Systematic review of facial asymmetry
Yuh-Jia Hsieh, Shih-Wen Fan, Nuttapong Udomlarptham, Piyanan Keardkhong, Yu-Fang Liao
Facial asymmetry could have a significant impact on perceived attractiveness. It’s also a common chief complaint of patients with various type of dentofacial deformities. However, perfect bilateral facial symmetry is almost a theoretical concept that it seldom exists in the nature. A mild degree of asymmetry is commonly seen and acceptable and could even add to attractiveness whereas a greater degree of asymmetry might lead to severe psychosocial problems. Major asymmetry involving both the upper and lower jaws often requires a combination of orthodontic treatment and orthognathic surgery.
This systematic review was based on structured search of electronic databases and hand searching, and covered three main aspects in facial asymmetry. First, scientific evidence was searched to define a range of facial asymmetry that is esthetically acceptable and clinically significant threshold value or cutoff point at which a facial asymmetry is perceived as unattractive was investigated. Second, relevant literature was reviewed to assess the treatment outcome of facial asymmetry corrected by orthognathic surgery. Finally, conventional surgical planning is limited to 2 dimensions while facial asymmetry is usually a three-dimensional phenomenon. Recently, cone-beam computed tomography and 3dMD were widely used to provide a 3D visualization of hard and soft tissues, having applications from diagnosis to simulation of orthognathic surgery. The three dimensional virtual planning is thus likely to overcome the shortcomings of traditional planning and may allow more comprehensive analysis and surgical planning, especially for patients with facial asymmetry. Literature search was therefore undertaken to investigate the accuracy of 3D virtual planning and to see if 3D virtual planning could have better surgical outcomes than traditional ones.