Evaluation of validity of Tanaka‑Johnston analysis in Mumbai school

children
Chaitali Umesh Hambire, Sunanda Sujan1

Abstract
Introduction: Estimation of the mesiodistal dimensions of the unerupted canines and premolars in the early mixed dentition
is a necessary diagnostic aid in space management. Tanaka‑Johnston analysis was developed for North American children.
Anthropological study reveals that tooth size varies among different ethnicities. The present study was performed to evaluate
the validity of Tanaka‑Johnston method of mixed dentition arch analysis in Mumbai school children. Aims: (1) To determine the
correlation between the sum of the mesiodistal widths of the permanent mandibular incisors and combined mesiodistal widths
of the permanent mandibular and maxillary canines and premolar in Mumbai school children. (2) To examine the applicability of
Tanaka‑Johnston method of prediction. Materials and Methods: Dental casts of maxillary and mandibular arches of 300 children,
147 boys and 153 girls within the age group of 12–15 years, with permanent dentitions were fabricated. The mesiodistal crown
dimensions of teeth were measured with a dial caliper. Tanaka‑Johnston method of mixed dentition arch analysis was performed
for the study population, and statistical analysis was done. Statistical Analysis Used: Descriptive statistics including the mean,
standard deviation, range, and standard error were calculated and tabulated. Results: Tanaka‑Johnston’s equation when applied to
the data available for Mumbai school children, it was observed that it slightly overestimates the tooth size. Conclusions: (1) There
was a positive correlation between the width of mandibular incisors and mandibular and maxillary canines and premolars. (2) The
Tanaka‑Johnston prediction method was not accurate for a sample of Mumbai school children.

Keywords: Mesiodistal widths, mixed dentition analysis, Tanaka‑Johnston analysis

Introduction or (3) a combination of both methods. [7‑9] Of all the

mixed‑dentition analysis, the regression equations based
Mixed dentition arch analysis is an important criterion in on already erupted permanent teeth are used most widely,
determining whether the orthodontic treatment plan is going especially the Moyers probability charts and Tanaka‑Johnston
to involve serial extraction, guidance of eruption, space equations.[10]
maintenance, space regaining, or just periodic observation
of the patient. The determination of tooth size‑arch length A simplified analysis proposed by Tanaka and Johnston[3] comes
discrepancy in the mixed dentition requires an accurate handy for chair side evaluation. Original Tanaka‑Johnston
prediction of the mesiodistal width of the unerupted analysis was done on a population of North European
permanent teeth.[1] descent.[11] Thus, the accuracy of these predictive methods
is questionable when applied to the Indian population.
Space analysis in mixed dentition can be grouped into three The objective this study was to evaluate the validity of
categories: (1) Use regression equations,[2,3] (2) radiographs,[2,4‑6] Tanaka‑Johnston method in predicting the size of unerupted
permanent canines and premolars in children of Mumbai.
Departments of Pedodontics and Preventive Dentistry, SMBT
Dental College, Sangamner, Maharashtra, 1Ex-Associate Professor The present study, therefore, was conducted in Department of
of Nair Hospital Dental College, Mumbai, Maharashtra, India Paediatric and Preventive Dentistry, Nair Hospital and Dental
College with following aims and objectives:
Correspondence: Dr. Chaitali Umesh Hambire, • To determine the correlation between the sum of the
17, Shreekunj, Samadhan Colony, Behind Sessions Court, mesiodistal widths of the permanent mandibular incisors
Aurangabad, Maharashtra, India. and combined mesiodistal widths of the permanent
E‑mail: umeshvhambire@gmail.com mandibular and maxillary canines and premolar in
Mumbai school children
Access this article online • To examine the applicability of Tanaka‑Johnston method
Quick Response Code: of prediction.
Website:
www.contempclindent.org
Materials and Methods

DOI: The study was carried out in Department of Pedodontics

10.4103/0976-237X.161878 and Preventive Dentistry of Nair Hospital and Dental
College, Mumbai. The sample for the study consisted of
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 Hambire and Sujan: Validity of Tanaka Johnston analysis

300 children (147 boys and 153 girls) each within the age Statistical analysis
group of 12–15, studying in four Municipal Secondary Descriptive statistics including the mean, standard deviation,
Schools, Mumbai. Schools selected for the study were: and minimum and maximum values, range, and standard error
West Byculla Municipal School, Shanti Nagar Municipal were calculated and tabulated.
School, Agripada Municipal School, East Byculla Municipal
School. Results

Inclusion criteria Means, standard deviations, range, and standard error of the
• Children with complete eruption of permanent means for the sum of four lower mandibular incisors, sum of
mandibular incisors and permanent mandibular and the lower canine and premolars, and the sum of the maxillary
maxillary canines and premolars canine and premolars for the male, female, and combined
• Children with a maximum age of 15 years to preclude were tabulated.
any discrepancies based on significant proximal wear.
Comparisons of tooth size between the right and left sides
Exclusion criteria No significant difference was found between the mesiodistal
• Teeth with clinical evidence of hypoplasia or diameter of the permanent canine and first and second
hypocalcification premolars of the right and left sides. P value ranged from
• Teeth with proximal caries, proximal wear restoration, P = 0.675–0.786 showing a greater amount of similarity in
or fractures size of both sides [Tables 1 and 2].
• The subject with history of orthodontic therapy
• Presence of dental anomalies Male and female comparisons
• The presence of cross bite relationship, reverse curve of The mesiodistal width of teeth in males was significantly
spee, attrition, or other abnormality. larger than that of female [Tables 1 and 2].

Cast preparation Differences between the actual and predicted tooth size
Alginate impressions were made using standard procedures Tables 3 and 4 show statistically significant differences
for material mixing as recommended by the manufacturer. observed between the measured values of children from
The impressions were rinsed in running water and were schools of Mumbai and the Tanaka‑Johnston prediction values
disinfected with 2% glutaraldehyde. The impressions were for the mandibular and maxillary arches for males and females.
poured on the same day with a hard dental stone using the
standard procedure for mixing. The dental casts were neither A good correlation between the actual and predicted values
soaped nor waxed. was found with greater deviation from the actual values in
a mandibular arch in females [Table 4]. This being caused
Measurement of teeth by the fact that Tanaka‑Johnston analysis over‑predicts the
The teeth were measured using a dial caliper accurate to combined tooth sizes and that the teeth are smaller in females
0.05 mm (Mitutoyo Corporation, Tokyo, Japan) shown in as compared to males. The mean difference between actual
Figure 1. The largest distance between the contact points of and predicted combined widths of canines and premolars was
the four mandibular incisors and the maxillary and mandibular found to be 0.6 mm in maxilla and 0.7 mm in mandible in
canines and premolars was measured with the dial caliper males, 1.1 mm in maxilla, and 2.4 mm in mandible in females.
held parallel to the occlusal plane and perpendicular to the
long axis of the tooth. Inter‑ and intra‑examiner variability Graphs 1 and 2 show the scatter diagram of comparison
was also calculated, and it was observed that correlation for between actual and predicted values of combined widths of
inter‑examiner variation was 0.95, and for intra‑examiner, canines and premolars in male and female subjects
the correlation was 0.98.
Discussion

Prediction of the mesiodistal dimensions of unerupted

permanent canines and premolars during the mixed dentition
is of clinical importance in diagnosis and planning treatment.
Accurate estimation of the size of the canines and premolars
allows the dentist to better manage tooth size/arch length
discrepancies. However, great care must be taken to avoid
letting numbers dictate the prediction of tooth size because
dental arch perimeter may change with time. In addition, it is
obvious that the best predictor tooth is the erupted antimere in
Figure 1: Dial caliper
the same patient, and the best estimate is from radiographs.[12]

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 Hambire and Sujan: Validity of Tanaka Johnston analysis

Table 1: Mesiodistal width of mandibular and maxillary teeth of males (in mm)
Right Left Canine 1st premolar 2nd premolar
Central incisor Lateral incisor Central incisor Lateral incisor Right Left Right Left Right Left
Mandibular teeth
Maximum 7.3 7.6 7.3 7.6 9.0 9.0 8.7 8.7 8.5 8.5
Minimum 5.0 5.5 5.0 5.5 6.7 6.7 6.9 6.9 6.7 6.7
Range 2.3 2.1 2.3 2.3 2.3 2.3 1.8 1.8 1.8 1.8
Maxillary teeth
Maximum 11.0 11.0 9.7 9.7 9.2 9.2
Minimum 7.5 7.5 6.5 6.5 6.8 6.8
Range 3.5 3.5 3.2 3.2 2.4 2.4

Table 2: Mesiodistal width of mandibular and maxillary teeth of females (in mm)
Right Left Canine 1st premolar 2nd premolar
Central incisor Lateral incisor Central incisor Lateral incisor Right Left Right Left Right Left
Mandibular teeth
Maximum 6.4 7.0 6.4 7.0 8.3 8.3 8.7 8.7 8.4 8.4
Minimum 5.0 5.5 5.5 5.5 6.7 6.7 6.9 6.9 6.7 6.7
Range 1.4 1.5 1.4 1.5 1.6 1.6 1.8 1.8 1.7 1.7
Maxillary teeth
Maximum 10.0 10.0 8.7 8.7 8.0 8.0
Minimum 7.2 7.2 6.5 6.5 6.0 6.0
Range 2.8 2.8 2.2 2.2 2.0 2.0

Table 3: Actual sum of mesiodistal width of teeth groups being caries, attrition, measuring methods of the mesiodistal
Tooth group Sex Sum of mesiodistal width (mm) tooth size which includes method of cast preparation, material
Mandibular incisors Male 26.8
used for cast preparation, instrument used for measurement
of tooth size, and method of analysis of error.
Female 25.7
Maxillary canine, Male 25.2
Tanaka‑Johnston analysis for predicting mesiodistal diameters
1st and 2nd premolar Female 22.7 of canines and premolars was based on Northern European
Mandibular canine, Male 24.4 children; the present study was performed to assess the test’s
1st and 2nd premolar Female 20.2 precision among Mumbai school children.[13] The literature
review showed that of all the three methods applied in mixed
Table 4: Comparison between actual and predicted values
dentition analysis, Tanaka‑Johnston’s is widely used.[14] Young
of combined widths of canines and premolars in male age group (12–15 years) was chosen for measurement to
and female subjects minimize the alteration of the mesiodistal tooth dimensions
Tooth group Sex Sum of mesiodistal width (mm)
because of attrition, restoration, or caries.
Predicted width for Male 24.8
Deciduous teeth are not used as predictors of the breadths
maxillary arch Female 21.6 of unerupted premolars and permanent canines because the
Actual width for Male 25.2 relation between the breath of deciduous teeth and permanent
maxillary arch Female 22.7 teeth is weaker than that between the breaths of permanent
Predicted width for Male 23.7 teeth.[7] Furthermore, one or more of the deciduous teeth is
mandibular arch Female 22.6 often missing because of premature extraction or exfoliation.
Most of the previous studies used mandibular incisors in their
Actual width for Male 24.4
mandibular arch mixed analysis.[2,3,15,16] Multiple advantages of using mandibular
Female 20.2
incisors in the mixed dentition analysis including early
eruption, ease of measurement, least prone to caries, and fewer
Factors that affect tooth size are extrinsic as well as intrinsic. The anomalies have been reported.[17,18] The maxillary incisors were
intrinsic factors being heredity, race, sex. The extrinsic factors not used in any predictive procedures because they show too

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 Hambire and Sujan: Validity of Tanaka Johnston analysis

Conclusion

• The mesiodistal width of teeth in males was significantly

larger than that of female
• There was a positive correlation between the combined
mesiodistal width of mandibular incisors and mandibular
and maxillary canines and premolars
• The Tanaka‑Johnston prediction method was not accurate
for a sample of Mumbai School children.

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largest sex difference was in the canines in both dentitions.[13,17,19] of Tanaka-Johnston analysis in Mumbai school children. Contemp Clin
Analysis of our data collected also revealed that on average, Dent 2015;6:337-40.

males had larger tooth size than females. Source of Support: Nil. Conflict of Interest: None declared.

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