Studying the effect of artificial aging, made by using different methods, on monolithic CAD/CAM materials' opticial properties

Optical properties of restorative materials change over time due to intraoral conditions. The aim of this study is to examine the change in the optical properties of materials of different contents that can be used with computer aided design and computer aided manufacturing (CAD/CAM) technology after artificial aging methods performed with 3 different techniques and to evaluate them comparatively. In this study, for high translucency A1 colour; GC LRF(GC), IPS Emax Cad (EM), IPS Empress Cad (ES) and Celtra Duo (CD) blocks were used. Totally 120 samples from 4 different materials were prepared by the help of automatic high-speed precision cutting machine (Metkon Micracut 201 Bursa, Turkey) under water cooling as 1±0,05mm thick. The L*, a*, b* values of the samples were measured with a spectrophotometer (Easy Shade V, Vita Zahnfabric; Germany) on a white, black and gray background. These measured values were recorded for each sample marked. After ultraviolet (UV) aging, thermal cycle (TC) and autoclave aging (A) processes, the optical measurements of the samples were repeated under the same conditions. The values of ∆E00, TP001 and TP002 were calculated according to the CIEDE2000 formula. The data were evaluated statistically using 2-way analysis of variance (ANOVA), fishers LSD and paired samples T-Test (P≤0.05). The highest value of ∆E00 was observed in the EMUV group and the lowest value of ∆E00 was observed in the ESA group after artificial aging applications. Regardless of the artificial aging method, the material that underwent the least significant decolorization was GC; there was no significant difference between the CD, EM and ES groups. While UV aging caused significantly more color changes, there was no significant difference between the thermal cycle and autoclave aging methods. It was determined that the TP00 parameter decreased significantly in the GCTC and EMUV groups after aging procedures. It was observed that the ∆E00 value gave results below the clinically observable level (ΔE00 <1.30) in all groups after artificial aging procedures. In artificial aging performed with different techniques, UV aging caused the most color changes.