Prenatal skeletal maturation of the human maxilla.

Previous investigations on the prenatal development of the human maxilla have focused mainly on the elevation and fusion of the soft tissue palatal shelves. The bony development has received only sporadic attention. The aim of the present investigation was to analyze and set up bony developmental stages in the human maxilla, as knowledge of normal skeletal developmental course, which has never been elucidated, is the prerequisite to understanding the abnormal course of development. The present study was based on a radiographic and histochemical investigation of maxillae from 104 human embryos and fetuses from the first half of the prenatal period. A marked regularity in the maxillary ossification pattern was observed, and consequently seven maturity stages, Max I-Max VII, were described. The material was divided according to these stages and related to general fetal size (crown-rump length) and to general fetal maturation (composite number of ossified bones in hand and foot). The material available did not justify a description of skeletal development of the maxilla as a function of CRL or CNO.