded mini-implants obtained is 19.977 Nmm at 90° and 19.991 Nmm at 45° angulation. The strain of the bone at 90° angulation for single-threaded mini-implant is 0.00893 mm and for single-threaded mini implant at 45° angulation is 0.01257 mm. The strain in double-threaded mini-implant at 90° angulation is 0.0125 mm and that of 45° angulation is 0.01773 mm.

For maximum stability single-threaded mini-implant with perpendicular insertion, angle is preferred.