Abstract
High orthodontic forces and various directions of applied forces can be associated with loosening of the screw anchorage in the bone. Screw designs have been modified to increase the stability of the miniscrews. This research evaluates the influence of three-designs on the stability of orthodontic miniscrews. A conventionally cylinder-type miniscrew design (Bio-Action screw, Jin-Biomed co., Bucheon, Korea) was set as a control, and three conditions were studied based on modifications of this control design. Condition-1 has narrowed threads in the upper part of the screw; Condition-2 has a notch at the middle part; and Condition-3 has the combination of Condition-1 and Condition-2. The moment required to unwind the miniscrew to five degrees is tested, and the moment generated at the cortical bone and the trabecular bone were calculated with finite element analysis. Compared to the control, all three conditions showed a higher moment required to unwind the miniscrew and a higher moment generated at the cortical bone. At the trabecular bone, condition-2 and -3 showed higher moment than the control, and condition-1 showed similar moment to the control. Condition-3 required a higher overall moment to unwind the miniscrew. These findings validate the design modifications used to increase the rotational resistance.
Highlights
IntroductionMechanical design enhancements have improved the development of orthodontic materials
The distinctive and critical feature of dental implants is that they are designed to integrate with the bone to achieve long term stabilization, which is called as osseointegration [7,8,9]
The thickness of cortical bone was set at 1.2 mm and the trabecular bone underneath was deep enough to place an orthodontic miniscrew with thread length of 6.0 mm
Summary
Mechanical design enhancements have improved the development of orthodontic materials. Stability rates or failure rates of orthodontic miniscrews have been studied. In a meta-analysis study of the failure rates and associated risk factors of orthodontic miniscrews, the overall failure rate was 13.5%. The distinctive and critical feature of dental implants is that they are designed to integrate with the bone to achieve long term stabilization, which is called as osseointegration [7,8,9]. Researchers have tried to improve bone-to-implant contact by modification of the surface characteristics of dental implants. It enhanced the surface roughness to improve the osseointegration. A study using high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDS), and scanning
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