Department of Mechanical Engineering, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, Chennai - 603203, Tamil Nadu, India.
Craniofacial Orthodontist and Oral Surgeon, Teeth 'N' Jaws Center, No. 23 & 25, 1st Cross Street, Lake Area, Nungambakkam, Chennai - 600034, Tamil Nadu, India.
Biomed Phys Eng Express. 2024 Jul 19;10(5). doi: 10.1088/2057-1976/ad6160.
Miniscrews are widely used in orthodontics as an anchorage device while aligning teeth. Shear stress in the miniscrew-bone interface is an important factor when the miniscrew makes contact with the bone. The objective of this study was to analyze the shear stress and force in the screw-bone interface for varying Cortical Bone Thickness (CBT) using Finite Element Analysis (FEA). Varying CBT of 1.09 mm (1.09) and 2.66 mm (2.66) with miniscrews of Ø1.2 mm, 10 mm length (T1), Ø1.2 mm, 6 mm length (T2) and Ø1.6 mm, 8 mm length (T3) were analyzed. Six Finite Element (FE) models were developed with cortical, cancellous bone, miniscrews and gingiva as a prism. A deflection of 0.1 mm was applied on the neck of the miniscrews at 0°, +30° and -30° angles. The shear stress and force in the screw-bone interface were assessed. The results showed that the CBT affects the shear stress and force in the screw-bone interface region in addition to the screw dimensions and deflection angulations. T1 screw generated lesser shear stress in 1.09and 2.66compared to T2 and T3 screws. Higher CBT is preferred for better primary stability in shear aspect. Clinically applied forces of 200 gms to 300 gms to an anchorage device induces shear stress in the miniscrew-bone interface region might cause stress shielding. Thus, clinicians need to consider the effect of varying CBT and the size of the miniscrews for the stability, reduced stress shielding and better anchorage during orthodontic treatment.
微螺钉作为一种正畸支抗装置，在排齐牙齿过程中被广泛应用。当微螺钉与骨接触时，微螺钉-骨界面的剪应力是一个重要因素。本研究旨在通过有限元分析（FEA），分析不同皮质骨厚度（CBT）下螺钉-骨界面的剪应力和力。分析了直径为 1.2mm、长 10mm（T1）、直径为 1.2mm、长 6mm（T2）和直径为 1.6mm、长 8mm（T3）的微螺钉，CBT 分别为 1.09mm（1.09）和 2.66mm（2.66）。用皮质骨、松质骨、微螺钉和牙龈作为棱柱体建立了六个有限元（FE）模型。在 0°、+30°和-30°角度下，在微螺钉颈部施加 0.1mm 的挠度。评估了螺钉-骨界面的剪应力和力。结果表明，除了螺钉尺寸和挠度角度外，CBT 还会影响螺钉-骨界面区域的剪应力和力。与 T2 和 T3 螺钉相比，T1 螺钉在 1.09 和 2.66 时产生的剪应力较小。较高的 CBT 有利于在剪切方面获得更好的初始稳定性。临床应用于锚固装置的 200 克至 300 克的力会在微螺钉-骨界面区域产生剪应力，可能会导致应力屏蔽。因此，临床医生需要考虑 CBT 和微螺钉尺寸的变化对稳定性、减少应力屏蔽和正畸治疗中更好的锚固的影响。
