A Study of the Facial Soft Tissue Morphology in Nasal- and Mouth-Breathing Patients

OBJECTIVES: This study aimed to investigate the 3-dimensional (3D) facial morphology of children with skeletal Class II structure with different breathing patterns. METHODS: The 3dMDFace system (3dMD Inc.) was used to obtain 3D facial images. A total of 65 patients aged 10 to 12 years with skeletal Class II malocclusion (A point-Nasion-B point angle >5°) were grouped by sex into nasal-breathing (NB) and mouth-breathing (MB) participants. A total of 19 measurements, including linear distances, angles, and ratios, were measured. The measurements were compared using independent sample t test and Mann–Whitney U test. Factor analysis and logistic regression were used to test the correlation between facial morphology and different breathing patterns. RESULTS: For male children, the lower lip was longer in the MB group than in the NB group (P < .05). For female children, compared to NB, MB patients had a narrower mandibular width (P < .05), a smaller ratio of mandibular width to face height (MB: 0.99 ± 0.08 vs NB: 1.04 ± 0.09; P < .05), and a larger ratio of lower lip height to lip width (MB: 1.24 ± 0.10 vs NB: 1.19 ± 0.16; P < .05). In both male and female children, MB participants had a more convex nasolabial angle (P < .05) and an increased ratio of the lower part of the face to the upper facial height (male MB: 1.61 ± 0.17 vs male NB: 1.50 ± 0.12; female MB: 1.52 ± 0.10 vs female NB: 1.50 ± 0.20; P < .05). The logistic regression test showed no significant correlation between facial morphology and breathing patterns. CONCLUSIONS: In participants with skeletal Class II pattern, MB children compared with NB children showed different facial morphology in the same sex group. The children with MB showed a more protruded upper lip and increased lower facial height, accounting for a larger proportion of the facial height. However, no significant correlation was found between facial morphology and breathing pattern. Only correlative trends were found.