Association of Normal Values of Nasolabial Angle and Lip Length with Incisal Display at Rest Position of Lips

Abstract

Objective: To determine correlation between values of nasolabial angle and lip length with incisal display at rest position of lips.

Methodology: This descriptive cross-sectional study was conducted at Institute of Dentistry LUMHS, Jamshoro from Jan-June 2023. Individuals aged between 18 to 40 years visiting for prosthesis of posterior teeth, both genders, with fully erupted anterior maxillary teeth and well aligned teeth and with intact upper central incisors, with no significant wear, fractures, or discoloration were included. A photogrammetric approach was employed to analyze the nasolabial angle, and two photographs with frontal and lateral views, with the camera placed 1.5 meters, which were digitally analyzed, with the nasolabial angle measured in degrees and the lip length and incisal display measured in millimeters. Vernier caliper was used for measurement of the lip length from the base of the nose to the lowest point of the upper lip, and these measurements were cross-referenced with digital measurements to ensure accuracy.

Results: Overall mean age of patients was 28.4 ± 6.7 years. Overall mean nasolabial angle was 93.38°, total lip length average 20.02 mm, and incisal display average 2.09 mm, with the majority of the cases (60.3%) had minimal exposure of 0–2.0 mm. 

Conclusion: Nasolabial angle and lip length are significant independent determinants of incisal display at rest in the Pakistani population, with females exhibiting greater display values.