Cephalometric norms for craniofacial asymmetry using submental-vertical radiographs.

The submental-vertical (S-V) radiograph has become popular in the assessment of craniofacial asymmetry because of ease in identifying reliable midline reference structures. To date, no standards of asymmetry that use the S-V projection have been reported. Submental-vertical radiographs were obtained on 44 adults. Subjects were excluded if previous orthodontic treatment or temporomandibular joint symptoms were reported. With the use of a system of asymmetry analysis developed by Ritucci and Burstone, asymmetry was reported for cranial base, zygomaxillary complex, and mandibular structures. Mean and standard deviations were used to report the asymmetry values across 23 pairs of anatomic landmarks. The data showed that asymmetry is present to some degree in all landmarks and patients. Further, strong asymmetry associations existed between landmarks within patients, with most high positive correlation coefficient values found between regionally or geometrically related points. A refined version of the asymmetric analysis was presented that included easily identified and clinically relevant points. This system is more feasible for the orthodontic clinician.