[Assessment of the accuracy of moyers prediction tables and Tanaka Johnston regression equations in a sample of Iranian population and introducing new regression equations in prediction of unerupted teeth]

Statement of Problems: Ethnic and sex differences in the mesiodistal width of the teeth have been proved in different studies. The prediction methods of the canine and premolar width have been obtained from other populations, which are in controversy with the results of previous Iranian studies

Purpose: The aim of this study was to determine the accuracy of the Tanaka-Johnston prediction equations and Moyer's prediction tables in the prediction of un-erupted canines and premolars in a South Iranian population. Also, new regression equations and tables are presented to predict the width of the un-erupted canines and premolars based on the sum of the mesiodistal width of the lower incisors

Materials and Method: For this cross-sectional study, a total of 715 dental casts were recruited from southern Iranian population. The greatest mesiodistal widths of all the teeth were measured using digital caliper with the accuracy of 0.01 mm. All the data were compared with Moyers's and Tanaka-Johnston predictions using Pearson Correlation, independent t-test and paired sample t-test. New regression equations were presented with multiple linear regression tests and new prediction tables were presented with LMS chart maker software

Results: Tanaka-Johnston equations and Moyer's prediction tables revealed a significant difference with the mesiodistal dental width of southern Iranian population and the predictions were overestimated in this population. Also, there was a significant difference between the mesiodistal width of the teeth of males and females. So, new regression equations and tables [based on the sum of the lower incisors] were introduced for different jaws and sexes in this study. The suggested regression for prediction of the maxillary canine and premolars based on the summation of mesiodistal width of the lower incisors was y=0.529x+9.161 and for prediction of the mandibular canine and premolarsit was y=0.567x+7.827

Conclusion: Tanaka-Johnston and Moyer's prediction tables overestimate the actual size of southern Iranian's teeth width; Moyers prediction tables are not accurate in the prediction of the width of the canines and premolars in none of the percents. So, application of these methods is not suggested for Iranian population

[ software for space analysis and comparison of the accuracy of tooth measurements by digital and manual methods]

Statement of Problems: Several methods have been presented for the prediction of mesiodistal width of the unerupted canines and premolars. Nowadays, application of digital methods is suggested in dental analysis in orthodontics

Purpose: The aim of this study was to design a software for space analysis and comparison of the accuracy of tooth measurements by digital and manual methods in an Iranian population

Material and Method: By using Delphi and C++ programming languages, a software was designed. After insertion of 2 dimensional scanned images of dental casts, the software can predict mesiodistal width of the unerupted canines and premolars by using 12-variable regression equations based on the incisors and first molars. After providing 2 dimensional images of 125 dental casts in permanent dentition [75 females and 50 males], the prediction accuracy of regression equations was investigated. By providing 2-dimensional images of dental casts in 50 patients with mixed dentition, the accuracy of dental measurements was evaluated through the designed software. Moreover, the time duration of manual and digital measurements was evaluated. Data was analyzed in SPSS, version 17, using paired sample t-test for comparing the manual and digital measurements and evaluation of interobserver and intraobserver errors

Results: Prediction of the width of the canines and premolars by the designed software was not significantly different from manual measurement of those teeth on dental casts with digital Caliper [p >0.05]. There were no significant differences between manual and digital measurement of mesiodistal width of the teeth [p >0.05]. Also, there were no significant differences between intra-observer and inter-observer measurements and the speed of measurements in digital and manual methods. However, the time duration and speed of space analysis with these two methods were significantly different

Conclusion: The designed software has a good accuracy in prediction of unerupted canines and premolars with equations and it is an efficient tool for predicting the mesiodistal width of the teeth as to the time duration or speed