The erosion caused in vitro by cola-type and guaraná-type beverages (the latter is a soft drink sold in Brazil), and a canned lemon juice on the enamel of human deciduous teeth was analyzed. Morphological analysis of affected enamel was done using stereomicroscopy and scanning electron microscopy (SEM). The harmful effect of all test products on deciduous enamel was clearly demonstrated. Stereomicroscopy showed loss of gloss and an alteration in normal color of enamel, with irregular loss of dental tissue in variable degrees. Such a loss became more serious as the time of incubation increased. Different degrees of solubilization of enamel prisms were demonstrated by SEM, affecting initially the sheaths and the heads of prisms and later their tails. Areas of erosion increased in proportion to the time of incubation. All the products showed a great erosive potential on human deciduous dental enamel.

The microbicidal activity of macrophages in an inflammatory milieu has been related to the production of a large number of cytokins and intermediary metabolites of oxygen and nitrogen among them, nitric oxide (NO). Considering that granulomatous inflammation is predominantly composed of macrophages and epithelioid cells, we decided to investigate the participation of NO in this peculiar type of inflammation. Two models were used: glass cover slip implantation into the subcutaneous tissue of mice and, the inoculation of live bacillus Calmette-Guérin (BCG) into the footpad of the animals. Using a histochemical method for the detection of NO synthase and of the concentration of citrulin metabolized by cells obtained from cover slips implanted on different time intervals or BCG-activated peritoneal cells, it was possible to demonstrate that epithelioid cells do not produce NO. Cells from granuloma induced by BCG inoculation express NO synthase, with different degrees of reactivity with a higher intensity in the cytoplasm of cells located in the edge of the lesions. The expression of NO synthase in the cytoplasm of these cells decreases with the age of the lesions. It could also be demonstrated that in mice treated with l-name, an inhibitor of NO metabolism, the lesions induced by BCG lost the granulomatous architecture, were necrotic, and had a significant increase in the bacillary load of the lesion. These data allow us to conclude that NO production by macrophages is a determining factor in the organization of the granulomatous lesion and that it also controls the bacterial load in BCG-induced lesions in mice.

No abstract

RESUMO: "Infl uência do óleo essencial de Melaleuca alternifolia na cicatrização de alveolite dental infectada: um estudo histológico em ratos". A planta Melaleuca alternifolia é nativa da Austrália e a destilação de suas folhas produz um óleo essencial conhecido por óleo de Melaleuca, ou Tea tree oil, usado como antimicrobiano. Nesse estudo, foi verifi cado a atividade deste óleo no processo de reparo de alvéolos dentais infectados. 48 ratos foram utilizados (Rattus novergicus albinus, Wistar) e após a extração do dente e posterior infecção do alvéolo com Staphylococcus aureus, os animais foram separados em três grupos: Grupo I: curetagem e irrigação do alvéolo com soro fi siológico; Grupo II: curetagem e irrigação com soro fi siológico e tratamento com Rifocina 25 mg; e Grupo III: curetagem e irrigação com soro fi siológico e aplicação tópica de óleo de Melaleuca 20%. Os animais foram sacrifi cados 24 horas, 7, 14 e 21 dias após o tratamento e o processo de reparo do alvéolo dental foi analisado por microscopia ótica. Os resultados foram submetidos à análise quantitativa e qualitativa e foi possível concluir que o óleo a 20% causou um retardo no processo de reparo dos alvéolos dentais infectados dos ratos, demonstrado por maior área de necrose e menor osteogênese. Unitermos: Melaleuca alternifolia, Staphylococcus aureus, alvéolo dental. ABSTRACT:The plant Melaleuca alternifolia is native to Australia. The distillation of its leaves produces an essential oil, commonly known as oil of Melaleuca, or Tea tree oil, which present antimicrobial activity. This study investigates the action of this oil on the repair process of infected dental alveoli. 48 rats were used (Rattus novergicus albinus, Wistar). After tooth extraction and posterior infection of the dental alveoli with Staphylococcus aureus, the animals were separated into three groups: Group I: curettage and irrigation with physiologic saline solution; Group II: curettage and irrigation with physiologic saline solution and topical application of rifamycin diethylamide B 25 mg; and Group III: curettage and irrigation with physiologic saline solution and topical application of oil of Melaleuca 20%. The animals were sacrifi ced 24 hours, 7, 14 and 21 days after the treatment with powder and the repair process of the dental alveoli was analyzed using an optical microscope. The results were submitted to qualitative and quantitative analysis and it was concluded that tea tree oil at 20% caused a delay in the repair process of infected dental alveoli in rats, as demonstrated by the presence of more necrosis area and less osteogenesis.

ObjectiveTo evaluate the efficiency of two vitrification protocols for rat immature testicular tissue and heterotopic transplantation.MethodsTwenty-four pre-pubertal Wistar rats were divided into three groups (n=8). After orchiectomy, testicular fragments (3mm) from Groups 1 and 2 were vitrified with different cryoprotectant concentration solutions, using sterile inoculation loops as support. After warming up, the fragments were submitted to cell viability assessment by Trypan blue and histological evaluation. Vitrified (Groups 1 and 2) and fresh (Group 3) fragments were grafted to the animals periauricular region. After 8 weeks of grafting, the implant site was histologically analyzed.ResultsThe viability recovery rate from Group 1 (72.09%) was higher (p=0.02) than that from Group 2 (59.19%). Histological analysis showed similar tubular integrity between fresh fragments from Groups 1 and 3. Group 2 samples presented lower tubular integrity. We ran histological analyses in the grafts from the Groups. In all groups, it was possible to see the implant site, however, no fragment of testicular tissue or signs of inflammation were histologically found in most samples from Groups 1 and 3. In one sample from Group 2, we found degenerated seminiferous tubules with necrosis and signs of an inflammatory process. In another sample from Group 2, we found seminiferous tubules in the implant site.ConclusionThe vitrification of pre-pubertal testicular tissue of rats showed little damage to cell viability through histological analysis when we used cryoprotectants in a lower concentration. Heterotopic transplantation could not preserve the structural organization of the testicular tissue.