Evaluation of a new dynamic erosive aging method on the properties of restorative CAD/CAM dental materials

Objectives: Acidic immersion is the current aging method for estimating the effect of gastric disorders on dental restorative materials. The aim of this study was to evaluate the effect of a dynamic method on the properties of restorative CAD/CAM materials. Methods: Disks (n = 15, Ø14 × 1.2 mm) from CAD/CAM blocks (RC: ceramic-reinforced resin composite, LS: lithium silicate, ZR: zirconia) were subjected to 4 treatments for 96 h: immersion on artificial saliva (AS – negative control) or acidic solution (AI - HCl 1 %; pH 1.2 – positive control); acidic solution flow on anterior (AF) or posterior (PF) locations in the maxillary arch. Surface roughness (Ra), microhardness (MH), wettability (WT), gloss (GL), and flexural strength (BFS) were assessed. Surface topography was characterized by SEM. Data analysis was carried out (One-way ANOVA, t-test, α = 0.05) for each restorative material. Results: None of the properties of RC were affected (p > 0.05) by the proposed aging cycling. For LS, PF exhibited significantly lower Ra values (p = 0.02), while AI showed higher WT values (p = 0.02). GL was significantly higher for all acid-exposed groups (p < 0.001). For ZR, the immersion and dynamic acidic exposure had significantly different effects on WT (p < 0.001), with lower values for immersion and higher values for both AF and PF. SEM showed surface changes in LS and ZR for all groups exposed to acidic treatments, with distinct alteration patterns between immersive and dynamic methods. Conclusions: The flow factor from the dynamic acid erosion method differently impacted topography and surface properties of LS and ZR, and the optical properties of LS. Clinical significance: Methods that more closely represent the challenges that restorations and teeth are exposed to are required in order to develop materials that can withstand gastric disorders.