Download Dental and Alveolar Arch Widths in Normal Occlusion and Class III

Original Article
Dental and Alveolar Arch Widths in Normal Occlusion
and Class III Malocclusion
Tancan Uysala; Serdar Usumezb; Badel Memilic; Zafer Sarid
Abstract: The aim of this study was to compare the transverse dimensions of the dental arches
and alveolar widths of Class III malocclusion group with a group of untreated normal occlusion
subjects. This study was performed using measurements on dental casts of 150 normal occlusion
(mean age, 21.6 6 2.6 years) and 100 Class III malocclusion (mean age, 15.4 6 2.2 years)
subjects. Independent samples t-test was applied for comparing the groups. The findings of this
study indicated that the mandibular intercanine and intermolar alveolar widths were significantly
larger in the Class III group when compared with the normal occlusion sample (P , .001). Maxillary interpremolar, intermolar widths and all maxillary alveolar width measurements were significantly narrower in the Class III group (P , .001). In addition, the lower canine and premolar
alveolar width measurements were also statistically significantly larger in the normal occlusion
group when compared with the Class III malocclusion group (P , .001). Subjects with Class III
malocclusion tend to have the maxillary teeth inclined to the lingual and mandibular teeth inclined
to the buccal direction because of the restriction of maxillary growth and development according
to dental arch width measurements. Therefore, rapid maxillary expansion should be considered
before or during the treatment of a Class III patient with or without face-mask therapy. (Angle
Orthod 2005;75:809–813.)
Key Words: Class III; Normal occlusion; Dental width; Alveolar arch width
INTRODUCTION
and Helm4 in the Danish populations. Among 965
Turkish children, in the region of Konya, Turkey, a
3.5% incidence of Class III malocclusion was found.5
The size and form of the dental arches can have
considerable implications in orthodontic diagnosis and
treatment planning, affecting the space available, dental esthetics, and stability of the dentition.6 The growth
changes of arch widths in normal occlusion subjects
and a comparison of arch widths in normal occlusion
and different malocclusion samples have been studied
extensively.7–13
Most of the studies in the literature compare dental
arch widths of Class II patients with the normal occlusion samples.7,8,10,12,13 Some of them indicate that absolute arch widths of children with malocclusion did not
differ appreciably from those with normal occlusion.8,12
However, in other studies, statistically significant differences were determined in dental and alveolar width
measurements of Class II patients.7,13
Braun et al14 indicated that the mandibular dental
arches associated with Class III malocclusions are
wider than the Class I mandibular arches beginning in
the premolar area. In addition, they found that Class
III maxillary dental arch widths are larger than the
Class I widths. This begins in the lateral incisor–canine
area and proceeds distally.
Investigators have recommended strongly the early
detection of all Classes of malocclusion.1 Furthermore,
they endorse preventive and interceptive orthodontics
and dentofacial orthopedics for young patients to
avoid, or at least to minimize the occurrence of Class
III malocclusion at the adult stage.
The prevalence of Class III malocclusion is reported
to be 16.8% by Garner and Butt2 in the Kenyan, 14%
by Salzmann3 in the American, and 1.4% by Solow
Assistant Professor and Head, Department of Orthodontics,
Faculty of Dentistry, Erciyes University, Kayseri, Turkey.
b
Associate Professor, Department of Orthodontics, Faculty of
Dentistry, Marmara University, Istanbul, Turkey.
c
Research Assistant, Department of Orthodontics, Faculty of
Dentistry, Selcuk University, Konya, Turkey.
d
Associate Professor, Department of Orthodontics, Faculty of
Dentistry, Selcuk University, Konya, Turkey.
Corresponding author: Tancan Uysal, DDS, PhD, Erciyes
Üniversitesi, Dişhekimliği Fakūltesi Ortodonti AD, Melikgazi,
Kampüs Kayseri, Kayseri 38039, Turkey
(e-mail: [email protected])
a
Accepted: December 2004. Submitted: November 2004.
Q 2005 by The EH Angle Education and Research Foundation,
Inc.
809
Angle Orthodontist, Vol 75, No 5, 2005
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UYSAL, USUMEZ, MEMILI, SARI
occlusion groups with those of 150 untreated normal
occlusion subjects. The null hypothesis to be tested
states that there is no statistically significant difference
in maxillary and mandibular dental arch and alveolar
width dimensions between Class III malocclusion and
normal occlusion samples.
MATERIALS AND METHODS
This study was performed on dental casts of 150
normal occlusion and 100 Class III malocclusion subjects from the archives of the Selcuk University, Faculty of Dentistry, Department of Orthodontics. The distribution of age in different groups for all subjects is
shown in Table 1.
Normal occlusion sample
FIGURE 1. Maxillary dental cast measurements (modified from
Sayın and Turkkahraman7).
Dental casts were taken from 150 adult subjects (72
male and 78 female) with normal occlusion, which met
the following criteria:15 (1) Class I canine and molar
relationship with minor or no crowding, normal growth
and development, well-aligned upper and lower dental
arches; (2) all teeth present except third molars; (3)
good facial symmetry determined clinically; (4) no significant medical history; (5) no history of trauma; and
(6) no previous orthodontic or prosthodontic treatment,
maxillofacial or plastic surgery.
Class III malocclusion sample
FIGURE 2. Mandibular dental cast measurements (modified from
Sayın and Turkkahraman7).
A review of the literature revealed few studies that
evaluated transverse dimensions in Class III patients
in the permanent dentition. Therefore, the aim of this
study was to compare the transverse dimensions of
the dental arches and alveolar widths of Class III mal-
A sample of 100 subjects (42 males and 58 females)
with Class III malocclusion was selected from the patient’s record files. The criteria used to select the malocclusion sample were: (1) bilateral Class III molar relationship in centric occlusion with the cusp tip of the
maxillary second premolar within the range of one mm
(anterior or posterior) from the buccal groove of the
mandibular first molar, (2) Class III permanent canine
relationship with excessive negative overjet, (3) all
teeth present except third molars, (4) no significant
medical history, (5) no history of trauma, and (6) no
previous orthodontic or prosthodontic treatment, maxillofacial or plastic surgery.
Twelve width measurements were performed on the
dental casts of each subject.13 The arch width measurements were recorded from each subject’s dental
casts by one examiner, using a dial caliper and re-
TABLE 1. The Distribution of Age in Different Malocclusion Groupsa
n
Mean Age (y) SD (y)
Normal occlusion
150
21.6
2.6
Class III malocclusion
100
15.4
2.2
a
Sex
n
Male
Female
Male
Female
72
78
42
58
n indicates sample size; SD, standard deviation; Min, minimum; and Max, maximum.
Angle Orthodontist, Vol 75, No 5, 2005
Mean Age (y) SD (y)
22.1
21.1
13.5
16.3
3.1
2.1
2.9
1.8
Min (y)
Max (y)
18.1
18.0
12.9
16.1
35.1
30.0
18.8
20.0
811
ARCH WIDTHS IN CLASS III MALOCCLUSION
TABLE 2. Maxillary and Mandibular Dental and Alveolar Width Measurements Used in the Study
1 Maxillary intercanine width (UC-C): the distance between the cusp tips of the right and left canines or the center of the wear facets in
cases of attrition.
2. Maxillary interpremolar width (UP-P): the distance between the cusp tips of the right and left first premolars.
3. Maxillary intermolar width (UM-M): the distance between the mesiobuccal cusp tips of the right and left first molars.
4. Mandibular intercanine width (LC-C): the distance between the cusp tips of the right and left mandibular canines.
5. Mandibular interpremolar width (LP-P): the distance between the cusp tips of the right and left mandibular first premolars.
6. Mandibular intermolar width (LM-M): between the most gingival extensions of the buccal grooves on the first molars or, when the
grooves had no distinct terminus on the buccal surface, between points on the grooves located at the middle of the buccal surfaces.
7. Maxillary canine alveolar width (UAC-C): the distance between two points at the mucogingival junctions above the cusp tips of the maxillary right and left canines.
8. Maxillary premolar alveolar width (UAP-P): the distance between two points at the mucogingival junctions above the interdental contact
point of the maxillary first and second premolars.
9. Maxillary molar alveolar width (UAM-M): the distance between two points at the mucogingival junctions above the mesiobuccal cusp tips
of the maxillary first molars
10. Mandibular canine alveolar width (LAC-C): the projection of UAC-C point in the lower jaw
11. Mandibular premolar alveolar width (LAP-P): the projection of UAP-P point in the lower jaw
12. Mandibular molar alveolar width (LAM-M): the projection of UAM-M point in the lower jaw
TABLE 3. Error of the Method
Transverse
Measurement
Dahlberg’s
Calculation
Reliability
Coefficient
UC-C
UP-P
UM-M
LC-C
LP-P
LM-M
UAC-C
UAP-P
UAM-M
LAC-C
LAP-P
LAM-M
0.910
0.913
0.589
0.750
0.911
0.674
0.789
0.590
0.502
0.475
0.427
0.561
0.956
0.983
0.923
0.945
0.985
0.934
0.919
0.918
0.913
0.951
0.916
0.949
cording the data to the nearest 0.1 mm. These dental
and alveolar arch width measurements are shown in
Table 2, and Figure 1 and 2.
Three weeks after the first measurements, 20 dental
casts were selected randomly and remeasured. A
paired samples t-test was applied to the measurements. The difference between the first and second
measurements was insignificant. Correlation analysis
yielded the highest r value, .985, for LP-P and the lowest r value, .913, for UAM-M measurements. The
method error was calculated using Dahlberg’s formula.
Values changed from 0.427 mm to 0.913 mm and
were within acceptable limits (Table 3).
Independent samples t-test was applied for comparison of the groups. All statistical analyses were performed using the SPSS software package (Statistical
Package for Social Sciences for Windows, version
10.1, SPSS Inc, Chicago, Ill).
RESULTS
Descriptive statistics (mean, standard deviation, and
minimum and maximum) and statistical comparisons
of dental and alveolar width measurements for dental
casts in two groups (normal occlusion and Class III
malocclusion) are shown in Table 4. According to independent samples t-test, statistically significant differences were found in maxillary and mandibular dental arch and alveolar width dimensions between Class
III malocclusion and normal occlusion samples. Thus,
the null hypothesis was rejected.
Statistical comparisons of the two groups showed
no significant differences in maxillary intercanine (UCC), maxillary premolar alveolar width (UAP-P) and
mandibular molar alveolar width (LAM-M) measurements (P . .05).
Statistically significant differences were found in
nine of the 12 measurements. The mandibular intercanine and intermolar alveolar widths were significantly larger in the Class III group when compared
with the normal occlusion sample (P , .001). Maxillary
interpremolar, intermolar widths and all maxillary alveolar width measurements were significantly narrower in the Class III group (P , .001). The lower canine
and premolar alveolar (P , .001) width measurements
were also significantly larger in the normal occlusion
group when compared with the Class III malocclusion
group (P , .001) (Table 4).
DISCUSSION
Information regarding maxillary arch dimensions in
human populations is important to clinicians in orthodontics, prosthodontics, and oral surgery. It also is of
interest to anthropologists and other students of human oral biology.16 A survey of arch size could help
the clinician in choosing correctly shaped stock impression trays for prosthodontic treatment. In addition
to the selection of stock trays, the sizes of artificial
teeth and the overall form of the artificial dental arch
Angle Orthodontist, Vol 75, No 5, 2005
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UYSAL, USUMEZ, MEMILI, SARI
TABLE 4. Descriptive Statistics and Statistical Comparisons of Dental and Alveolar Widths of Normal Occlusion and Class III Malocclusion
Samplesa
Normal Occlusion
UC-C
UP-P
UM-M
LC-C
LP-P
LM-M
UAC-C
UAP-P
UAM-M
LAC-C
LAP-P
LAM-M
Class III Malocclusion
Mean
SD
Min
Max
Mean
SD
Min
Max
Normal Occlusion
vs Class IIIb
34.4
42.1
50.7
25.9
34.6
45.7
38.6
49.8
58.1
35.7
48.5
58.0
2.1
2.5
3.7
1.7
1.9
2.8
2.4
2.6
5.3
2.3
2.7
2.8
29.8
34.5
45.2
20.7
29.4
38.3
33.4
41.5
56.0
29.5
41.2
50.1
40.3
52.8
59.4
33.1
40.3
51.8
45.3
58.1
67.5
41.5
54.5
64.4
33.8
40.6
50.3
27.7
34.9
48.4
35.7
44.5
56.4
32.3
45.8
58.0
2.6
3.4
4.1
2.0
2.7
2.8
2.5
3.2
4.1
2.1
2.4
2.8
27.8
32.0
33.3
23.5
28.8
42.2
29.0
34.0
44.2
27.0
35.0
49.9
40.5
51.5
63.2
33.1
42.5
57.8
41.5
53.0
69.3
39.6
48.0
65.5
NS
***
***
***
NS
***
***
***
***
***
***
NS
SD indicates standard deviation; Min, minimum; Max, maximum; NS, not significant.
Statistical significance as per independent samples t-test.
*** P , .001.
a
b
at the wax trial stage are amenable to modification by
the dental surgeon in orthodontic treatment.14
This study was carried out to compare the dental
arch and alveolar base widths of Class III malocclusion
groups with the untreated normal occlusion sample.
Width measurements described in this article will help
clinicians diagnose and plan the treatment of patients
with Class III malocclusions.
Because of the scarcity of Class III patients in the
general population, a larger sample size in this study
might have increased its power. Increasing the sample
size would lead to a greater probability of establishing
statistical significance for the observed trends in all
dental and alveolar width measurements. Investigators
who have studied transverse arch changes in subjects
have reported that molar and canine arch widths did
not change after 13 years of age in females and 16
years of age in males.17–20 The minimum ages of the
subjects measured in this study were chosen on the
basis of these previous studies. Therefore, we assumed that the arch widths of the subjects studied
were fully developed.
Clinicians have speculated that nasal obstruction,
finger habits, tongue thrusting, low tongue position,
and abnormal swallowing and sucking behavior were
reasons for narrower maxillary dental arch widths in
malocclusion patients compared with normal occlusion
sample. Braun et al14 investigated the form of the human dental arch using 40 sets of pretreatment orthodontic models of patients and found that Class III maxillary dental arch widths are an average of 5.1 mm
greater than the arch widths of Class I widths and this
begins in the lateral incisor–canine area and proceeds
distally. They explained this surprising result by frequently referring to the anteroposterior skeletal discrepancy and the fact that the mandibular arch is adAngle Orthodontist, Vol 75, No 5, 2005
vanced relative to the maxillary arch. In contrast, in
this study the maxillary interpremolar, intermolar
widths and all maxillary alveolar width measurements
were found to be significantly narrower in the Class III
group than in the normal occlusion sample. When the
corresponding interarch widths were matched correctly, the maxillary arch widths were usually narrower
than the mandible arch widths.
Lingually positioned maxillary posterior crossbites
are often seen in the Class III malocclusion. One could
speculate that during eruption in Class III subjects, the
maxillary posterior teeth compensate for the buccal relationships (that result from the anteroposterior displacement of the jaws) by palatal movement to avoid
inappropriate contacts with the lower teeth. Besides, it
was widely believed that a wide and big mandible obstructed growth and development of the maxillary dental and alveolar arches. Braun et al14 found that the
mandibular dental arch widths associated with Class
III occlusions are, on an average, 2.1 mm wider than
the Class I mandibular arches beginning in the premolar area.
In this study, the mandibular dental arches associated with Class III occlusions were wider than the normal occlusion sample. This begins in the canine area
and proceeds distally. A possible explanation for the
increased arch width associated with Class III dental
arches is that the sum of all the mesiodistal widths of
the dental units around an arch represents a specific
dimension. Sperry et al21 showed that the Class III
group with mandibular prognathism more commonly
had mandibular tooth size excess for the overall ratio
than the Class I and Class II groups. Similarly, Lavelle22 and Nie and Lin23 showed that Class III cases
are characterized by smaller maxillary tooth dimensions and bigger lower teeth. Hnat et al24 also reported
813
ARCH WIDTHS IN CLASS III MALOCCLUSION
that, when the mandibular tooth size is increased,
mandibular arch length and arch width increase occurs, and this suggestion supports our results.
The findings of this study indicated that almost all
the upper dental and alveolar width measurements
were narrower in patients with Class III malocclusion
when compared with the normal occlusion sample. In
addition, the mandibular dental width measurements
were larger in the Class III group. Subjects with Class
III malocclusion tend to have the maxillary teeth inclined to the lingual and mandibular teeth inclined to
the buccal direction because of the restriction of maxillary growth and development. Therefore, rapid maxillary expansion may be considered before or during
the treatment of a Class III patient.
CONCLUSIONS
• Maxillary interpremolar, intermolar widths and all
maxillary alveolar width measurements were significantly narrower in the Class III group.
• The mandibular intercanine and intermolar alveolar
widths were significantly larger in the Class III group.
• The lower canine and premolar alveolar width measurements were statistically significantly larger in the
normal occlusion group when compared with the
Class III malocclusion group.
8.
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