The remodeling pattern of human mandibular alveolar bone during prenatal formation from 19 to 270Â mm CRL

In early stages (19-31 mm CRL) developing bone was characterized by appositional only. At 41, in the canine region, mm CRL bony extensions were found forming on the bottom of the trough. Besides general apposition, regions with resting surfaces were also found. At a fetal size of 53 mm CRL, septa have developed and led to a compartment for canine development. Furthermore, one shared compartment for the incisor primordia and another shared compartment for the molars also developed. Moreover, the inner surfaces of the dental crypts showed resorption of bone. From this stage on, a general pattern became established such that the compartmentalizing ridges and septa between all of the dental primordia and the brims of the crypts were noted, and were due to appositional growth of bone, while the crypts enlarged on their inner surfaces by resorption. By 160 mm CRL, the dental primordia were larger, and all of the bony septa had become reduced in size. The primordia for the permanent teeth became visible at 225 mm CRL and shared the crypts of their corresponding deciduous primordia.