Accuracy and precision of three intraoral scanners in shade matching.

Abstract

Statement of the Problem: Accurate replication of tooth shade is an important factor in the success of esthetic restorative dentistry. Various instruments for shade matching have been introduced to dentistry to overcome the limitations associated with visual shade matching. Many intraoral scanners are now equipped with the capability to measure shade during the scanner process. However, few studies have investigated the accuracy and precision, of intraoral scanners (IOSs) in the shade matching process. Accuracy is a measure of how close an instrument reads the actual shade. Precision is a measure of a system’s consistency to achieve identical results through multiple testing.

Purpose: The purpose of this study is to evaluate the accuracy and precision of three intraoral scanners for shade matching.

Materials and Methods: 3Shape TRIOS 4, TRIOS 5, and Medit i700 were evaluated. Using the three scanners, color measurements were obtained over the shade tabs from 2 shade guides: VITA Classic (16 tabs) and VITA Toothguide 3D Master (26 tabs) .

A single shade tab was placed in the center of a gingiva-colored matrix with identical shade tabs placed adjacent to the measured tab to simulate the oral environment. 0-lux ambient lighting condition and a room with no windows and no light was used. Measurements were made at the middle third of the shade tab positioned, while inside a black box. Accuracy was evaluated over the 420 shade tabs from 10 Vita Classic and 10 Vita 3D shade guides. The scanner findings were tabulated based on the shade-matching outcome. If the ISOs shade measurement matches the shade tab, it was reported as “yes”. To assess the precision, the color of 42 randomly selected shade tabs from VITA Classic and VITA 3D Master guides were measured 10 consecutive times per shade tab. The precision of each shade tab was calculated as the number of measurements that were identical for each shade tab. Repeated shade measurements by the device were considered to be reliable regardless of whether or not the measurement matched the actual shade tab. The overall precision for the shade-matching IQS was then calculated as the average reliability across all 42 shade tabs.

Statistical Analysis: Statistical analysis was performed on the data using analysis for Variance (abbr. ANOVA) at the 5% level of significance to assess precision. For accuracy, a chi-square test will be used to calculate statistical significance at the 5% level of significance.

Results: Measurements from the TRIOS 5 scanner resulted in 34.5% accuracy, whereas accuracy from the Medit i700 and TRIOS 4 was measured at 7.4% and 6.9%, respectively. Chi- square test on accuracy revealed significant differences among the three intraoral scanners for both shade guides (P=0.001). TRIOS 5 performed better for both VITA Classic and 3D Master guides in accuracy with 24.4% and 40.8% of the measurements being accurate respectively. On a 10-point scale, The Medit i700 scanner resulted in the highest average score of precision at 9.1, followed by TRIOS 5 at 8.7. Measurements from the TRIOS 4 intraoral scanner had a score of precision of 7.8. The analysis for variances ANOVA for precision revealed significant differences amongst the 3 intraoral scanners (P=0.005).

Conclusion: Within the limitations of this study, the following conclusions can be made: 1. Significant differences were found in accuracy among the three intraoral scanners with TRIOS 5 performing best in shade matching with both the VITA Classic and 3D Master shade guides (P<0.001). 2. Significant differences were found in precision among the three intraoral scanners with Medit i700 showing more precise shade matching measurements with both shade guides (P=0.005).