International Journal of Advanced Biotechnology and Research (IJBR)
ISSN 0976-2612, Online ISSN 2278–599X,
Vol-7, Special Issue3-April, 2016, pp1182-1189
http://www.bipublication.com
Research Article
The Width to Height Ratio of Clinical Crown of Maxillary
Anterior Teeth in Iranians
Tania Ghasemi1, Ramin Kaviani2, Alireza Mackinejad3,
Orkideh Radmehr4, Mehrnoosh Kazemi5 and Samira Kavoli6
1
Resident, Department of Orthodontics,
Babol University of Medical science, Babol, Iran
2
Scientific Member, Department of Dental Morphology,
Islamic Azad University, Dental Branch of Tehran, Iran.
3
Scientific Member, Department of Dental Morphology,
Islamic Azad University, Dental Branch of Tehran, Iran.
4
Scientific Member, Department of Dental Morphology,
Islamic Azad University, Dental Branch of Tehran, Iran.
5
Dentist in private practice, Australia
6
Corresponding Author, Resident, Department of Orthodontics,
Babol University of Medical Science, Babol, Iran
[[email protected] Faculty of Dentistry,
Babol University of Medical Science, Babol-Iran
Tel:+981132291408-9 fax:+981132291093]
ABSTRACT:
Purpose: Length and mesiodistal width of teeth are important factors to orthodontists, prosthodontists, general
dentists, and anthropologists. This study assessed the width-to-length ratios of the crowns of maxillary anterior teeth.
Moreover, the ratio of these measurements determines the esthetics of smile.
Methods: Mesiodistal widths and occlusogingival heights of anterior teeth of 569 participants (281 males and 288
females)were measured using a digital caliper. The width-to-height ratios of these teeth were calculated. Data were
analyzed statistically by t-test and Pearson correlation coeffiicent.
Results: W/H ratios of central, lateral, and canine were 92.99 ± 9.37, 84.44 ± 10.78, and 87.69 ± 9.76 in males and
96.93±13.69, 91.66±12.36, and 89.75±7.89 in females, respectively. The difference between ratios in males and
females were significant for all three teeth (P<0.005).
Conclusion: the width-to-length ratio of central is more than lateral, and lateral's W/H is more than canine's; while in
men this ratio is higher in central, followed by canine and lateral. Central have the most variation and the least
variation of width-to-length belongs to canine. There were significant differences between the ratios of all investigated
teeth in males and females.
Keywords: clinical crown length, mesiodistal width, width-to-length ratio.
INTRODUCTION
Patients’ esthetics is one of the main goals in
orthodontic treatments.1-7 Teeth are main
components of an esthetic smile. An important
anatomic feature of teeth is its dimensions, which
not only play a crucial role in esthetics, but also is
an important factor in build-up treatments and
orthodontic space estimations.8-10Three important
aspects of dimensions are length, width, and the
ratio of length to width.7,9,11-13 The latter might be
attractive when it is closer to the golden ratio.7,9,11-
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
3
Lombardy, one of the pioneers in presenting the
golden ratio of the incisors, believes that using the
golden ratio is not helpful in every case.14 Also
Peterson's measuring confirms the unreal nature of
Golden ratio.14,15 The golden ratio is used in
thoughtlessly is some cases, because of the narrow
maxillary arch and also overcrowding of the teeth
in anterior section.14 Some researches have
reported the differentiation of dental dimensions
between female and male in total ratio and
incisors ratio.16,17
In restoration of the
incisors, the natural look of anterior teeth and their
esthetics can be associated with these
dimensions.7-13 Because these dimensions can
change between different geographical regions
and also between sexes,it should be evaluated in
each country. Therefore,due to inconsistencies in
width-to-length ratios (ranging from 75% to
85%)15 and the lack of information in Iranian
community, this study was conducted. Its goal
was to determine the width-to-length ratio of
clinical crown of maxillary anterior teeth in
Iranian people.
METHODS AND MATERIALS:
This descriptive cross-sectional research was done
on 569 people(281 males and 288 females), who
were 18 to 25 years old, to calculate the width-tolength ratio of three groups of maxillary anterior
teeth (central, lateral and canine) in Iranian
community. The method of collecting the
information is observation, filling the data forms
and measuring. In this research we made an
Alginate mould from maxillary dental arches of
qualified persons, by Zhermack moulding
materials and prefabricated Trays, then casted by
yellow stone plaster. After that we measured the
width and the length of the clinical crown of
Centrals, Laterals and Canines by digital Collis
(with one hundredth accuracy) and registered
them in information forms, then calculate the
width-to-length ratio. The width-to-length ratio of
clinical crown of the selected group was registered
and the information was calculated by Pearson
Correlation Coefficient. The technique was bunch
accidental. The research investigated 282 of male
students and patients of Islamic Azad Dental
University in 1388, who had the fallowing
conditions: The studied persons were 18 to 25
years old. Free border of the gingival in anterior
part (in facial view) was more apical in
comparison with cervical height of contour. No
evidence for losing the attachment. The tissue of
the gingival border looked like a hard consisted
blade with pink color. No evidence of gingival
changes, like unusual growth of gingival, gingival
hyperplasia, inflammation, changes during the
teeth growth, missing attachment, gingival
corrosion and periodontal operation records. No
evidence or records for changes in incisal or
proximal edge of the tooth, like restoration and
filling interferences, injuries caused by storks,
clinical crown fraction, tooth and plate erosion.
There was at least one proper tooth in each dental
group. The studied persons were Iranian, and
white. The information was obtained by exact
tests.
RESULTS
The resulted as fallowing (Tables 1 to 9, Figures 1
to 3). According to t-test, there were significant
differences between males and females regarding
the ratios of centrals (P = 0.0001), laterals (P =
0.0001), and canines (P = 0.0057, Table 1)
.Table 1.The average of maximum and minimum of width-to-length ratio of central, lateral and canine (in
percentage).
Sex
Male
Female
Tooth
Central
Lateral
Canine
Central
Lateral
Canine
Samira Kavoli, et al.
Mean ± SD (mm)
92.99 ± 9.37
84.44 ± 10.78
87.69 ± 9.76
96.93±13.69
91.66±12.36
89.75±7.89
Range
55.09
71.34
59.24
47.3
62.6
53.1
Max
119.3
126.2
113.9
120.4
122.9
120
Min
55.1
71.3
59.2
73.1
60.3
66.9
C.V
10.1
12.2
11.2
14.3
13.42
8.69
95% CI
92.95 – 93.03
88.48 – 88.49
87.65 – 67.73
95.35 – 98.51
90.23 – 93.09
88.84 – 90.66
1183
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
Table 2. Average, minimum and maximum of the width of central, lateral and canine incisors (in millimeters)
Dimension
Sex
Tooth
Mean ± SD (mm)
Range
Max.
Min.
Width
Male
Central
8.59 ± 0.74
5.61
10.79
5.18
Lateral
6.9 ± 0.7
3.9
8.62
4.74
Canine
7.96 ± 0.74
5.8
9.9
4.8
Female
Central
8.74 ± 2.14
3.38
10.80
7.42
Lateral
6.96 ± 0.68
3.96
8.98
5.02
Canine
7.81 ± 1.72
2.47
8.92
6.45
Length
Male
Central
9.30 ± 1.02
6.46
13.1
6.7
Lateral
7.92 ± 0.9
6.58
11.2
4.7
Canine
9.16 ± 1.05
6.66
12.3
6
Female
Central
9.29 ± 1.98
4.17
11.20
7.03
Lateral
7.67 ± 1.64
4.14
10.12
5.98
Canine
8.76 ± 1.77
3.63
10.61
6.98
With due attention to the table 3 and meaningful level of 0.001 for Pearson correlation test (r > 0.998), we
express with 99% confidence that there is a meaningful relation between obtained ratios of three dental
group of centrals, laterals and canines.
Table 3.Correlation between the width-to-length ratios of Central, Lateral and Canine (using Pearson correlation
coefficient).
Sex
Teeth
t
df
p
Central, lateral
4.97
574
0.001
Male
Central, canine
8.01
574
0.001
Lateral, canine
3.38
574
0.001
Central, lateral
4.87
574
0.001
Female
Central, canine
7.72
574
0.001
Lateral, canine
3.27
574
0.001
Table 4.Frequency of width of the maxillary centrals.
Sex
Male
Female
Width range (mm)
8-7
9-8
10-9
11-10
Total
8-7
9-8
10-9
11-10
Total
Table 5.Frequency of length of the maxillary centrals.
Sex
Length range (mm)
7-8
8-9
Male
9-10
10-11
11-12
Total
7-8
8-9
Female
9-10
10-11
Total
Samira Kavoli, et al.
Number
6
49
147
80
282
27
163
93
5
288
Frequency (%)
2.13%
17.38%
52.13%
28.37%
100%
9.38%
56.60%
32.29%
1.74%
100%
Number
1
13
106
92
70
282
27
163
93
5
288
Frequency (%)
0.35%
4.61%
37.59%
32.62%
24.82%
100%
9.38%
56.60%
32.29%
1.74%
100%
1184
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
Figure 1.Frequency (%) of width to height ratios of maxillary centrals in males and females.
Table 6.Frequency of the width of maxillary laterals.
Sex
Width range (mm)
Number Frequency (%)
Male
8-7
24
8.51%
9-8
125
44.33%
10-9
120
42.55%
11-10
13
4.61%
Total
282
100%
Female
8-7
12
4.17%
9-8
142
49.31%
10-9
116
40.28%
11-10
18
6.25%
Total
288
100
Table 7.Frequency of the length of maxillary laterals.
Sex
Length range (mm)
Number
Frequency (%)
Male
7-6
32
11.35%
8-7
129
45.74%
9-8
92
32.62%
10-9
19
6.74%
11-10
10
3.55%
Total
282
100%
Female
7-6
70
24.31%
8-7
122
42.36%
9-8
75
26.04%
10-9
21
7.29%
11-10
4
1.39%
Total
288
100%
Figure 2.Frequency (%) of width to height ratios of maxillary laterals in males and females.
Samira Kavoli, et al.
1185
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
Table 8.Frequency of the width of maxillary canines.
Sex
Width range (mm)
Male
7-6
8-7
9-8
10-9
11-10
Total
Female
7-6
8-7
9-8
Total
Table 9.Frequency of the length of maxillary canines.
Sex
Width range (mm)
Male
7-6
8-7
9-8
10-9
11-10
Total
Female
8-7
9-8
10-9
11-10
Total
Number
9
154
95
19
5
282
9
184
95
288
Number
32
129
92
19
10
282
58
108
109
13
288
Frequency (%)
3.19%
54.61%
33.69%
6.74%
1.77%
100%
3.13%
63.89%
32.99%
100
Frequency (%)
11.35%
45.74%
32.62%
6.74%
3.55%
100%
20.14%
37.50%
37.85%
4.51%
100%
Figure 3.Frequency (%) of width to height ratios of maxillary canines in males and females.
DISCUSSION
The goal of this research is to present the W/L
ratio of Iranian participants 18 to 25 years old.
The maxillary central had the greater W/L ratios.
Canines had the least variations and the most
continuity in width-to-length ratio (lesser standard
Samira Kavoli, et al.
deviation). Successful operative and esthetic
dentistry depends on proper restoration of the
teeth specially incisors.7-13One of the methods of
registering the dental dimensions is to appointing
the width-to-length ratio in fractional form that is
presented in the most cases (not all), near to the
1186
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
golden ratio.14,15 For example in narrow dental
arches, using the golden ratio can result in
inconsistency.15 Although the artistic sense of
dentists can be useful in restorations, but
presenting these dental ratios by a scientific
research, helps this field.15Pearson correlation
coefficient indicated a close relationship between
width-to-length ratios of the teeth. This can
implicate that in persons with one long and
extensive anterior teeth absolutely have shorter
anterior teeth. This subject was justifiable with
due attention to common genetic and growth
resources of the incisors.In some researches, the
ratio were reported 86% for central, 79% for
lateral and 81% for canine,14 which were similar
to the obtained numbers in our research. This
similarity can show the validity and vastness of
the results. In their research the canine's width-tolength ratio was reported greater than lateral,
whereas in our research the lateral's width-tolength ratio was greater. This difference may be
driven from racial differences or few numbers of
samples (71 subjectsin that study versus 570
subjects in this study). In another research on 82
subjects, the width-to-length ratio was 90% for
central, 82% for lateral and 84% for canine,15
which were similar to our results. In our research,
lateral's width-to-length ratio was greater than
canine's, but in their research canine's width-tolength ratio was greater than lateral's. Another
research reported 89.9% of total ratio for incisors
17
which were similar to our result that was 92.7%.
Probably the reason of these close results is racial
similarities of Iran and Turkey and racial
mixture.In another research in 2003 the obtained
width-to-length ratios were 78% for centrals, 73%
for laterals and 73% for canines.19However, the
ratios in our research are higher. This maybe
driven from racial differences or different
research's methods, such as using anatomic crown
that is useless in clinical restorations, using digital
photos that are not proper for measuring dental
dimensions, and unequal numbers of studied
teeth.In another study in 2007, width-to-length
ratio was 38% for central, 31% for lateral, and
Samira Kavoli, et al.
20% for canine.20 Their research was done on 90
persons in the race of Caucasian .20 The width-tolength ratio of central, lateral, and canine in our
research is tremendously more than their results.20
Their results need a second check because it didn't
match with this and previous researches; as widthto-length ratio of central is more than lateral, and
the laterals is more than canine as well. Another
research reported the greatest coefficient of
variaton for the lateral in both sexes,21 whereas in
our research the most dispersion belonged to
central. This difference maybe driven from racial
differences or improper omission of intermediates
in their researches.Some studies could not find
any significant differences between width-tolength ratios in males and females 14,15 and some
others could.16,17 In agreement with the results of
the studies conducted in Turkey,16,17 we found a
significant difference between ratios in males and
females.In this research, sample size was
calculated from a pilot study and the number of
the subjects was estimated about 570 that seem
proper, while, in the most previous researches,
samples were smaller.7-14 Research method in this
study, which includes using the clinical crown,
study casts and digital calibers with one hundredth
accuracy was proper. The research can present
useful information for using in operative dentistry
and choosing proper tooth for denture.The
outcome of this research shows some similar
results with the most previous researches, which
can confirm the findings and equations. With
having these W/L ratios, dentists in repairing and
restorations, by having one of the two parameters
(width or length) of the tooth can calculate proper
width or length dimensions with referring to
width-to-length ratio of the specific group.7-13
CONCLUSIONS:
This research indicates that in females, the widthto-length ratio of central is more than lateral, and
lateral's ratio is more than canine's; while in men
this ratio is higher in central, followed by canine
and lateral. Central has the most variation, and the
1187
The Width to Height Ratio of Clinical Crown of Maxillary Anterior Teeth in Iranians
least variation of width-to-length belongs to
canine.
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