Spectrophotometric analysis of the influence of zirconia core on the color of ceramic / 대한치과보철학회지

ABSTRACT

STATEMENT OF PROBLEM: Problem of matching the appearance of porcelain restorations with the patient's natural dentition has always been a concern to dental clinicians. Recently, demands for esthetics, even in restorations requiring strength, has brought a revolution to dentistry and increased use of zirconia. Among the various factors, shade and translucency of the core can significantly affect the overall esthetics of the restoration and should be considered when selecting an all-ceramic system. PURPOSE: The purpose of this study was to spectrophotometrically evaluate the influence of different zirconia systems and core thickness on the final shade of all-ceramic restorations using the CIEL*a*b* system. MATERIAL AND METHODS: Core specimens (n = 20 per group) of In-Ceram Alumina, In-Ceram Zirconia, Digident CAD/CAM Zirconia, Cercon Zirconia were fabricated 20mm in diameter. 10 specimens of each group were fabricated at core thickness of 0.5mm and 0.7mm. These core specimens were veneered with shade A1 and A3 porcelain of the recommended manufacturer. CIEL*a*b* coordinates were recorded for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). Color differences were calculated using the equation delta E*=[(delta L*)2+(delta a*)2+(delta b*)2]1/2. RESULTS: 1. Specimens of core thickness 0.5mm and 0.7mm did not exhibit clinically perceived color difference. 2. Regarding shade reproducibility, In-Ceram Alumina and In-Ceram Zirconia showed significant difference within each group. 3. Cercon Zirconia group showed the highest L* value and Digident Zirconia group showed lowest a* and b* value. 4. Generally, the shade difference between materials was higher in the A3 shade group than in the A1 shade group. CONCLUSION: Within the limitations of this study, there was no color difference after increase in core thickness and every all-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.