Evaluation of an automated color reproduction method for dental porcelain restorations

Objectives: The purpose of this study is to evaluate a novel computerized color measuring system and an automated color reproduction system for dental porcelain restorations. The method provides porcelain prescriptions to match the color of target teeth by a computerized calculation using a formula based on the Allen’s two constants theory. Methods: The color of the middle third of maxillary central incisors of 500 human volunteers and 62 shade tabs from 3 dental shade guides (VITAPAN CLASSICAL, VITAPAN 3D MASTER and IPS CHROMASCOP) was measured by a spectrophotometer (MSC-2000, Olympus, Japan). 34 subjects (out of 500) showed a dE > 3.6 between the tooth and the closest shade tab, indicating a poor color match. 23 subjects (out of 34 mismatches) volunteered for the evaluation of the automated color reproduction methodology. The ceramic prescription to reproduce the middle area of the target tooth color was calculated using the computerized calculation formula. Layered porcelain specimens were produced using a mix of 4 shades of opaque (5 mm thick) overlaid by one shade of dentin porcelain (1 mm thick). The colors of these specimens were compared to the target teeth by spectrophotometer and visual evaluation using a matching score from 1 (poor match) to 5 (Perfect Match). Results: The mean dE value between the ceramic specimens and the target teeth was 2.3±0.8. The Mean Visual matching score for all specimens was 4.5±0.8. Conclusions: The computerized color measuring and automated color reproduction system tested provided clinically acceptable color reproducibility of porcelain for teeth that were a poor match for conventional shade guides. (dnathan@bu.edu)