American Journal of Orthodontics and Dentofacial Orthopedics
Original articleInfluence of cortical bone thickness on miniscrew microcrack formation
Section snippets
Material and methods
Three porcine tibia bones were obtained from a local abattoir after approval from the Animal Ethics Committee (number M-2015-032) of the University of Adelaide. The proximal and distal ends of the bones were removed with a bandsaw, and the specimens were sectioned into quarters. Before use, the specimens were carefully stripped of attached soft tissues. A total of 30 bone specimens were machined under irrigation, using a slow-speed diamond saw, measuring 15 by 20 mm wide with nominal
Results
Cortical bone thickness in groups A, B, and C did not differ significantly from 1.0, 1.5, and 2.0 mm, with mean values of 1.06 mm (SD, 0.06), 1.51 mm (SD, 0.08), and 1.96 mm (SD, 0.08), respectively. Intraclass correlation coefficient analysis indicated excellent intrarater and interrater reliabilities, ranging from 0.99 to 0.91 and 0.99 to 0.76, respectively.
Data from the compression load cell showed some variations between the 3 groups, despite implementation of the insertion protocol by 1
Discussion
The purpose of this study was to investigate the influence of cortical bone thickness on microdamage formed immediately after OM insertion. The observations show distinct differences in microdamage between the different cortical bone thicknesses; therefore, the null hypothesis was rejected. The entry surface for group C (2.0 mm) showed statistically higher total damage area (P <0.05), diffuse damage area (P <0.05), and maximum crack length (P <0.05) compared with the entry surfaces of groups A
Conclusions
The results of this study show the significant influence of cortical bone thickness on the amount of microdamage formed immediately after insertion in porcine bone. An increase in cortical bone thickness was statistically associated with an increase in microdamage. Based on this study on porcine tibia bone, the following provisional recommendations can be made.
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Clinicians need to consider the thickness of cortical bone at the insertion site, since mechanisms to reduce cortical bone thickness
Acknowledgments
We thank the Australian Society of Orthodontists, Foundation for Research and Education, for support of this research project; Suzanne Edwards, statistician at the University of Adelaide, for assistance with the statistical analysis and interpretation of the data; and the facilities and the scientific and technical assistance of the Australian Microscopy and Microanalysis Research Facility at the University of Adelaide.
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All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.