Orthognathic surgery

Symphysis

Cadaveric spasm

Mandible (arthropod mouthpart)

Biology

Genus

Computed tomography

Botany

Genioplasty

Dentistry

Geology

Mandibular symphysis

Radiology

Paleontology

Chin

Anatomy

Orthodontics

Morphology (biology)

Medicine

Cephalometry

American Journal of Orthodontics and Dentofacial Orthopedics

•Chin and symphysis size and shape are facial type–dependent. •A short face is associated with a square-shaped protruding chin. •Patients with a long face present long symphysis. •Chin width is facial type–dependent in females but not in males. •Mandibular incisor inclination is independent of chin and symphysis morphology. Introduction The chin is a major determinant of the facial profile; hence, it plays a major role in orthodontics and orthognathic surgery. It is thus essential to follow and better understand its expression in different facial types. The major objectives of the current study were to characterize morphometrically the chin and symphysis and reveal their association with different facial types. Methods Computed tomography scans of the head and neck of 311 adults (163 males, 148 females; age range, 18-95 years) were classified into 3 facial types: short, average, and long. Height, width, projection, inclination, thickness, and area were measured on the chin and symphysis. Results The majority of the population (70%) manifested an average facial type; the other 30% were almost equally distributed between short and long facial types. The long facial type was more common among females and the short facial type among males. Chin projection, area, and size were significantly greater in short-faced patients. Chin width in males was similar for all facial types, whereas, in females, chin width was the widest in the short facial type and the narrowest in the long facial type. Symphysis height was significantly greater in long-faced patients in both sexes. The mandibular incisors’ inclination relative to the mandibular plane was not significantly associated with the chin or symphysis morphology. Conclusions Chin and symphysis morphology is facial type–dependent. Orthodontists and maxillofacial surgeons should be aware of the complex relationship between facial types and chin/symphysis size and shape when planning treatment.

Are chin and symphysis morphology facial type–dependent? A computed tomography-based study