Stress distribution in peri-miniscrew area with different insertion angle of cylindrical and taper type miniscrews

Abstract

Initial stability is important for miniscrew success. To increase initial stability, the type of miniscrew and insertion angle should be considered. However, excessive stresses caused by miniscrew insertion and orthodontic forces can induce deformation of the peri-miniscrew area. This study aimed to analyze the effects of cylindrical and tapered miniscrews positioned at various insertion angles on the deformation of peri-miniscrew areas by using a finite element analysis. Cylindrical and tapered miniscrews were inserted between the maxillary second premolar and first molar at angles of 30°, 60° and 90° to the bone surface. The von Mises stress distribution during miniscrew insertion and after the application of a horizontal force of 200 g to the miniscrew to assume space closure during orthodontic treatment were calculated for the roots and periodontal ligaments of the maxillary second premolar, maxillary first molar, and cortical and cancellous bone using a finite element analysis. 1. The stress in the cortical bone area was affected more strongly than other areas by miniscrew insertion and horizontal force.2. During insertion, the maximum von Mises stress in cortical bone was greater for tapered miniscrew than cylindrical miniscrew.3. After force application, the maximum von Mises stress increased as the insertion angle decreased in all areas, except in cancellous bone.Placing a miniscrew as perpendicular to the bone surface as possible is recommended to reduce stress to the bone during insertion and to bear horizontal force of 200 g during orthodontic treatment.