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The objective of this study is to test the validity of sex determination in children and adolescents using lateral radiographic cephalometry and discriminant function analysis. Fifty male and 50 female cephalograms of Taiwanese children were used (males and females with mean age of 15.52 +/- 1.38 and 15.67 +/- 1.54 years, respectively). Twenty-two cephalometric measurements were performed using computerized cephalometry. Statistical analysis shows that all measurements were sexually dimorphic (p < 0.05). Nine measurements, statistically validated and clinically relevant, were used for discriminant function analysis. A stepwise discriminant procedure selected seven of the nine variables, producing 95% accuracy in sex determination. Resubstitution classification reveals the same discriminant rate. Cross-validation classification (the leave-one-out method) reveals that the correct sex determination rate is 91%. However, the combination of four variables using both the stepwise procedure and the resubstitution method achieves a 92% accuracy rate. A cross-validation classification procedure with the same four variables resulted in a 91% accuracy rate. Therefore, this study uses four cephalometric measurements as the minimum number of traits yielding the maximum discriminant effectiveness of sex determination in children and adolescents.

Palatal bone thickness measurements obtained by cone-beam computed tomography (CBCT) in 30 men and 28 women were evaluated for associated factors. Palatal bone thickness was measured at 20 locations unilateral to the midpalatal suture and posterior to the incisive foramen. Tongue position, presence of posterior crossbite, and palatal morphology were recorded. Lateral cephalograms acquired from CBCT data were used to calculate Frankfort-mandibular plane angles (FMA). At almost all sites, bone thickness was greater in males than in females, but the difference was statistically significant at only seven sites. Bone thickness showed no associations with tongue position, palatal morphology, or presence of posterior crossbite. In women, FMA significantly correlated with bone thickness at 12 locations. In conclusion, palatal bone thickness is unassociated with tongue position, posterior crossbite, or palatal morphology. In hyperdivergent women, however, available bone may be smaller than normal in the middle and posterior palatal areas; in such cases, a shorter than normal miniscrew may be needed to avoid penetrating the nasal cavity.