Effect of Simulated Gastric Acid on Aesthetical Restorative CAD‑CAM Materials’ Microhardness and Flexural Strength

Abstract

Background: Gastric acid, which is among erosive substances, gradually rises to the mouth in individuals with reflux and bulimia nervosa  disorders, and this causes various effects on dental restorations. 

Aim: The objective of this study is in vitro investigation of  gastric acid’s effect on flexural strength and hardness on aesthetic restorative computer‑aided design and computer‑aided  manufacturing (CAD‑CAM) materials. 

Materials and Methods: For this study, four materials have been used, namely Enamic (Vita),  Superfect Zir (Aidite) Zirconia, IPS e.max CAD (Ivoclar Vivadent), and Mark II (Vita). From these four different materials, 24 samples with  14 × 4 × 1 dimensions in rectangular prism form are used, which makes a total of 96 samples. One group was separated as the control  group, while the rest was allowed to wait at 37°C, 5 ml gastric acid for 96 hours. Hardness value and flexural strengths were measured as  pre‑exposure and post‑exposure to gastric acid. 

Results: There is a statistically significant difference between the groups in terms of the  amount of decrease in the mean hardness after exposure to gastric acid compared to pre‑exposure values (p: 0,000; P < 0,05). There was  no statistically significant difference between the groups in terms of the amount of decrease in the post‑exposure average flexural  strength compared to the pre‑exposure value (p: 0.063; P > 0.05). There is a statistically significant difference between the groups in  terms of the average flexural strength after exposure to the acid. 

Conclusions: According to the data obtained, it was concluded that  exposure to gastric acid affects the hardness and flexural strength properties of dental restorative ceramic materials.