Normal range of facial asymmetry in spherical coordinates: a CBCT study

Abstract

PurposeThis study aimed to measure the bilateral differences of facial lines in spherical coordinates from faces within a normal range of asymmetry utilizing cone-beam computed tomography (CBCT).Materials and MethodsCBCT scans from 22 females with normal symmetric-looking faces (mean age 24 years and 8 months) were selected for the study. The average menton deviation was 1.01±0.66 mm. The spherical coordinates, length, and midsagittal and coronal inclination angles of the ramal and mandibular lines were calculated from CBCT. The bilateral differences in the facial lines were determined.ResultsAll of the study subjects had minimal bilateral differences of facial lines. The normal range of facial asymmetry of the ramal and mandibular lines was obtained in spherical coordinates.ConclusionThe normal range of facial asymmetry in the spherical coordinate system in this study should be useful as a reference for diagnosing facial asymmetry.

Use of spherical coordinates to evaluate three-dimensional facial changes after orthognathic surgery

“…Similarly, the symmetry of human anatomical structures in 3D space can be also evaluated with the spherical coordinate system 18. This system can be modified to define the length, midsagittal, and coronal inclinations of facial lines in 3D images of human structures 19,20…”

“…Recently, a new spherical coordinate system for the 3D analysis of facial asymmetry was introduced. Using this new system, facial lines can be more clearly defined by their length as well as vertical and horizontal angle in the spherical coordinate system 18,19,20. The spherical coordinate system may be used to indicate definitive changes to the facial area before and after orthognathic surgery.…”

A Retrospective 3D Radiologic Analysis of 52 Patients with Mandible Fractures

“…The need for clear images of cranial morphology played a large part in the development of 3D imaging and more recently solid anatomic modeling. 10,11 Improvements in computer hardware and software have not only made 3D images more realistic and detailed, but also allowed shape analysis and the measurement of distance and volume. [10][11][12][13][14] Spherical coordinate systems are used for various purposes such as astronomy and geology.…”

“…10,11 Improvements in computer hardware and software have not only made 3D images more realistic and detailed, but also allowed shape analysis and the measurement of distance and volume. [10][11][12][13][14] Spherical coordinate systems are used for various purposes such as astronomy and geology. For example, in geology, a spherical coordinate system describes a flying object over the earth with its distance from the center of the earth and its latitude and longitude.…”

“…9,10 As there are numerous complications reported, different treatment modalities are followed for the betterment of the patient. 10,11 However, the relationship between the angulation degree of fracture, MMF need operation time, and the complication rates has not been well investigated. Complications included were malocclusion, malunion, nonunion, infection, and extrusion of the implants.…”