bolton discrepancies among different classes of malocclusion in

Original Article
BOLTON DISCREPANCIES AMONG DIFFERENT CLASSES OF
MALOCCLUSION IN PESHAWAR POPULATION
1
MUHAMMAD TAYYAB, BDS, Diploma in Orthodontics, Fellowship in Laser Dentistry
2
SONIA ZAKIR, BDS
3
UMAR HUSSAIN, BDS
4
RUQQAYA JEHAN, BDS
5
ZARQA NASRULLAH, BDS
ABSTRACT
For proper alignment and good interdigitation at the end of orthodontic treatment, the tooth size
should be in harmony in both dental arches to achieve normal overjet and overbite. Bolton’s analysis
should be taken into consideration when diagnosing, treatment planning and predicting prognosis
in clinical orthodontics. Many other methods have been devised to estimate tooth size discrepancy
but Bolton’s analysis is still widely used in clinical practice. A sample of 90 patients with age ranging from 13 to 30 years were included in the study. The greatest mesiodistal width of each tooth in
maxillary and mandibular arches (except for second and third molar) was measured using manual
vernier caliper. Each tooth was measured twice from right first permanent molar to left fist permanent
molar in each arch. The readings were then used to compute the anterior and overall Bolton’s ratios
for each patient. The mean age was 20.75±2.9. Female to male ratio was 1.17:1. No statistical significant differences were present among different malocclusion groups with P-value of 0.38 for anterior
ratio and for 0.122 overall ratio. There were no significant difference among males and females with
P-value of 0.361 for anterior ratio and 0.592 for overall ratio.
Key Words: Orthodontic treatment, overjet, overbite, Bolton’s analysis.
INTRODUCTION
For proper alignment and good interdigitation
at the end of orthodontic treatment, the teeth sizes
should be in harmony in both dental arches.1 Specific
dimension relationship must exist between maxillary
and mandibular teeth to ensure proper interdigitation,
overjet, and overbite.2 Discrepancy in tooth size should
be known early during the initial diagnosis and treatment stages if perfect results in orthodontics finishing
are to be obtained. Although natural teeth match very
well in most individuals, approximately 5% population
has some degree of tooth size discrepancy (TSD).3
Variations in the size of teeth could lead to malocclusion.4 Different means and tables were developed for
mesiodistal dimensions of teeth by G.V Black’s study,
and were further modified by different authors.5-8
Senior Clinical Lecturer Orthodontics, Khyber College of Dentistry,
Peshawar University Campus Address: Khalily House No. 70 Street
No. 1 Sector N/4 Phase 4, Hayatabad, Peshawar
Email: dr_tayyabk@yahoo.com, Cell: 0333-9105746
2
MCPS Trainee Periodontics
3
FCPS-II Trainee Orthodontics
4
MCPS Trainee Periodontics
5
MCPS Trainee Orthodontics
Received for Publication:
September 22, 2014
Revision Received:
October 14, 2014
Revision Accepted:
October 17, 2014
1
Pakistan Oral & Dental Journal Vol 34, No. 4 (December 2014)
Few studies in literature have correlated malocclusion with tooth size discrepancy.9 In some studies no
significant difference in incidence of tooth size discrepancies for overall and anterior ratio has found.10,11 But
in Brazilian population angle class I and III malocclusion subjects showed greater prevalence of tooth size
discrepancy than angle class II malocclusion subjects.12
Some studies has shown greater incidence of TSD in
angle class III malocclusion followed by class I and then
class II.13,14 Ta et al15 reported that Bolton standard is
applicable to class I occlusion in Chinese children but
not to class II or class III.
Specific ratios of mesiodistal widths must exist
between maxillary and mandibular teeth to obtain
optimum occlusion.16 The variations greater than 2
SD of the normal ratios is considered clinically significant.17,18 Nef7 developed a ratio between sum of
mesiodistal widths of maxillary and mandibular teeth.
A ratio of 1.20 to 1.22 was considered normal. Many
other methods have been devised to estimate tooth
size discrepancy but Bolton’s analysis is still widely
used.19-21 Bolton’s analysis should be taken into consideration when diagnosing, treatment planning and
predicting prognosis in clinical orthodontics.22 The
647
Bolton discrepancies among different classes of malocclusion
objective of this study was to determine the Bolton’s
discrepancy among different groups of malocclusion.
METHODOLOGY
In this cross-sectional study, a sample size of 90
patients, age ranged from 13 to 30 years were analyzed
prior to orthodontic treatment. Subjects were selected
randomly from patients reported at Orthodontic department of Khyber College of Dentistry, Peshawar. The
inclusion criterion was; (1) Study cast casts which are
of good quality. (2) All the permanent teeth to be fully
erupted except for the third molars. (3) No mesiodistal
and occlusal abrasions. (4) No proximal caries or proximal fillings. (5) No crown and bridge restorations. (6)
No supernumerary teeth or dental malformations. (7)
No history of previous orthodontic treatment.
The sample was divided into three groups: Group
1 with angle class I malocclusion (n=30), Group 2 with
angle class II malocclusion (n=30) and Group 3 with
angle class III malocclusion (n=30).
A thorough examination of all the study casts was
done. The greatest mesiodistal width of each tooth in
maxillary and mandibular arches (except for second
and third molar) was measured using manual vernier
caliper. Each tooth was measured twice from right first
permanent molar to left fist permanent molar in each
arch.23 An average of 10 casts were measured per day
to prevent visual fatigue.24 The readings were then
used to compute the anterior and overall Bolton’s ratio
using the following formulas; According to Bolton, the
overall ratio is calculated by the following formula:
RESULTS
The mean age was 20.75±2.9. Female to male ratio
was 1.17:1. No statistical significant differences were
present among different malocclusion groups. Table 1
shows the means, standard deviations, standard errors,
minimum, maximum, F-value and p-value of overall
and anterior ratios observed among the different malocclusion groups. (P-value 0.380 and 0.122 for anterior
and overall ratios respectively).
There were no significant difference among males
and females. Student t-test was performed to determine
sexual dimorphism. Table 2 summarizes the means,
standard deviations, and standard errors, minimum,
maximum, F-value and p-value of overall and anterior
ratios observed between male and female genders.
DISCUSSION
An ideal functional occlusion with adequate overjet
and overbite requires among other factors, an adequate size ratio between upper and lower teeth. The
importance of tooth size discrepancies in orthodontic
diagnosis and treatment planning has been the subject of various discussions in orthodontic literature
and accepted by orthodontic community because the
TABLE 1: ANOVA OF ANTERIOR AND OVERALL
BOLTON RATIO AMONG DIFFERENT
MALOCCLUSION GROUPS
Class
Sum of 12 lower teeth
----------------------------------X 100 = Overall Ratio
Sum of 12 upper teeth
while, the anterior ratio is calculated by:
Pakistan Oral & Dental Journal Vol 34, No. 4 (December 2014)
Overall ratio
Mean
80.4
93.1
Std.dev
3.98
3.08
Std.error
0.728
.56
Minimum
72.50
87.00
Maximum
99.7
90.0
Class II
Mean
78.9
91.76
Std.dev
5.39
3.39
Std.error
0.96
0.60
Minimum
71.40
83.00
Maximum
90.90
98.60
79.24
91.63
Std.dev
4.00
3.12
Std. error
0.74
0.57
Minimum
69.0
85.0
Maximum
87.70
96.60
P-value
0.380
0.122
F-value
0.979
2.153
Sum of 6 lower teeth
---------------------------------- X 100 = Anterior ratio
Sum of 6 upper teeth
The data were analyzed by SPSS version 16.0.
Kolmogrov-smirnov test was applied to see whether the
sample was normally distributed or not. The test indicated that the data are normally distributed. Therefore,
parametric tests were used. To statistically compare
the anterior and overall ratios among the different
malocclusion groups, analysis of variance (ANOVA)
was applied. Statistical difference was found at p<0.05
and 95% confident interval. For gender differences
independent student t-test was performed.
Anterior
Class III Mean
Significant level= <0.05
648
Bolton discrepancies among different classes of malocclusion
TABLE 2: STUDENT T-TEST OF ANTERIOR AND OVERALL BETWEEN GENDERS
Anterior ratio
Overall ratio
Gender
N
Mean
Std. Deviation
Std. Error
F-value
P-value
Male
41
78.7902
3.94055
.61541
0.844
0.361S
Female
48
80.3896
4.69238
.67729
Male
41
91.91
3.46
0.541
0.289
0.592
Female
48
92.41
3.07
0.44
relationship between upper and lower teeth is related
to orthodontic finishing excellence.19,25 In this study,
Bolton’s anterior and overall ratio in three different
classes of malocclusion were studied.
by Ivan Ricci et al34 consisting of 105 individuals of age
range 13-17 years in Brazilian population showed no
significant difference between genders for both anterior
and overall ratio in different classes of malocclusion.
In present study, the statistical analysis of Bolton’s
anterior and overall ratio calculated in three different
classes of malocclusion showed no significant differences. This finding is in agreement with earlier studies done
by other researchers.26,27 No correlation between angle’s
classification of malocclusion and Bolton’s discrepancy
was shown by Crosby and Alexander. They studied 109
pretreatment casts of orthodontic patients of class I,
class II Div. 1 and class II Div. 2 malocclusion.18
Bernabe et al24 demonstrated sexual dimorphism,
which is in disagreement with the present study result. Overall ratio between male and female samples
was significantly different, but anterior ratio between
males and females was not different. Similarly a study
in Nigerian population reported that overall ratio and
anterior ratio were higher in females than males.29
Fahad et al9 analyzed sample size of 160 pretreatment casts of orthodontic patients and concluded that
there is no statistically significant difference between
these groups. Also Laino et al28 speculated after their
study on different malocclusion groups that there is no
evidence of any predisposition for tooth size discrepancy
in any of malocclusion groups.
1
Bolton WA. Disharmony in tooth size and its relation to analysis
and treatment of malocclusion. Angle Orthod 1958; 28: 113-30.
2
Othman SA, Harridine NWD. Tooth size discrepancies and
Bolton’s ratio, A literature review. J Orthod 2006; 33: 45-51.
3
Profitt WR, Fields HW, Sanier DM. Contemporary Orthodontics.
5th edition. Elsevier; 2012; 181-5.
4
Lombardi VA. The adaptive value of dental crowding. A consideration of biologic basis of malocclusion. Am J Orthod 1982;
81: 38-42.
5
Black GV. Descriptive anatomy of human teeth. 4th edition.
SS white Philadelphia, 1902; 123-34.
6
Ballard ML. Asymmetry in tooth sizes, a factor in etiology,
diagnosis and treatment of malocclusion. Angle Orthod 1944;
14: 67-71.
7
Neff CW. Tailored occlusion with the anterior co-efficient. Am
J Orthod 1949; 35: 309-14.
8
Steadmann SR. The relationship of upper anterior teeth to lower
present on plaster models of a group of acceptable occlusion.
Angle Orthod 1952; 21: 91-7.
9
Fahad FH. sulaimani A, Afify AR. Bolton analysis in different
classes of malocclusion in Saudi Arabian sample. Egypt Dent
J 2006; 52:119-25.
10
Hashim HA. Bolton tooth size ratio among different malocclusion
groups, a pilot study. J Pak Dent Assoc 2002; 2: 81-86.
11
Afzal A , Ahmad A, Vohra F, Uzair M. Bolton tooth size discrepancies among different malocclusion groups. J Pak Dent
Assoc 2005, 10 (1): 670-75.
In conflict with the current results, Batool et al29
found significantly higher mean anterior ratio for
class II group than class I and class III groups. They
selected cross sectional data from study casts of 135
patients reported to Armed Forces Institute of Dentistry,
Rawalpindi. All other ratios were within close range of
Bolton’s norms. Also Oeyemi et al30 collected data of 372
school children, aged between 12-16 years and reported
that significant difference exist between Bolton’s mean
tooth size ratio and of different malocclusion groups.
This study demonstrated that there was no gender
difference in both anterior and overall ratio Bolton’s
ratio, a finding which is in agreement with other studies.1,31 Arya et al32 speculated mean size of each tooth
for different groups i.e., class I and class II boys and
girls in their study. Difference for individual between
different arches was not analysed. Basaran et al33 failed
to show any gender dimorphism or statistically significant difference of Bolton’s tooth size discrepancy among
different malocclusion groups. The study was conducted
in Turkish population. The sample size consisted of 60
normal occlusion group and 300 patients divided into
various malocclusion groups. Another study carried out
Pakistan Oral & Dental Journal Vol 34, No. 4 (December 2014)
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