Biomimetic regulation of dentine remineralization by amino acid in vitro

Abstract

ObjectiveThe aim of this study was to evaluate the effect of conditioning solutions containing DL-aspartic amino (Asp) on dentine remineralization induced by bioactive glass 45S5 (BAG) in a simulated oral environment. MethodsSixty dentine discs from human third molars were used. Dentine specimens were treated with ethylene diamine tetraacetic acid (EDTA) to create a partially demineralization model and randomly divided to 4 groups: Artificial saliva (AS) group, Asp group (pretreated with Asp and remineralized with distilled water), BAG group (pretreated with distilled water and remineralized by BAG), Asp-BAG group (pretreated with Asp and remineralized by BAG).Each samples were measured at various time points, and at the end of the experiment, 6% citric acid challenge were taken. The remineralization characteristics were analyzed by using the spectroscopic data from attenuated total reflectance spectroscopy (ATR-IR) and Raman spectroscopy. The micro-morphology and structure were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Dentine permeability was measured before and after each treatment to evaluate the resistance of remineralized layer to acid and simulated oral environment. ResultsBoth BAG and Asp-BAG groups significantly reduced dentine permeability and formed enamel-like apatite layers on dentine surface. For the mineralization of BAG, Asp showed inhibition effect. The 7-day mineral matrix area ratio in BAG group (12.54±2.29) was lower than the value in the Asp-BAG group (17.77±2.27) (p<0.05) and the Raman intensity (RI%) in Asp-BAG Group (1.49±0.26) was also significantly higher than that of BAG group (1.34±0.14) (p<0.05). According to permeability test, the apatite layer in BAG group and Asp-BAG group effectively occluded the dentinal tubules (p<0.05) and had certain acidic resistance (p>0.05). Furthermore, adsorbed acidic amino acid on hydroxyapatite (HAP) altered the crystal to increase into a larger size in diameter during crystal growth. SignificanceThe study demonstrated that a superior remineralization efficacy of BAG with Asp pretreatment on dentine.