Many studies have examined the characteristics of the frontal sinuses and their use for forensic purposes, particularly when an individual is edentulous. One of the most widespread classification systems is that proposed by Yoshino et al. The aim of this study was to improve the performance of Yoshino's method for identifying unknown skeletal remains by replacing the first two morphological items, frontal sinus size and bilateral asymmetry, by SOR 2 = left frontal sinus area/left orbit area, and SOR2 = right frontal sinus area/right orbit area. According to the bivariate distribution of SOR = (SOR1, SOR2) and available data, we also estimated the probability of positive misclassification.