Aquaporins (AQPs) are a family of small integral membrane proteins made up of 6 hydrophobic, a-helical, membrane-spanning domains surrounding a highly selective aqueous pore. AQP3, AQP7, and AQP9, termed aqua-glyceroporins, are known to be involved in the transport of water, glycerol, and other small molecules. In this study, we investigated the expression and localization of aqua-glyceroporins in rat oral stratified squamous epithelia of the palate, the buccal mucosa, the inferior aspect of the tongue, and the oral floor by using RT-PCR, immunofluorescence, and immunogold electron microscopy. AQP3 and AQP9 mRNAs were expressed in whole oral epithelium. Immu-nostaining for AQP3 was recognized in each type of epithelium. The results suggest that AQP3 synthesis begins predominantly in the cytoplasm of the basal cells. During the process of epithelial cell differentiation, AQP3 protein appears to accumulate and be transported to the plasma membrane, from where it is incorporated into the cornified or surface layers. The intracellular localization of AQP3 appears to correlate with the differentiation of keratinocytes, suggesting that it acts as an enhancer of the physiological permeability barrier together with membrane coating granules. The distribution pattern of AQP9 was limited to the marginal areas of the basal and suprabasal layers, which was different from that of AQP3. This difference in distribution between AQP3 and AQP9 suggests that AQP9 in rat oral epithelia acts as a channel by facilitating glycerol uptake from the blood through the endothelial cells of the capillary vessels to the oral stratified squamous epithelium. AQP3 and AQP9 facilitate both transcellular osmotic water flow and glycerol transport as pore-like passive transporters in the keratinocytes of oral epithelia, and may play a key role in not only hydration and the permeability barrier, but also cell proliferation, differentiation, migration, development, and wound healing by generating ATP.

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The purpose of this study was to investigate the effect of type of rubber dam and application method on the moisture exclusion effect. The intraoral temperature and relative humidity were compared among various moisture exclusion appliances. Various dry field techniques were applied to 5 subjects and intraoral temperature and relative humidity measured 5 min after placing a digital hygro-thermometer in the mouth. The relative humidity was 100% in all subjects when moisture was excluded by means of cotton rolls alone. When only tooth 36 was exposed, relative humidity was significantly lower with latex, urethane, or 3-dimensional sheets than with cotton rolls alone, and was similar to the level of humidity in the room. When a local rubber dam was used, the relative humidity was significantly higher than the indoor humidity (p <0.05). No significant differences were noted in the intraoral temperature or relative humidity between exposure of 4 teeth and 1 tooth, but variation in the relative humidity was more marked in 4- than in 1-tooth exposure. The creation of an air vent did not influence the moisture exclusion effect. These results suggest that the rubber dam isolation technique excludes moisture to a level equivalent to the humidity in the room when only a single tooth is exposed, but the moisture exclusion effect may be inconsistent when several teeth are exposed.

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A new semi-quantitative enumeration system has been developed for the detection of Streptococcus mutans in saliva. Using two kinds of species-specific monoclonal antibodies, this system can quickly detect salivary S. mutans within 30 min and classify the results into three levels. The aim of this study was to evaluate the potential of this test kit in determining risk for the development of caries. Saliva samples collected during a compulsory dental examination from 56 children aged 18-months were tested. The children were classified into 3 groups according to the level of salivary S. mutans determined. After 18 months, 36 of the children underwent a second examination to investigate whether there was a correlation between salivary S. mutans level at the first examination and subsequent increment in caries. The results showed a good correlation between the two. This indicates that salivary S. mutans level before the window of infection is an indicator of caries risk and can be quickly detected using this test kit. This rapid test should be particularly useful in assessing risk of future caries in very young children.

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Mucoepidermoid carcinomas in the minor salivary glands usually originate in the palatine gland, and their occurrence in the retromolar region is rare. We report a rare case of mucoepidermoid carcinoma with clear cell components occurring in the retromolar region. The patient was a 63-year-old woman referred to our hospital with the chief complaint of a painless mass in the right retromolar region initially found during treatment at a local dental clinic. The 20×10-mm mass was well-defined, elastic, and flexible. The surface of the mucosa was healthy. The mass was clinically diagnosed as a gingival benign tumor in the right retromolar region. There were no significant findings in the patient's medical history. The tumor was resected under local anesthesia. Histopathology revealed that squamoid cells, undifferentiated intermediate cells, and clear cells were dominant, with mucus-producing cells in some areas. A mucoepidermoid carcinoma with clear cell components was diagnosed. There were no signs of recurrence or metastasis at 15 months postoperatively and the patient's progress has been satisfactory. Because the tumor was a painless, slow-growing mass, it was clinically diagnosed as a benign tumor of the gingiva, and resection was performed under local anesthesia without performing a biopsy. However, even if a mass in the retromolar region is clinically diagnosed as a benign tumor, the course of treatment should be decided after performing fine-needle aspiration cytology, taking into consideration the possibility of mucoepidermoid carcinoma.

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The microflora in the periodontal pockets can affect the dental pulp and cause endodontic-periodontal lesions or retrograde pulpitis. Here we report an endodontic-periodontal 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.

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While osteomas often occur in the orofacial area, it is relatively rare for one to occur in the temporomandibular joint area. Here, we report a patient who underwent multidisciplinary treatment including high condylectomy for peripheral osteoma arising in the left mandibular condyle. The patient was a 46-year-old woman with the chief complaint of facial asymmetry. Cephalometric analysis revealed skeletal anterior crossbite due to anterior deviation of the mandible, with chin deviation of 10 mm to the right. A computed tomography scan revealed bone hyperplasia in the mesiodistal and inner areas of the left mandibular condyle, which exhibited outward anterior displacement. Bone scintigraphy showed a circular area of strong radioisotope accumulation with indistinct boundaries, consistent with the lesion in the left mandibular condyle. The above findings led to a diagnosis of skeletal mandibular prognathism with facial asymmetry due to peripheral osteoma originating in the left mandibular condyle. After orthodontic treatment and surgical resection of the tumor and mandibular condyle, preservation and prosthetic treatment were undertaken. A well-balanced facial appearance and good occlusion were achieved.

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Here we describe two patients in whom prostheses were applied for flap protection after buccal mucosal incision. In the first case, the patient was a 65-year-old man with a diagnosis of buccal mucosa squamous cell carcinoma (T2N0M0). Left buccal mucosa squamous cell tumor resection and dermoplasty were performed, followed by alveolar ridge augmentation and buccal mucosal graft in the scar area. The carcinoma recurred, however, and left buccal mucosa carcinoma resection was performed, followed by reconstruction surgery using a free forearm flap. After a 12-week healing period, a molar support was constructed on the unaffected side and a protective prosthesis placed on the affected side. Training in ingestion and swallowing were given postoperatively. The patient in the second case was a 62-year-old woman with a diagnosis of buccal mucosa squamous cell carcinoma (T2N1M0). Right buccal mucosa carcinoma resection and supra-omohyoid neck dissection were performed, followed by reconstruction surgery using a free forearm flap. A molar support was constructed on the unaffected side and a protec tive prosthesis placed on the affected side at 5 months postoperatively. Training was given in ingestion and swallowing postoperatively. The prostheses prevented bite wounds to the flaps in the affected areas due to jaw movement during swallowing or speaking. The postoperative courses were uneventful, and the average masticatory score was 92.5 (85, 100), not affecting daily life. The prostheses were placed after reconstruction surgery using free flaps after buccal mucosa squamous cell carcinoma resection. Dysphasia recovered to the preoperative level by dysphasia and pronunciation training in both cases. The postoperative prognosis was favorable, with the prosthesis preventing damage to the flap.

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The aim of this study was to investigate cases of accidental ingestion or aspiration occurring at Tokyo Dental College Chiba Hospital over the last 4 years in order to determine how the incidence of such events could be reduced. Forty cases of accidents occurring at our hospital over a 4-year period commencing in 2008 (representing 27% of the total number of accidents) included accidental ingestion in 39 patients and aspiration in one. Most of these accidents occurred during the removal or placement of restorations or prosthetics, and the ingested objects were mostly crowns and inlays. Accidental ingestion or aspiration occurred more frequently in the right molar region and when procedures were conducted by practitioners with less than 1 to 7 years of experience, and especially 1 to 3 years only. A higher rate of such accidents was observed in male patients in their 50s to 70s. The conventional safety procedures developed by the Medical Risk Management Team should be adhered to wherever possible. Furthermore, we propose the following measures based on the present results: accident prevention training for students and clinical trainees; improvement of the in-hospital manual; personal coaching for those breaching the guidelines of the safety manual; and raising awareness of the need for greater care in preventing incidents of accidental ingestion or aspiration at the Tokyo Dental College Chiba Hospital.

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