Morphology of the Labial Frenum by Age Cohort: A Cross-Sectional Study

Background/Objectives: The labial frenum is a variable oral structure with potential impacts on infant feeding, speech development, periodontal health, and aesthetics. Several classification systems have been established, but the age-related natural history and its relationship with midline diastema remain incompletely defined. This study aimed to systematically evaluate age-related changes in maxillary and mandibular labial frenum morphology and tension, and their association with midline diastema across pediatric age groups. Methods: A cross-sectional study was conducted on 1068 patients (ages 1 day–47 years) presenting for routine dental examinations at two pediatric dental clinics. Frenum morphology was classified as mucosal, gingival, papillary, or papillary-penetrating. Palpable tension was assessed by manual lip pulling and recorded as present or absent. Midline diastema was defined as ≥1 mm spacing between the maxillary central incisors, measured at the incisal midline with a periodontal probe. Data were analyzed using Pearson’s chi-square tests with Bonferroni correction for multiple comparisons, and logistic regression was applied to evaluate independent predictors. Inter-examiner agreement was assessed using Cohen’s κ. Results: Among 1068 participants, maxillary frenum morphology varied significantly by age. In children < 3 years, papillary and papillary-penetrating insertions predominated (65.7%), while gingival and mucosal insertions were more frequent in older children and adults (72.8%). Palpable tension declined sharply with age, from 92.5% in infants to <10% in adults. Midline diastema was significantly associated with papillary-penetrating frena (RR = 3.47, 95% CI 2.45–4.91) and with the presence of tension (RR = 1.68, 95% CI 1.34–2.11). Logistic regression confirmed both phenotype (OR = 6.2, 95% CI 3.8–10.1) and tension (OR = 2.1, 95% CI 1.5–2.9) as independent predictors of diastema. In contrast, mandibular frena showed minimal variation by age and limited functional impact. Conclusions: The maxillary labial frenum demonstrates predictable developmental change, migrating apically and losing tension most prominently between 3 and 6 years of age, while the mandibular frenum remains largely stable. Papillary and papillary-penetrating phenotypes with palpable tension carry the greatest risk of midline diastema. These findings emphasize that management should prioritize functional symptoms and growth trajectory rather than appearance alone, with frenectomy reserved for cases of demonstrable impairment.