Farklı seramik tipi, seramik kalınlığı ve yaşlandırmanın lityum disilikat, zirkonya ile güçlendirilmiş lityum silikat, lösit ile güçlendirilmiş cam seramik ve feldspatik seramiklerin renk stabilitesi ve translüsensi üzerine etkisinin ın vitro olarak incelenmesi

The aim of the present study was to evaluate the color stability (CS) and translucency change of different glass-ceramic CAD/CAM blocks in two different thicknesses (0.5mm and 1.00mm) after hydrothermal aging. Four types of CAD/CAM blocks; lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; E.Max), leucite-reinforced (Initial LRF, GC; LRF), zirconia-reinforced lithium silicate (Celtra Duo, Dentsply; CD), and feldspathic (Cerec, Dentsply; CER) glass-ceramics were cut in 0.5mm and 1.00mm slabs (n=12 for each thickness) using a low-speed diamond saw (Isomet). To represent dental hard tissues, a total of 96 micro-hybrid resin composite discs (G-eanial, GC; A2) were prepared in 2mm thickness. CAD/CAM slabs and resin composite substrates were luted with a light-cured resin cement (G-CEM; GC) and polymerized (VALO Cordless, Ultradent) according to the manufacturer's instructions. Immediate after cementation initial color measurements (E0) were evaluated using a spectrophotometer (CM-2600d, Minolta). Following storage in distilled water for 24 hours at 37 OC, second color measurements (E1) were evaluated using a spectrophotometer (CM-2600d, Konica Minolta) and this readings set as baseline measurement. Then all the specimens were exposed to hydrothermal aging between 5-55°C for 30000 cycles (SALUBRİS). Color and TP measurements were repeated after every 10000 cycles (E1, E2, E3). Color differences (∆E) and TP measurements were evaluated by CIEDE2000. Data were analyzed with three-way ANOVA and post hoc Tukey's tests (p<0.05). ∆E00 was significantly influenced by ceramic type (p<0.001), ceramic thickness (p<0.001), and aging (p<0.001). Regarding to ceramic thickness, only CER 0.5mm and 1.0mm showed statistically significant differences at 10000, 20000, 30000 cycles aging (p=0.006, p<0.001, p<0.001, respectively). With respect to ceramic type, in 0.5mm thickness at 10000 cycles LRF showed statistically higher CS than CER (p=0.001), after 20000 and 30000 cycles CER showed statistically lower CS than LRF (p<0.001) and E.Max (p=0.008, p<0.001). TP was significantly influenced by the type of material (p<0.001) by the thickness of the material (p<0.001) and by aging (p<0.001). A significant interaction between material, thickness and aging was found (p<0.001). Meanwhile, the association between material and thickness was significant (p=0.44), whereas between thickness and aging (p=0.124) and between material and aging were not significant (p=0.125). All materials in all aging periods showed statistically significant differences in different thicknesses (postcementation, Cerec 0.5mm-1.0mm p<0.001, CD 0.5mm-1.0mm p<0.001, E.max 0.5mm-1.0mm p<0.001, LRF 0.5mm-1.0mm p<0.001. 24 hours (baseline), Cerec 0.5mm-1.0mm p<0.001, CD 0.5mm-1.0mm p<0.001, E.max 0.5mm-1.0mm p<0.001, LRF 0.5mm-1.0mm p<0.001. 10000 thermocycling, Cerec 0.5-1.0 p=0.001, CD 0.5mm-1.0mm p<0.001, E.max 0.5mm-1.0mm p<0.001, LRF 0.5mm-1.0mm p<0.001. 20000 thermocycling, Cerec 0.5mm-1.0mm p<0.001, CD 0.5mm-1.0mm p<0.001, E.max 0.5mm-1.0mm p<0.001, LRF 0.5mm-1.0mm p<0.001, 30000 thermocycling CD 0.5mm-1.0mm p<0.001, E.max 0.5mm-1.0mm p<0.001, LRF 0.5mm-1.0mm p<0.001). CS of glass ceramics were affected by ceramic type, ceramic thickness, and aging. LRF and E.MAX glass ceramics presented more CS then the CD and CER glass ceramic CAD/CAM blocks after aging. CS of the CER CAD/CAM block was highly thickness-dependent. In 0.5mm thickness, feldspathic ceramic showed the lowest translucency, while in 1.0 mm zirconia-reinforced glass ceramic exhibited the lowest translucency after 3-years of aging. Luted CAD /CAM ceramic materials showed acceptable changes in translucency after 3-years of aging, regardless of thickness. Keywords: CAD/CAM, ceramic, veneers, color stability, translucency, TP, hydrothermal, aging.