The Barcelona Line as a Sagittal Soft Tissue Reference in Orthodontic Diagnosis and Treatment Planning: A Validation Study

OBJECTIVES: The Barcelona Line (BL) has recently been introduced as a soft tissue-oriented reference for evaluating sagittal incisor position. This study aimed to assess the relationship between BL and skeletal, dental, and soft tissue parameters across different malocclusion classes and to evaluate its clinical applicability in orthodontic diagnosis. MATERIALS AND METHODS: This retrospective cross-sectional study included pretreatment lateral cephalometric radiographs of 312 adult individuals (mean age: 23.6 y) with class I, II, and III malocclusions. Skeletal (SNA, ANB, and Wits), dental (U1/NA), and soft-tissue (upper lip to E-line and S-line, nasolabial angle) parameters were analyzed. The distance between the upper incisor and the BL (U1-BL) was measured. Intergroup comparisons were performed using one-way ANOVA with Tukey post hoc tests. Correlation and linear regression analyses were conducted to evaluate associations between BL and other variables. RESULTS: BL values showed statistically significant differences according to both sex and malocclusion type (P<0.05). Weak but significant positive correlations were found between BL and ANB (r=0.198, P=0.026), upper lip to E-line (r=0.218, P=0.016), and S-line (r=0.189, P=0.033). No significant correlations were observed with SNA, Wits, U1/NA, or nasolabial angle (P>0.05). Regression analysis demonstrated limited explanatory power of the model (R2=0.161, P=0.073). CONCLUSIONS: The Barcelona Line is associated with sagittal skeletal relationships and soft tissue profile characteristics; however, its predictive capacity is limited. BL may serve as a complementary clinical reference for evaluating upper incisor position in relation to facial aesthetics, particularly when used alongside established soft tissue analyses, rather than as a standalone diagnostic parameter. CLINICAL RELEVANCE: BL may assist clinicians in assessing incisor positioning within the soft-tissue profile and support decision-making for aesthetic treatment planning, especially in borderline cases.