A CBCT Study Comparing the Outcomes of Volumetric Bone Mass and Mini-Implant Success with Different Types of Malocclusions

Abstract

Objective: The present study aimed to determine the favorable site for orthodontic mini-implant insertion in both the maxilla andmandible in terms of cortical and trabecular bone thickness and density in different types of skeletal malocclusion using cone-beamcomputed tomography (CBCT). Methods: In this study, seventy-five CBCT examinations that were requested for different purposes were used, twenty-five in eachmalocclusion group (class I, class II and class III), class I (ANB: 2°-4°), class II (ANB > 4°), and class III (ANB < 2°) groups. RadiAntDicom Viewer was utilized, measurements were done at different sites in the jaws using standardized orientations, and the threemalocclusion groups were compared for cortical bone thickness and density as well as the density of trabecular bone, using the Kruskal-Wallis and Mann-Whitney test for non-parametric data and one-way ANOVA for parametric data. Results: The highest cortical bone thickness was between 1st and 2nd molars at a 6 mm distance from the alveolar crest ranging from1.03 mm to 1.2 mm in maxilla and 2.13 mm to 2.26 mm in the mandible. The difference between groups was only noticed betweencanine and 1st premolar which showed less buccal cortical bone thickness in class II cases with 1.07 mm. Cortical bone density wasnot significantly different between the three groups with maximum density between canine and 1st premolar with a density of 997.9 to1078 HU in the maxilla and the mandible 1245.4 to 1329.3 HU. The trabecular bone density was also highest between canine and 1stpremolar of both jaws, in maxilla 422.13 to 564.15 HU and mandible 509.81 to 799.04 HU. The difference between the groups wasonly in the anterior location between canine and 1st premolars which was less in class III cases with 509.81 HU. Conclusions: Skeletal relations can have an impact on the thickness of the cortical bone, although all skeletal classes have the samepattern in the maxilla, in the mandible between the canine and the 1st premolar, variations in bone thickness and trabecular densitymay be seen in various skeletal malocclusions. So, it is important to properly consider the placement of mini-implants with the skeletalrelation to achieve the maximum primary stability. Further researches are recommended, with long term follow up, on stability of mini-implants and its correlation with bone thickness and density.