High-power light-curing units have emerged that reduce the time of procedures in dental clinical work. However, patients sometimes complain of pain during the polymerization of composite resin. In this experiment, we investigated how differences in light-curing mode affect the temperature rise during composite resin polymerization in vitro. Light-curing mode conditions were divided into four groups: 3 s in plasma mode (Plm3) and 5, 10, and 20 s in standard mode. The temperature curve under Plm3 exhibited a rapid increase during the first 3 s of light curing before reaching a maximum of around 55°C. In contrast, the temperature rose rapidly but less sharply for irradiation in each standard mode compared with Plm3. These results suggest that irradiation using a high-power mode increases the temperature at an excessively high rate, and this may raise concern about side effects on the pulp.
Successful regeneration of tissues and organs relies on the application of suitable substrates or scaffolds in scaffold-based regenerative medicine. In this study, Ti-6Al-4V alloy films (Ti alloy film) were produced using a three-dimensional printing technique called Selective Laser Melting (SLM), which is one of the metal additive manufacturing techniques. The thickness of produced Ti alloy film was approximately 250 μm. The laser-irradiated surface of Ti alloy film had a relatively smooth yet porous surface. The non-irradiated surface was also porous but also retained a lot of partially melted Ti-6Al-4V powder. Cell proliferation ability of mouse fibroblast-like cells (L929 cells) and mouse osteoblast-like cells (MC3T3-E1 cells) on both the surfaces of Ti alloy film was examined using WST assay. Both L929 and MC3T3-E1 cells underwent cell proliferation during the culture period. These results indicate that selective laser melting is suitable for producing a cell-compatible Ti-6Al-4V alloy film for biomaterials applications.
The physical characteristics and biological compatibility of surfaces produced by electron beam melting (EBM) are not well known. In particular, there are not many reports on biocompatibility qualities. In this study, pure Ti films were manufactured using EBM. While it is reported that moderately hydrophilic biomaterial surfaces display improved cell growth and biocompatibility, contact angle measurements on the EBM-produced pure Ti films showed slight hydrophobicity. Nonetheless, we found the cell count of both fibroblast-like cells (L929) and osteoblast-like cells (MC3T3-E1) increased on pure Ti films, especially the MC3T3-E1, which increased more than that of the control. In addition, the morphology of L929 and MC3T3-E1 was polygonal and spindle-shaped and the cytoskeleton was well developed in the pure Ti surface groups. Upon staining with Alizarin red S, a slight calcium deposition was observed and this level gradually rose to a remarkable level. These results indicate that pure Ti films manufactured by EBM have good biocompatibility and could be widely applied as biomedical materials in the near future.
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