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OBJECTIVE: To evaluate formulations of 1 % silver (Ag) nanoparticles for treating traumatic lesions induced in the oral mucosa of rats, because these lesions are commonly observed in the dental clinic, and their therapeutic forms are scarce. METHODS: Wistar rats were punch-injured (two circular fragments, 4.0 mm in diameter) in the oral mucosa (one on each side), and were treated topically (twice per week) with the treatments/groups including: no injury, control, vehicle, diluted Ag, soluble Ag, and solid Ag. On the 2nd, 7th, and 14th days postinjury, biopsies were collected for immunohistochemistry and biochemical analysis. RESULTS: The group diluted Ag revealed a higher level of inflammatory infiltrate on the 2nd day, whereas solid Ag presented lower levels. The Ag solid group presented higher IL-1ß on the 2nd day and increased IL-10 and TGF-ß1 throughout the follow-up. Moreover, all three Ag groups presented lower levels of oxidative stress markers and, on the 7th day, the diluted Ag and solid Ag groups revealed higher antioxidants. Diluted Ag and soluble Ag groups presented greater blood vessels proliferation, whereas soluble Ag and solid Ag groups revealed greater VEGF on the 2nd and 14th days. Furthermore, all three Ag groups were highlighted during fibroplasia, although collagenesis was similar to that observed in the control group. CONCLUSIONS: Although diluted Ag was noticeable for its important angiogenesis and fibroplasia, solid Ag was the most suitable formulation in healing oral lesions as it efficiently controlled inflammation and oxidative stress, thus favoring angiogenesis and tissue formation.

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O presente estudo avaliou a influência do pré-alargamento na escolha das limas patência e apical inicial. Quarenta canais mesiais de molares inferiores foram divididos em dois grupos. No primeiro, não foi realizado pré-alargamento e no segundo o mesmo foi realizado com brocas Gates Glidden. A mensuração do diâmetro anatômico do forame apical e do canal no comprimento de trabalho foi realizada com o auxílio de microscópio de forma retrógada. A escolha das limas patência e apical inicial foi determinada via canal. Quando o pré-alargamento não foi realizado, a diferença entre os diâmetros das limas e anatômicos foi maior. O pré-alargamento mostrou ser essencial na determinação da escolha das limas patência e apical inicial.

The present study evaluated the influence of cervical preflaring in the choice of patency and initial apical files. Forty mesial canals of mandibular molars were divided into two groups. In the first, no cervical preflaring was performed while in the second it was performed with Gates Glidden drills. The measurement of the anatomic diameter of the apical foramen and of the working length was performed by the retrograde method with the aid of a microscope. The choice of patency and initial apical files was determined in the root canal. When the preflaring was not performed, the difference between the diameters of the files and the anatomic diameters was greater. Preflaring was shown to be essential for the determination of patency and initial apical files.

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