Relationship between masseter muscle size and maxillary morphology

• Published in: European journal of orthodontics 2011-12, Vol.33 (6), p.654-659
• Main Authors: Uchida, Yasuki, Motoyoshi, Mitsuru, Shigeeda, Toru, Shinohara, Akihiko, Igarashi, Yu, Sakaguchi, Masahito, Shimizu, Noriyoshi
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Anatomy, Cross-Sectional; Bite Force; Cephalometry - methods; Dental Arch - anatomy & histology; Dental Occlusion, Centric; Dentistry; Face - anatomy & histology; Female; Humans; Male; Mandible - anatomy & histology; Masseter Muscle - anatomy & histology; Masseter Muscle - diagnostic imaging; Maxilla - anatomy & histology; Maxilla - diagnostic imaging; Muscle Contraction - physiology; Nasal Bone - anatomy & histology; Palate - anatomy & histology; Rotation; Sella Turcica - anatomy & histology; Skull Base - anatomy & histology; Ultrasonography; Vertical Dimension; Young Adult
• ISSN: 0141-5387; 1460-2210
• DOI: 10.1093/ejo/cjq152

The aim of this study was to investigate the relationship between masseter muscle size and craniofacial morphology, focusing on the maxilla. Twenty-four patients (11 males and 13 females; mean age 27.6 ± 5.6 years) underwent cephalometric analyses. Ultrasonography was used to measure the cross-sectional area (CSA) of the masseter muscle and bite force was measured using pressure sensitive film. The results showed that CSA-relaxed was positively correlated with upper anterior face height (UAFH)/total anterior face height (TAFH) and negatively with lower anterior face height (LAFH)/TAFH and LAFH (P < 0.05). CSA-clenched was correlated positively with SN-palatal, FH-palatal, UAFH/TAFH, and lower posterior face height (LPFH)/total posterior face height (TPFH) and negatively with LAFH/TAFH, LAFH, upper posterior face height (UPFH)/TPFH, and UPFH (P < 0.05). Bite force was positively correlated with LPFH/TPFH and negatively with UPFH/TPFH (P < 0.05). As the masseter became larger, the anterior maxillary region tended to shift downwards relative to the cranial base, whereas the posterior region tended to shift upwards. The decrease in LAFH/TAFH and increase in LPFH/TPFH as the size of the masseter muscle increases may be influenced not only by the inclination of the mandibular plane but also by the clockwise rotation of the maxilla.