Effectiveness of facemasks to reduce exposure hazards for airborne infections among general populations.

Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.

Glutathione concentration in oral cancer tissues.

Glutathione (GSH) concentrations in human epidermoid carcinoma tissues were measured by high performance liquid chromatography. The mean glutathione content of 26 epidermoid carcinoma intratumor tissue specimens was 24.36 nmol/mg protein, which was significantly higher than that in adjacent non-tumor tissue parts (3.04 nmol/mg protein). The mean concentration found in normal oral mucosa was 4.80 nmol/mg protein. Tissue GSH levels were not correlated with the age of the patients or tumor size. Additionally, cellular GSH levels in nine different cell lines were found to spread over a wide range from 0.97 to 50.97 nmol/mg protein. Elevated GSH levels in cancer tissues were probably due to their abnormal proliferative activities. These results indicate that the glutathione level of oral tissues may be a useful marker for oral cancer, which is in agreement with findings from lung squamous cell carcinoma, cervical squamous cell carcinoma and other squamous cell carcinomas.

Hypodontia and nail dysplasia syndrome. Report of a case.

The ectodermal dysplasias are a clinically and genetically heterogeneous group of more than 120 syndromes involving ectodermally derived structures. The syndrome that is autosomal dominantly inherited and characterized by hypodontia, dysplastic nails, and normal hair is known as hypodontia-nail dysplasia syndrome, or tooth-and-nail syndrome. Because of the minimal manifestations, this syndrome may be difficult to diagnose. Patients with hypodontia should be examined for dysplastic nails of the hands and feet and referred to medical and dental genetic specialists for verification of the diagnosis and counseling. We report a case of tooth-and-nail syndrome in a young woman.

Presurgical tomographic assessment for dental implants. 1. A modified imaging technique.

A modified technique for presurgical evaluation of intraosseous implant placement using linear tomography has been developed. The simplified technique is applicable to tomographic systems equipped with a cephalometric head positioner (cephalostat) and a fiberoptic positioning light system. It provides precise cross-sectional images for the assessment of bone morphology and associated anatomic structures. This technique is more comfortable for patients who are unable to tolerate the positioning of submentovertex projections used to estimate horizontal angulation of the head position and to determine the depth of radiographic cut. Instead, the positioning light and casts are used to make these two determinations.

Leiomyosarcoma of gingiva: report of a case and review of the literature.

Leiomyosarcoma of the oral region has rarely been reported. A review of the literature yield only 24 cases. The histopathology with special reference to ultrastructural findings and immunohistochemical examination of an additional case of leiomyosarcoma of mandibular gingiva has been presented. The manifestation and symptoms, treatment and prognosis, and the origin of this tumor are discussed. Because of the high rate of local recurrence and metastases, extensive surgical excision and long-term follow-up are mandatory.

Histologic study of tissue response to implanted hydroxylapatite in two patients.

The tissue response to hydroxylapatite implants that had been used to augment deficient mandibular alveolar ridges was examined histologically in samples taken from two patients at five-months and one-year after implantation, respectively. New bone formation in the interparticular spaces was found in both cases. There was no evidence of foreign body response around the subperiosteal implanted particles.