|
KMID : 0378019840270020154
|
|
New Medical Journal
1984 Volume.27 No. 2 p.154 ~ p.170
|
|
|
A Roentgenographic Study on the Root Development with aging of Lower Second Bicuspid and Lower Second Molar in Korean
|
|
|
|
|
Abstract
|
|
|
This study was performed for the evaluation of the root development with aging of lower second bicuspid and lower second molar in Korean.
The roentgenographs of healthy 1,213 male and 1,049 female from 12 to 29 years of age were taken by paralleling technique.
And the degree of root development was evaluated respectively by two different methods; actual measuring of root length with caliper and visual measurement by Nolla´s method, and were analyzed statistically.
The obtained results were as follows.
1. Average length of the completed crown and root, and the crown-root ratio were as follows.
In the lower second bicuspid, average crown length was 7.36mm where the length in male was 0. 20mm longer than that in female, and average root length was 14.30mm where the length in male was 0. 53mm longer than that in female. And the crown-root ratio was 1:1.94.
In the lower second molar, average crown length was 7.42mm where the length in male was 0.07mm longer than that in female, and average root length was 12.32mm where the length in male was 0.33mm longer than that in female. And the crown-root ratio was 1: 1.66.
2. The average root length with aging by actual measuring were as follows.
In the lower second bicuspid, it was 12.07mm in the age of twelve and first half year, thereafter it was increased about 0.39±0.10mm every 6 months and was completed at 15 years of age.
In the lower second molar, it was 9. 09mm in the age of twelve and first half year, thereafter it was increased about 0.36±0.29mm every 6 months and was completed in the age of sixteen and second half year.
From the view of sex difference, in the lower second bicuspid, female´s root length was longer than male´s up to 13.5 years of age, since then male´s became longer than female´s´ and m -de´s was 0.53mm longer than female´s after root completion.
In the lower second molar, female´s root length was longer than male´s up to 14 years of age, since then male´s became longer than female´s, and male´s was 0. 33mm longer than female´s after root completion.
3. As the results of the amount of root development measured by Nolla´s method were compared with those of actual measuring in each age group, the former seemed to be slightly greater than the latter.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|