Smile frameworks defined by the patient's facial pattern: A cross-sectional study

The aim of this study was to evaluate the association between patients' facial pattern (brachyfacial, mesofacial, and dolichofacial) and the smile framework, defined as the exposure frame of intraoral tissues delineated by the lip contours during smile.

Overall, 120 participants were divided into 3 groups (n = 40) based on their facial pattern: brachyfacial, mesofacial, and dolichofacial, as determined by cephalometric analysis. Smile and rest displays were assessed using the smile framework (primary outcome), interlabial distance, intercommissural distance, maxillary incisor exposure, and gingival exposure, among other outcome measures. A two-way analysis of variance was conducted to analyze how facial pattern and sex influenced each outcome.

A single smile framework was identified for each facial pattern: elliptical or football-shaped in dolichofacial patterns, shallow crescent-shaped in mesofacial patterns, and flat in brachyfacial patterns. Dolichofacial group showed significantly higher values in vertical outcome measures, including interlabial distance, gingival exposure, and maxillary incisor exposure, both at rest and during smile (P < 0.001). In contrast, brachyfacial group presented greater values in horizontal outcome measures, such as intercommissural distance (P < 0.001). Sex was not a significant factor influencing most measurements across the facial pattern groups.

Patients' facial patterns are associated with specific smile frameworks regardless of sex, with elliptical or football-shaped patterns in dolichofacial group, shallow crescent-shaped patterns in mesofacial group, and flat patterns in brachyfacial group, reflecting anatomic constraints and the working zone for orthodontic treatment planning.