Overexpression of receptor for advanced glycation end products and high-mobility group box 1 in human dental pulp inflammation.

High mobility group box 1 (HMGB1), a nonhistone DNA-binding protein, is released into the extracellular space and promotes inflammation. HMGB1 binds to related cell signaling transduction receptors, including receptor for advanced glycation end products (RAGE), which actively participate in vascular and inflammatory diseases. The aim of this study was to examine whether RAGE and HMGB1 are involved in the pathogenesis of pulpitis and investigate the effect of Prevotella intermedia (P. intermedia) lipopolysaccharide (LPS) on RAGE and HMGB1 expression in odontoblast-like cells (OLC-1). RAGE and HMGB1 expression levels in clinically inflamed dental pulp were higher than those in healthy dental pulp. Upregulated expression of RAGE was observed in odontoblasts, stromal pulp fibroblasts-like cells, and endothelial-like cell lining human pulpitis tissue. Strong cytoplasmic HMGB1 immunoreactivity was noted in odontoblasts, whereas nuclear HMGB1 immunoreactivity was seen in stromal pulp fibroblasts-like cells in human pulpitis tissue. LPS stimulated OLC-1 cells produced HMGB1 in a dose-dependent manner through RAGE. HMGB1 translocation towards the cytoplasm and secretion from OLC-1 in response to LPS was inhibited by TPCA-1, an inhibitor of NF-κB activation. These findings suggest that RAGE and HMGB1 play an important role in the pulpal immune response to oral bacterial infection.

Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms.

OBJECTIVE: To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. METHODS: The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. RESULTS: All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5-3.0 µm) and more uniformly shaped than AgZ. CONCLUSIONS: Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

In vitro antifungal activities of longan (Dimocarpus longan Lour.) seed extract.

Longan, Dimocarpus longan Lour., contains polyphenolic compounds which exhibit several pharmacological properties. This study aims to evaluate antifungal activities of longan fruit extract in comparison to its active compounds. The results showed that longan seed exhibited antifungal activity against the opportunistic yeasts (Candida species and Cryptococcus neoformans). In contrast, longan pulp and whole fruit did not demonstrate any inhibitory effects. Ellagic acid showed the most potent antifungal activity followed by corilagin and gallic acid, respectively. Ellagic acid inhibited Candida parapsilosis and C. neoformans more effectively than Candida krusei and also some Candida albicans clinical strains. Baidam cultivar possessed higher antifungal activity (MIC=500-4000 µg/ml) as it contained higher contents of ellagic acid and gallic acid than Edor (MIC=1000-8000 µg/ml). For antibacterial activity, only corilagin and gallic acid possessed weak to moderate inhibitory effects against Staphylococcus aureus and Streptococcus mutans, respectively. Longan seed was then applied in the oral care products. Longan effervescent granule (5% extract) significantly reduced adhesion of C. albicans to acrylic strips. Mouthwash containing 0.5% extract exhibited good antifungal activity compared to a commercial product. These findings indicated that longan seed extract and its polyphenolic compounds can be used as an antifungal agent in oral care products for the treatment of opportunistic yeast infection.

Potential induction of bone regeneration by nacre: an in vitro study.

PURPOSE: Because of limitations of autogenous grafts, alternative bone substitute material was investigated for its capacity in promoting bone formation. This study compared the osteogenic effects of nacre (mother of pearl) and beta-tricalcium phosphate (ß-TCP). MATERIALS AND METHODS: Human bone cells (HBCs) were obtained from the culture of bone tissues after orthognathic surgery. The HBCs were cocultured with nacre chips of the giant oyster Pinctada maxima and with ß-TCP particles for 1, 2, 3, and 4 weeks. Cells of each week specimens were used to study alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OC) gene expression by noncompetitive reverse-transcriptase polymerase chain reaction and to study BSP synthesis by means of an immunocytochemical technique in conjunction with fluorescent microscopy. RESULTS: Reverse-transcriptase polymerase chain reaction demonstrated stronger expression levels of ALP mRNA in HBCs cocultured with the nacre chips than those with ß-TCP at weeks 2 and 4. BSP gene expression levels in HBCs with nacre were more intense compared with ß-TCP at weeks 3 and 4. Although the OC gene expression level in HBCs with ß-TCP was higher than those with nacre at week 2, the expression was not different at weeks 3 to 4. Immunocytochemical study revealed that BSP synthesis were presented in the nacre and ß-TCP from week 2 and decreased toward week 4. CONCLUSION: This study indicated that nacre promotes ALP, BSP, and OC gene expression.

Antimicrobial activity of Cratoxylum formosum on Streptococcus mutans.

The gum of Cratoxylum formosum, commonly known as mempat, is a natural agent that has been used extensively for caries prevention by hill tribe people residing in Thailand. The objective of this study was to investigate the antimicrobial activity of Cratoxylum formosum gum on Streptococcus mutans (S. mutans) in vitro. The gum extracted from stem bark of Cratoxylum formosum was investigated for antimicrobial activity against different strains of S. mutans, including S. mutans KPSK2 and 2 clinical isolates. Inhibition of growth was primarily tested by agar diffusion method. A two-fold broth dilution method was then used to determine the minimum inhibitory concentration (MIC) of the extract. The extract of Cratoxylum formosum was effective against S. mutans with the inhibition zones ranging from 9.5 to 11.5 mm and MIC values between 48 microg/ml and 97 microg/ml. The gum of Cratoxylum formosum has high antimicrobial activity against S. mutans and may become a promising herbal varnish against caries.

Long term follow-up of reconstruction with allogeneic mandibular bone crib packed with autogenous particulate cancellous bone marrow.

Allogeneic mandibular bone processed by the deep frozen method was used as a biologic crib for mandibular reconstruction. The allogeneic mandible is biocompatible, bioresorbable, of low antigenicity and provides the morphology for symphysis contour, angle of mandible and dental arch form. The particulate cancellous bone marrow (PCBM) contains marked osteogenic potential of hematopoietic marrow, which promotes osteogenesis. The cancellous marrow graft lacks structure and requires a crib to house it during the bone regeneration to the consolidation phase. Fresh frozen mandible was hollowed out for packing with PCBM prior to securing it to the defect by a rigid fixation method. Four cases of large mandibular defects resulting from treatment of benign odontogenic tumors were reconstructed utilizing this technique. All cases showed excellent facial contour and function satisfactorily in mastication and pronunciation. Complete graft incorporation and restoration of the osseous continuities were observed for four to 12 years after the operation.