Inclination Changes in Incisors During Orthodontic Treatment with Passive Self-Ligating Brackets

Background: Correct inclination of the incisors is crucial for function and occlusion. The aim of this retrospective cephalometric study was to investigate the effect of orthodontic treatment with passive self-ligating (SL) brackets on the incisor inclination compared to untreated controls. Methods: This study evaluated an orthodontic treatment group (n = 30, Ø13.4 years, ANB Ø2.3°) before (T1) and after (T2) orthodontic therapy with passive SL-brackets (MBT prescription, 0.022″ slot) by one experienced orthodontist. The control group was matched according to age and sex (n = 30, Ø13.3 years, ANB Ø2.5°). The incisor inclination was evaluated digitally using cephalometric lateral radiographs. Results: The cephalometric evaluation showed a significant incisor proclination during orthodontic treatment with SL brackets. The upper incisors proclined by +3.8° (U1–PP) and +3.7° (U1–SN) and the lower incisors proclined by +4.4° (L1–MP). The control group presented a reclination of the upper incisors by −1.4° (U1–PP) and −0.6° (U1–SN) and the lower incisors by −0.4° (L1–MP). The clinically relevant protrusion effect during orthodontic treatment with SL brackets summed up to +5.2° (U1–PP), and +4.3° (U1–SN) for the upper incisors (+2.0°/year, +1.6°/year) as well as +4.8° (L1–MP) for the lower incisors (+1.6°/year) compared to controls. Sex-specific differences were found. Males showed a greater proclination of the upper incisors by +5.3° (U1–PP) and +5.9° (U1–SN) compared to females in the treatment group. Conclusions: Orthodontic treatment with SL brackets results in protrusion of the upper and lower incisors by +5° compared to controls. These findings must be considered in orthodontic treatment planning according to initial diagnostics.