Color gradation and optical properties of multilayer CAD/CAM resin crowns

抄録

Purpose : Considering the lack of studies regarding the color gradation and optical properties of multilayer CAD/CAM resin blocks for anterior teeth, those parameters were evaluated in this study.

Materials and Methods : Seven commercial multilayer CAD/CAM resin blocks, a translucent multilayer zirconia and a lithium disilicate glass ceramic were used to fabricate crowns. The CIELAB coordinates of the cervical, central, and incisal regions of the crown against gray, black, and white backgrounds were measured using a dental spectrophotometer (n＝8) ; color differences and optical property parameters were calculated and compared. The parameters were Lightness of the central region (L^＊), Chroma of the central region (C^＊), Color difference between the cervical and central regions (ΔE₁), Color difference between the central and incisal regions (ΔE₂), Translucency parameter of the incisal region (TP) and Opalescence parameter of the incisal region (OP). Kruskal-Wallis and Scheffé tests were used to compare parameters among the crowns (α＝0.05).

Results : There were significant differences among brands in the color gradation and optical properties of multilayer resin blocks, even when the same nominal shade was used.

Conclusions : The results of this study, indicating the characteristics of multilayer CAD/CAM resin blocks, will provide a basis for material selection in aesthetic prosthetic treatment. Additionally, the seven multilayer CAD/CAM resin crowns exhibited less translucency than that of a lithium disilicate glass ceramic ; however, they showed optical properties similar to those (TP and OP) of a multilayer zirconia crown and may have value as aesthetic prosthetic devices.