In this study, the cytotoxicity of commonly used local anesthetics was evaluated on odontoblasts which are essential for pulpal homeostasis in vitro. Local anesthetics, such as articaine, bupivacaine, levobupivacaine, lidocaine, mepivacaine, prilocaine, and procaine, were tested on the odontoblast cell line, MDPC-23. The concentration-and time-dependent cytotoxic effects of local anesthetics on odontoblasts were measured by MTT assay. Among local anesthetics treated for 18 h, only bupivacaine significantly showed cell death in a concentration-($LC_{50}=1.2mM$) and time-dependent manner. To confirm cell death induced by bupivacaine, the observation of cell morphology and FACS using Annexin V and propidium iodide (PI) staining were performed. As a result of Annexin V and PI staining, as well as the morphological change, only bupivacaine induced apoptotic cell death on odontoblasts when compared with levobupivacaine and lidocaine. These results suggest that bupivacaine might affect normal pulpal integrity even after uneventful local anesthesia.

Cyclosporin A (CsA) plays an important role in clinical medicine and basic biology as an immunosuppressant and a mitochondrial permeability blocker, respectively. It was reported that CsA has a protective role by preventing apoptosis and promoting the proliferation in severed neurons. However, the molecular mechanisms for CsA-induced neuronal cell proliferation are unclear. In this study, we examined the mechanisms underlying the CsA-induced proliferation of PC12 cells. CsA increased the viability of PC12 cells in a dose(over $0.1{\sim}10\;{\mu}M$)-and time-dependent manner. The level of ROS generation was decreased in the CsA-treated PC12 cells. Expression of Bcl-2, an antiapoptotic molecule that inhibits the release of cytochrome c from the mitochondria into the cytosol, was upregulated, whereas Bax, a proapototic molecule, was not changed in the CsA-treated PC12 cells. CsA downregulated the mRNA expression of VDAC 1 and VDAC 3, but VDAC 2 was not changed in the CsA-treated PC12 cells. The level of cytosolic cytochrome c released from the mitochondria and the caspase-3 activity were attenuated in the CsA-treated PC12 cells. These results suggest that the mitochondria-mediated apoptotic signal and Bcl-2 family may play an important role in CsA-induced proliferation in PC12 cells.

It has been well known that excitatory amino acids, primarily glutamate, are involved in the transmission of nociception in pathological and physiological conditions in the spinal and brainstem level. Recently, peripheral glutamate also play a critical role in the peripheral nociceptive transmissions. The present study investigated the role of N-methyl-D-aspartic acid (NMDA) or non-NMDA ionotropic glutamate receptors in formalin-induced TMJ pain. Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Intra-articular injection was performed under halothane anesthesia. Under anesthesia, AP-7 (10, $100\;{\mu}M$, $1\;mM/20\;{\mu}L$), a NMDA receptor antagonist, or CNQX disodium salt (0.5, 5, 50, $500\;{\mu}M/20\;{\mu}L$), a non-NMDA receptor antagonist, were administered intra-articularly 10 min prior to the application of 5% formalin. For each animal, the number of behavioral responses, such as rubbing and/or scratching the TMJ region, was recorded for nine successive 5-min intervals. Intra-articular pretreatment with 1 mM of AP-7 or $50\;{\mu}M$ CNQX significantly decreased the formalin-induced scratching behavioral responses during the second phase. Intra-articular pretreatment with $500\;{\mu}M$ of CNQX significantly decreased the formalin-induced scratching behavior during both the first and the second phase. These results indicate that the intra-articular administration of NMDA or non-NMDA receptor antagonists inhibit formalin-induced TMJ nociception, and peripheral ionotropic glutamate receptors may play an important role in the TMJ nociception.

Periodontitis is a chronic infectious disease that leads to periodontal destruction, and is one of the major causes of tooth loss in humans. The osteoclast differentiation factor (ODF), which is also known as the receptor activator of the NF-kB ligand (RANKL), is a surface-associated ligand on bone marrow stromal cells and osteoblasts. RANKL activates its cognate receptor, RANK, on osteoclast progenitor cells, which leads to the differentiation of mononucleated precursor cells. Osteoprotegerin (OPG) is a decoy receptor that is released from stromal cells and osteoblasts to inhibit the interaction between RANKL and RANK. Although the precise mechanism of bone loss in periodontitis is unknown, the differentiation and activation of osteoclasts by OPG-ODF-RANK signaling might play the role in periodontal bone destruction. The relationship between the concentration of sex hormones and the expression of ODF and OPG was examined by treating human gingival fibroblasts and periodontal ligament cells with the normal serum concentration of estrogen or progesterone during menstruation or at menopause. The ODF/OPG relative ratio was elevated at the concentration observed during ovulation in human gingival fibroblasts and at the concentration observed between ovulation and menstruation in periodontal ligament cells treated with estrogen. However, the ratio was <1 at all concentrations in both cells treated with progesterone. In the case of menopause simulated by estrogen depletion, the ratio was <1 in human gingival fibroblasts but >1 in periodontal ligament cells.

The periodontal diseases and dental caries are major infectious diseases in oral cavity. Many of the preventive and therapeutic dental products contain the antimicrobial and anti-inflammatory components. But some of these antimicrobial have weak points such as coloration, burning sensation and insolubility in water. We have screened the therapeutic herbal extracts of the Plant Extract Bank for the antimicrobial activity on the major dental pathogens by growth inhibition assay. For the Porphyromonas gingivalis, 8 herbal extracts had an antimicrobial activity, 11 herbal extracts for the Prevotella intermedia, 43 herbal extracts for the Haemophilus actinomycetemcomitans and 61 herbal extracts for the Streptococcus mutans. Among these extracts, 6 herbal extracts had an antimicrobial activity for more than 3 species of dental pathogens. These extracts are Araliae Cordatae Radix, Crassirhizomae Rhizoma, Mori Radicis Cortex, Psoraleae Semen, Pini Ramulus and Sieges- beckiae Herba. All of effective extracts were CA group, ethanol extracts. Among these 6 herbal extracts, only Crassirhizomae is known to have a antibacterial effects. Therefore these herbal extracts have a possibility to be a candidate for a major antibacterial components in dental products.

Oral squamous carcinoma (OSC) is the most common malignant neoplasm of the oral mucosa. Although the etiology of OSC is not fully understood, accumulated evidences indicate that the activation of proto-oncogenes and the inactivation of tumor suppressor genes underlie the disease development. An OSC cell line, YD-9 was newly established and characterized. However, the mutational analysis of p53 gene was not performed. Thus, in this study, the presence of mutation in the p53 gene was examined by amplification of exon-4 to -8 and subsequent DNA sequencing. Two point mutations were found in exon-4 and -6: A to G, resulting in amino acid change Tyr to Cys in exon-4, and C to G, resulting in amino acid change Gly to Arg in exon-6, respectively. Any mutation was not found in the exon-5, -7 and -8. The presented results would contribute to basic research to understand the biological mechanism of OSC using YD-9 cells.