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Perception of Lip Cant as a Sign of Facial Deformity

Assessment by Laypersons and Professionals on Composite Face Photographs

Lee, Shou-Fan, BS*; Dumrongwongsiri, Sarayuth, MD; Lo, Lun-Jou, MD

doi: 10.1097/SAP.0000000000001724
Head and Neck Surgery

Objective Lip cant is a feature of facial deformity and commonly seen in patients with facial asymmetry. Because of its importance in aesthetic assessment, it is necessary to define the perceptions of lip cant and investigate differences in perception between laypersons and professionals. These data were insufficient in the literature.

Methods Photographs of 30 male and 30 female individuals with normal faces were collected, and the lip line angles were measured. A composite facial photograph was generated from superimpositions of the normal faces. Lip line angles from 0° to 9° were made, with other facial features remaining unchanged. The test photographs were arranged in random fashion and evaluated by 64 laypersons and 30 professionals. Comparisons and cumulative frequency were performed.

Results The lip line angle from the 60 normal persons was 1.20° ± 0.94°. From the composite test photographs, the average first perception of lip cant was 3.25° 1± 1.36° in the laypersons and 1.70° ± 0.69° in the professionals. The average first perception of unacceptable lip cant was 6.40° ± 1.79° in the laypersons and 4.40°1. ± 1.65° in the professionals. Significant differences were found between the first perception and perception as unacceptable lip cant, as well as between the laypersons and the professionals. Cumulative data showed that 82.8% of the laypersons perceived lip cant at 4°, and 17.2% of them felt it aesthetically unacceptable. Few laypersons (1.6%) considered less than 4° unacceptable.

Conclusions The data in this study provide helpful information in the evaluation of lip cant. A lip cant of 4° or more could be considered an indication for clinical management.

From the *Medical School of Chang Gung University; and

Plastic and Reconstructive Surgery and Craniofacial Research Center, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.

Received September 21, 2018, and accepted for publication, after revision October 3, 2018.

Conflicts of interest and sources of funding: This study was supported by a project from the Chang Gung Medical Foundation (CRRPG3G0021) and a project from the Ministry of Science and Technology (MOST 106-2314-B-182-060). The authors declare no conflict of interest.

Reprints: Lun-Jou Lo, MD, Plastic & Reconstructive Surgery, Chang Gung Memorial Hospital, 5 Fu-Shin Street, Kwei Shan, Taoyuan, Taiwan 333. E-mail:

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