Comparison Of Measured And Predicted Mesiodistal Tooth-widths Of 13-17 Year Old Kenyans
Abstract
Background: Odontometric measurements are important in the determination of the
space discrepancies in the dental arches. In clinical orthodontics, odontometric
measurements are done to determine the arch perimeter and total tooth mass. In
permanent dentition the odontometric measurements are straightforward. However,
in the mixed dentition analysis, it is a great challenge to accurately determine the
mesiodistal tooth-widths of unerupted permanent canines and premolars. Various
methods have been proposed and used in different ethnic groups. They fall into
three main categories; radiographic method, use of regression/prediction equations
and a combination of radiographic method and regression equations. The most
widely used prediction equations are the Tanaka and Johnston equation and the
Moyers prediction tables. However, they have their shortcomings. This has
necessitated the proposal of different prediction equations for use in various ethnic
groups.
Objectives: To measure mesiodistal tooth-widths of permanent teeth in both the
upper and lower dental arches from first molar to first molar, to estimate the
mesiodistal tooth-widths of permanent canines and premolars using two prediction
equations and to compare the measured values with values obtained using the two
prediction equations.
Materials and methods: A descriptive cross-sectional study was carried out on 13-
17 year old Kenyans in two secondary schools. Maxillary and mandibular arch
impressions were made using irreversible hydrocolloid impression material and the
impressions were then poured with type III dental stone. An electronic digital vernier
calliper was used to measure the mesiodistal tooth-widths from the first molar to the
antimeric first molar for both arches. Measurements were entered on a data
collection form and later transferred to Microsoft Excel software. Statistical Package
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for Social Sciences (SPSS) version 14.0 for Windows was used for data analysis.
Paired t-tests, independent t-tests and Pearson product moment correlation tests
were used to analyse the data. Data were presented in the form of tables (Table 3.1
to 3.18) and graphs (Figures 3.1 to 3.5). The Tanaka and Johnston and Melgaço et
al prediction equations were used to estimate the mesiodistal tooth-widths of the
permanent canines and premolars and these values were compared with the
measured values.
Results: Sixty eight subjects (28 males and 40 females) of mean age 14.89 ± 1.23
years (males) and 14.65 ± 1.21 years (females) were included in this study. Intraclass
coefficient was 0.99 and it was used to assess the accuracy of measurements.
The male subjects had larger mean mesiodistal tooth-widths than female subjects.
Statistically significant differences in mean mesiodistal tooth-widths were found in
the mandibular and maxillary canines, first permanent molars and the maxillary
lateral incisors. Except for the mandibular second premolar and the maxillary first
permanent molar, the male sample showed no statistically significant differences
between antimeric teeth. There were statistically significant differences between
antimeric mandibular first and second premolars and the maxillary first permanent
molar for the female sample. There were no statistically significant differences in the
antimeric sum of mesiodistal tooth-widths of the permanent canine and premolars for
both the mandibular and maxillary arches in males. However, in females both the
mandibular and maxillary arches had statistically significant differences. Inclusion of
the two first permanent mandibular molars to the four permanent mandibular incisors
as predictor teeth gave higher correlation coefficients than the use of only four
permanent mandibular incisors. The Tanaka and Johnston equation was useful as a
prediction equation for the female maxillary arch and in the combined sample. The
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Melgaço et al equation could be used as a prediction equation in the mandibular
arch for males, females and the combined sample. There were no statistically
significant differences in the sum of mesiodistal tooth-widths of the mandibular
permanent canine and premolars between the actual and predicted values obtained
using both the Tanaka and Johnston and Melgaço et al equations. There were no
statistically significant differences in the calculated/predicted value of the sum of
mesiodistal tooth-widths of the mandibular permanent canine and premolars
obtained using the Tanaka and Johnston and Melgaço et al equations. However, the
Melgaço et al equation had a correlation coefficient of 0.693 and the Tanaka and
Johnston equation correlation coefficient was 0.465 for the sum of mesiodistal toothwidths
of the mandibular permanent canine and premolars and the predictor teeth.
Conclusion: Males had larger mean mesiodistal tooth-widths than females. The
Melgaço et al equation predicted better the sum of mesiodistal tooth-widths of the
mandibular permanent canines and premolars than the Tanaka and Johnston
equation but had lower correlation coefficients compared to the original sample from
which it was derived. However, the Melgaço et al equation overestimated the
mesiodistal tooth-widths for the female and combined samples and under-estimated
for the male sample but the differences were not clinically significant.
Recommendation: Male and female mesiodistal tooth-widths should be
calculated/estimated separately. The prediction equations formulated from this study
should be used in predicting the sum of mesiodistal tooth-widths of mandibular
permanent canines and premolars in Kenyan populations.
Citation
Master Of Dental Surgery Degree In Paediatric DentistryPublisher
University of Nairobi