Dental measurements based on a three-dimensional digital technique: A comparative study on reliability and validity

Highlights

• Linear measurements of all teeth made on plaster models and digital models were compared.

• Dental measurements using the two methods were equally reliable, without clinically significant differences.

• The reliability and validity of dental measurements using 3D digital technique were assessed.

Abstract

Objective

In orthodontics and prosthodontics fields, it is often necessary to measure the crown dimensions of patient's teeth for further diagnosis and treatment. This study aims to assess the reliability and validity of dental measurements by comparing three-dimensional (3D) measurement of digital model derived from 3D handheld scanner with electronic digital caliper measurement of plaster model, providing a promising technology for dentistry.

Design

The mesiodistal diameter, buccolingual diameter and clinical crown height of 2800 teeth were measured on 100 sets of maxillary and mandibular dental plaster models as well as on the corresponding 3D digital models obtained by structured light scanning of the plaster models. Each measurement was performed twice by qualified operators and averaged. Twenty sets of maxillary and mandibular dentition models were randomly selected for intra and inter observer errors. The reliability was evaluated by intraclass correlation coefficient (ICC). Bland-Altman analysis was utilized to evaluate the validity of methods.

Results

Excellent reliability (ICC > 0.75) of intra and inter observer on traditional and digital methods were exhibited. Bland-Altman analysis showed the largest difference was the mesiodistal diameter (170/2800), and the smallest (130/2800) was the clinical crown height. Compared with other teeth, buccolingual diameter of incisors and molars, mesiodistal diameter and clinical crown height of premolars and molars displayed relative differences. The mean biases were close to zero, upper and lower 95 % limits of agreement were within 0.5 mm.

Conclusions

Linear measurements obtained from 3D technique are consistent with the conventional method. The 3D technology can be clinically accepted and suitable for dental metrology.