A new harmony box supplemented with gonial angle and age based on a growing Swiss population

The scope of the present study was to create a new harmony box by adding two diagnostically and clinically important cephalometric variables, the gonial and interincisal angles, while also considering the effect of sex and age for a growing Swiss population.

A healthy sample with an overjet and overbite between 2 and 4 mm, and 1.5 and 4.5 mm, respectively, of the Zurich Craniofacial Growth Study was considered. Pairwise correlations between the cephalometric angles were evaluated with the Pearson correlation coefficient (r). Regression models were built for each cephalometric variable serving as the dependent one. The Akaike Information Criterion and the Bayesian Information Criterion were used to structure and select the final multivariable regression model. Bland-Altman plots and the Lin's concordance correlation coefficient were used to assess inter- and intraexaminer agreement.

The sample consisted of 301 individuals with a mean age of 13.4 years. Measurement concordance was confirmed both within and between examiners. The strongest correlations were observed between the angles SNB and SNA (r = 0.81), ArGoMe and SN-ML (r = 0.57), and SN-ML and SNB (r = 0.56). The SNB angle qualified as the dependent variable in the multivariable regression that framed the newly provided harmony box, with the predictor variables age (p < 0.001) and the angles SNA (p < 0.001), SN-ML (p < 0.001), SN-NL (p = 0.005), NSBa (p = 0.001), and ArGoMe (p < 0.001). The interincisal angle did not increase the robustness of the model and was excluded (p > 0.05).

Contrary to the interincisal angle, gonial angle and age qualified for inclusion in the new harmony box for individualized cephalometrics in a sample of healthy schoolchildren from Zurich, Switzerland.