Predictors Of Gingival Wedge Space Opening In Non-Extraction Orthodontics

This study aims to evaluate the clinical incidence of open gingival embrasures (OGEs) in the mandibular central incisor region following non-extraction fixed orthodontic treatment using a retrospective cohort design, identify preoperative characteristic factors predictive of OGE formation, and provide a theoretical basis for establishing a pre-treatment risk assessment system. Fifteen preoperative characteristics of orthodontic patients were collected from intraoral digital photographs, digital dental models, and lateral cephalograms. Patients were divided into two groups: normal gingival embrasure and open gingival embrasure. The interdental papilla area was divided into four regions to determine the presence of OGEs between the mandibular incisors. Univariate and multivariate logistic regression models were used to quantify associations between preoperative characteristics and OGEs; odds ratios (ORs) and 95% confidence intervals (95% CIs) were reported. Among 980 patients, 147 were included (mean age: 14.92 ± 4.91 years). The incidence of OGEs in non-extraction fixed orthodontic patients was 23.1%. Statistically significant differences were observed between the normal and OGE groups in age, crowding degree, anteroposterior distance between mesial incisal angles, and angulation between incisal edges (P < 0.05). Regression analysis revealed that age and anteroposterior distance between mesial incisal angles were significantly associated with OGE occurrence (P < 0.05), both serving as risk factors. The incidence of OGEs in the mandibular central incisor region after non-extraction fixed orthodontic treatment is relatively high. Older age and greater anteroposterior distance between mesial incisal angles increase the risk of OGE formation.