Morphological differences in lower facial third soft tissues in children with and without gingival smile: A cross‐sectional comparative study

Abstract

Aim The aim of the present study was to establish the relationship between lower facial third and smile type in silent mixed‐dentition patients. Methods This cross‐sectional study, approved by the ethics committee, was conducted in a population of 2760 children, from which a convenient sample of 198 was included: 75 with gingival smile (GS) and 123 without GS (1:1.64). Clinical examination and videos were taken. Occlusal relation, overjet (OJ), overbite (OB), superior lip length at rest, superior lip length while smiling (SLLS), lower facial third height (LFTH), mid‐facial third height (MFTH), clinical crown length, and lip lift ability (LLA) were measured by two calibrated examiners (intraclass correlation coefficient: ≥.95). A normality test and demographic and bivariate analyses were undertaken. A non‐paired Student's t test was carried out in order to observe statistically‐significant differences between variables. Results There were no differences between sexes or associations between LFTH and GS. Statistically‐significant differences (P < .05) in MFTH, SLLS, LLA, OJ, and OB were found. A logistic regression model showed that the sum of LLA (odds ratio [OR]: .65, 95% confidence intervals [CI]: .50,.83]) and OB (OR: .88, 95% CI: .82, .93]) were GS predictive factors in 81.3% of cases. Conclusions OB and LLA are GS predictive factors in prepubertal participants. There is no relation between LFTH and GS.