A new system for scanning, measuring and analyzing dental casts based on a 3D holographic sensor

To evaluate the reliability of a new technique for measuring 3D-scanned orthodontic cast models with cross-section planes using teledent, a new software, developed at Technion - for the purpose of this research.

Thirty orthodontic plaster models were divided into three equal groups according to severity of teeth crowding. Measurements of mesio-distal tooth width and the arch length were performed manually on the casts using a conventional caliper. Thereafter, the models were scanned and processed into the software using a 3-D measuring scanner with a holographic sensor 'ConoProbe' (by Optimet, Jerusalem, Israel). teledent used two types of digital measurements; linear and cross-section planes to perform a space analysis on the scanned teeth. Significance was determined by the paired Wilcoxon rank sum test.

Results show that 3D measurements of tooth width and arch length obtained by cross-section planes were generally similar to manual caliper measurements, while linear measurements were statistically smaller. When comparing space analysis, both digital measurements were statistically smaller than the caliper (p < 0.05). The difference in space analysis between the caliper and the cross-section plane measurements was very small (0.38-0.74 mm) and can be considered clinically acceptable. However, a difference of 1.19-3 mm between the linear measurements and the caliper might have clinical implications especially in severely crowded dentition.

This study suggests that measurements performed by cross-section planes are as accurate as the manual caliper and can be employed clinically while the accuracy of linear measurements is sometimes questionable.