The role of alveolar bone in the noneruption of molar teeth in grey lethal mice.

The in utero and neonatal development of the molar teeth in osteopetrotic grey lethal mice and normal litter mates was observed in timed embryos which were obtained by caeserian section, and in neonatal litters which were sacrificed on the day of birth and each day thereafter until day 7. Serial coronal and sagittal sections through the heads were prepared. The earliest disturbances in the alveolar bone-tooth germ complex were seen at day 19 in utero. At birth, the grey lethal first molar germs are severely distorted by encroaching alveolar bone. The abnormalities become progressively more marked until day 7. The failure in alveolar bone remodeling is the factor which prevents tooth eruption in grey lethal mice.