Applicability of Tanaka Jhonston Method and Prediction of Mesiodistal Width of Canines and Premolars in Children.

Abstract

Essential part of diagnostic procedures in mixed dentition analysis is to determine adequate space available for the erupting permanent teeth. Various methods of analysis for mixed dentition are available; among them Tanaka Johnston method of space analysis for children was developed for North American children and is widely used. Its reliability among different racial and ethnic groups is yet to be determined. To check the applicability of Tanaka Jhonston method and to derive the mesiodistal width of unerupted canines and premolars and also derive new regression equations for Bangalore population. Considering the selection criteria, 400 subjects of Bangalore aged 13-16 years were randomly selected and study models were prepared. Mesiodistal widths of permanent lower incisors, canines and premolars were measured. Estimated width of upper, lower canines and premolars were also derived using Tanaka Jhonston method. Data was utilized to predict mesiodistal widths of erupting permanent canines and premolars. Descriptive analysis, independent student t-test, correlation and regression analysis were carried out. Measured and estimated widths of upper and lower canines and premolars were compared and the results showed that estimated widths of upper and lower canines and premolars over estimated as to the actual measurements. A new regression equation was developed by using the formula Y=a+b(X) where Y= predicted width of canine and premolars, "a" and "b" are the constants and X= lower incisal width. Regression equations for males and females were derived separately. The original Tanaka Jhonston method over estimated for local Bangalore population. New regression equations and prediction tables were derived for males and females separately, which should be more conveniently used chairside by the clinician.