OCCLUSAL PLANE ORIENTATION IN KLINEFELTER-SYNDROME (47,XXY MALES)

Occlusal plane position was analysed cephalometrically in 35 Klinefelt er adults (47,XXY) and compared with 60 eugnath control males (46,XY). The significantly smaller angles between the occlusal plane and the c ranial base (NSL-OLs) and between the occlusal plane and the Frankfort horizontal plane (Fr-OLs) were obtained in 47,XXY males (P < 0.01), w hile the angles between the maxillary base and the occlusal plane (NL- OLs) and between the Camper's line and the occlusal plane (Camp.-OLs) were not significantly different (P > 0.05) from the control group. Si gnificantly smaller angles between the occlusal plane and the cranial base (NSL-OLs) and between the occlusal plane and the Frankfort horizo ntal plane (Fr-OLs) in Klinefelter males are attributed to the heredit ary influence of an extra X chromosome on the smaller growth of the cr anial base and the greater growth of the lower border of the mandible. Although the maxilla was also shifted forward in XXY males in relatio n to the cranial base it was not enough to compensate for the heredita ry influence, due to the greater growth of the lower border of the man dible and the smaller cranial base in 47, XXY males, on the inclinatio n of the occlusal plane to the Frankfort horizontal plane and the cran ial base. The forward shift of the maxilla was sufficient to compensat e for the inclination of the occlusal plane in 47, XXY males to the ma xillary base and the Camper's line(P > 0.05).