SPECTRORADIOMETRIC AND SPECTROPHOTOMETRIC TRANSLUCENCY OF CERAMIC MATERIALS

Statement of problem. The spectroradiometer (SR) was introduced as an alternative instrument to the spectrophotometer (SP) for measuring color in dentistry. No published studies were identified on the SR-based translucency of clinically simulated dental ceramics that closely reflect clinical conditions. Furthermore, it is unclear whether there is a correlation between SR- and SP-based translucency values. Purpose. The purpose of this study was to compare the translucency parameter (TP) of core, veneer, and layered ceramics determined by an SR, and to determine the correlations in TPs measured by an SR and a reflection SP. Material and methods. Seven A2 shade core ceramics and corresponding A2 and A3 shade veneer ceramics were fabricated with a layered thickness of 1.5 mm. The color of core, veneer, and A2- and A3-layered ceramics was measured over white and black backgrounds by an SR with 2 measuring apertures of 2.63 and 5.25 mm in diameter, and also by an SP (n=7). TP values were calculated and the differences in SR (5.25)-based TP values of the layered ceramics were analyzed with 2-way ANOVA with the fixed factors of shade designation and type of ceramic core (alpha=.05). The influence of the brand on the TP values of core, veneer, and A2- and A3-layered ceramics was also analyzed with 1-way ANOVA. Correlation analysis and paired t test were performed for the SR- and SP-based TP values (alpha=.05). Results. SR (5.25)-based TP values of layered ceramics ranged from 4.4 to 12.5, and were influenced by the type but not by the shade designation. SR-based TP values of core, veneer, and A2- and A3-layered ceramics were influenced by the brand. SR- and SP-based TP values were highly correlated (r=0.982 to 0.987, P<.01), although TP values based on SR measurement were significantly higher (P<.05). Conclusions. SR measurements showed significantly different translucency for different types of clinically simulated ceramic specimens. TP values measured by the SR and the SP were significantly different but highly correlated. (J Prosthet Dent 2010;104:239-246)