[Measurement of deciduous canine and construction of standardized virtual crown based on ray projection]

To explore the construction process of a standard virtual crown for deciduous canine teeth, provide a foundation for the establishment of a standard crown model for deciduous canine teeth, and reference and basis for the application of CAM/CAM technology in pediatric dentistry.

A total of 65 children aged 4-5 years old with caries free deciduous canine were selected from the Imaging Department of Nantong Stomatological Hospital, including 34 boys and 31 girls. The obtained DICOM format data was imported into 3DSlicer 5.0.3 software for ray projection rendering and reconstruction. Using the ruler tool in the software, crown data of deciduous teeth were extracted, crown width, thickness and length were measured, and the data were divided into male and female, upper and lower deciduous teeth for Student's t test. The reconstructed model was modified according to the test results, and the mean and median models of crown width, thickness and length of male/female upper/lower deciduous teeth were established. A vernier caliper was used to measure the isolated milk fangs. The results of virtual measurement and specimen measurement were compared by Student's t test. MATLAB R 2016a software was used for statistical analysis.

There were significant differences in the three radial directions between males and females; There was a statistical difference in crown width and thickness between the upper and lower deciduous canines, but there was no significant difference in crown length. The average values of crown width, crown thickness, and crown length of girls' maxillary deciduous canines were 6.20, 3.97, and 5.61 mm, respectively, with a median of 6.15, 3.82 and 5.53 mm. The average values of crown width, crown thickness, and crown length of girls' mandibular deciduous canines were 5.47, 4.25 and 5.66 mm, respectively, with median values of 5.45, 4.22 and 5.68 mm, respectively. The average values of crown width, crown thickness, and crown length of male primary teeth were 6.40, 4.14 and 5.87 mm, respectively, with median values of 6.40, 4.04 and 6.05 mm. The average values of crown width, crown thickness, and crown length of male mandibular deciduous canines were 5.69, 4.53 and 6.00 mm, respectively, with median values of 5.64, 4.65 and 6.06 mm. Based on the above values, virtual crown mean and median models were established for male/female maxillary and mandibular deciduous canines.

The diameter values obtained by ray projection and measurement in 3DSlicer have higher reliability compared to specimen measurements. The measurement results can be used to establish a virtual model of the male/female upper and lower primary canine standard crown, providing a reference for the establishment of the primary canine standard crown model.