K. Chintakanon et P. Boonpinon, ECTOPIC ERUPTION OF THE FIRST PERMANENT MOLARS - PREVALENCE AND ETIOLOGIC FACTORS, The Angle orthodontist, 68(2), 1998, pp. 153-160
The purpose of this research was to study the prevalence of ectopic er
uption of the first permanent molars and possible etiologic factors. A
group of 4,232 Thai students, from 6 to 9 years old, was examined. Th
e prevalence of ectopic eruption of the first permanent molars in the
subjects was 0.75%. Both the severity of the ectopic eruption and the
amount of root resorption on the second primary molars were more prono
unced in the maxilla than in the mandible. The important etiologic fac
tors we re the eruption path of the fi rst permanent molars relative t
o reference lines and the size of the mandibular second primary molars
. The amount of proximal caries did not seem to affect the prevalence
of ectopic eruption.