Effects of Red LED Irradiation in Enhancing the Mineralization of Human Dental Pulp Cells In Vitro.

Dentin regeneration is the preferred method used to preserve dental pulp vitality after pulp exposure due to caries. Red light-emitting diode irradiation (LEDI), which is based on photobiomodulation (PBM), has been used to promote hard-tissue regeneration. However, the underlying mechanism still needs elucidation. This study aimed to explore the mechanism involved in red LEDI affecting dentin regeneration. Alizarin red S (ARS) staining revealed that red LEDI induced mineralization of human dental pulp cells (HDPCs) in vitro. We further distinguished the cell proliferation (0-6 d), differentiation (6-12 d), and mineralization (12-18 d) of HDPCs in vitro and treated cells either with or without red LEDI in each stage. The results showed that red LEDI treatment in the mineralization stage, but not the proliferation or differentiation stages, increased mineralized nodule formation around HDPCs. Western blot also indicated that red LEDI treatment in the mineralization stage, but not the proliferation or differentiation stages, upregulated the expression of dentin matrix marker proteins (dentin sialophosphoprotein, DSPP; dentin matrix protein 1, DMP1; osteopontin, OPN) and an intracellular secretory vesicle marker protein (lysosomal-associated membrane protein 1, LAMP1). Therefore, the red LEDI might enhance the matrix vesicle secretion of HDPCs. On the molecular level, red LEDI enhanced mineralization by activating the mitogen-activated protein kinase (MAPK) signaling pathways (ERK and P38). ERK and P38 inhibition reduced mineralized nodule formation and the expression of relevant marker proteins. In summary, red LEDI enhanced the mineralization of HDPCs by functioning to produce a positive effect in the mineralization stage in vitro.

Albiflorin Inhibits Advanced Glycation End Products-Induced ROS and MMP-1 Expression in Gingival Fibroblasts.

BACKGROUND: Periodontitis is a common complication of diabetes, with advanced glycation end products (AGEs) playing a key role in its pathogenesis. Albiflorin, a monoterpene glycoside, has shown potential anti-inflammatory and antioxidant properties. This study aims to investigate the effects of albiflorin on AGEs-induced gingival fibroblasts and its underlying mechanisms. OBJECTIVE: This study aimed to evaluate the role of albiflorin in mitigating ROS production, inflammation, and MMP-1 expression in AGEs-induced gingival fibroblasts. METHODS: The viability of gingival fibroblasts treated with albiflorin and AGEs was assessed using CCK-8 assays. ROS levels were measured by DCF staining, and the expression of inflammatory markers and MMP-1 was evaluated by ELISA and qPCR. The involvement of the NF-κB and Nrf2 pathways was examined by immunoblotting. RESULTS: Albiflorin enhanced the viability of AGEs-induced gingival fibroblasts and reduced ROS production. It also decreased the expression of IL-6, IL-8, RAGE, and MMP-1, suggesting an anti- inflammatory effect. Mechanistically, albiflorin modulated the NF-κB and Nrf2 pathways in AGEs-induced gingival fibroblasts. CONCLUSION: Albiflorin exhibited protective effects against AGEs-induced oxidative stress and inflammation in gingival fibroblasts, highlighting its potential as a therapeutic agent for periodontitis in diabetic patients. The modulation of the NF-κB and Nrf2 pathways by albiflorin provides insight into its mechanism of action.

Wear Resistance and Biocompatibility of Co-Cr Dental Alloys Fabricated with CAST and SLM Techniques.

Cobalt-chromium (Co-Cr) alloys have been widely used as dental-restoration materials for many years. This study sought to investigate whether selective laser melting (SLM) is a more appropriate process than traditional casting (CAST) for fabricating dental Co-Cr alloys. Metallurgical microscopy, X-ray photoelectron spectroscopy (XPS), Vickers hardness and nanoindentation tests, and friction and wear tests were used to evaluate the microstructure, surface compositions, mechanical properties, and wear resistance, respectively. Additionally, the biocompatibilities and cell adhesion of the alloys were evaluated with L-929 fibroblasts via CCK-8 assay, Live/Dead staining, flow cytometric analysis, scanning electron microscopy (SEM) observation and real-time PCR (RT-PCR) assay. The XPS results showed that the two alloys were all mainly comprised of Co, Cr, and O. The hardness in the CAST group equaled 7.15 ± 0.48 GPa, while in the SLM group, it equaled 9.06 ± 0.49 GPa. The friction coefficient of SLM alloys remained at approximately 0.46, but the CAST specimens fluctuated significantly. SLM alloys exhibited shallower wear scars and less wear debris compared with CAST alloys, simultaneously. Additionally, there were higher survival and expression of cell-adhesion-related genes on SLM alloys of L-929 cells, which meant that the deleterious effect on L-929 cells was significantly reduced compared with that for the CAST alloys. Overall, the wear resistances and biocompatibilities of the Co-Cr dental alloys were dramatically affected by the fabrication technique. The SLM technique is advantageous over the CAST technique for fabricating Co-Cr dental alloys.