RESUMEN
BACKGROUND: Volatile sulfur compounds (VSCs) produced inside the mouth are a well-known cause of halitosis. Recent studies have suggested that VSCs modify the pathology of periodontitis by encouraging the migration of bacterial toxins associated with increased permeability of gingival epithelia, and enhancing the production of matrix metalloproteinases in gingival connective tissue. Nonetheless, the effects on the enamel of direct exposure to VSCs within the oral cavity remain unclear. In the present study, we observed the effects of VSCs in the form of hydrogen sulfide (H2S) on enamel surfaces and determined their effects on restorations. MATERIALS AND METHODS: Extracted human tooth and bovine tooth samples were divided into the H2S experimental side and the control side. We observed the effects of H2S on enamel surfaces using electron microscopy and conducted a shear test. RESULTS: We found that exposure to H2S obscured the enamel surface's crystal structure. The surface also exhibited coarseness and reticular changes. Shear testing did not reveal any differences in bond strength. CONCLUSIONS: Our findings suggested that H2S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations.
RESUMEN
We isolated adherent fibroblastic cells after collagenase and dispase treatment of human dental pulp. When human dental pulp cells (hDPCs) were cultured in the presence of basic fibroblast growth factor (bFGF), the ratio of hDPCs in the S-phase was significantly higher in comparison with incubation without bFGF. The ratio of hDPCs expressing STRO-1 as a marker of stem cell populations increased approximately eightfold in the presence of bFGF as opposed to that in the absence of bFGF. We demonstrated the characterization and distinctiveness of the hDPCs and showed that, when cultured with the medium containing serum and bFGF, they were highly proliferative and capable of differentiating in vitro into osteoblasts, chondrocytes, and adipocytes. Furthermore, the in vitro differentiation was confirmed at both the protein and gene expression levels. Transplantation of hDPCs -- expanded ex vivo in the presence of bFGF into immunocompromised mice -- revealed the formation of bone, cartilage, and adipose tissue. The donor hDPC-derived cells were labeled in the bone tissues located near the PLGA in the subcutaneous tissues of recipient mice using a human-specific Alu probe. When cultured with a serum-free medium containing bFGF, the hDPCs strongly expressed STRO-1 immunoreactive products and sustained self-renewal, and thus were almost identical in differentiation potential and proliferation activity to hDPCs cultured with the medium containing serum and bFGF. The present results suggest that the hDPCs cultured in the presence of bFGF irrespective of the presence or absence of the bovine serum are rich in mesenchymal stem cells or progenitor cells and useful for cell-based therapies to treat dental diseases.