Smile Line and the Psychosocial Impact of Gingival Esthetics in Costa Rican Adults: A Cross-Sectional Study

Objective: The objective of this study is to assess whether smile line is associated with the psychosocial impact of gingival esthetics in adult dental patients. Methods: A cross-sectional observational study was conducted among 164 patients attending the Restorative Dentistry Clinic at the Faculty of Dentistry, University of Costa Rica. The psychosocial impact of gingival esthetics was assessed using a culturally adapted and validated version of the Psychosocial Impact of Gingival Esthetics Questionnaire (PIGAQ), which evaluates four dimensions: gingival self-confidence, social impact, psychological impact, and esthetic concern. Smile line was classified according to the criteria proposed by Tjan et al. (1984) as high, average, or low based on the extent of gingival display during smiling. Unadjusted associations were assessed using categorical comparisons, and multivariable linear regression models were made to evaluate the independent association between smile line and PIGAQ scores after adjustment for age category, sex, educational level, and previous orthodontic treatment. Results: The mean overall PIGAQ score was 16.82 ± 19.80, indicating a generally low psychosocial impact of gingival esthetics. Mean scores for the individual dimensions were also low: gingival self-confidence, 5.01 ± 5.90; social impact, 4.42 ± 7.07; psychological impact, 5.20 ± 5.91; and esthetic concern, 2.20 ± 3.32. The average smile line was the most prevalent category (60.4%), followed by low (31.1%) and high (8.5%) smile lines. In the unadjusted analysis, smile line was significantly associated with gingival self-confidence (p = 0.043), whereas no significant associations were observed for social impact (p = 0.574), psychological impact (p = 0.884), esthetic concern (p = 0.265), or the overall PIGAQ score (p = 0.533). However, after adjustment for age category, sex, educational level, and previous orthodontic treatment, neither high nor low smile line was significantly associated with the total PIGAQ score or any of its individual dimensions. For gingival self-confidence, the adjusted β was 0.8 (95% CI, −4.4 to 6.0; p = 0.763) for high versus average smile line and −0.7 (95% CI, −2.6 to 1.2; p = 0.472) for low versus average smile line. Conclusions: The overall psychosocial impact of gingival esthetics was low in this sample. Although an unadjusted association was observed between smile line and gingival self-confidence, this association was not maintained after adjustment for relevant sociodemographic and clinical characteristics. These findings suggest that smile line alone may not independently explain differences in patients’ psychosocial perceptions of gingival esthetics. Larger studies with more balanced representation across smile line categories are warranted to further investigate these relationships.