Mandibular dental-basal arch forms in skeletal Class III patients with mandibular prognathism

Abstract

Purpose

The aims of this study were to investigate the relationship of the labio-lingual position of the mandibular dental arch form to the corresponding basal arch form using three-dimensional dental cast analysis in skeletal Class III patients with mandibular prognathism who were indicated for mandibular setback surgery and to compare the results with those of participants with orthodontically untreated Angle Class I normal occlusion.

Materials and methods

Mandibular dental casts of 56 skeletal Class III patients with mandibular prognathism (MP-group) and 56 control participants (C-group) with Angle Class I normal occlusion were examined. To evaluate dental and basal arch forms, the FA and WALA points, respectively, were located, and eight linear measurements and six ratio variables were calculated. Relationships between the dental and basal arch forms were evaluated and compared between the groups.

Results

Dental arch widths, basal arch widths and depths, and the basal arch ratio were greater and the dental arch depth was smaller in the MP-group than in the C-group. The FA points in the MP-group were more lingually positioned from the central incisor to the second premolar and were more buccally positioned for the first molar. Significant positive correlations were observed between the dental and basal arch dimensions and ratios in both groups.

Conclusion

The observed morphological characteristics of the dental and basal arch forms and dental arch form-basal arch form relationships in the MP-group suggest the possibility of using dental cast analysis to identify an individualized therapeutic target for dental decompensation.

Keywords:

• Skeletal Class III
• Mandibular prognathism
• Dental arch form
• Basal arch form