A Retrospective, Digital Evaluation of Tip and Torque of Teeth in Patients with Skeletal Class I, II and III Using Lateral Cephalograms, Orthopantomograms and Digitized Models

TL;DR

This study uses digital tools to evaluate tooth angles in adolescents with different skeletal classes, finding significant dental compensations that could influence orthodontic treatment planning.

Contribution

The study introduces a combined two- and three-dimensional digital evaluation of tooth axes in skeletal classes I, II, and III, revealing new insights into dental compensation patterns.

Findings

Skeletal class II shows overjet compensation via retroinclined upper incisors compared to class I and III.

Skeletal class III exhibits transversal compensation through buccal and lingual tipping of molars compared to other classes.

Mesial tipping of lower molars is observed in class II compared to class III for distal occlusion compensation.

Abstract

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.

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