Dimensional accuracy of digital dental casts compared with conventional plaster casts: A cross-sectional study

Introduction: Orthodontic diagnosis requires accurate analysis of dental morphology and occlusion. While plaster casts were the standard, several drawbacks such as breakages, storage requirements and retrieval challenges have led to a digital shift, exemplified by intraoral scanning, which is more efficient and comfortable. To justify clinical adoption, the diagnostic accuracy of intraoral scanners must be validated. 

Aim and Objectives: This study aimed to compare the accuracy and reliability of intraoral orthodontic assessments performed using conventional plaster casts versus digital dental casts generated by the AlliedStar AS 260 scanner.

Materials and Methods: This comparative cross-sectional study assessed 14 orthodontic variables on conventional dental casts and corresponding digital models in 34 subjects. Variables included arch lengths, mesiodistal widths of teeth 11, 41, 13, 43, 14, 44, 16, and 46, overjet, overbite, and upper and lower space analyses. Measurements were performed using digital calipers on conventional casts and AS Connect software for digital models. Data analysis employed Paired Samples T-tests to assess validity, and Intraclass Correlation Coefficients (ICC) to evaluate reliability.

Results: Data normality was confirmed (Shapiro-Wilk, p > 0.05). Paired t-tests revealed no statistically significant differences between conventional and digital measurements for any of the 14 variables (p > 0.05). Mean differences ranged from −0.08 mm to 0.17 mm, all within the clinically acceptable threshold of 0.5 mm. Reliability analysis demonstrated excellent agreement (ICC > 0.9)

Conclusion: Digital casts produced by the AlliedStar AS260 are statistically equivalent to conventional plaster casts and offer a reliable, clinically accurate alternative for routine orthodontic assessment.