Anterior cranial base features in skeletal Class III patients with maxillary recession: a cephalometric study.

Aim: The relationship of anterior cranial base to midface dimensions in skeletal Class III malocclusions is said to be unclear. The purpose of this retrospective study was to investigate and correlate various cephalometric parameters depicting anterior cranial base and cranial base flexure to maxillary dimensions in skeletal Class III malocclusions.

Methods: Lateral cephalometric radiographs of 60 skeletal Class III subjects aged 16 to 29 years comprising 30 cases with maxillary retrusion (group A) and 30 cases with normal maxillae (group B) were analyzed for 14 variables, along with 60 skeletal Class I controls (group C) matched for both age and sex.

Results: The Bonferroni multiple comparison and ANOVA tests revealed a statistically significant decrease of maxillary (Co-A, Ptm-A, ANS-PNS) and anterior cranial base (S-N, S-Ca) linear dimensions (P < .001) as well as a decrease in N-S-Co (P < .001) and N-S-Ar (P < .05) in group A subjects. Comparison of ratios of the skeletal dimensions to each of the maxillary dimensions showed statistically significant increased values for group A (P < .001). The Pearson correlation coefficient showed a positive correlation between each cranial base parameter and the maxillary parameters (P < .001).

Conclusion: The anterior cranial base dimensions were found to be decreased in only skeletal Class III cases with maxillary deficiencies. Significant decrease of angle N-S-Co may prove diagnostically reliable in maxillary retrusion. Significant positive correlations were found to exist between each cranial base parameter and the maxillary parameters. The strongest correlation was observed between S-N and Co-A, and the weakest with respect to S-Ca and ANS-PNS.