Evaluation of craniometric methods for determination of vertical dimension of occlusion--Part 2.

The study examines the relationships between different craniometric distances and the nasion-gnathion (N-Gn) distance which represents the lower two thirds of the face in vertical dimension determination. The highest degree of correlation (r = 0.9217; p < 0.05) was observed between the N-Gn and zygion-zygion (Zy-Zy) distances. The N-Gn distance could be determined using the formula N-Gn = Zy-Zy/1.15 or by means of regression analysis: N-Gn = 0.54749 + 0.82822 x Zy-Zy. Considering that the coefficient of correlation between N-Gn and Zy-Zy was higher than the one between the eye-ear (E-E) and the subnasale-gnathion (Sn-Gn) distances reported earlier (r = 0.8676) it was concluded that calculating the N-Gn distance from the Zy-Zy distance was more reliable. The fact that none of the calculated correlation coefficients was 1, but was lower than 1, points to the presence of individual variations of the cephalometric parameters. Although the method cannot be taken as absolutely reliable, owing to its simplicity and practical applicability it can be recommended for use in everyday clinical practice in combination with other methods for the determination of the vertical dimension of occlusion.