Rat dental pulp RPC-C2A cells, established and kindly provided by Kasugai et al. (1988), were maintained in minimum essential medium (MEM, Invitrogen, Carlsbad, CA, USA) supplemented with 10% heat-inactivated fetal bovine serum (FBS) and 10 mg/mL kanamycin at 37°C in a humidified atmosphere at 5% CO 2 with 20% O 2 . As hypoxic conditions, cells were cultured in a humidified atmosphere at 5% CO 2 with 2% O 2 . Cell Proliferation AssayCells were seeded in 96-well plates at a density of 5 x 10 4 cells/well and cultured for 24 hrs, and then further cultured for an additional 6, 12, or 24 hrs under normoxic or hypoxic conditions. Cell viability was measured by water-soluble tetrazolium salt (WST-1) reduction activity, with a cell counting kit (Dojindo, Kumamoto, Japan). WST-1 was added at a final concentration of 0.5 mM and ABSTRACT AMP-activated protein kinase (AMPK) is a stressresponsive enzyme involved in cell adaptation to an energy crisis. We hypothesized that hypoxia suppresses oxidative phosphorylation and ATP production, resulting in AMPK activation to protect cells. We investigated the effects of hypoxia on cell proliferation, the expression of AMPK and hypoxia-inducible factor 1␣ (HIF-1␣), the activation of AMPK, and the relationship between AMPK and HIF-1␣ expression in rat dental pulp RPC-C2A cells. AMPK in the cells was composed of catalytic ␣1, and regulatory ␤1 and ␥1 subunit isoforms. Cell proliferation was initially suppressed under hypoxia, but it increased thereafter, together with an increase in the expression of AMPK and HIF-1␣, and the activation of AMPK. Down-regulation of AMPK␣1 by siRNA inhibited cell proliferation under both normoxia and hypoxia, revealing that AMPK induction and activation were required for cell proliferation, although HIF-1␣ expression under hypoxia was not affected.

The microflora in the periodontal pockets can affect the dental pulp and cause endodontic-periodontal lesions or retrograde pulpitis. Here we report an endodonticperiodontal lesion together with its bacterial profile. The lesion occurred in the maxillary right first molar of a 40-year-old woman who presented at our hospital complaining of a violent toothache since the previous night. Clinically, the tooth was caries-free and an electric pulp test showed it to be vital. The tooth showed signs of advanced periodontitis and the periodontal pocket was deep, reaching the apex of the palatal root. The clinical diagnosis was an endodontic-periodontal lesion with primary periodontal disease. Subsequent endodontic treatment comprised pulp extirpation and root canal filling, followed by periodontal treatment consisting of scaling and root planing. The tooth was finally restored with a full metal crown. No further signs of periodontal disease or periapical lesions have been observed to date. Bacteria were sampled from the root canal and periodontal pocket for a microbiological assessment using 16S rRNA gene-based PCR. Microbiologically, the profile of the bacterial species from the palatal root canal was similar to that from the periodontal pocket of the palatal root. Porphyromonas gingivalis, Fusobacterium nucleatum and Eikenella corrodens were detected in both samples. The occurrence of bacteria common to both sites in this patient further supports the proposition that periodontal disease is the definitive source of root canal infections. The present results suggest that a bacterial examination would be helpful in confirming and supporting the clinical diagnosis in such lesions.

This study evaluated the wear resistance and sealing property of endodontic temporary restoratives by means of functional stressing using a wear simulator. The pulp chamber of 28 extracted molars was opened and filled with cotton, and then the cavity was filled with a temporary material -Caviton, Temporary Pack, Neodyne-α, or TERM. Specimens were subjected to a wear test, and data for wear and dye penetration were analyzed by one-way ANOVA independently（p＜0.05） . Wear values of Neodyne-α（0.09±0.05 mm）and TERM（0.24±0.06 mm）were significantly less than those of Caviton（1.79±0.15 mm）and Temporary Pack（1.02±0.40 mm） . In terms of dye penetration, Neodyne-α leaked significantly less than the other materials at 0.40±0.32 mm. On the other hand, there were no significant differences between TERM（1.30±0.57 mm）and Temporary Pack（2.10±0.12 mm） , and between Caviton（2.60±0.41 mm）and Temporary Pack.

Calcium deposited within a root canal due to exogenous stimuli may hamper root canal treatment. In endodontic treatment, an operating microscope allows the conditions within the root canal to be directly viewed and evaluated. This report describes a case in which an operating microscope was used to facilitate the excision of a calcified structure from within a root canal at an early stage in the treatment of an infection. An 18-year-old man was referred to our clinic due to suspected chronic suppurative apical periodontitis of the right maxillary central incisor. Periapical radiography confirmed the presence of a radioopaque structure inside the root canal that was likely to pose an obstacle to endodontic treatment. After opening the pulp chamber, an operating microscope was used to directly confirm the presence of the calcified structure in the root canal, which was removed using an ultrasonic tip. The infected root canal was treated using calcium hydroxide. Two months later, closure of the apical foramen as a result of calcification of the apical foramen was confirmed and the root canal filled. Using an operating microscope to directly view a structure posing an obstacle to root canal treatment made it possible to perform an excision while avoiding risks such as canal perforation.

Recently, optical microscopes have been used in endodontic treatment, as they offer advantages in terms of magnification, illumination, and documentation. Documentation is particularly important in presenting images to patients, and can take the form of both still images and motion video. Although high-quality still images can be obtained using a 35-mm film or CCD camera, the quality of still images produced by a video camera is significantly lower. The purpose of this study was to determine the potential of RegiStax in obtaining high-quality still images from a continuous video stream from an optical microscope. Video was captured continuously and sections with the highest luminosity chosen for frame alignment and stacking using the RegiStax program. The resulting stacked images were subjected to wavelet transformation. The results indicate that high-quality images with a large depth of field could be obtained using this method.