• Noppadol Chanpongsaeng D.D.S., M.S., Dip.Th.B.O.

Objectives The purposes of this study were to survey the prevalence of ectopic eruption of the first
permanent molars in children, 7-10 years of age in Bangkok and to study the etiologic factors.

Materials and methods A survey of prevalence of ectopic eruption of the first permanent molars
was carried out in three types of school: municipal school, public school and private school,
in children 7-10 years of age (6,957 children). Questionaires of etiologic factors were sent to the
parents of children in experimental group and control group. Afterthen body weight, height and age of
children in both groups were used to evaluate the growth status. Data in questionaires and growth
status of all subjects were used to analyze the relationship between etiologic factors and ectopic
eruption of the first permanent molars with Chi-square test and Cramerûs V at significant level .05.

Results The study showed that the prevalence of ectopic eruption of the first permanent molars was
0.59% (41 from 6,957 children). The study also showed statistically significant relationship between
ectopic eruption of the first permanent molars and two etiologic factors, one of which was the masticatory
problems in childhood from 2 to 6 years old (p = .027) and the other was the growth status of
children (p = .000) especially of those in the short group and in the slightly low body weight group.

Conclusion The prevalence of ectopic eruption of the first permanent molars was 0.59% and there
were statistically significant relationship between ectopic eruption of the first permanent molars and
two etiologic factors (masticatory problems and growth status).

(CU Dent J. 2005;28:39-50)