A Retrospective, Digital Evaluation of Tip and Torque of Teeth in Patients with Skeletal Class I, II and III Using...

Objectives: Knowledge of tooth axes is important in orthodontics; however, using just one method for evaluation, e.g., orthopantomograms for tip, is not highly reliable. This study aimed to investigate tooth axes in skeletal class I/II/III using two- and three-dimensional evaluations. Methods: In this retrospective study, lateral cephalometric radiographs, orthopantomograms and digitized models of 107 adolescent patients (Ø 13.5 years; n = 36/33/38 with cI/cII/cIII) prior to orthodontic treatment were analyzed digitally regarding tip and torque of teeth. Statistical analysis was performed using SPSS (p ≤ 0.05), G*power and a multiple testing tool (Bonferroni-Holm/Hochberg). Results: Dental compensation of skeletal cII/cIII was significant acc. to Bonferroni-Holm/Hochberg for the following variables: overjet compensation in cII was seen by more retroinclined upper incisors in cII by -5.9°/-5.3° and by -8.8°/-6.6° (U1-SN/U1-PP) vs. cI/cIII (effect size f = 0.489/0.446, power 0.996/0.988). In cIII, the lower incisors were more retroinclined by -8.5°/-10.9° (L1-MP) vs. cI/cII (f = 0.576, power 1.000) and by -8.5°/-8.9° and -6.0°/-7.0° (three-dimensional analysis: L1/L2) vs. cI/cII (f = 0.522/0.527, power 0.999). Compensation of distal occlusion was found by mesial tipping of L3 by 3.5° in cII (f = 0.242, power 0.591) vs. cIII. CIII showed transversal compensation by buccal tipping of the U5 by 5.9°/4.6° vs. cII/I (f = 0.355, power 0.910) and lingual tipping of L3 by -6.4° vs. cII and -3.8° vs. cI (f = 0.446, power 0.988) and L4 by -4.0°/-2.6° vs. cII/I (f = 0.326, power 0.846). Conclusions: Decompensation, e.g., uprighting of distal tipped canines, and further protrusion of incisors might not be desired in orthodontic treatment of adolescents.