The purpose of this study was to obtain the data on the growth changes of dental
arches of males .aged from 6 to 7 years, to make the dental arch growth prediction
model. The eight measurements which were describing the dental arch morphology were
obtained from the dental arch stone models of the 140students in 1995 and of the same
students in 1996. The dental arch forms were classified by the cluster analysis on the
basis of the eight measurements. The growth changes of the dental arch during one
year were compared among these classified arch forms. The obtained results were as
follows :
1. The dental arches were classified into nine kinds of forms such as a long arrow
short string middle arch with anteriorly located deciduous canine, a long arrow short
string middle arch with posteriorly located deciduous canine, a longest arrow long string
longest arch, a short arrow shortest string shortest arch, a middle arrow shortest string
short arch, a shortest arrow middle string shortest arch, a long arrow longest string
long arch, a middle arrow middle string middle arch and a middle arrow long string
middle-arch
2. The change of the length from the contact pint of the upper right and left central
incisors to the midpoint of the upper intercanine width was more lengthened than the
rest seven measurements in all kind of arch forms.
3. There were significant differences in the growth change of the upper intercanine
width among 0 arch forms. And there were significant differences in the change of the
longth from the contact point of the upper right and left central incisors to the midpoint
of the upperintercanine width among 9 arch forms. There were significant differences in
the growth change of the length from the contact point of the lower right and left
central incisors to the midpoint of the lower intercanine width among 9 arch forms, too.
4. The growth change of the upper intercanine width was simillar to that of the lower
intercanine width in all kinds of arch forms.
5. The growth change of the upper inter-first-molar width is simillar to that of the
lower inter-first-molar width in 8 arch forms except a long arrow longest string long
arch form.
6. The growth change of the length from the contact point of the upper right and left
central incisors to the midpoint of the upper intercanine width was simillar to that of
the length from the contact point of the lower right and left central incisors to the
midpoint of the lower intercanine width in six arch forms except a longest arrow long
string longest arch, a middle arrow shortest string short arch and a middle arrow long
string middle arch.
7. The change of the length from the contact point of the upper right and left central
incisors to the midpoint of the upper inter-first-molar width was simillar to that of the
length from the contact point of the lower right and left central incisors to the midpoint
of the lower inter-first-molar width in four arch forms except a longest arrow long
string longest arch, a short arrow shortest string shortest arch, a middle arrow shortest
string short arch, a shortest arrow middle string shortest arch and a middle arrow
middle string middle arch.
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