Overjet as a predictor of sagittal skeletal relationships

Skeletal relationships in the sagittal plane do not always correspond with dental relationships. The aim of this study was to determine in which type of malocclusion the correlation between overjet and skeletal sagittal parameters assessed by lateral cephalogram analysis is the highest. The extent to which overjet can predict skeletal relationships in the sagittal plane was also assessed. Eighty-three subjects fulfilled the inclusion criteria (40 males and 43 females, mean age 16.3 +/- 4.3 years). Overjet was measured on study casts and sagittal skeletal relationships were analysed on lateral cephalograms. ANB angle, Wits appraisal, and convexity at point A were determined. Mean values and standard deviations of measured parameters were calculated for Class I, Class II division 1, and Class III malocclusion subjects. Correlation between overjet measured on study casts and sagittal skeletal parameters measured on lateral cephalogram was calculated. Overjet as a predictor of skeletal relationships was assessed by means of linear regression analysis. A statistically significant positive correlation (P < 0.01) was found between the values of overjet and ANB (r = 0.690), overjet and Wits appraisal (r = 0.750), and overjet and convexity at point A (r = 0.608) when assessing the whole sample. When linear regression between overjet and cephalometric parameters was assessed separately in Class I, Class II division 1, and Class III malocclusion subjects, the percentage of variability was statistically significant in just four pairs. The findings show that overjet is a good predictor of sagittal relationship only in subjects with a Class II division 1 malocclusion.