A surface pre-reacted glass-ionomer (S-PRG) fillers have been used for incorporation into a variety of dental materials. Owing to their diverse applications, it is important to evaluate their biological safety under various test conditions. This study evaluated the cytotoxic effect of exposure to various concentrations of S-PRG fillers or their eluates in RAW264 cells employing cytotoxic assays and morphological observation using a transmission electron microscope. No cytotoxic effects were found in the presence of the eluates under all concentrations tested, whereas the direct exposure of higher concentrations of S-PRG fillers to RAW264 cells showed cytotoxicity. By microscopic observations, S-PRG fillers or their depositions were found in the cells or nuclei. These findings indicated that the eluates from the S-PRG fillers exerted no influence on cytotoxicity of the RAW264 cells. Although the direct exposure of the S-PRG fillers to the cells resulted in cytotoxicity due to endocytosis, filler eluates possessed no cytotoxicity. Thus, cytotoxicity of the S-PRG fillers depends on the conditions of the exposed fillers.

Alzheimer's disease is a progressive brain disorder that affects areas of the brain that control cognitive functions and memory, and the number of patients in Japan is increasing. It is important for dentists to improve the oral quality of life of Alzheimer's patients, but for that, it is necessary to know the pathology of Alzheimer's disease. In this study, we examined the effects of Alzheimer's disease on the initial adhesion of bone marrow cells and the ability to induce hard tissue differentiation. Bone marrow mesenchymal cells extracted from the femurs of 7-week-old SAM mice and C57BL / 6 mice were seeded on titanium surface. When various markers related to the initial adhesion of bone marrow cells and the ability to induce hard tissue differentiation were examined, SAM mice showed low values ​​at all measurement times. In addition, strong expression of TNF-α was observed in bone marrow cells of SAM mice seeded on titanium surface.In conclusion, it was revealed that when the bone marrow cells of the Alzheimer model mouse were seeded on titanium surface, the initial adhesion and the ability to induce hard tissue differentiation were reduced, and the hard tissue formation was inhibited.

Secure removal of remnants on tooth surfaces by rotary cutting instruments after an orthodontic treatment could be guaranteed if the orthodontic adhesive used is highly visible. Fluorescent imaging is a potentially effective solution for increasing the visibility of orthodontic adhesives. In this study, Y₂O₃:Eu³⁺ nanoparticles were synthesized by a homogeneous precipitation method followed by firing at 1,000 °C. The size of most of the synthesized nanoparticles was approximately 200 nm in diameter. The photoluminescence properties of the nanoparticles were similar to that of the typical 4f-4f transition of Eu³⁺. Regardless of the concentration of the particle, the nanoparticles were almost uniformly dispersed and remained in their polymerized bodies without deteriorating the intrinsic flexural modulus of the dimethacrylate resin. Although the fluorescence of the 10 wt%-phosphor-containing resins was adequately recognizable to the naked eye, it was suggested that the preferred concentration of Y₂O₃:Eu³⁺ nanoparticles should be more than 10 wt% in terms of fluorescence intensity.

To examine the biosafety of nano- and submicron-materials, the biological effects of MWCNTs, for which human carcinogenicity is of concern, similar to asbestos, and carbon black, the most commonly used nanomaterial, on mouse-derived fibroblast Bulb/c 3T3 cells were examined by the LDH and MTT methods using three-dimensional culture with collagen. The dose-dependent effects of MWCNTs on cell viability were demonstrated by LDH methods. On the other hand, the dose-dependent effects of carbon black were confirmed by the LDH method but not significantly by the MTT method.

In the future, the safety of other nanomaterials should be evaluated in an in vitro system more closely reflecting the human body.

Three-dimensional culture has been utilized as an experimental system simulating an in vivo environment to evaluate the biosafety of dental materials. In the present study, cell viability was examined for various commercially available denture base lining materials, widely used in the field of dental prosthesis, and platinum nanocolloid-containing dentifrices, with antioxidative and antibacterial properties, in three-dimensional culture with collagen gel to examine the cellular effects of the materials. As a result of comparison of 6 samples, prepared from various commercially available denture base lining materials, immediately and at 24 hours after mixing, cell viability was markedly lowered with a photopolymerizable acrylic resin material, although there was little difference in the other experimental groups. Furthermore, platinum nanocolloid-containing dentifrices showed no significant decrease in cell viability with a stock solution and all the test solutions of different dilution rates.

The field of regenerative medicine has recently made marked advances in stem cell research. Adult stem cells, called somatic or tissue stem cells that can only be differentiated into limited cell types have been generally used for regenerative medicine. However, with the development of iPS cells, tissues and cells of interest will be artificially generated and implanted into patients to repair sites of damage. In the present study, technical objectives for this purpose are summarized.

Furthermore, studies on cell adhesion have demonstrated that the surface morphology of materials influences cell differentiation and proliferation. The influence of intelligent material surface structures and nanomaterials on cell differentiation has been greatly highlighted. The artificial materials and regeneration are being investigated for regenerative medicine in the field of dentistry.