1. Thickness change of masseter muscles and the surrounding soft tissues in female patients during orthodontic treatment: a retrospective study
- Author
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Yichen Pan, Yungeng Zhang, Si Chen, Linhui Shen, Yuru Pei, and Tianmin Xu
- Subjects
Adult ,Cephalometry ,Treatment duration ,Computed tomography ,Esthetics, Dental ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Female patient ,Machine learning ,medicine ,Humans ,General Dentistry ,Retrospective Studies ,Orthodontics ,medicine.diagnostic_test ,Adult patients ,business.industry ,Masseter Muscle ,Soft tissue ,CBCT ,Retrospective cohort study ,030206 dentistry ,Cone-Beam Computed Tomography ,Masseter muscles ,Computer-assisted image processing ,Sagittal plane ,lcsh:RK1-715 ,medicine.anatomical_structure ,lcsh:Dentistry ,Face ,Oral and maxillofacial surgery ,Female ,business ,Research Article - Abstract
Background Facial esthetics is a major concern of orthodontic patients. This study aims to evaluate orthodontic treatment-related thickness changes of the masseter muscles and surrounding soft tissues and the potential factors that would influence these changes during orthodontic treatment in female adults. Methods Forty-two female adult patients were included in this retrospective study and were divided into extraction (n = 22) and nonextraction (n = 20) groups. Pretreatment and posttreatment cone-beam computed tomography (CBCT) images were superimposed and reconstructed. The thickness changes of the masseter area of facial soft tissue (MAS), masseter muscles (MM) and surrounding fat tissue (FT) were measured. Pretreatment age, treatment duration, sagittal relationship (ANB), and vertical relationship (Frankfort-mandibular plane angle, FMA)-related MAS, MM and FT changes were compared between extraction and nonextraction groups. Spearman’s correlation coefficient was calculated between the above variables. Regression analysis was conducted to confirm the causal relations of the variables. Results The thickness of MAS and MM significantly decreased in both groups, with larger decreases (> 1 mm) in the extraction group. There were strong correlations (r > 0.7) between the thickness decrease in MAS and MM in both groups and moderate correlations (r > 0.4) between MAS and FT in the nonextraction group. A significantly greater decrease of MAS and MM were found to be moderately correlated with a smaller FMA (r > 0.4) in the extraction group. Scatter plots and regression analysis confirmed these correlations. Conclusions Masseter muscles and the surrounding soft tissue exhibited a significant decrease in thickness during orthodontic treatment in female adults. Low-angle patients experienced a greater decrease in soft tissue thickness in the masseter area in the extraction case. But the thickness changes were clinically very small in most patients. more...
- Published
- 2020