Al-Rafidain Dental Journal

Abstract

The purpose of this study was to compare two mixed dentition
prediction methods that do not require the use of periapical
radiographs of the unerupted permanent lower teeth.
The two compared methods were the Tanaka/Johnston (T/J)
and the Boston University (BU) prediction approaches.
Study casts of 52 children (20 males and 32 females)
were used; those children were selected from primary and secondary
schools located in different areas of Mosul City. All
subjects have normal Class I molar relationship.
The finding indicated that on the average the T/J approach
overestimated the tooth size of the unerupted teeth (mean
+ SD = 1.02 + 1.07 mm). On the other hand, the BU approach
underestimated the tooth size of the unerupted teeth (mean +
SD = –0.2 + 1.07 mm). The findings further indicated that there
were statistically significant correlation between the predicted
and actual tooth size.
The error involved in the use of the prediction equations
was expressed as the standard error of the estimate (SEE).
The present findings indicated that the SEE for T/J prediction
ranged between 0.52–0.63 mm and the corresponding values
for BU equation ranged between 0.45–0.68 mm. Depending
on the stage of dental development; i.e., which deciduous and
permanent teeth are present, the T/J approach can be used
when the only permanent four mandibular incisors have completely
erupted, whereas the BU approach can be used when
all the deciduous (canines and first molars) are still present.