Orally administered methionine alters the growth of tooth germs in newborn rats.

The effects of methionine intubation via gastric needle on the growth of incisor and molar tooth germs in newborn rats were investigated. Upon delivery, the pups were divided into groups of 8 and randomly assigned to dams which were then randomly assigned to three groups. Then the pups were intubated in the stomach with (a) no methionine - group I, (b) 0.1 g methionine per 100 g body weight - group II, or (c) 0.2 g methionine - group III, from day 3 to day 13 on every other day. At day 15, the average body weights of pups among the three groups showed no difference statistically, though animals in group III showed a 17.5% mortality rate; there were no deaths in the other two groups. There was inadequate hair growth in some pups in group III. The weights of incisor and of molar tooth germs in group II were heavier than in groups I and III. The total hydroxyproline content of incisor tooth germs in group II was also greater than in the other groups, whereas there was no difference in molar tooth germs on this parameter among all groups. Collagen synthesis of both tooth germs was highest in group III compared to other groups. The total amount of calcium in both tooth germs showed no difference among groups, but values were consistently higher in group II. 45Ca uptake showed no difference among groups. The present results indicate that the amount of methionine received by growing pups alters the composition of developing tooth germs, but that incisor and molar tooth germs are affected differently.