Accuracy and evaluation of a new regression equation in predicting the width of unerupted permanent canines and premolar teeth

Comparison of measured and predicted mesiodistal tooth-widths of 13-17 years old Kenyans: a descriptive cross-sectional study to develop a new prediction equation for use in the mixed dentition in a Kenyan population

BACKGROUND

The Tanaka and Johnson equation is commonly used in mixed dentition analysis. However, the analysis is based on  a Caucasian population making clinical decisions challenging when used in different ethnic groups. This study developed a prediction equation based on a Kenyan population.

DESIGN

A descriptive cross-sectional study done in 68 13-17 years old Kenyans of African descent in two boarding secondary schools. Alginate impressions were taken, study models obtained, and mesiodistal tooth-widths measured on upper and lower study models from the first molar to the contralateral first molar. Descriptive statistics, paired t-tests and independent t-tests were conducted and Pearson product-moment correlation coefficients calculated (p < 0.05).

RESULTS

The mean age was 13.78 years (SD ± 0.70), females were 59%. The mesiodistal tooth-widths of the permanent canines and premolars were different between males and females (p ˂ 0.1). The Tanaka and Johnston equation significantly under-estimated the mesiodistal tooth-widths of the permanent canines and premolars (p ˂ 0.05). The addition of lower first permanent molars to the permanent lower incisors provided higher correlation coefficients than the Tanaka Johnston equation.

CONCLUSIONS

A new equation that includes the permanent lower incisors and first permanent molars as predictor teeth seems to be more suitable for mixed dentition analysis for this Kenyan population. A larger study is needed to validate these findings.

Size estimation of unerupted canines and premolars using various independent variables: a systematic review

INTRODUCTION

Prediction of unerupted permanent teeth is an essential part of orthodontic diagnosis and treatment planning. This prediction is done by mixed dentition space analysis based on the estimation of mesiodistal dimensions of unerupted permanent canine and premolars from already erupted permanent teeth. Permanent mandibular incisors are most commonly used for prediction. Recent literature reveals that mandibular incisors are not accurate predictors and other independent variables have been introduced to make a more accurate and precise prediction. The objective of this paper was to evaluate the literature in light of a variety of independent variables and their predictive accuracy.

METHODS

Electronic databases such as MEDLINE, PubMed, Scopus, Embase, Web of Science, CINAHL Plus were searched to identify articles published until September 2021.

RESULTS

The search resulted in a total of 1098 articles, of which 24 papers met our inclusion criteria and were included in this review. Articles using permanent mandibular incisors only as a predictor were excluded during the eligibility assessment. The results show that various independent variables including mesiodistal and vestibulo-oral dimensions of permanent maxillary and mandibular incisors and molars, molar basal arch length, intermolar distance, maxillary and mandibular arch and gender have been used as predictors to more accurately determine mesiodistal width of unerupted canine and premolars in different populations.

CONCLUSION

Ethnic tooth size variations strongly emphasize the need to determine which independent variable gives a more accurate prediction of unerupted permanent teeth to develop a population-specific prediction model. This will play a significant role in managing space problems and developing malocclusions.