RESUMEN
PURPOSE: To determine the reproducibility and statistical measures of the torque coordination angle (TCA). METHODS: A total of 107 final cephalograms and corresponding casts were included, all reflecting treatment outcomes that met high qualitative standards, one of them being a Peer Assessment Rating (PAR) score of ≤3. Based on these records, the TCA was measured as a parameter to identify differences related to tooth morphology and bracket position between the torque-relevant reference plane at the bracket base and the long axis of a tooth. All measurements were performed on upper and lower central incisors (U1 and L1). RESULTS: Several reproducibility assessments for the TCA measurements yielded good results, including objectivity at 1.26⯱ 0.81° (U1) or 1.41⯱ 1.18° (L1), examiner reliability at 1.30⯱ 0.97° (U1) or 1.25⯱ 0.82° (L1), and method reliability at 1.80⯱ 1.13° (U1) or 1.53⯱ 1.07° (L1). The statistical measures revealed a high degree of interindividual variability. With bracket placement 4.5â¯mm (U1) or 4.0â¯mm (L1) above the incisal edge, the differences between the maximum and minimum TCA values were similarly large in both jaws (21.0° for U1 or 20.0° for L1), given mean TCA values of 24.6⯱ 3.6° (U1) or 22.9⯱ 4.3° (L1). Moving the bracket placement from 3.5 to 5.5â¯mm (U1) or from 3.0 to 5.0â¯mm (L1) changed the mean TCA values by 4.5° (U1) or 3.2° (L1). CONCLUSIONS: The TCA is a suitable cephalometric parameter to identify differences related to tooth morphology and bracket placement. Given its high interindividual variability, the fixed torque value of a specific bracket system should not be expected to produce the same incisor inclinations across patients.