Evaluation of buccolingual inclination of posterior teeth in skeletal Class III with or without asymmetry

Abstract

The aim of this study was to evaluate the buccolingual inclination of posterior teeth in skeletal Class III patients with or without asymmetry based on CBCT analysis, which was compared with that in skeletal Class I patients. Also, this study assessed the relationship between asymmetry and buccolingual inclination of posterior teeth.

A total of 63 skeletal Class III patients (32 males, 31 females) in age of 22.4 ± 4.00 were selected and divided into 2 groups according to Menton (Me) deviation from midsagittal plane: skeletal Class III, symmetry; Me deviation < 2mm (group S) and skeletal Class III, asymmetry; Me deviation > 4mm (group AS). The control group (group I) was consisted of 25 skeletal Class I patients (11 males, 14 females) in age of 22.7 ± 5.31. The buccolingual inclination of posterior teeth (premolars and molars) was measured in relation to Frankfurt horizontal (FH) plane in maxillary teeth and tangent line to inferior border of mandible in mandibular teeth. The buccolingual inclination of skeletal Class III patients was compared with that of skeletal Class I patients and significant differences among groups were examined. Also, the influence of asymmetry on the buccolingual inclination of posterior teeth was examined. The results are as followings,

1. The maxillary teeth had a tendency to be buccally inclined and the mandibular teeth lingually inclined from premolars through molars in all groups.

2. Group S showed more buccal inclination of maxillary premolars and molars, and more lingual inclination of mandibular first premolar and second molar compared to those of group I (p<0.05).

3. Group AS had significant difference in buccolingual inclination of posterior teeth between on the deviated side and non-deviated side (p<0.001). On the deviated side, maxillary teeth were more buccally inclined and mandibular teeth were more lingually inclined than the non-deviated side.

4. In Group AS, all teeth on the deviated side showed more buccally inclined maxillary teeth and lingually inclined mandibular teeth than those in other groups (p<0.05). On the non-deviated side, maxillary teeth had no significant difference with group I (p>0.05) and only mandibular first molar was more buccally inclined than that of group I (p<0.05).

5. In group AS, Me deviation had negative correlation with the buccolingual inclination of all mandibular teeth on the deviated side (p<0.05), and canting of maxilla had negative correlation with only buccolingual inclination of maxillary second premolar on the non-deviated side (p<0.05).

There was transverse dental compensation in skeletal Class III patients with asymmetry, especially on the deviated side, and Me deviation had correlation with the dental compensation of mandibular teeth on the deviated side.