Biological tissue response to a new formulation of a silicone based endodontic sealer

Satisfactory biological behavior is a necessary requirement for clinical application of endodontic materials. In this study, the connective tissue responses to silicone (GuttaFlow 2), epoxy resin (AH Plus) and zinc oxide and eugenol (Endofill) based sealers were compared. Twelve Wistar rats had polyethylene tubes (four per animal) containing one of the tested sealers and empty tubes (negative control) implanted in their subcutaneous tissue. The tubes were randomly placed 2 cm from the spine and at least 2 cm apart from one another. Tissue samples with implants were processed for histological analysis after 7 or 60 days (n=6 animals per period). Inflammatory cells, fibrous condensation and abscess were scored according to their intensity. Friedman, followed by Dunn’s post hoc, was used to compare sealers. Differences between the two experimental periods were verified using Mann-Witney U test (p<0.05). At 7 days, most of the histological parameters showed no significant differences amongst groups. Endofill group scored higher than the others for giant cells (o<0.05) and promoted a greater number of samples presenting abscess formation. GuttaFlow 2 tended to show a less intense inflammatory infiltrate compared to the other materials. At 60 days, there were no significant differences between groups in most of the histological parameters evaluated. However, it was observed that Endofill scored higher for macrophages (p<0.05) compared to the control group, and GuttaFlow 2 tended to present lower scores than the others for neutrophils and abscess. GuttaFlow 2 showed proper biological behavior and should be considered adequate for clinical practice

In vitro antibacterial activity of a silicone-based endodontic sealer and two conventional sealers

: The aim of this study was to evaluate whether the modification in the silver component is capable of providing GuttaFlow 2 with antibacterial activity against Enterococcus faecalis compared with epoxy resin-based (AH Plus) and zinc oxide and eugenol-based (Endofill) sealers. The antibacterial activity was evaluated using a reference strain of E. faecalis (ATCC 29212). Freshly mixed sealers were subjected to the agar diffusion test (ADT), while the direct contact test (DCT) was performed after materials setting. ADT results were obtained through measurements, in millimeters, of the inhibition zones promoted by the materials, using a digital caliper. In DCT, values of CFU/mL promoted by the three sealers were compared in three experimental periods (1 min, 1 h, and 24 h). The data were analyzed using Kruskal-Wallis and Dunn post-hoc tests (p < 0.05). In both ADT and DCT, GuttaFlow 2 presented no effect against E. faecalis, while Endofill and AH Plus showed similar inhibition zones. Endofill was the only material capable of reducing bacterial growth in DCT. In conclusion, modifications in the silver particle of GuttaFlow 2 did not result in a sealer with antibacterial effect against E. faecalis

Efici?ncia de corte de instrumentos rotat?rios de n?quel-tit?nio para alargamento cervical de canais radiculares : an?lise em estereomicroscopia, perfilometria e microtomografia computadorizada

Made available in DSpace on 2015-04-14T13:30:18Z (GMT). No. of bitstreams: 1 444223.pdf: 7075899 bytes, checksum: e2b966a0c07482d14bfbf7d107754d2e (MD5) Previous issue date: 2012-11-07This study aimed to: evaluate, using different methods and substrates, the cutting efficiency of nickel-titanium rotary instruments for coronal flaring; investigate the influence of rotational speed and number of uses on the cutting efficiency of such instruments; observe the presence of surface defects. First, bovine dentin blocks (n=20) and acrylic blocks (n=20) were made, as substrate for evaluating the performance of the following instruments: BR0 BioRaCe (BR), HyFlex CM 1 (HY), ProFile OS #2 (PF) and ProTaper Sx (PT). Each instrument worked sideward for 60 seconds, mounted on a testing platform. The instruments were used at two rotational speeds (250 and 500 rpm) up to 5 times. On the first stage, those blocks were observed under a stereomicroscope and the notches created by the instruments were measured.Area and length were used as parameters to assess cutting efficiency. Data were statistically analyzed with significance level set at 5%. HY and PF were the most and least efficient instruments (P<0.05), respectively. Against acrylic, with greater speed, significant increase in area and length was observed for all instruments. Against dentin, there was significant increase in area for HY and PT and in length for BR, HY and PT. Regarding the number of uses, there was no cutting efficiency loss against acrylic. On dentin, however, PF and PT instruments were significantly less efficient after the fourth and fifth use (shorter length). Strong correlation was found between the results on acrylic and dentin for all brands. On the second stage, two new parameters were used to assess cutting efficiency.Dentin blocks were evaluated under a profilometer to determine the maximum cutting depth of the notches. Half of them were also investigated by microcomputed tomography (micro-CT) to check the volume of extracted dentin. Data were statistically analyzed with significance level set at 5%. Again, HY and PF were the most and least efficient instruments (P<0.05). Speed increase significantly improved maximum cutting depth (BR, HY and PT) and volume of extracted dentin (HY and PF). BR and PT instruments lost their cutting efficiency after repeated use (depth and volume) as well as HY (volume).Positive correlation coefficients were found between profilometry and micro-CT results. Finally, instruments were examined under scanning electron microscopy (SEM) for the presence of surface defects. Most instruments had blunt cutting edges after use, but there was no relevant deformation or fracture. In conclusion, stereomicroscopy showed similar results to wellrecognized methods (profilometry and micro-CT), evidencing HY superiority. Rotational speed and number of uses had a positive and negative influence, respectively, on the cutting efficiency of nickel-titanium coronal flaring instrumentsOs objetivos deste estudo foram: avaliar, utilizando diferentes metodologias e substratos, a efici?ncia de corte de instrumentos rotat?rios de n?quel-tit?nio para alargamento cervical; investigar a influ?ncia da velocidade e do n?mero de usos na efici?ncia de corte de tais instrumentos; observar a presen?a de defeitos na superf?cie dos mesmos. Primeiramente, foram confeccionados blocos de dentina bovina (n=20) e de acr?lico (n=20), os quais serviram de substrato para a atua??o dos seguintes instrumentos: BioRaCe BR0 (BR), HyFlex CM 1 (HY), ProFile OS #2 (PF) e ProTaper Sx (PT). Cada instrumento atuou por 60 segundos lateralmente aos blocos, montados em uma plataforma de testes. Os instrumentos foram utilizados em duas velocidades (250 e 500 rpm), at? cinco vezes. Em um primeiro momento, os blocos foram observados em um estereomicrosc?pio e as medidas de ?rea e comprimento dos sulcos formados pelos instrumentos foram utilizadas como par?metro para avaliar a efici?ncia de corte.Os dados obtidos foram analisados estatisticamente, com n?vel de signific?ncia de 5%. HY e PF foram os instrumentos mais e menos eficientes (P<0.05), respectivamente. Em acr?lico, com o aumento da velocidade, houve aumento significativo da ?rea e do comprimento dos sulcos para todos os instrumentos. Em dentina, houve aumento significativo da ?rea para HY e PT e do comprimento para BR, HY e PT. Com rela??o ao n?mero de usos, n?o houve perda de efici?ncia de corte em acr?lico. J? em dentina, os instrumentos PF e PT apresentaram efici?ncia significativamente menor ap?s o quarto e quinto uso (menor comprimento dos sulcos). Para todos os instrumentos, foi detectada forte correla??o entre os resultados em acr?lico e dentina. Em um segundo momento, outros dois par?metros foram utilizados para determinar a efici?ncia de corte.Os blocos de dentina foram avaliados em um perfil?metro, para determina??o da profundidade m?xima de corte dos sulcos gerados e metade deles tamb?m foi investigada em microtomografia computadorizada, para verifica??o do volume de dentina extra?da. Os dados foram analisados estatisticamente, com n?vel de signific?ncia de 5%. Novamente, HY e PF foram os instrumentos mais e menos eficientes (P<0.05). O aumento da velocidade proporcionou aumento significativo da profundidade de corte (BR, HY e PT) e do volume de dentina extra?da (HY e PF). Os instrumentos BR e PT perderam a efici?ncia de corte ap?s uso repetido (profundidade de corte e volume), assim como o HY (volume).Foi detectada correla??o positiva entre os resultados do perfil?metro e microtom?grafo. Por fim, parte dos instrumentos foi examinada em microscopia eletr?nica de varredura (MEV), quanto ? presen?a de defeitos de superf?cie. A maioria deles apresentou bordos de corte arredondados ap?s o uso, por?m n?o foi observada deforma??o relevante ou fratura. Pode-se concluir que a estereomicroscopia apresentou resultados semelhantes aos m?todos consagrados (perfilometria e microtomografia), mostrando a superioridade do instrumento HY. Os aumentos da velocidade e do n?mero de usos influenciaram positiva e negativamente, respectivamente, a efici?ncia de corte dos instrumentos de n?quel-tit?nio para alargamento cervica