Patient-associated and treatment-related predictive factors influencing the duration of orthodontic treatment with fixed appliances

Objectives: To examine various patient- and treatment-related factors contributing to prolonged therapy. Materials and Methods: This retrospective study analyzed clinical records of consecutively treated patients from a private orthodontic clinic. Univariate and multivariable linear regression were conducted to investigate patient- and treatment-related factors associated with increased orthodontic treatment duration. Results: A total of 357 patients, with a median age of 14 years (IQR = 13, 17), females (n = 220, 61.6%), was included. Orthodontic treatment lasted a mean of 28.5 ± 10 months. Multivariable linear regression revealed that significant patient-related factors for increased duration were Angle Class II-Class I (B = 4.78; 95% CI = 2.74, 6.81; P < .001) and impacted (B = 9.68; 95% CI = 5.41, 13.94; P < .001), while treatment-related factors were dental arch (B = -9.89; 95%CI = -13.14, -6.64; P < .001), molar attachment (B = 3.05; 95% CI = 0.35, 5.76; P = .027), and extraction (B = 3.73; 95% CI = 1.52, 5.94; P = .001). Investigation in Class II cases indicated that Class II subdivision exhibited significantly shorter duration than bilateral Class II (P = .033). Conclusions: Class II compared with Class I and the presence of at least one impacted tooth were significant patient-related factors, while dual-arch orthodontic treatment, preferring bands over tubes, and including at least one extraction in the treatment plan were significant treatment-related factors for prolonged therapy. Class II (nonsubdivision) was associated with extended duration in contrast with Class II subdivision.