Article Type

Original Article


Orthodontics and Dentofacial Orthopedics



This study aimed to assess whether Tanaka-Johnston mixed dentition analysis using digital models is applicable to Egyptians.

Materials and methods

Ninety patients were included in this study with ages ranging from 12 to 25 years old. Impressions were taken from all patients using alginate impression material and casts were poured immediately using a dental plaster with quality dimensional accuracy and surface detail reproduction. The casts were trimmed and polished to obtain high-quality study models. Three-dimensional (3D) digital models were reconstructed using a laser scanner. Measurements of teeth widths by both manual and digital techniques were compared for intra-operator reliability testing. Measurements of the predicted width of canine and premolars according to Tanaka-Johnston mixed dentition analysis were compared with the measured values on digital models.


The results showed exceptional intra-operator reliability for both techniques for measurement of teeth width (ICC values are 0.998 and 0.987, respectively). A statistically significant difference was found between predicted and measured values for both the upper and lower jaws.


It is inaccurate to use Tanaka-Johnston mixed dentition analysis for Egyptians.


digital cast analysis, laser scanning, mixed dentition analysis, Tanaka and Johnston space analysis