-Abstract-
This study was performed to investigate the age distribution with tooth calcification
and degree of eruption of permanent teeth. For the study, healthy 184 patients from 5 to
9 years old without any previous serious dental treatment were randomly selected, and
intraoral standard films and dental casts were taken for evaluation of stage of
calcification and degree of eruption, respectively. Tooth calcification of 13 stages,
designed by the author based on the Nolla’s classification and eruption level of 4 or 5
degree was used. Data were processed by SAS/Stat program and the obtained results
were as follows;
1. The age of root completed with open apex in lower posterior teeth were 13.8 years
for first premolar, 14.0 years for second premolar, 10.5 years for first molar, and 14.2
years for second molar. There were no significant difference between right and left
side.
2. As for the sequence of eruption, first molar was the first teeth erupted in upper arch,
while central incisor was the first teeth in lower arch. In general, eruption of lower
teeth were slightly earlier than the corresponding teeth of upper arch.
3. There were no difference of age of the same stage of development between Noll’s
and the author’s classification. From the results, the author’s classification can be
used for estimation of age with more finely in age of 7 to 15 years old.
4. Multiple regression equations for age with Nolla’s (Ns) and the author’s (Ks)
classification of tooth calcification, and degree of eruption(DE) were as follow;
Age(by #34) = 7.55 + 0.76Ks34 + 0.80DE34 - 0.72Ns34
Age(by #35) = 7.10 + 0.81Ks34 + 0.61DE35
Age(by #37) = 6.61 + 0.82Ks34 + 0.51DE37
Age(by #44) = 7.02 + 0.62Ks44 + 0.82DE44
Age(by #45) = 8.04 + 0.93Ks45 + 0.64DE45 - 0.89Ns45
Age(by #47) = 6.40 + 0.86Ks47 + 0.56DE47
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