APPLICABILITY OF TANAKA AND JOHNSON'S EQUATIONS IN A SAMPLE OF NIGERIAN POPULATION
Keywords:
Tanaka and Johnson's equations, Mixed dentition analysis, Yoruba ethnic groupAbstract
BACKGROUND: Tanaka and Johnson's probability equations are used to predict the future sizes of the permanent canines and premolars based on the measurements of the mandibular four incisors. This tool has been applied in numerous settings, including Nigeria, and has been found by many researchers to exhibit ethnic and gender variations.
AIM: Applicability of Tanaka and Johnson's probability equation among mixed dentition patients of the Yoruba ethnic group in southwest Nigeria.
METHOD: A total of 504 casts from patients aged 12 to 20 years were analyzed. The mesio-distal tooth measurements of the four
mandibular incisors and the canines and premolars of both the maxilla and the mandible from one contact point to the other were done using a digital caliper.
RESULTS: A total of 504 pairs of upper and lower cast models were obtained from 252 males and 252 females, each with a mean age of
15.68±1.50 and 16.38±1.72 years, respectively. In the maxilla and mandible, highly significant differences (p-value: 0.000–0.001) were
observed between the actual measurements of the cuspid and bicuspids in the study group and those predicted by Tanaka and Johnson.
CONCLUSION: A statistically significant difference was observed between the mean mesio-distal value of the actual and predicted measures. Hence,Tanaka and Johnson's equation was found to overestimate the predictive mesio-distal width of the canines and premolars in the currentstudy sample.
