Enhanced effectiveness of silver diamine fluoride application with light curing on natural dentin carious lesions: an in vitro study.

This study aimed to compare the mean mineral density difference (mMDD) and surface morphology of 10- and 60-s silver diamine fluoride (SDF)-applied dentin carious lesions and to study the effect of an additional 20-s light curing (LC) on SDF-treated teeth. Forty primary molar blocks with natural dentin carious lesions were measured for baseline lesion depth and mineral density using Image-Pro Plus software. The samples were randomly distributed into 4 groups; 38% SDF applied for 1) 10-s (10SDF), 2) 60-s (60SDF), 3) 10-s + LC (10SDF + LC), 4) 60-s + LC (60SDF + LC) and an additional control group to assess the outcome of pH-cycling only. Then all the groups underwent a 7-d bacterial pH-cycling. The dentin carious lesions' mMDD was determined by digital subtraction radiographic analysis. The surface morphology and elemental profile were assessed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The mMDD of the dentin lesions was analyzed using two-way ANOVA, generalized linear models analysis. Light curing was the only factor that affected the mMDD (p = 0.007). The mMDD in the 10SDF + LC and 60SDF + LC groups were significantly higher than those without light curing (p = 0.041 and 0.041, respectively). The 60SDF + LC group demonstrated a significantly higher mMDD than the 10SDF group (p = 0.010), while that in the 10SDF + LC group was similar to the 60SDF group (p = 1.00). Scanning electron microscopy revealed denser mineral content layers, which were likely silver and chloride, in the 10SDF + LC and 60SDF + LC groups than in the 10SDF and 60SDF groups, respectively. In conclusion, shortened application time with light curing enhanced SDF remineralization similarly to the conventional method.

Chlorhexidine gluconate enhances the remineralization effect of high viscosity glass ionomer cement on dentin carious lesions in vitro.

BACKGROUND: To compare the mean mineral density (MMD) and examine the remineralization of carious dentin after cavity disinfection with chlorhexidine gluconate (CHX) and restoration with high viscosity glass ionomer cement (H-GIC) in vitro. METHODS: Selective caries removal to leathery dentin was performed in 40 extracted primary molars. The samples were scanned using micro-computed tomography (micro-CT) to determine the MMD baseline and randomly divided into 4 groups (n = 10): Equia™ group, applied dentin conditioner and restored with H-GIC (Equia Forte™), CHX-Equia™ group, disinfected the cavity with 2% CHX before applying dentin conditioner and restored with H-GIC (Equia Forte™), Ketac™ group, restored with H-GIC (Ketac Universal™) and CHX-Ketac™ group, disinfected the cavity with 2% CHX before restored with H-GIC (Ketac Universal™). The samples underwent micro-CT scanning post-restoration and post-pH-cycling to determine their respective MMDs. One sample from each group was randomly selected to analyze by scanning electron microscopy (SEM). RESULTS: The MMD gain in the 4 groups post-restoration was significantly different between the Equia™ and CHX-Ketac™ groups (oneway ANOVA with Post hoc (Tukey) test, P = 0.045). There was a significant difference in MMD gain post-restoration between the Equia™ and CHX-Equia™ groups (Independent t-test, P = 0.046). However, the Ketac™ and CHX-Ketac™ group's MMD were similar. The SEM images revealed that the CHX-Ketac™ group had the smallest dentinal tubule orifices and the thickest intertubular dentin among the groups. However, the CHX-Equia™ group had thicker intertubular dentin than the Equia™ group. CONCLUSION: Applying 2% CHX on demineralized dentin enhances the remineralization of the dentin beneath the restoration.

Biphasic Effect of ATP on In Vitro Mineralization of Dental Pulp Cells.

Dental pulp cells release adenosine triphosphate (ATP) in response to intrapulpal pressure and the amount released depends on the magnitude of the pressure. ATP regulates the differentiation of stem cells into adipocytes and osteoblasts. However, it is unknown whether extracellular ATP influences the stemness and osteogenic differentiation of stem cells from human exfoliated deciduous teeth (SHEDs). Therefore, this study investigated the effects of extracellular ATP at a low (0.1 µM) and high (10 µM) concentration on the stemness and osteogenic differentiation of SHEDs. Cells were cultured in either growth medium or osteogenic medium with or without 0.1-10 µM ATP. In growth medium, both concentrations of ATP increased the mRNA expression of pluripotent and osteogenic markers. In contrast, in osteogenic medium, 0.1 µM ATP enhanced in vitro mineralization, whereas 10 µM ATP inhibited this process. In addition, 10 µM ATP stimulated the mRNA expression and activity of ectonucleotide pyrophosphatase/phosphodiesterase (ENPP), an enzyme that regulates the phosphate/pyrophosphate ratio. Thus, depending on the growth condition and its concentration, ATP stimulated stemness and in vitro mineralization or inhibited mineralization. In growth medium, both ATP concentrations stimulated pluripotent and osteogenic marker gene expression. However, in osteogenic medium, a biphasic effect was found on in vitro mineralization; the low concentration stimulated, whereas the high concentration inhibited, mineralization. We propose that ATP released due to mechanical stress modulates the stemness and differentiation of SHEDs. J. Cell. Biochem. 119: 488-498, 2018. © 2017 Wiley Periodicals, Inc.