The essential role of toll like receptor-4 in the control of Aggregatibacter actinomycetemcomitans infection in mice.

OBJECTIVE: Aggregatibacter actinomycetemcomitans is an oral Gram-negative bacterium that contributes to periodontitis progression. Isolated antigens from A. actinomycetemcomitans could be activating innate immune cells through Toll-like receptors (TLRs). In this study, we evaluated the role of TLR4 in the control of A. actinomycetemcomitans infection. MATERIAL AND METHODS: We examined the mechanisms that modulate the outcome of A. actinomycetemcomitans-induced periodontal disease in TLR4(-/-) mice. The production of cytokines was evaluated by ELISA. The bacterial load was determined by counting the number of colony-forming units per gram of tissue. RESULTS: The results showed that TLR4-deficient mice developed less severe periodontitis after A. actinomycetemcomitans infection, characterized by significantly lower bone loss and inflammatory cell migration to periodontal tissues. However, the absence of TLR4 facilitated the A. actinomycetemcomitans dissemination. Myeloperoxidase activity was diminished in the periodontal tissue of TLR4(-/-) mice. We observed a significant reduction in the production of tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta in the periodontal tissue of TLR4(-/-) mice. CONCLUSION: The results of this study highlighted the role of TLR4 in controlling A. actinomycetemcomitans infection.

The role of toll-like receptor 2 in the recognition of Aggregatibacter actinomycetemcomitans.

BACKGROUND: Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) is a Gram-negative bacterium present in the oral cavity and is usually associated with localized aggressive periodontitis. Isolated antigens from A. actinomycetemcomitans can activate innate immune cells through Toll-like receptors (TLRs), which are molecules that recognize structural components conserved among microorganisms. In this study, we evaluate the role of TLR2 in the recognition of A. actinomycetemcomitans. METHODS: Macrophages and neutrophils from knockout mice with targeted disruption of TLR2 (TLR2(-/-) mice) and wild-type mice were collected and used for the subsequent assays. The production of cytokines and chemokines was evaluated by enzyme-linked immunosorbent assay (ELISA), and the presence of apoptotic cells was determined by flow cytometry. In addition, the mechanisms that modulate the outcome of A. actinomycetemcomitans-induced periodontal disease in TLR2(-/-) mice were examined. RESULTS: The results show that TLR2-deficient mice developed more severe periodontitis after A. actinomycetemcomitans infection, characterized by significantly higher bone loss and inflammatory cell migration to periodontal tissues. The inflammatory cell influx into the peritoneal cavities of TLR2(-/-) mice was three-fold lower than that observed for the littermate controls. A significantly diminished production of the cytokines tumor necrosis factor-alpha and interleukin-1beta as well as the chemokine CC-ligand-5 in the peritoneal cavities of TLR2(-/-) mice was observed. In addition, a high frequency of apoptotic cells in the inflammatory exudates from TLR2(-/-) mice was observed. Phagocytosis and nitric oxide production was diminished in cells from TLR2(-/-) mice, facilitating the dissemination of the pathogen to the spleen. CONCLUSION: The results of this study highlight the involvement of TLR2 in recognizing A. actinomycetemcomitans and its essential role in controlling A. actinomycetemcomitans infection.

Isolation of Candida dubliniensis from denture wearers.

Candida albicans is considered the most important Candida species able to cause oral infections in denture wearers. In recent years, Candida dubliniensis has emerged as a pathogenic yeast in humans. The close phenotypic similarities of C. albicans and C. dubliniensis have led to the misidentification of these species. In this work, our aim was to verify through PCR the presence of C. dubliniensis in palate and maxillary denture samples from 112 denture wearers presenting with or without denture-related stomatitis (DRS). C. dubliniensis was isolated at low rates from both palate (5.3 % and 10.7 %) and maxillary denture (5.3 % and 8.9 %) samples from wearers regardless of the presence of the disease. However, when C. dubliniensis was detected in individuals with DRS, it was always associated with C. albicans. In addition, our results showed that C. albicans was the most commonly identified candidal species in maxillary denture and hard palate samples from DRS patients (78.5 % and 89.2 %, respectively) as well as from controls (31.2 % and 28.5 %, respectively). In conclusion, C. dubliniensis was detected in the oral environment of denture wearers. The association of C. dubliniensis with C. albicans occurred in approximately 10 % of the DRS cases.

Remoção do material obturador dos canais radiculares empregando instrumentos de níquel-titânio, sistema quantec, acionados a motor / Filling material removal using nickel-titanium rotary instruments - quantec system

Quando ocorre alguma falha em um tratamento endodôntico,seja ela constatada pela presença de sinais, sintomas clínicos ou por alterações radiográficas, uma nova terapêutica deve ser instituida. Sempre que possível, a primeira opção de tratamento, nesses casos, deve ser o retratamento endodôntico. No entanto, uma das fases mais dispendiosas é a de remoção do material obturador pré-existente. Trinta dentes humanos unirradiculares extraídos foram divididos em dois grupos: canais amplos e canais atrésicas. Em seguida, foram instrumentados, obturados e subdivididos em três grupos, empregando as seguindos técnicas para a remoção do material obturador: a Sistema Quantec; b. Sistema Quantec associado ao solvente Eucaliptol; c. Técnica manual/mecânica associada ao solvente Eucaliptol. Os resultados demosntraram que não houve diferença estatisticamente significante entre as técnicas propostas para a remoção do material obturador, no entanto, o diâmetro dos canais (amplos ou atrésicos) influenticou na qualidade da limpeza, pois nos grupos de canais atrésicos, obteve-se a melhor limpeza das paredes com o menor tempo operatório, visto que havia um maior contato entre o instrumento rotatório e a guta-percha