Cone-beam computed tomography study of mandibular morphology and tooth compensation in asymmetrical patients.

INTRODUCTION: This study evaluated mandibular morphology and transverse dental compensation between symmetrical and asymmetrical subjects, allocated according to sagittal skeletal patterns. In addition, the hypothesis that mandibular morphology and dental compensations differed between symmetrical/asymmetrical groups and also among the different types of sagittal skeletal patterns was tested. METHODS: Cone-beam computed tomography images of 96 patients were included in this study and were divided into 2 groups according to the degree of menton deviation: a symmetrical group with deviation up to 2.0 mm (n = 48; mean age, 15 ± 6 years), and an asymmetrical group with deviation from 3.5 mm (n = 48; mean age, 16 ± 8 years). The 2 groups were divided in accordance with the ANB angle: Class I, II, and III. Skeletal and dental measurements were performed. Intergroup and intragroup analyses were carried out, using a 2-way analysis of variance to assess the interaction of factors: symmetry and sagittal skeletal pattern; and the Student t test for differences between deviated (Dv) and nondeviated (NDv) sides. RESULTS: Symmetrical/asymmetrical groups and Class I, II, and III groups were similar in relation to demographic aspects (P = 0.412 and P = 0.357 for sex and age, respectively). Asymmetrical patients had higher values for body length and mandibular ramus and condyle height on the NDv side (P = 0.011, P = 0.024, and P = 0.001, respectively). When comparing the different skeletal patterns, patients with a Class III relationship demonstrated higher values for mandibular ramus height. Intergroup analysis showed no differences in dental parameters. In the comparison between the sides, the asymmetrical group showed a significant difference in canine inclination (P = 0.008), mandibular ramus height (P = 0.004), condyle height (P = 0.010) and gonion to midsagittal plane distance (P = 0.018). CONCLUSIONS: Asymmetrical subjects showed higher values for canine inclination and mandibular body, ramus and condylar height on the NDv side. The hypothesis was partially confirmed that mandibular morphology and dental compensations are different between symmetrical/asymmetrical groups and among different sagittal skeletal patterns.

Evaluation of facial soft tissue thickness in symmetric and asymmetric subjects with the use of cone-beam computed tomography.

INTRODUCTION: The aims of this study were to evaluate facial bilateral soft tissue thickness in symmetric and asymmetric subjects and to investigate whether soft tissue compensates for skeletal asymmetry. METHODS: Cone-beam computed tomography (CBCT) scans of 97 subjects were divided into a symmetry group (GSm) and an asymmetry group (GASm). Seven bilateral points were established. Each point involved 3 variables: hard tissue distance (Hard-D), soft tissue distance (Soft-D), and soft tissue thickness (Soft-Th). Measurements were taken from software-generated multiplanar reconstructions. A paired t test was used to assess intragroup differences and an independent t test for intergroup analysis. Pearson coefficient tested correlations between variables. RESULTS: In GASm, significant differences were found in all Hard-D and Soft-D measurements, with higher values observed on the deviated side (P <0.01). As for Soft-Th evaluation, results of only 1 reference point presented statistical significance. Intergroup comparison detected significant differences in all Hard-D and Soft-D variables (P <0.01), but no significant differences in Soft-Th. CONCLUSIONS: Asymmetric subjects presented differences in hard and soft tissue distances between deviated and nondeviated sides, although without affecting soft tissue thickness. It can be concluded that soft tissue does not compensate or disguise an underlying skeletal asymmetry.