Evaluation of mechanical and optical properties of different CAD-CAM materials after gastric acid exposure

The aim was observation of changes in optical and mechanical characteristics of CAD-CAM restorative materials under the well-established blumia nervosa (BN) and control conditions. Three different CAD-CAM materials chosen as A1 shade and high translucent (HT) [IPS e.max CAD (E), Celtra Duo CAD (C), Ceramill Zolid HT+ PS (Z)]. All samples (N=120) with 1.5 mm were polished with 3 step Optra Fine Intra Oral Polishing Kit. Samples were distributed into 6 subgroups (n=18), 2 samples from each group were chosen for topography evaluations. The exposure time was 486.5 hours to simulate patients who have BN for five years. Blumic subgroups were stored in BN solution with 1.6 pH and control subgroups were stored in artificial saliva with 7 pH. Measurements were done for parameters as color and translucency change (∆E, ∆TP) by spectrophotometer, surface roughness change (∆Ra) by contact profilometer, surface microhardness and fracture toughness change (∆VHN, ∆KIc) by Vickers hardness device, and surface topography by scanning electron microscope and 3D optical profilometer. As a result, the ∆Ra value of Z samples exposed to blumic solution was significantly higher than those exposed to control solution (p=0.004). Control solution significantly increased the VHN of E samples more than blumic solution (p=0.000). Blumic solution significantly decreased the VHN of C samples (p=0.000) and KIc of E and Z samples more than control solution (p=0.000, p=0.000). The ∆E after the blumic solution exposures were significantly higher than the control solution exposures among three materials (p=0.000, p=0.000, p=0.000). Blumic solution significantly decreased the TP of E and Z samples more than control solution (p=0.000, p=0.000), while control solution changed the TP value on C samples more than blumic solution (p=0.000). In non-blumic patients, Ceramill Zolid HT+ PS was found as the most stable material choice, and then IPS e.max CAD follows as the second stable material. In blumic patients, all materials' mechanical properties were found sufficient, but color stabilities of IPS e.max CAD and Celtra Duo CAD were superior to Ceramill Zolid HT+ PS. In blumic patients, high color change of polished Ceramill Zolid HT+ PS restricted its use at anterior region. Key Words: Blumia nervosa, Gastric acid, Artificial saliva, CAD-CAM materials