Eruption of the permanent dentition of Southern Chinese children in Hong Kong

Abstract The times and sequence of eruption of the first twenty-eight permanent teeth were investigated among 3,308 boys and 3,024 girls, aged 6–16 years, of Southern Chinese origin. Emergence through the gingiva was the criterion for eruption. The children were classified into high, middle and low socio-economic groups. The total number of permanent teeth erupted at each age level showed no significant difference between the three socio-economic groups. However, the anterior teeth (I 1 , I 2 and C) erupted earlier and some of the posterior teeth (M 1 , P 1 and P 2 ) erupted later in the high socio-economic groups. The interval of rest between the two active eruption periods was consequently longer in the high socio-economic groups. The eruption ages of the permanent dentition of other ethnic groups (U.S.A., England, New Zealand, and Hawaiian Chinese) were compared with those of Hong Kong children. The interethnic differences follow the pattern of our socio-economic differences, and the differences of the means between the ethnic groups are no larger than our socio-economic differences. The variability of eruption of permanent dentition as shown by the coefficient of variation was rather large (13.8). It was more variable than some other developmental phenomena, namely, sexual and skeletal maturation of the same boys and girls.