Inflammatory cytokines such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were previously shown to be secreted in pulpitis tissue during the caries process. Matrix metalloproteinases (MMPs) such as MMP-1, -2, -3, and -14 were also shown to be expressed in inflamed dental pulp. MMP-3 activates other MMPs. MMP-1 and MMP-3 can degrade the extracellular matrix (ECM). Dental pulp destruction may be regulated, in part, by MMP-1, and MMP-3 activated by MMP-3 has been shown to regulate the degradation and regeneration of dental pulp. In this study, we tested an activator and an inhibitor of Wnt/β-catenin signaling to regulate IL-1β and TNF-α -induced production of MMP-1 and MMP-3 in human dental pulp fibroblasts cells (HPFs). We demonstrated that MMP-1 and MMP-3 were produced from HPFs in response to TNF-α in a Wnt/β-catenin signaling -dependent manner. These results suggest that a Wnt/β-catenin signal regulating drug may have utility for dental pulp tissue regeneration.
The effect of controlled photothermal stimulation on new bone formation ability using a calvarial defect model in rats over 40 weeks old was evaluated. Photothermal stimulation was carried out using a photothermal device composed of an alginate-gel-containing carbon nanotubes (CNT-Alg gel) and an irradiator supplying near-infrared light. Photothermal stimulation (42°C, 15 min) was repeated every day for up to 3 months to assess the effect of thermal stimulation on bone healing of defects treated with commercially available collagen sponge. Photothermal stimulation accelerated bone regeneration with collagen sponge treatment compared with treatment without photothermal stimulation. There were no significant differences in microhardness values between the newly formed bone, with or without photothermal stimulation. Microhardness measurement revealed that the regenerated bones were sufficiently mature. The results of this study suggested that photothermal stimulation enhanced bone regeneration induced by expression of heat shock-related molecules.
Apatite crystals include both natural apatite crystals and biological apatite crystals. We analyzed the difference between natural apatite crystals and biological apatite crystals to investigate the possibility of using natural apatite crystals as a standard sample of quality of biological hard tissues. By EPMA analysis and the X-ray diffraction method, natural apatite crystal samples were shown to be fluorapatite. On the microscopic by Raman spectroscopic analysis method, the four Raman bands of the phosphate were also confirmed in the natural apatite crystals, the enamel apatite crystals, and the mandible apatite crystals. In natural apatite crystals, the Raman band of 964 - 965 cm-1 shifted to the higher wavelength side compared to the biological apatite crystal. In the mandible, the difference of apatite crystal orientation was observed due to the site of cortical plate and trabecular bone.
This study was designed to examine the effects of transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) on bone formation using a bioabsorbable scaffold at palatal subperiosteal sites in rats.
Alginate gel containing TGF-β1 (0.0 or 0.1 μg /μL) and BMP-2 (0.0 or 0.1 μg /μL) were used for implantation, and experimental sites were divided into four groups according to the cytokines contained in the scaffold: TGF group (TGF-β1), BMP group (BMP-2), TGF+BMP group (TGF-β1 and BMP-2) and Control group.
Four weeks after implantation, thickness of new bone (TNB) was significantly higher in TGF group and BMP group than in Control group (P<0.05). There was no significant difference in TNB between TGF group and BMP group (P>0.05).
On the other hand, TNB was significantly higher in TGF+BMP group than in TGF group and BMP group (P<0.05).
These results suggest that TGF-β1 and BMP-2 contained in alginate gel have interactive effects on bone formation in the case of palatal subperiosteal sites.