In Vitro Evaluation of Translucency and Color Stability of CAD/CAM Polymer-Infiltrated Ceramic Materials after Accelerated Aging

Purpose To investigate and compare the translucency and color stability of a newly introduced polymer-infiltrated ceramic network (PICN) material (Crystal Ultra) to those of clinically well-established restorative materials. Materials and Methods A total of 80 specimens measuring (12 x 14 x 1 mm +/- 0.05 mm) were prepared from five CAD/CAM (IPS e.max (IPS), Lava Ultimate (LU), Cerasmart (CS), Vita Enamic (VE), Crystal Ultra (CU)) high translucency (HT) blocks in A2 or equivalent shades. Specimens were randomly allocated into two groups (A and B) (n = 8), and were subjected to 5,000 thermal-cycles (TC). This was followed by one-week immersion of group A specimens in coffee (staining) solution and group B specimens in distilled water. Following immersion, the specimens from both groups were further subjected to 5,000 TC. A spectrophotometer was used to measure the translucency parameter (TP) and color change (Delta E-00) of the samples using CIELAB color coordinates at baseline, after 5,000 TC, following immersion, and after further 5,000 TC. Color stability was evaluated using the CIEDE2000 formula. Data were analyzed by non-parametric tests (alpha = 0.05). Results The TP values of the CAD/CAM materials ranged from 18.0-22.0. Following the initial TC, the changes in TP values were significant for VE (p= 0.012). Coffee immersion and further TC significantly impacted the TP values of PICN (VE and CU) materials compared to glass- ceramics (IPS), and resin nanoceramic (CS and LU) materials (p= 0.012). The comparison between CAD/CAM materials at different intervals showed a significant difference in the TP values (p< 0.01). The materials showed perceptible color changes following the initial TC except for PICN materials which demonstrated acceptable color changes. The major color difference was noticed for the resin nanoceramic specimens immersed in coffee; LU and CS showed higher color changes (Delta E-00= 2.45 and 2.09, respectively) than VE and CU (Delta E-00< 1.8). Conclusions The translucency of the newly introduced Crystal Ultra PICN material was low compared to the resin nanoceramics and lithium disilicate glass-ceramic. The Crystal Ultra material exhibited better color stability compared to resin nanoceramics, but higher color change when compared with Vita Enamic PICN and lithium disilicate glass-ceramic CAD/CAM materials.