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We have previously fabricated hydroxyapatite (HAP) nanoparticle-assembled powder (nano-HAP) plates and granules by assembling low-crystallinity HAP nanoparticles without template/binder molecules or high-temperature/pressure treatments. In this study, we combined the nano-HAP with fibroblast growth factor (FGF) 2, which promotes odontoblast differentiation, and used this as a pulpcapping agent for dentin defects created in rat molars. The tissue response was then radiologically and histologically assessed at 1 and 2 weeks after capping, to assess the biocompatibility and ability of this material to promote hard tissue formation. The application of nano-HAP/FGF2 induced the invasion of dental pulp cells and vessels, and was consistently found to stimulate formation of a dentinal bridge containing numerous dentinal tubules. We thus succeeded in treating the pulp exposure by using a physiological approach to promote tissue regeneration. Further investigations should be performed to explain exactly how the nano-HAP/FGF2 combination contributes to calcified tissue formation. [ABSTRACT FROM AUTHOR]

Orthodontists use a self-etching adhesive system when attaching brackets, to enamel. The purpose of this study was to evaluate the erosion effects of common clinically used adhesive systems on human enamel surfaces by atomic force microscopy (AFM). Four commercially available adhesive systems (i.e., Kurasper F, Beauty Ortho Bond, Orthophic LC, and Transbond XT) were applied to ground enamel surfaces of extracted human teeth. Enamel surface roughness (ESR), absolute depth profile (ADP), and surface hardness were evaluated by AFM. The ESR and ADP were significantly higher after the pretreatment with the phosphoric acid-etching adhesive system than after the pretreatments with the three self-etching adhesive systems. The surface nanohardness decreased after the pretreatment with the phosphoric acid-etching adhesive system but increased after the pretreatments with the self-etching adhesive systems. These results suggest that the use of a self-etching primer for enamel conditioning might prevent decalcification caused by phosphoric acid etching. [ABSTRACT FROM AUTHOR]

Surface modification of titanium has been extensively investigated in implant science and technology in an effort to improve its osteoconductivity. The rate of protein adsorption on titanium surfaces is known to vary depending on the chemistry, structure, morphology, and titanium-specific biological aging of the surface. It is thus desirable to modify smooth titanium surfaces of mini-implants used as orthodontic anchors immediately prior to use. In this study, we have developed a simple surface modification of titanium alloy that improves its biofunctional activity. The surface of a Ti-6A1-4V disk was modified by applying 3% H2O2 hydrothermal treatment using an autoclave. A nanostructured porous network TiO2 was observed on the treated surface. Treated surfaces exhibited higher hydrophilicity, protein adsorption, and cell proliferation than untreated surfaces. 3% H2O2 hydrothermal treatment is thought to provide biofunctional activity for aged titanium surface. [ABSTRACT FROM AUTHOR]

We evaluated the effects on bone formation of combining synthesized collagen model polypeptides consisting of a Pro-Hyp-Gly [poly(PHG)] sequence and alpha-tricalcium phosphate (α-TCP) particles with various median sizes (large: 580.8 μm; small: 136.2 μm; or large and small mixed: 499.3 μm) in a skull defect model in mini-pigs. Quantitative image analyses for the volume density (VD) of new bone revealed that the VD in each α-TCP group was significantly higher than that in the poly(PHG) control group, with the mixed group showing the highest VD among all the groups at 4 weeks after implantation. Histological assessments revealed that the small α-TCP particles were almost completely degraded at 8 weeks. At 12 weeks, all sizes of α-TCP particles were completely degraded and remodeling of the lamellar bone was observed. The present findings suggest that particle size may influence the success of bone formation in defects. [ABSTRACT FROM AUTHOR]

To date, there has been no study on the development of novel regimens based on the following tissue engineering principles: seeding and culturing mesenchymal stem cells (MSCs) on a scaffold before surgery or injecting cultured MSCs into a scaffold during surgery. The purpose of this study was to assess the in viuo osteogenic ability of scaffold/MSCs implanted beneath the periosteum of the cranial bone of rats in three different sample groups: one in which MSCs were pre-seeded and cultured on a scaffold to produce the 3-D woven fabric scaffold/MSC composite using osteo-lineage induction medium, one in which cultured MSCs produced by osteo- lineage induction in cell cultivation flasks were injected into a scaffold during surgery and a control group, in which only the 3-D woven fabric scaffold was implanted. The results indicate that pre-seeding MSCs on a scaffold leads to a higher osteogenic ability than injecting cultured MSCs into a scaffold during surgery. [ABSTRACT FROM AUTHOR]

In the current study, we examined the cytocompatibility of eight vinyl esters as candidate plasticizers for producing phthalate- and ethanol-free tissue conditioners. We measured the estrogenic activity and cytotoxicity of vinyl esters in human fibroblasts and keratinocytes using an E-screen assay and a mitochondrial dye conversion assay, respectively. We also assessed the cytotoxicity of three prototype materials and commercially available tissue conditioners on human fibroblasts grown in collagen gels. Finally, we measured the effects of these materials on the expression of cytokines in three-dimensional cultures by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assays. None of the tested vinyl esters had estrogenic activity. Vinyl octanoate and vinyl pivalate were the least cytotoxic of the eight tested vinyl esters. In the same vein, a prototype tissue conditioner containing vinyl octanoate had equivalent or weaker cytotoxicity and induction of cytokine expression than conventional materials. [ABSTRACT FROM AUTHOR]

Synthetic biomaterials have been developed and used for bone grafting. Here, we developed a biodegradable sponge composite for bone tissue engineering by combining β-tricalcium phosphate (β-TCP) and collagen. In addition, we sought to determine the optimal β-TCP granules/collagen ratio by evaluating and bone formation in vivo. Porous β-TCP granules were mixed with atelocollagen hydrochloride solution at various ratios -- 0.02, 0.05, 0.1, and 0.2 g/mL. The resultant mixtures were freeze-dried and subjected to dehydrothermal treatment in vacuo. The final composites obtained were designated β-TCP/collagen sponge composites (β-TCP/CS). Through compression testing, it was found that the stress values for β-TCP/CS (0.2 g/mL) were higher than those of the other three composites over the whole strain range. Histological evaluation at four weeks after implantation revealed that the collagen sponge had degraded and newly formed bone was present on the surface of the β-TCP granules. At 12 weeks, the β-TCP granules were completely degraded and remodeling of the lamellar bone was observed. [ABSTRACT FROM AUTHOR]