ORIGINAL RESEARCH

https://doi.org/10.5005/jp-journals-10005-2926
International Journal of Clinical Pediatric Dentistry
Volume 17 | Issue 09 | Year 2024

Comparison between Tanaka–Johnston and Boston University Approach for Prediction of Mesiodistal Width of Canines and Premolars in Mixed Dentition Children: A Cross-sectional Study

Priyanka Balakrishnan¹, Daya Srinivasan², AR Senthil Eagappan³, Pragadesh Ganesan⁴, Priyadharshini Suresh Babu⁵, Nandini Sundar⁶

^1–6Department of Pedodontics, Chettinad Dental College and Research Institute, Chennai, Tamil Nadu, India

Corresponding Author: Priyanka Balakrishnan, Department of Pedodontics, Chettinad Dental College and Research Institute, Chennai, Tamil Nadu, India, Phone: +91 8838603094, e-mail: priyabalu1907@gmail.com

ABSTRACT

Introduction: Malocclusion, a common dental issue in children, necessitates early intervention to mitigate future orthodontic challenges. Predictive methodologies like Tanaka and Johnston analysis (TJA) and Boston University approach (BUA) aid in mixed and primary dentition analysis for optimal treatment planning. This study aimed to compare TJA and BUA in predicting the mesiodistal width of unerupted permanent canines and premolars and assess gender-based variations.

Materials and methods: A cross-sectional study involving 120 children (7–11 years) was conducted at Chettinad Dental College and Research Institute, Chennai, Tamil Nadu, India. Dental models were analyzed using TJA and BUA methods. The mean predicted values of permanent canines and premolars were calculated for both approaches in the upper and lower dental arches. Pearson correlation coefficients were calculated to assess the relationship between TJA and BUA predictions, and statistical significance was determined.

Results: Both TJA and BUA exhibited strong positive correlations in predicting dimensions, with slight gender-based variations. TJA predicted values for permanent canines and premolars in the upper arch were 21.13 ± 0.50 and 21.32 ± 0.39, respectively, whereas for BUA, they were 21.45 ± 0.42 and 21.67 ± 0.38, respectively. In the lower arch, TJA predicted values were 20.88 ± 0.63 for canines and premolars combined, while BUA predicted 21.02 ± 0.58. Significant differences were observed only in the upper arch predictions (p = 0.001).

Conclusion: Tanaka and Johnston analysis and BUA are valuable in mixed dentition analysis, offering insights into space availability for orthodontic treatment planning. BUA serves as a reliable substitute for TJA when fully erupted permanent incisors are absent, emphasizing the importance of tailored predictive methods in interceptive orthodontics. Model analysis remains pivotal for informed treatment decisions, ensuring optimal dental health outcomes.

Keywords: Deciduous tooth, Dental model, Interceptive orthodontics, Mixed dentition analysis, Model analysis

How to cite this article: Balakrishnan P, Srinivasan D, Senthil Eagappan AR, et al. Comparison between Tanaka–Johnston and Boston University Approach for Prediction of Mesiodistal Width of Canines and Premolars in Mixed Dentition Children: A Cross-sectional Study. Int J Clin Pediatr Dent 2024;17(9):976–980.

Source of support: Nil

Conflict of interest: None

INTRODUCTION

Malocclusion refers to the improper alignment of the teeth in the upper and lower jaws, as well as a disparity between the teeth and the supporting bone structure in the jaw. Malocclusion is multifactorial in nature and is caused by genetic factors, environmental influences during fetal development, injuries, other medical conditions, etc. Thus, finding a single cause is difficult. The World Health Organization (WHO) identifies malocclusion as the second most common oral issue in children in mixed dentition, after dental caries, highlighting its importance in interceptive orthodontics.¹ Primary dentition plays a vital role in maintaining arch length for proper eruption of permanent teeth. Indicators of good dental development include spacing, anthropoid spaces near maxillary canines and distal to mandibular canines, and straight or mesial step occlusion of primary second molars. However, early loss of primary teeth leads to unfavorable alignment of the permanent dentition. Certain malocclusion conditions can be intervened in the mixed dentition itself to reduce the burden of future orthodontics. Early orthodontic intervention, categorized as preventive or interceptive, aims to optimize dental, skeletal, and muscular development before permanent teeth eruption.²^,³ In mixed dentition analysis, a comprehensive space analysis is done to anticipate the mesiodistal width of unerupted canines and premolars. This predictive assessment serves a critical purpose in diagnosing between the available space within the dental arch and the space required for accommodating these teeth. It is pivotal for ascertaining whether there exists ample room for the posterior teeth to erupt unimpeded and assume optimal alignment. Thus, the analytical process holds profound significance in the realm of orthodontic diagnosis and treatment planning. It functions in guiding the path toward informed decisions regarding the course of treatment. Through this analysis, pedodontists can delineate whether the proposed treatment regimen necessitates interventions such as serial extractions, guidance for proper tooth eruption, reclamation of lost space, maintenance of existing space, or mere observation over a designated period. The precision with which the size of unerupted posterior teeth is forecasted is of paramount importance. It forms the base upon which a robust orthodontic treatment plan is constructed, ensuring optimal outcomes and long-term dental health.⁴^,¹¹

In the realm of mixed dentition analysis, several methodologies exist to predict the mesiodistal width of unerupted canines and premolars, using radiographic methods or regression equations, each with its strengths and limitations. Tanaka and Johnston analysis (TJA) uses regression equation for prediction. The TJA method incorporates mandibular incisor measurements to provide a more comprehensive evaluation of space availability both in the maxillary and mandibular arch. Moreover, it offers simplicity and ease of use compared to other techniques. One of its drawbacks lies in its limited applicability, as it can only be used during the mixed dentition stage after the eruption of the mandibular incisors.⁴^,¹²

Following discussions with Gianelly, a predictive methodology emerged at Boston University (BU), centring on the mesiodistal widths (MDWs) of primary mandibular canines and first molars. This innovative approach aimed to anticipate the widths of unerupted permanent mandibular teeth in their early stages of development. Termed the BU approach, it garnered recognition within the dental community. Subsequent studies were conducted to verify its efficacy, encompassing diverse populations such as those from Iowa to Iraq.¹³ More recently, this predictive model underwent adaptation and implementation within the Indian population, highlighting its adaptability and potential to enhance dental prognostic techniques.¹⁴^,¹⁵ Thus, this study aims to validate the Boston University approach (BUA) compared to TJ analysis in school children in Kelambakkam.

MATERIALS AND METHODS

Objective

To compare and correlate the values of the mesiodistal width of unerupted permanent canine, first and second premolar using (Fig. 1):

Fig. 1: Study procedure flowchart

Tanaka and Johnston analysis.
Boston University approach.

Study Design

His study was designed as an observational cross-sectional study to compare and correlate the values obtained from TJA to BUA.

Ethical Clearance

The ethical clearance for the study was obtained from the ethical clearance board (ref. no.: IHEC-I/1985/23), Chettinad Dental College and Research Institute, Chennai, Tamil Nadu, India.

Study Sample

The participants of the study included children in the 7–11 years age-group. These children reported with their parents for a routine general check-up to the Department of Pediatric and Preventive Dentistry, Chettinad Dental College and Research Institute, Chennai, Tamil Nadu, India. The sample size was calculated using G*Power software as 120 samples. After initial clinical diagnosis and screening, children were selected based on the following selection criteria.

Inclusion Criteria

Children in mixed dentition phase with the presence of primary canine, primary first and second molar without dental caries.
Children with completely erupted permanent mandibular incisors.
Children whose parents are willing to participate in the study.
Children with proper occlusion.

Exclusion Criteria

Children having interproximal caries or restorations any missing or supernumerary teeth.
History of lip or palate cleft, oral or maxillofacial trauma.
Previous history of surgery in the oral and maxillofacial region.
Children experiencing mental or cognitive challenges that may hinder their understanding or participation in the study.
Children who have medical conditions affecting their overall health and may impact their ability to take part in the study.
Children with temporomandibular joint dysfunction.
Children with previous history of orthodontic or orthopedic management.
Children with parafunctional habits like bruxism.

After the complete screening of 200 participants, 120 children were selected for the study.

All 120 children underwent medical evaluation. The parents were informed of the study procedure in the form of a participant information sheet, and written and informed consent was obtained. Upper and lower alginate impressions were made for all 120 children. The impressions were poured, and dental study models were obtained without porosities. Every cast was subjected to two types of model analysis:

Type I: Tanaka and Johnston analysis.
Type II: Boston University approach.

The mesiodistal width (MDW) of the following teeth was measured using a vernier caliper (Fig. 2).

Fig. 2: Vernier caliper measurement

Permanent mandibular central and lateral incisors.
Primary canine.
Primary first molar.

Tanaka and Johnston Analysis

In TJA, the sum of the MDW of permanent mandibular central and lateral incisors was used to predict the width of the unerupted permanent canine and premolar using the following formula for maxillary and mandibular dental arch.

MDWs of permanent maxillary canines and premolars = 11 + 0.5 (sum of MDWs of permanent mandibular incisors)
MDWs of permanent mandibular canines and premolars = 10.5 + 0.5 (sum of MDWs of permanent mandibular incisors)

Boston University Approach

The mesiodistal width of the primary mandibular canine and primary mandibular first molar was used to determine the MDW of unerupted permanent mandibular canine and premolar using the formula:

MDW of unerupted mandibular permanent canine and premolar = MDW of primary canine + 2 (MDW of primary mandibular first molar)

This was originally given for the mandibular arch by Gianelly, which was extended for the maxillary arch in the present study as follows:

MDW of unerupted maxillary permanent canine and premolar = MDW of primary maxillary canine + 2 (MDW of primary maxillary first molar)

The formula was used to calculate the MDW of unerupted permanent canine and premolar on both sides in all four quadrants, respectively.

Once the measurements were obtained for all 120 samples using both approaches, the values were noted for individual samples and tabulated. The tabulated values were statistically analyzed.

Statistical Analysis

Descriptive and Inferential statistics were analyzed by IBM Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, New York: IBM Corp). Mean and standard deviation were used to summarize quantitative data. Correlations between two variables were calculated using Pearson correlation.

RESULTS

Table 1 indicates no statistically significant difference in predicted dimensions of permanent canines and premolars between genders, both in the maxillary and mandibular arches, according to the TJA, with males tending to have slightly smaller predicted dimensions, particularly in the mandibular arch. Similarly, Table 2 shows no significant gender-based differences in predicted mean dimensions of permanent canines and premolars in the upper and lower dental arches using the BUA, as all p-values indicate no statistically significant variations between males and females.

**Table 1:** Predicted permanent canine and premolar dimensions using TJA
	Gender	N	Mean	SD	t	Mean difference	p-value
Maxillary	Male	60	21.2517	0.37986	−1.738	−0.12494	0.085
Maxillary	Female	60	21.3767	0.40016	−1.738	−0.12494	0.085
Mandibular	Male	60	21.0603	0.55754	1.456	0.15701	0.148
Mandibular	Female	60	20.9033	0.61146	1.456	0.15701	0.148

**Table 2:** Predicted permanent canine and premolar dimensions using BUA
Arch	Gender	N	Mean	SD	t	Mean difference	p-value
Boston UR	Male	60	21.1259	0.46850	0.045	0.00420	0.964
Boston UR	Female	60	21.1217	0.54340	0.045	0.00420	0.964
Boston UL	Male	60	21.1259	0.46850	0.045	0.00420	0.964
Boston UL	Female	60	21.1217	0.54340	0.045	0.00420	0.964
Boston LR	Male	60	20.9724	0.57971	1.642	0.19075	0.103
Boston LR	Female	60	20.7817	0.67635	1.642	0.19075	0.103
Boston LL	Male	60	20.9724	0.57971	1.642	0.19075	0.103
Boston LL	Female	60	20.7817	0.67635	1.642	0.19075	0.103

The Pearson correlation coefficients (Table 3) between the TJA and BUA reveal the extent of the relationship between these methods for predicting dimensions of permanent canines and premolars. For males, there were significant positive correlations observed in both the upper (UR) and lower (UL) dental arches, as well as in the combined arches (LR and LL), indicating that as the dimensions predicted by one method increase, so do the dimensions predicted by the other method. The correlation coefficients ranged from 0.59 to 0.77, with p-values indicating statistical significance at ≤0.002. Conversely, for females, there were no significant correlations observed in the upper and lower arches (UR and UL), suggesting that the predictions made by the TJA and BUA es did not consistently correspond in these specific arches. However, significant correlations were found in the combined arches (LR and LL), indicating a relationship between the methods in predicting dimensions when considering both upper and lower arches together. The correlation coefficients for females in the combined arches were 0.65, with p-values indicating statistical significance at ≤0.0001. This suggests that while there may not be consistent correlations in individual arches for females, there is a relationship between the methods when considering both arches collectively.

**Table 3:** Correlations between TJA and BUA
Gender	Correlation stats	UR	UL	LR	LL
Male	Pearson correlation	0.586^**	0.586^**	0.773^**	0.773^**
	p-value	0.002	0.002	0.0001	0.0001
	Significance	S	S	S	S
Female	Pearson correlation	0.724	0.724	0.647^**	0.647^**
	p-value	0.002	0.002	0.0001	0.0001
	Significance	S	S	S	S

**implies significance

In Table 4, the comparison between TJA and BUA revealed statistically significant differences in the mean measurements of the upper dental arch alone, with p-values of 0.001 for both arches. However, no significant differences were found in the mean measurements of the lower dental arch or when considering both arches combined, with p-values of 0.19. Therefore, while both approaches differed significantly in their predictions for the upper arch, they showed similar results for the lower arch and when considering both arches together.

**Table 4:** Difference between TJA and BUA
Side	Group	N	Mean	SD	p-value
UR	Boston	120	21.3183	0.39193	0.001
UR	Tanaka	120	21.1300	0.50453	0.001
UL	Boston	120	21.3183	0.39193	0.001
UL	Tanaka	120	21.1300	0.50453	0.001
LR	Boston	120	20.9867	0.58539	0.19
LR	Tanaka	120	20.8833	0.63290	0.19
LL	Boston	120	20.9867	0.58539	0.19
LL	Tanaka	120	20.8833	0.63290	0.19

DISCUSSION

In the mixed dentition phase, primary and permanent teeth coexist, representing a critical period for occlusion development. This phase receives close attention from pediatric dentists. A minor difference of even ±2 mm between predicted and actual width holds significance for treatment choices such as extraction or space management. Early detection of arch length-to-tooth size differences is crucial, driving researchers to develop methods for predicting unerupted permanent teeth sizes, especially canines and premolars. Accurate predictions during deciduous or mixed dentition stages empower clinicians to intervene preemptively, potentially averting malocclusion development. By closely monitoring this stage and employing predictive methods, clinicians can address dental discrepancies early on, ensuring optimal dental health outcomes for patients.¹⁶ Mixed dentition analysis can be conducted using various methods, including radiographic and non-radiographic approaches, or a combination of both utilizing cephalometric and periapical radiographs. Among the various mixed dentition analyzes like Moyer’s, Tanaka and Johnston’s, Hixon and Oldfather’s, Nance’s, Ballard and Wylie’s, Huckaba’s, and Stanley Kerber’s analysis, Tanaka and Johnston’s is a nonradiographic technique utilizing the measurements of permanent mandibular incisors.¹⁷

The TJA method is widely applied in children with mixed dentition, serving as a valuable means to gauge space irregularities. In contrast to Moyers’ method, which depends on prediction tables, TJA utilizes straightforward measurements on dental casts, making it favored for dental professionals.¹⁸ Additionally, it offers minimal systematic error, ease of use, and reliability and applies to both the upper and lower jaws. However, the TJA method has certain drawbacks as it requires the presence of fully erupted permanent mandibular incisors to predict the mesiodistal width of unerupted teeth. In the case of unerupted permanent mandibular incisors, other radiographic methods or prediction charts with less accuracy are used for space analysis. Gianelly, in his communication, established a method for the prediction of space in the primary dentition period where the mesiodistal width of the primary canine and first molar were used. Thus, the applicability of this method in the mixed dentition phase was analyzed in the present study.

The results of the study were withdrawn from 120 healthy children with a mean age of 8.5 ± 0.9 years. Our investigation meticulously examined gender variations within each predictive method and between the two methodologies employed. Gender-based disparities in predicting the dimensions of unerupted canines and premolars are frequently noted in dental studies, with male gender typically exhibiting greater mesiodistal diameters compared to females.¹⁵ However, from the present study, the male gender had slightly smaller predicted dimensions, particularly in the mandibular arch, compared to the female. Although the male gender showcased small dimensions, it was not statistically significant.

Pearson’s correlation coefficient was employed to analyze the relationship between predicted canine and premolar widths using both the TJA and BUA. The comparison of these predicted values revealed a notably strong positive correlation, ranging from 0.568 to 0.773. According to Nuvvula et al., boys displayed a weak positive correlation, which was not statistically significant, ranging from 0.17 to 0.42. On the other hand, girls exhibited a statistically significant strong positive correlation, ranging from 0.72 to 0.77 when TJA and BUA were used to predict the MDW of unerupted canine and premolar in both upper and lower arch.¹⁴ In the Iowa study, actual tooth dimensions correlated at 0.59 with those predicted using the TJA method and at 0.39 with the BUA.¹⁹ In a study conducted by Thomas and Bajaj, a positive correlation of 0.71–0.85 was reported by using both the TJA and BUA.¹⁵ Similarly, in a study involving the Iraqi population, correlations between the TJA and BUA and the original tooth dimensions were 0.17 and 0.22, respectively.¹³ Given the cross-sectional design of the current study and the examination of children in mixed dentition, a direct comparison of predicted values with the original measurements was not feasible.

The mean predicted value of canines and premolars in the upper arch was 21.13 ± 0.50 and 21.32 ± 0.39 using TJA and BUA. The predicted mean showed a statistically significant difference between both approaches (p = 0.001). This was in correlation with the studies that had been previously conducted.¹³^,¹⁵^,¹⁹ TJA predicted value was found to be less compared to BUA. This was contrary to the existing literature.¹⁵ In the lower arch the mean predicted value was 20.88 ± 0.63 and 20.99 ± 0.59 using TJA and BUA. However, these values did not show any statistical significance (p = 0.19). Hence, it can be seen that the predicted values by both approaches were similar to each other for the mandibular arch.

The opponents of BUA as a primary dentition analysis are into that opinion because the primary dentition analysis cannot predict and compensate for the future jaw growth, the positional changes of the tooth, increase in the length and width of the alveolar bone at a very early stage and it is not about the validity of the BUA per se.¹⁴^,²⁰ It’s important to note that the study’s limitation lies in its sample selection, which mainly consisted of individuals in the mixed dentition stage. Additionally, the recorded values were only predicted at a single time point, without subsequent follow-up, to assess their accuracy upon eruption of the same.

CONCLUSION

Both TJA and BUA showed strong positive correlations in predicting dimensions, and gender-based variations were observed. Males tended to have slightly smaller predicted dimensions, particularly in the mandibular arch, though not statistically significant. TJA and BUA demonstrated statistically significant differences in predicted values for the upper arch, while similar results were shown for the lower arch. These findings underscore the importance of employing accurate predictive methods tailored to individual patient needs in interceptive orthodontics. Model analysis is crucial in orthodontic treatment planning, aiding in predicting space availability for proper tooth eruption and alignment. BUA serves as a valuable alternative to TJA when fully erupted permanent incisors are not available, offering reliable predictions for unerupted permanent canines and premolars during mixed dentition.

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