Effects of cortical bone thickness and trabecular bone density on primary stability of orthodontic mini-implants

• Published in: Journal of dental sciences 2019-12, Vol.14 (4), p.383-388
• Main Authors: Pan, Chin-Yun, Liu, Pao-Hsin, Tseng, Yu-Chuan, Chou, Szu-Ting, Wu, Chao-Yi, Chang, Hong-Po
• Format: Article
• Language: English
• Subjects: Cortical bone thickness; Mini-implants; Original; Primary stability; Resonance frequency; Trabecular bone density
• ISSN: 1991-7902; 2213-8862
• DOI: 10.1016/j.jds.2019.06.002

Mini-implant screws are now routinely used as anchorage devices in orthodontic treatments. This study used synthetic bone models to investigate how the primary stability of an orthodontic mini-implant (OMI) as measured by resonance frequency (RF) is affected by varying cortical bone thickness and trabecular bone density. Three synthetic cortical shells (thicknesses of 1, 2, and 3 mm) and three polyurethane foam blocks (densities of 40, 20, and 10 pound/cubic foot) were used to represent jawbones of varying cortical bone thicknesses and varying trabecular bone densities. Twenty-five stainless steel OMIs (2 × 10 mm) were sequentially inserted into artificial bone blocks to depths of 2, 4, and 6 mm. Five experimental groups of bone blocks with OMIs were examined by Implomates® RF analyzer. Statistical and correlation analyses were performed by Kruskal-Wallis test, Wilcoxon rank-sum test, and simple linear regression. As trabecular bone density decreased, RF decreased; as cortical bone thickness decreased, RF also decreased. Simple linear regression analysis showed highly linear correlations between trabecular bone density and RF (R2 > 0.99; P  0.98; P