Determinants of Severe Orthodontic Treatment Need Using Clinically Categorized Occlusal Features

Background/Objectives: Systematic assessment of orthodontic treatment needs is essential for prioritizing care in public health programs. The Dental Aesthetic Index (DAI) provides a composite severity score; however, understanding which individual occlusal traits drive severe treatment needs has a practical screening value. This study aimed to determine which occlusal features, categorized using established clinical thresholds, independently associated with severe orthodontic treatment need. Methods: Pretreatment records of 292 patients (141 men, 151 women; aged 13–42 years) were analyzed. The outcome was severe treatment need (DAI ≥ 31). Ten DAI components were categorized using IOTN-DHC severity cutpoints; Angle and skeletal classifications were also assessed. Candidate predictors (p < 0.20) were entered into multivariate logistic regression with backward elimination. Discrimination was assessed by ROC analysis; internal validation used bootstrap resampling and cross-validation. Results: Of the 292 patients, 141 (48.3%) had severe treatment needs. Six occlusal features were independently associated with severe treatment need (all p < 0.001): overjet severity (adjusted odds