Chronology of Deciduous and Permanent Dentition in Japanese Children II

Part 1 : Deciduous Dentition

Abstract

We performed a cross-sectional national investigation of deciduous tooth eruption timing and sequence in 8724 children in Japan between the ages of 3 months and 3 years 11 months in order to assess changes in deciduous tooth emergence. The following results were obtained.

1.Tooth emergence in boys occurred as follows. A emergence occurred between 5 and 9 months of age, A between 7 and 11 months, B between 9 months and 1 year 2 months, B between 9 months and 1 year 3 months, D between 1 year 1 month and 1 year 6 months, D between 1 year 1 months and 1 year 7 months, C between 1 year 2 months and 1 year 8 months, C between 1 year 2 months and 1 year 9 months, E between 1 year 11 months and 2 years 7 months, and E between 2 years and 2 years 11 months. There was no significant difference in regard to eruption timing between B and B, D and D, C and C, D and C, and D and C.

2.Tooth emergence in girls occurred as follows. A emergence occurred between 6 and 9 months of age, A between 7 and 11 months, B between 9 months and 1 year 1 month, B between 9 months and 1 year 2 months, D between 1 year 1 month and 1 year 7 months, D between 1 year 1 months and 1 year 7 months, C between 1 year 3 month and 1 year 9 months, C between 1 year 4 months and 1 year 9 months, E between 1 year 11 months and 2 years 7 months, and E between 2 years 1 month and 2 years 10 months. There was no significant difference in eruption timing between A and A, A and B, B and B, D and D, and C and C.

3.A comparison between boys and girls showed no significant difference in eruption timing, except for C and C, as that occurred 1 month earlier in boys.

4.As compared to a previous report presented in Japan in 1988, eruption timing was significantly earlier for A, A, C, and D in boys, and for A and D in girls.