The Effects of Gastric Acid Exposure on the Surface, Color, and Mechanical Properties of Dental Ceramics: An In Vitro Study.

Abstract

Purpose: This study aimed to evaluate the impact of gastric acid exposure on the surface roughness (Ra), color change (ΔE), and biaxial flexural strength (BFS) of lithium disilicate (IPS), zirconia-reinforced lithium silicate (VS), and feldspathic (VM) ceramics, simulating the conditions in patients with eating disorders (EDs).

Methods: CAD-CAM blocks were sectioned into 1.2mm disks, sequentially polished, and heat-treated. Hydrochloric (HCl) solution (pH 1.2) was prepared to simulate gastric acid (SGA), and specimens were immersed at 37°C for 18h 25 min. Ra was measured with a profilometer, ΔE with a digital spectrophotometer. BFS testing was performed. Data were analyzed with SPSS17. Normality was assessed with the Shapiro-Wilk test. For non-normally distributed data, Mann-Whitney U was used for independent groups, Wilcoxon signed-rank for paired data, and Kruskal-Wallis with Dunn's post-hoc for multiple comparisons (p<0.050).

Results: All ceramics showed a significant decrease in Ra after SGA exposure (p=0.002). VM exhibited the highest Ra before and after exposure; VS and IPS did not differ significantly. BFS significantly decreased in VS (p=0.029), while reductions in VM and IPS were not significant. ΔE00 values differed among groups (p=0.046), but no pairwise differences were found. All ΔE00 values remained below the clinical acceptability threshold (2.25).

Conclusions: This study found that SGA exposure, simulating the conditions in ED patients, affected the surface roughness, color, and BFS of ceramics. SGA reduced the Ra of all ceramic groups and did not cause clinically unacceptable ΔE. Although acid exposure decreased BFS, the ceramics maintained sufficient strength for clinical use.