Related Experiment Video
Updated: Sep 26, 2025

Foreign Accent and Forensic Speaker Identification in Voice Lineups: The Influence of Acoustic Features Based on Prosody
Published on: September 27, 2024
Perception and analysis of lip-line canting by different populations
Jing Lu1, Di Wu1, Shengguo Wang1
1Department of Stomatology, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, China.
Introduction:
This study aimed to provide a valuable reference for the precise diagnosis and treatment of lip-line canting (LLC) in an orthodontic clinic, determine the average observed LLC that would need treatment, and compare the differences in different populations.
Methods:
We took frontal photographs of an adult female with rough facial symmetry and processed them into fully symmetrical frontal images using Photoshop (Adobe Systems, San Jose, Calif). After that, the lip line was rotated clockwise with a gradient of 1° to obtain 8 different pictures. Next, without informing the observers of the aim of the study, we randomly selected 60 dentists, 60 orthodontic patients, and 60 non-oral-related practitioners to observe the LLC in the photographs. We numbered all the images randomly, and the evaluators categorized them as a little LLC not requiring treatment and marked LLC requiring treatment. We then analyzed the results statistically.
Results:
Among the 240 observers, the average perception of LLC was 2.65°, and it was 4.1° for those requiring treatment. Orthodontists were more sensitive to the LLC than dentists and non-oral-related practitioners, and orthodontic patients were more sensitive than non-oral related practitioners (P <0.05). Overall, the tolerance value of the orthodontic patients was the least (P <0.05).
Conclusions:
Among all the observers, orthodontic patients had the highest requirement for LLC. This finding could help therapists consider patient expectations when determining treatment plans.
Related Concept Videos
Non-Verbal Cues
Language and Cognition
Facial Feedback Hypothesis
Social Proof
Lateralization
Understanding Deception

