Photodynamic therapy (PDT) is a treatment for both neoplastic and nonneoplastic diseases utilizing photochemical reactions induced by a photosensitizer, light and oxygen in the target tissue. PDT consists of administration of a photosensitizer that selectively accumulates in the target tissue and laser irradiation at a specific wavelength to produce photochemical reactions. This photoactivation produces singlet oxygen and other reactive oxygen species that cause oxidative damage to cellular components, triggering either cellular repair and recovery or cell death by apoptosis and/or necrosis. The mechanisms of PDT tumor eradication include the direct damage by phototoxic action, collapse of the tumor vasculature, and induced inflammatory cell infiltration and tumor immunity. Our experimental approach to enhance PDT effects revealed the following results : (1) fractionated laser irradiation improves PDT efficacy due to reoxygenation in the target tissue (2) combined administration of PDT and cisplatin enhances both antitumor effect and apoptotic cell death (3) hyperthermic PDT enhances antitumor effect (4) PDT combined with a biological response modifier, OK-432 improves PDT efficacy. Our clinical trial for oral cancer treatment is described. PDT is a minimally invasive modality and, unlike ionizing radiation, can be applied repeatedly at the same site.

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Two factors possibly break the lip seal at rest. The first is mouth breathing for some reason. The second is lip incompetence due to antero-posterior and vertical disharmony of the dentofacial complex. In this study, we investigated the relationship between lip sealing and mouth breathing, by measuring EMG activities of mentalis (MM), suprahyoid (SHM) and masseter muscles in nasal obstruction. Thirty-four subjects were divided into two groups of competent lip (CL : 11 subjects) and incompetent lip (IL : 23 subjects) groups on the basis of EMG activity of the mentalis muscle at rest. Mouth breathing was induced by obstructing the nostrils. EMG activities were recorded at rest and during chewing gum with the lips closed and apart. EMG activities of these muscles and the masticatory cycle time were estimated during chewing gum for 30 seconds. The Main findings were as follows : 1) EMG activity of MM was higher when obstructing the nostrils than when consciously opening the lips in the CL group at rest. 2) EMG activity of SHM was lowest when obstructing the nostrils in the IL group at rest. 3) The duration of the mastication cycle was shorter when chewing gum with open lips and by obstructing the nostrils than with closed lips in the IL group. This was ascribed to shortening the duration of the non-active masseter phase. 4) In both groups, coefficient of variation values for the total masticatory cycle increased when obstructing the nostrils, but in IL, this decreased when subjects consciously opened the lips and obstructed the nostrils. 5) In the active masseter phase, MM activity of the CL group was highest when subjects obstructed the nostrils and consciously opened the lips, while that of the IL group showed no significant change. 6) In the non-active masseter phase, MM activity of both groups was highest with closed the lips. Furthermore, that of the IL group was higher than the CL group. 7) In the active masseter phase, SHM activity of the two groups was highest when subjects obstructed the nostrils and consciously opened the lips. Furthermore, that of the CL group was higher than the IL group. 8) In the non-active masseter phase, SHM activity of the CL group was highest when subjects obstructed the nostrils and consciously, opened the lips, while, that of the IL group showed no significant change. The results suggest that subjects with incompetent lips tend to easily adopt the habit of mouth breathing. We conclude that it is neccessary to improve the lip sealing function by orthodontic or orthognathic surgical treatment to prevent damage by mouth btreathing.

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It is important for dentures to be kept clean to maintain the wearer's oral hygiene. Various types of denture cleaners are available on the market. Although they are easy to use, some of them are corrosive to metal framework and some are related to the deterioration of the acrylic resin denture base. The present study examined the utility of the electrolyzed water having excellent bactericidal and virucidal activities for a denture cleaner. The heat-cured acrylic resin denture was experimentally contaminated with 2.5×10^5 Staphylococcus aureus 209P. A commercial cleaner including a foaming agent could remove most of the attached bacteria by 5-minute immersion according to the manufacturer's instruction. On the other hand, the denture was completely sterilized by 1-minute immersion in the electrolyzed water. For the denture lined with a tissue conditioner, it took 10-minute immersion or 5-minute ultrasonic cleaning in the electrolyzed water before no bacteria were detected on the denture while 10^3 order of bacteria still survived in the commercial cleaner. No significant differences were found among the electrolyzed strong acid, weak acid and neutral water. Taking into consideration the superiority of the neutral water to the acid water in terms of shelf life longevity, less offensive odor, less corrosiveness to metal and biological safety, it was suggested that the electrolyzed neutral water would be the most desirable denture cleaner, since it shows excellent sterilization effects in a short time treatment with the least side effects on the resin and metal components. It is also expected to be useful for disinfection in the dental office when the denture or its wearer undergoes dental treatment.

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The granular cell tumor (GCT) is an infrequent and usually benign neoplasm, which may be encountered in almost any tissue of the body. We report here a case of GCT arising in the tangue. A 37-year-old Japanese woman was admitted because of a small and painless tumor mass in the right portion of the tongue. She underwent tumor excision of the tongue. The tumor, measuring approximately 14×9mm in diameter, was elastic hard and non-encapsulated. Microscopically, the tumor was composed of round or polygonal cells with abundant cytoplasm that was filled with eosinophilic granules and contained an uniformly small and round nuclei. Immunohistochemical staining revealed that the tumor cells were positive for S-100 protein and neuron specific enolase but negative for myoglobin. These findings led to the conclusion that this tumor was a granular cell tumor of Schwann cell origin.

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