Effect of Liquefied Digestive Medicine on the Surface of Composite Resin

Background: The purpose of this study is to investigate the effect of liquefied digestive medicines on the composite resin surface.Methods: Three types of liquefied digestive medicines (Gashwalmyeongsu, Wicheongsu, and Saengrokcheon) were selected as experimental groups, Samdasoo and Chamisul as negative controls, and Trevi as positive controls were selected to measure pH and titratable acidity. The samples filled with resin at acrylic were made total 300, 50 per group. To evaluate the erosion risk of the composite resin, the specimens were immersed in a liquefied medicine for 1, 3, 5, 15, and 30 minutes, and then the surface microhardness was measured using the Vickers Hardness Number, and the surface change was observed with scanning electron microscope (SEM).Results: The average pH of the three liquefied medicine was 3.75±0.30, the Saengrokcheon was the lowest at 3.45±0.01, and the Trevi was 4.66 and Samdasoo and Chamisul were 7.40 and 8.58, respectively. The amount of NaOH reaching pH 5.5 and 7.0 was the lowest in the order of Trevi, Gashwalmyeongsu, Wicheongsu, and Saengrokcheon. The largest surface hardness reduction value was shown in Gashwalmyeongsu (−11.85±3.73), followed by Saengrokcheon (−9.79±3.11) and Wicheongsu (−8.28±2.83), and Samdasoo (−0.84±1.56) and Chamisul (−6.24±0.42) had relatively low surface hardness reduction values. However, Trevi (−16.67±5.41), a positive control group containing carbonic acid, showed a higher decrease in surface hardness than the experimental group. As a result of observation with SEM, experimental group and positive control group, showed rough surfaces and irregular cracks, and negative control groups showed smooth patterns similar to before immersion.Conclusion: The liquefied digestive medicine with low pH could weaken the composite resin surface, and the carbonic acid component could more effect on the physical properties of the composite resin than pH.