Mandibular buccal shelf asymmetry and bone density in vietnamese adults: a CBCT study

Abstract Objectives To assess using CBCT, the mandibular buccal shelf (MBS) bone thickness asymmetry and its relationship with cortical and cancellous bone density in Vietnamese adults presenting with Class I bimaxillary protrusion (Class I BP) and skeletal Class III malocclusions. Materials and Methods CBCT scans of 60 Vietnamese adults (30 Class I BP: 7 males, 23 females, mean age 27.63 years; 30 Class III: 15 males, 15 females, mean age 23.63 years) were analysed. Total bone thickness (dTB) was measured at 6, 9, and 12 mm below the cementoenamel junction at the mandibular first and second molars (R6G, R6X, R7G, R7X). Cortical (MĐV) and cancellous (MĐX) bone density were evaluated. Left-right asymmetry was tested using Wilcoxon or t-tests, and correlations were assessed using Spearman’s rho coefficient ( P <0.05). Results Class I BP cases showed significant left-right asymmetry in dTB at R6G and R6X (e.g., R6G 6 mm: 1.57±0.93 mm vs. 2.25±1.38 mm, P =0.004). The Class III group showed no asymmetry ( P >0.05). No significant correlations were found between dTB and MĐV or MĐX (e.g., Class I BP, R7X 12 mm: r=-0.087, P =0.646 for MĐV). No intergroup differences in dTB were observed ( P >0.05). Conclusions A Class I BP malocclusion exhibited MBS asymmetry at R6G and R6X, unlike a symmetrical Class III malocclusion. No correlation between bone thickness and density suggested independent adaptations, aiding miniscrew placement in Vietnamese adults.