Assessment of the apparent contact dimension and co-variates in non-treated and orthodontically treated dentitions

This study assessed the existence of the Apparent Contact Dimension, a determinant of dental esthetics, using casts of orthodontically treated (n=40) and non-treated (n=27) subjects deemed to possess excellent occlusion. Co-variates studied included tooth size, tooth shape, tip and torque. The average ACD proportions in this study, relative to the height of an ipsilateral central incisor, were found to be 49, 38 and 27% between the central incisors, central and lateral incisor, and the lateral incisor and canine, respectively. The ACD exhibited a positive correlation (p<0.05) with the height of the clinical crown and a negative correlation (p<0.05) with W/H ratios of the corresponding teeth. No statistically significant correlations were evident between the ACD with the shape of the clinical crown, the tip, and torque. This study is the first to validate the existence and proportions of the ACD.