Evaluation and comparison of planum clival angle in three malocclusion groups : ACBCT study.

Abstract

Cranial base flexure is an overlooked topic in craniofacial research. The aim of this retrospective observational study was to compare anew parameter, the planum clival angle (PCA), which represents cranial base flexure, in skeletal classI,II, andIII malocclusions using cone beam computed tomographic images (CBCT) and correlate PCA with the stages of the fusion of the spheno-occipital synchondrosis (SOS). A total of 125 CBCTs were divided into two groups based on chronological age (19-25years and 12-18years). The CBCT images from 57 subjects (19-25years old) were categorized into three groups based on their skeletal malocclusion for measuring PCA and cranial base angles (CBA). In the second group, comprising 68CBCT data sets of individuals in the age group of 12-18years, the PCA angle was correlated with stages of fusion of the SOS. Data were statistically analyzed using independent samples ttest, one-way analysis of variance (ANOVA, intergroup), Pearson correlation, and χ2 test. There was astatistically significant linear correlation (P < 0.001) between the two parameters PCA and CBA but no significant difference was found in PCAs between the three groups. One-way ANOVA to compare the PCA values in the three stages of fusion of the SOS revealed ahighly significant relationship in male subjects (p < 0.001), thereby, suggesting that as fusion progresses, the planum clival angle increases. The χ2 test to compare the planum clival angle in males and females revealed that SOS fusion occurred earlier in females. There is aconstant dynamic change in the value of the parameter PCA that progresses until completion of SOS fusion. The SOS fuses earlier in females. Assessment of the stage of fusion of the SOS can be used in deciding whether growth modification of the craniofacial complex is still possible during orthodontic therapy.