Pretreatment characteristics associated with orthodontic treatment duration

Introduction: Pretreatment characteristics can assist orthodontists in accurately estimating treatment duration. Methods: This case-control study identified 400 patients, 9 to 18 years of age. Short treatment duration was 20 months or less, and long treatment duration was 30 months or longer. Potential pretreatment explanatory variables included planned treatment, sociodemographic, behavior, dental, skeletal, and soft-tissue characteristics. Univariable and multivariable logistic regression modeling was used to quantify the association between patient characteristics and treatment duration by reporting the unadjusted odds ratios (OR-crude), the adjusted odds ratios (ORadj), and the 95% confidence intervals (CIs). Results: Patients planned as nonextraction (ORadj = 2.3; 95% CI, 1.3-4.2), no deciduous teeth (ORadj = 3.0; 95% CI, 1.5-5.9), less than 80% overbite (ORadj = 2.4; 95% CI, 1.3-4.4), less than 6 mm of maxillary crowding (ORadj = 3.6; 95% CI, 1.7-7.7), and good oral hygiene (ORadj = 3.2; 95% CI, 1.3-1.8) were 2 to 3 times more likely to have short treatments. Patients with decreased lower facial height (ORadj = 3.4; 95% CI, 1.6-7.1), extractions (ORadj = 1.8; 95% CI, 1.0-3.2), deciduous teeth (ORadj = 1.9; 95% CI, 1.0-3.4), poor grades (ORadj = 2.0; 95% CI, 1.1-3.8), excessive overjet (ORadj = 2.3; 95% CI, 1.4-3.8), 80% or more overbite (ORadj = 2.0; 95% CI, 1.2-3.6), and 6 mm or more of maxillary crowding (ORadj = 2.6; 95% CI, 1.4-4.6) were 2 to 3 times more likely to have long treatments. Conclusions: Presence or absence of severe maxillary crowding, deciduous teeth, 80% overbite, and extractions were consistently, inversely, and independently associated with short and long treatment durations. (Am J Orthod Dentofacial Orthop 2010; 137: 178-86)