Digital orthodontic setup-based assessment of post-treatment open gingival embrasures in adult extraction cases with fixed appliances: a retrospective study

Background To evaluate agreement between assessments of post-treatment open gingival embrasure (OGE) presence and severity based on simulated three-dimensional gingival morphology in digital orthodontic setups and photographic reference classifications in adult extraction cases treated with fixed appliances. Methods This retrospective study included 62 adults treated with extraction of four first premolars and fixed appliances, each contributing 10 paired anterior interproximal sites (620 sites). A single examiner independent of patient treatment graded post-treatment photographs as the reference classification and the software-simulated three-dimensional gingival morphology in setups generated exclusively from pretreatment digital models. Overall linear weighted Cohen’s kappa (κ) for modified Jemt grades was the primary endpoint. Binary classification measures were secondary, and arch-, sex-, and site-stratified analyses were exploratory. All performance estimates were site-level; 95% confidence intervals (CIs) accounted for patient-level clustering. Results With 95% CIs in parentheses, overall linear weighted κ was 0.716 (0.657–0.769), exact-grade agreement was 0.808 (0.774–0.840), and mean absolute error was 0.194 (0.160–0.229) grades. Secondary binary accuracy was 0.918 (0.894–0.940), with sensitivity of 0.975 and specificity of 0.770. The photographic reference and setup-based proportions of OGE-positive sites were 71.9% and 76.6%, respectively, indicating a modest tendency toward setup-based overclassification (difference, 4.7% points). Conclusions Examiner-rated digital setup-based classifications showed preliminary within-sample agreement with post-treatment photographic reference classifications in this selected retrospective cohort. The findings support feasibility rather than validated prediction or examiner-independent reproducibility; prospective external validation with independent examiners is required before clinical utility can be established.