A total of 215 premature infants in Tokyo-97 male and 118 female-who had been nine months or more in the womb and weighed 2, 500g or less at birth, were subjected to clinical dental examination. The results were as follows:
1. The above infants were divided by weight at birth into two groups, A and B. Group A had a little more teeth erupting than Group B at each age (months), but in the range of two years to two years and five months, the two groups were close to each other. Comparison with the standard value for ordinary infants found Group A within the range of-16 and Group B, -26, but at 2 years or more both groups showed values to the average.
2. As for the ralation between the individual growth type and the number of erupting teeth the “B-to-A” group had the largest number of teeth, followed by the “A-to-A”, “B-to-B” and “A-to-B” groups in the order mentioned. At two years to two years and five months, however, all the groups showed much the same values.
3. Examination of central milk incisors, lateral milk incisors and first milk molars showed that, of each kind, the “B-to-A” group had more teeth than any other group, rollowed by “A-to-better”, “B-to-B”and “A-to-B” groups, the number of teeth increasing with the increased body weight.
4. As we have seen, the eruption of teeth and the weight of the body are in close relation to each other. In evaluating the physical growth of an infant, therefore, we believe it is necessary to consider its oral cavity region, particularly the number of teeth it has.