fa Effects of insertion angle and implant thread type on the fracture properties of orthodontic mini-implants during insertion ارتودنسی Orthodontics پژوهشي Research <p> <strong>Objective:</strong></p><p>  To determine the effects of insertion angle (IA) and thread type on the fracture properties of orthodontic mini-implants (OMIs) during insertion. </p><p> <strong>Materials and Methods:</strong> </p><p> A total of 100 OMIs (self-drilling cylindrical 11 mm in length) were allocated into 10 groups according to thread type (dual or single) and IA (0°, 8°, 13°, 18°, and 23°) (n  =  10 per group). The OMIs were placed into artificial materials simulating human tissues: two-layer bone blocks (Sawbones), root (polymethylmethacrylate stick), and periodontal ligament (Imprint-II Garant light-body). Maximum insertion torque (MIT), total insertion energy (TIE), and peak time (PT) were measured and analyzed statistically. </p><p> <strong>Results:</strong></p><p>  There were significant differences in MIT, TIE, and PT among the different IAs and threads (all P < .001). When IA increased, MIT increased in both thread groups. However, TIE and PT did not show significant differences among 0°, 8°, and 13° IAs in the dual-thread group or 8°, 13°, and 18° IAs in the single-thread group. The dual-thread groups showed higher MIT at all IAs, higher TIE at 0° and 23° IAs, and longer PT at a 23° IA than the single-thread groups. In the 0°, 8°, and 13° IA groups, none of the OMIs fractured or became deformed. However, in the 18° IA group, all the OMIs were fractured or deformed. Dual-thread OMIs showed more fracturing than deformation compared to single-thread OMIs (P < .01). In the 23° IA group, all OMIs penetrated the artificial root without fracturing and deformation. </p><p> <strong>Conclusions:</strong></p><p>  When OMIs contact artificial root at a critical contact angle, the deformation or fracture of OMIs can occur at lower MIT values than those of penetration. </p><hr><p></p><p> <strong>Source: </strong>The Angel Orthodontists</p><p><a href="http://www.angle.org/doi/abs/10.2319/082812-689.1" target="_blank"><font color="#0000ff"> Full Text</font></a></p> Fracture properties, Mini-implant, Insertion angle, Implant thread type 0 0 http://idai.ir/browse.php?a_code=A-10-32-2002&slc_lang=fa&sid=1 Il-Sik Cho 10031947532846009397 10031947532846009397 No Department of Orthodontics, School of Dentistry, Seoul National University; Clinical Instructor, Department of Dentistry, Korea University Guro Hospital, Seoul, South Korea Tae-Woo Kim 10031947532846009398 10031947532846009398 No Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea Sug-Joon Ahn 10031947532846009399 10031947532846009399 No Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea Il-Hyung Yang 10031947532846009400 10031947532846009400 No Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea Seung-Hak Baek drwhite@unitel.co.kr 10031947532846009401 10031947532846009401 Yes Department of Orthodontics, School of Dentistry, Dental Research Institute, Seoul National University, Seoul, South Korea