Niigata Dent. J. 35（1）：41 − 50,

2005

41

− ORIGINAL ARTICLE −A study on the anterior ratio in patients showing mandibular prognathism
Kazuo Edanami1,3）, Koichi Yamazaki1）, Taiki Matsubara1）, Isao Saito1）, Kazuto Terada2）
1)

Division of Orthodontics, Niigata University Graduate School of Medical and Dental Sciences (Chief: Prof. Isao Saito)
2)

Polyclinic Intensive Oral Care Unit, Niigata University Medical and Dental Hospital (Chief: Prof. Tadashi Noda)
3)

Edanami Dental Clinic

Received 5.12, 2005/Accepted 6.9, 2005
Key words：mandibular prognathism, anterior ratio, tooth-size ratio, mesiodistal crown widths

Abstract： Purpose: The purpose of this study was to evaluate the efficacy of the anterior ratio forappropriate occlusal relation using measurements of mesiodistal crown widths.
Materials and Methods: The subjects included 202 patients（71 males and 131 females）withskeletal Class III, referred to the Orthodontic clinic of Niigata University Medical and Dental
Hospital, and considered to be candidates for surgical treatments. The following cases were excluded
from the subjects used in this study: those who had any missing teeth, congenital defects, prosthesis,
interproximal fillings and differential mesiodistal crown widths of more than 0.5 ㎜ between the left
and right anterior teeth including microdont and/or peg teeth. A diagnostic cast of each patient
taken before treatment was used to measure the mesiodistal crown widths of the anterior teethon the maxilla and mandible. These values were then measured using a vernier caliper with anaccuracy of 1/20 ㎜ . Measurement values were taken using the mean score calculated based on two
sets of measurements taken on separate days. An anterior ratio was calculated using this formula:
Anterior ratio（%）=（mesiodistal crown widths of anterior teeth on mandible）/(mesiodistal crownwidths of anterior teeth on maxilla）x 100
Results and Discussion: Results showed a difference between males and females in mesiodistalcrown widths on the upper central incisors, upper and lower canines and lower lateral incisors,
respectively. Measurement data is as follows（males and females, respectively）; upper central
incisors; 8.77 ± 0.45 and 8.50 ± 0.49, upper lateral incisors; 7.27 ± 0.60 and 7.18 ± 0.61, upper canines;
8.23 ± 0.53 and 7.89 ± 0.46, lower central incisors; 5.51 ± 0.35 and 5.45 ± 0.40, lower lateral incisors;
6.17 ± 0.39 and 6.05 ± 0.41, lower canines; 7.22 ± 0.45 and 6.86 ± 0.46. The anterior ratio also showeda difference between males and females. These were 77.92 ± 2.36% and 77.93 ± 2.63% in males andfemales, respectively. The present data were smaller than those in similar reports as to patients withskeletal Class III, and were analogous to the data for patients with normal occlusion.
These results suggest that even cases with antero-posterior dentofacial anomaly due toovergrowth of the mandible mostly have balanced mesiodistal crown widths of the upper and lower
anteriors.
抄録：本研究は，骨格性下顎前突症を有する患者の歯冠近遠心幅径を計測し，適切な咬合関係の確立に関与する anterior ratio について検討することを目的とした。
資料と方法：新潟大学医歯学総合病院矯正歯科診療室を受診し，骨格性下顎前突と診断され，上下顎前歯部に欠損，補綴物，隣接面充填物がなく，矮小歯を含めて左右側の歯冠近遠心幅径の差が 0.5 ㎜以上ある症例を除いた 202 名（女性 131 名，男性 71 名）の歯列石膏模型を資料とした。計測は資料とした模型について上下顎６前歯の歯冠近遠心幅径を，1/20 ㎜の副尺付きのノギスを用いて行った。計測は
日を変えて２回行い，その平均値を測定値とした。得られた測定値から anterior ratio（＝（下顎６前歯の歯冠近遠心幅径の総和）／（上顎６前歯の歯冠近遠心幅径の総和）× 100）を算出した。
結果と結論：測定した歯冠近遠心幅径（単位；㎜）は，上顎中切歯が男性 8.77 ± 0.45 で女性 8.50 ±− 41 −

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Niigata Dent. J.

35（1）：2005

0.49，上顎側切歯が男性 7.27 ± 0.60 で女性 7.18 ± 0.61，上顎犬歯が男性 8.23 ± 0.53 で女性 7.89 ± 0.46，
下顎中切歯が男性 5.51 ± 0.35 で女性 5.45 ± 0.40，下顎側切歯が男性 6.17 ± 0.39 で女性 6.05 ± 0.41，下
顎犬歯が男性 7.22 ± 0.45 で女性 6.86 ± 0.46，上顎中切歯，上下顎犬歯と下顎側切歯について危険率５％未満で男女差を認めた。また，anterior ratio は，男性が 77.92 ± 2.36％で女性が 77.93 ± 2.63％であった。
今回算出した骨格性下顎前突患者の anterior ratio は，反対咬合者について調べた過去の報告と比べて小さい値を示し，正常者に近似していた。
以上の結果から，下顎骨過成長による上下顎骨の前後的不調和を示す症例でも，上下顎の前歯の歯冠
近遠心幅径は調和がとれている場合の多いことが示された。
anteriors are proportional or not.

Ⅰ．Introduction

Surgical-orthodontic patients with intermaxillaryanomaly have inadequate occlusion due to imbalanced

It is of great importance for orthodontic treatment

anterior-posterior growth of the maxilla and mandible.

to understand correlation between teeth, dental

It is important for achieving suitable occlusion

arch, and basal bones. Understanding this interaction

after surgery to determine whether anterior ratio

concisely, allows a precise diagnosis and treatment.

or mesiodistal crown widths of the anteriors showMorphological changes in teeth, maxilla and mandible

specific values in patients with skeletal discrepancy.

in successive periods have been often described as

Further, crown widths appear to change over twenty

1-3）. The softer

years due to one's dietary life or other surroundings.

dietary foods we take, the less functional properties

This study was undertaken to evaluate the preciseof mastication become, which leads to reduction inanterior ratio of patients diagnosed as skeletal Classa mode of dietary life or evolutionary

1-3）

the size of the mandible. On the other hand, otherreports have stated that there is no relation between

III malocclusion by measurements of mesiodistalcrown width.

consistency of food and developments of the maxilla
and mandible4）. Furthermore, recent studies show that

Ⅱ．Materials and Methods

the maxilla, mandible and alveolar bone have probably
increased in size as time has passed4）.

The subjects comprised 202 patients (71 males andTeeth size as well as mesiodistal crown widths both

131 females, mean age; 18.5 years old and 19.1 years

on deciduous and permanent teeth varied as larger5-8）

old, respectively) referred to the Orthodontic clinic of

9-12）. Moreover, there is a

Niigata University Medical and Dental Hospital fromdifference in mesiodistal crown widths based on the

October 1998 to September 2004. These patients wereor smaller over the ages
13, 14）

tooth order. However, both the changes in teeth

diagnosed as Class III malocclusion and considered tobe candidates for surgical treatment. The following

size and crown width with age still remain unclear.
It's a key role for maintaining the occlusal stability

cases were excluded from the subjects used; thoseand the smooth jaw movements after orthodontic

which had any missing teeth, congenital defects,

treatment to attain the symmetrical dental arch forms

prosthesis, and differential crown widths of more

as well as the intermaxillary relation. Especially,

than 0.5mm compared to the left and right anterior

mesiodistal crown widths on the maxilla and mandible

teeth, including peg teeth. A diagnostic cast of eachcontribute to improvement of the occlusion throughpatient taken before treatment was used to measureorthodontic procedure. If there is disharmony inthe mesiodistal crown widths of the upper and lower

mesiodistal crown widths on the maxilla and/or

anterior teeth (Table 1).

mandible, adjustment of the interproximal grinding

These values were measured using vernier caliper

will be needed to improve intercuspations. The

with an accuracy of 1/20mm. The measurements were15）

anterior ratio （%）( ＝ (Sum of mesiodistal crowntaken twice on different days and the values were

widths of anterior teeth on mandible)/(Sum of

taken based on the mean score. The skewness andmesiodistal crown widths of anterior teeth on maxilla)

the kurtosis indicating the aspects of distribution were

x 100 ) is a valuable index for determining whether

calculated based on data obtained.

the mesiodistal crown widths of the upper and lower− 42 −

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EDANAMI et al.

The anterior ratio was calculated by using the

0.41mm on lower lateral incisors, 7.22 ± 0.45mm and6.86 ± 0.46mm on lower canines, respectively (Table

following formula:
The anterior ratio (%) = (Sum of mesiodistal crown2). The skewness and kurtosis of each tooth for males

widths of anterior teeth on mandible)/ (Sum ofand females were -0.31 and -0.25, -0.06 and -0.15 on

mesiodistal crown widths of anterior teeth on maxilla)

upper central incisors, -0.69 and 1.41, 0.11 and -0.07 on

x100.

upper lateral incisors, -0.33 and 0.05, 0.21 and 0.15 on

The mean value, standard deviation, skewness

upper canine, -0.130 and 0.15, 0.27 and 0.65 on lower

and kurtosis were evaluated separately by gender.

central incisors, -0.32 and 1.41, -0.20 and -0.01 on lower

Statistical comparisons between males and females forlateral incisors, -0.39 and 1.29, -0.10 and 0.85 on lower

each dependent variable measured were performed

canines, respectively (Table 2) (Fig. 1-6).
A statistically significant difference in mesiodistalusing t-test for statistical signiﬁcance.

crown widths on the upper central incisors, upperand lower canines (P<0.01) and lower lateral incisors

Ⅲ．Results
The results of descriptive statistics and t-test are(P<0.05) was founded between males and females.
The mean value and standard deviation of theshowed in Table 2 and Table 3, and the values of theanterior ratio showed 77.92 ± 2.36% and 77.93 ±measurements are showed in Fig. 1 through 6.
The mean value and the standard deviation of each

2.63% for males and females, respectively (Table 3).

mesiodistal crown width for males and females wereNo signiﬁcance with respect to the anterior ratio was

8.77 ± 0.45mm and 8.50 ± 0.49mm on upper central

present between males and females.

incisors, 7.27 ± 0.60mm and 7.18 ± 0.61mm on upper

The skewness was showed as 0.26 and 0.28, and thelateral incisors, 8.23 ± 0.53mm and 7.89 ± 0.46mm

kurtosis was displayed as 0.20 and 0.30 for males andon upper canines, 5.51 ± 0.35mm and 5.45 ± 0.40mm

females, respectively (Table 3) (Fig. 7).

on lower central incisors, 6.17 ± 0.39mm and 6.05 ±Table 1 Sex and age distributions of the subjects (n=202)
Age

〜 14

15 〜 1718 〜 20

21 〜 23

24 〜 26

27 〜 29

30 〜 32

33 〜 35

36 〜

Total

Male

13

31

9

5

6

2

1

2

2

71

Female

28

42

23

12

10

6

5

3

2

131

Table 2 The descriptive statistic values of mesiodistal crown width
Maxillary central Maxillary lateralincisors**
incisors
Male

FemaleMale

FemaleMaxillarycanines**
Male

Mandibular
central incisors
FemaleMale

FemaleMandibular
lateral incisors*
Male

FemaleMandibularcanines**
Male

Female

Mean

8.77

8.50

7.27

7.18

8.23

7.89

5.51

5.45

6.17

6.05

7.22

6.86

SD

0.45

0.49

0.60

0.61

0.53

0.46

0.35

0.40

0.39

0.41

0.45

0.46

Skewness

-0.31

-0.06

-0.69

0.11

-0.33

0.21

-0.13

0.27

-0.32

-0.20

-0.39

-0.10

Kurtosis

-0.25

-0.15

1.41

-0.07

0.05

0.15

0.15

0.65

1.41

-0.01

1.29

0.85

Unit: mm**P < .01
* P < .05

− 43 −

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Niigata Dent. J.

Table 3

35（1）：2005

The descriptive statistic values of anterior ratio
Sum of 6
maxillaryanterior teeth (mm)Sum of 6
mandibular
anterior teeth (mm)Anterior ratio
(%)

Male

Male

Male

FemaleFemaleFemale

Mean

48.56

47.13

37.81

36.72

77.92

77.93

SD

2.61

2.46

1.95

2.17

2.36

2.63

Skewness

-0.45

0.09

-0.47

-0.16

0.26

0.20

Kurtosis

-0.12

-0.10

1.18

-0.20

0.28

0.30

Fig. 3 Distribution of mesiodistal crownFig. 1 Distribution of mesiodistal crownwidths of maxillary canines

widths of maxillary central incisors

Fig. 4 Distribution of mesiodistal crownFig. 2 Distribution of mesiodistal crownwidths of mandibular central incisors

widths of maxillary lateral incisors− 44 −EDANAMI et al.

45

Ⅳ．Discussion
1. The mesiodistal crown width
The alteration of anterior ratio is related to themesiodistal crown widths because of the anteriorratio derived from the values of upper and lower
mesiodistal crown widths on the anterior teeth.
Distribution of mesiodistal crown widths of theanterior teeth on the maxilla and mandible were
evaluated using the mean value, standard deviation,
skewness and kurtosis. In terms of the kurtosis, theseresults exceeded 1.0 on the upper and lower lateralincisors and lower canines, but this value guides
Fig. 5 Distribution of mesiodistal crownwidths of mandibular lateral incisors

the conditions required for statistics, with absolutevalues of less than 1.5. Furthermore, these data
were distributed in a linear manner when normal
probability paper (Fig. 8 and 9), and showed analmost normal distribution. The standard deviationof mesiodistal crown widths of the upper and lower
anteriors had a range from 0.35 to 0.60 which was
a l m o s t a n a l o g o u s t o t h o s e (0.20-0.77) i n o t h e rreports7, 10, 11, 16-21） (Table 4). This ﬁnding suggests thatthe subjects used in this study were almost the sameones compared to the previous studies.
2. The difference in mesiodistal crown widths amongsex, age, and region (Table 4)
In this study, statistically significant differencesin mesiodistal crown widths of the upper central
incisors, upper canines, lower lateral incisors, andFig. 6 Distribution of mesiodistal crownwidths of mandibular canines

lower canines were found between males and females.
In addition respective values for males showed larger
than those for females. Endo17）using, subjects withnormal occlusion and Akiyama et al.20）investigatingon the general population showed that the sizes ofall six anterior teeth were larger in males than infemales. Endo19）investigated subjects with reversed
occlusion and concluded that there was a statistical
diﬀerence in the upper anteriors and the lower canine
between males and females. Kubota et al.10）using
subjects with normal occlusion also obtained thesimilar results. Moreover, in terms of the cases withcrowding, Kubota et al.10）reported that the size of theupper central incisors and lower anterior teeth werelarger in males than in females. According to the otherreport using the general population22）, the sizes of theFig. 7 Distribution of anterior ratios

upper and lower central incisors and lateral incisors
for males showed larger values than those for females.
− 45 −

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Niigata Dent. J.

Table 435（1）：2005

Comparison with other studies on mesiodistal crown widths Mean ± Standard Deviation(mm）Year ofpublication

Subject

Maxillarycentralincisors

Maxillarylateralincisors

Maxillarycanines

Mandibular
centralincisors

Mandibular
lateralincisors

Mandibularcanines

Male
Present study

2005

Mandibular prognathism

8.77 ± 0.45

7.27 ± 0.60

8.23 ± 0.53

5.51 ± 0.35

6.17 ± 0.39

7.22 ± 0.45

Otsubo 16）

1957

Normal occlusion

8.59 ± 0.54

7.08 ± 0.77

8.04 ± 0.40

5.44 ± 0.43

6.03 ± 0.54

7.11 ± 0.42

Yamauchi et al. 18）

1965

Normal occlusion

8.52 ± 0.43

7.04 ± 0.56

7.94 ± 0.39

5.45 ± 0.29

6.06 ± 0.36

7.01 ± 0.34

Endo 17）1970

Normal occlusion

8.78 ± 0.46

7.36 ± 0.66

8.25 ± 0.36

5.56 ± 0.37

6.20 ± 0.36

7.19 ± 0.37

Kubota et al. 10）

1991

Normal occlusion

8.64 ± 0.39

7.16 ± 0.41

8.23 ± 0.31

5.50 ± 0.35

6.08 ± 0.35

7.14 ± 0.40

Nagaoka et al. 7）

1993

Normal occlusion

8.55 ± 0.48

7.00 ± 0.54

7.91 ± 0.41

5.44 ± 0.42

5.94 ± 0.41

7.00 ± 0.44

Endo et al. 19）

1971

Reversed occlusion

8.90 ± 0.44

7.42 ± 0.61

8.29 ± 0.49

5.70 ± 0.34

6.34 ± 0.35

7.46 ± 0.44

Kubota et al. 10）

1971

Crowding

9.12 ± 0.50

7.55 ± 0.59

8.33 ± 0.56

5.83 ± 0.35

6.40 ± 0.36

7.24 ± 0.39

Akiyama et al. 20）

1991

General population

8.63 ± 0.54

7.09 ± 0.63

8.04 ± 0.49

5.44 ± 0.37

6.04 ± 0.41

7.01 ± 0.43

Nakano et al. 11）

1993

General population

9.11 ± 0.64

8.55 ± 0.43

7.89 ± 0.45

5.86 ± 0.42

6.52 ± 0.45

7.52 ± 0.43

Sumi et al. 21）

1985

Okinawa

8.93 ± 0.43

7.59 ± 0.56

8.31 ± 0.50

5.74 ± 0.28

6.33 ± 0.41

7.35 ± 0.38

Nagasaki8.95 ± 0.58

8.52 ± 0.45

7.55 ± 0.49

5.70 ± 0.41

6.33 ± 0.46

7.37 ± 0.43

Akita

8.72 ± 0.55

7.18 ± 0.63

8.11 ± 0.48

5.46 ± 0.37

6.10 ± 0.43

7.08 ± 0.45

Tanegashima

8.43 ± 0.50

6.97 ± 0.62

7.97 ± 0.44

5.30 ± 0.36

5.92 ± 0.39

6.96 ± 0.34

Tsushima

8.77 ± 0.60

7.22 ± 0.61

8.02 ± 0.59

5.54 ± 0.39

6.16 ± 0.41

7.01 ± 0.49

Okinawa

8.64 ± 0.49

7.03 ± 0.65

8.06 ± 0.48

5.49 ± 0.35

6.02 ± 0.40

6.99 ± 0.44

Akiyama et al. 20）

1991

FemalePresent study

2005

Mandibular prognathism

8.50 ± 0.49

7.18 ± 0.61

7.89 ± 0.46

5.45 ± 0.40

6.05 ± 0.41

6.86 ± 0.46

Otsubo 16）

1957

Normal occlusion

8.24 ± 0.41

6.64 ± 0.60

7.65 ± 0.39

5.19 ± 0.36

5.81 ± 0.39

6.58 ± 0.38

Yamauchi et al. 18）

1965

Normal occlusion

8.17 ± 0.41

6.60 ± 0.51

7.59 ± 0.41

5.18 ± 0.32

5.83 ± 0.36

6.61 ± 0.42

Endo 17）1970

Normal occlusion

8.33 ± 0.45

6.91 ± 0.62

7.89 ± 0.40

5.36 ± 0.40

5.97 ± 0.41

6.75 ± 0.39

Kubota et al. 10）

1991

Normal occlusion

8.38 ± 0.46

6.92 ± 0.35

7.93 ± 0.55

5.40 ± 0.28

5.94 ± 0.32

6.69 ± 0.39

Nagaoka et al. 7）

1993

Normal occlusion

7.96 ± 0.46

6.61 ± 0.55

7.53 ± 0.43

5.10 ± 0.32

5.64 ± 0.37

6.41 ± 0.41

Endo et al. 19）

1971

Reversed occlusion

8.56 ± 0.53

7.02 ± 0.73

7.83 ± 0.39

5.63 ± 0.38

6.18 ± 0.35

6.98 ± 0.53

Kubota et al. 10）

1971

Crowding

8.95 ± 0.47

7.46 ± 0.50

8.14 ± 0.46

5.62 ± 0.31

6.26 ± 0.32

7.00 ± 0.40

Akiyama et al. 20）

1991

General population

8.43 ± 0.51

6.90 ± 0.64

7.75 ± 0.39

5.37 ± 0.20

5.98 ± 0.36

6.64 ± 0.34

Nakano et al. 11）

1993

General population

8.83 ± 0.53

7.41 ± 0.69

8.09 ± 0.40

5.71 ± 0.33

6.34 ± 0.37

7.05 ± 0.37

Sumi et al. 21）

1985

Okinawa

8.81 ± 0.39

7.25 ± 0.50

8.10 ± 0.32

5.68 ± 0.30

6.19 ± 0.31

6.99 ± 0.27

Nagasaki

8.52 ± 0.45

7.08 ± 0.57

7.89 ± 0.41

5.38 ± 0.30

6.02 ± 0.33

6.91 ± 0.35

Akita

8.44 ± 0.48

6.89 ± 0.64

7.84 ± 0.37

5.38 ± 0.31

6.03 ± 0.34

6.67 ± 0.32

Tanegashima

8.32 ± 0.55

6.82 ± 0.78

7.70 ± 0.38

5.25 ± 0.35

5.88 ± 0.40

6.62 ± 0.33

Tsushima

8.48 ± 0.57

6.97 ± 0.57

7.67 ± 0.42

5.42 ± 0.32

6.00 ± 0.34

6.60 ± 0.34

Okinawa

8.48 ± 0.49

6.93 ± 0.56

7.74 ± 0.40

5.43 ± 0.30

5.99 ± 0.36

6.64 ± 0.37

Akiyama et al. 20）

1991

Fig. 8 Normal probability distribution ofFig. 9 Normal probability distribution ofmesiodistal crown widths (Male)mesiodistal crown widths (Female)− 46 −

Fig. 10 Normal probability distributionof anterior ratio

EDANAMI et al.

47

Studies about tooth devolution have been publishedchronological transition, mesiodistal crown widths ofwidely. In accordance with the theory of terminal

anterior teeth obtained in this study were larger than

reduction 23）, many researchers have explained

those of 40-50 years ago in males and females, andthat human teeth tend to diminish in size overthe gender difference in mesiodistal crown widths

time. In comparison with the data from the generalprobably tends to decrease.

11, 20）population in the 1990's, the present data showedintermediate values of those findings except for the

3. The anterior ratio (Table 5)

upper canines in males. In addition, compared with

The skewness and the kurtosis of the anterior

normal occlusion groups in the 1990's of crown widths,

ratio in this study were 0.26 and 0.20, 0.28 and 0.30 in

we obtained almost the same values or slightly larger,

males and females, respectively. Since the total sum

except for the upper canines in females, than thoseof the skewness and the kurtosis on the upper andreported by Kubota et al. (1991) 10）and Nagaoka et al.

lower anterior teeth showed -0.47 to 0.09, -0.20 to 1.18,

7）. On the other hand, compared with the data

the anterior ratio calculated showed highly normalof the subjects with reversed occlusion, the ﬁnding in

distribution. In fact, the anterior ratios were aligned

this study showed that all the values in males wereon normal probability paper and seemed to fall into

smaller than those of Endo et al. (1971) 19）. For femalesa straight line. This suggests that more accurate

the present data were smaller than those of othervalues of ﬁt index were obtained using anterior ratio

studies, except for the upper lateral incisors and uppercompared to calculating only mesiodistal crown widths

canines.

(Fig. 10).

(1993)As the issues of both character and size in teeth

The anterior ratio is an important index independ on ethnicity, many relevant studies haveassociation with occlusion in the upper and lower

been performed not only in dentistry but also inanterior teeth; that is, the anterior ratio is helpful inanthropology. Both size and its phenotype of teeth

determining whether adequate overbite and overjet,

have a strong relation with ethnicity. There haveor Class I canine relation are achieved, and is useful

been many reports published about the issue on

for attaining smooth movements of the jaw. On theregional diﬀerences in sizes and phenotypes of teeth

other hand, the anterior ratio is highly dependent

in odontology as well as in anthropology. In Japanese,

upon its regional characteristics. For instance, there

regional differences in dental size and morphology

are the difference between the European and thehave been carried out from dental or anthropologicalJapanese in the anterior ratio in terms of development,

points of view. In comparison with the report on

acquired deformities or condition of teeth. The

regional diﬀerences in crown widths between Okinawa

Europeans have mostly Chisel-shaped incisors, but

21）), our results for

the Japanese have mostly shovel-shaped incisors.

males showed that the values of mesiodistal crown

Therefore, the data obtained suggest that it may

widths were smaller except for the upper canines.

be useful for future clinical diagnosis and treatment

The present data for upper canines fall in the middle

to investigate the regional differences in teethof the data for Okinawa and Nagasaki. All the values

phenotypes.

and Nagasaki (Sumi et al., 1985

for females obtained in this study except for the lower

Previous studies have reported that an anterior

canine existed in the middle of both regions, while

ratio obtained from patients having suitable occlusion

the values for the lower canine showed smaller thanshowed 78.3 ± 2.01 (male; 78.9 ± 2.02, female; 77.8 ±those of the two regions. Compared with this similar

1.95) (Matsumoto et al.)24) and 78.09 ± 2.19 (Motohashi

study20） performed in Akita, Tanegashima, Tsushima,

et al.)25）. Our results, 77.92 ± 2.36 for males andand Okinawa, our results were highly analogous to the77.93 ± 2.63 for females, were close to the previous

values in Tsushima with the exception of the upper

data, indicating that the anterior ratio measured was

and lower canines.

almost proportional in spite of anteroposterior skeletal

In conclusion, the results obtained in this study

discrepancy. However, there has been still few study

show that teeth are larger than those of the subjects

made on the anterior ratio for the Japanese. Therefore,

with normal occlusion and are almost the sameusing other studies on measurements of mesiodistal

as those for the general population. In terms ofcrown width7,10,11,16-21,24,25）, we calculated the anterior− 47 −

48

Niigata Dent. J.

Table 535（1）：2005

Comparison with other reports on anterior ratio
Year ofpublication

Subject

Sum of 6
anterior teeth (mm）MaxillaMandible

Anterior
ratio
Mean ±
SD(%）

Male

Mandible

Anterior
ratio
Mean ±
SD(%）

36.72

77.93 ± 2.63

Sum of 6
anterior teeth (mm）MaxillaFemalePresent study

2005

Mandibular prognathism

Matsumoto et al.24）

1971

Normal occlusion

16）

Otsubo1957

Normal occlusion

23.71

18.58

78.36

22.53

17.58

78.03

Yamauchi et al.18）

1965

Normal occlusion

23.50

18.52

78.81

22.36

17.62

78.80

Endo

1965

Normal occlusion

24.39

18.95

77.70

23.13

18.08

78.17

Kubota et al.10）

1991

Normal occlusion

24.03

18.72

77.90

23.23

18.03

77.62

7）

Nagaoka et al.

1993

Normal occlusion

23.46

18.38

78.35

22.10

17.15

77.60

Endo et al.19）

1971

Reversed occlusion

24.61

19.50

79.24

23.41

18.79

80.26

1971

Crowding

25.00

19.47

77.88

24.55

18.88

76.90

Akiyama et al.

1991

General population

23.76

18.49

77.82

23.08

17.99

77.95

Nakano et al.11

1993

General population

25.55

19.90

77.89

24.33

19.10

78.50

17）

Kubota et al.10）
20）

21）

1985

Sumi et al.

20）

1991

Akiyama et al.

48.56

37.81

77.92 ± 2.36

47.13

78.9 ± 2.02

77.8 ± 1.95

Okinawa

24.83

19.42

78.21

24.16

18.86

78.06

Nagasaki

25.02

19.40

77.54

23.49

18.31

77.95

Akita

24.01

18.64

77.63

23.17

18.08

78.03

Tanegashima

23.37

18.18

77.79

22.84

17.75

77.71

Tsushima

24.01

18.71

77.93

23.12

18.02

77.94

Okinawa

23.73

18.50

77.96

23.15

18.06

78.01

Males and females
combined
Matsumoto et al.24）

1971

Normal occlusion

78.3 ± 2.01

Motohashi et al.25）

1971

Normal occlusion

78.09 ± 2.19

1962

Normal occlusion

77.2 ± 1.65

15）

Bolton26）

Kayukawa

1956

Normal occlusion

23.91

18.30

76.54

Reversed occlusion

23.66

18.67

78.91

ratio for each study, and then compared them withbecame larger since the 1990's. On the other hand,

our results obtained. As a result, all the anterior ratio

Kayukawa (1956)26）, Endo et al.(1971)19）and Kubota

obtained from Otsubo (1957)16）, Yamauchi et al.(1965)18）

et al.(1991)10） investigated the anterior ratios for the17）

and Endo (1970), were larger than the present datacases with crowding, reversed occlusion and maxillary(-0.22 to 0.89 and 0.10 to 0.87 for males and females,

protrusion. Our data were larger than the crowding

respectively). Compared to the data obtained fromgroup, while they were smaller than in the reversed

Kubota et al.(1991)10） and Nagaoka et al.(1993)7） in

occlusion and maxillary protrusion.

1990's, our results showed intermediate values in male

The anterior ratio depends on several factors

and larger values in female in 0.31 to 0.33. On the

including morphological anomaly of teeth, such asother hand, the present anterior ratio showed larger

macrodont or microdont, congenitally missing teeth

in 1.38 than that obtained in Kayukawa (1956) 26） 's

or congenital defects. In comparison with the anterior

study using in mixed-up group in males and females.

ratio among normal and malocclusion groups, theAbove all, in comparison with normal groups, the malefrequency of occurrence of these varieties might bedata obtained were almost similar to normal groups

considered, because this study excluded the above

and there was no relationship in chronological terms,

parameters has been no evidence that patients withwhile there was a diﬀerence in the females; the data

malocclusion have more teeth anomaly and congenital

for females were smaller in the 1950'S to 1970's, but

defects than the normal population. Therefore, further− 48 −

49

EDANAMI et al.

studies concerning the relationship between the tooth11）Nakano M, Suzuki A, Murakami T, Takahamamorphology and occlusion may be needed to establish

Y: Tooth sizes and dentofacial forms of thea more ideal occlusion provided with orthodontic

orthodontic patients with tooth crowding, J Jpn
Orthod Soc, 52: 104-118, 1993. (in Japanese)treatment.

12）Suzuki A, Morimoto N, Amano Y, Takemoto

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