19th World Conference on Open Learning and Distance Education

Todos os trabalhos se desenvolveram no Austria Center Vienna, o mais moderno centro de congressos da capital austríaca, adjacente ao complexo das Nações Unidas, na margem esquerda do Danúbio, a menos de quinze minutos de metro do centro da cidade. Com mais de mil e trezentos participantes, na Conferência estiveram representados setenta e nove países, sendo trinta europeus, dezasseis asiáticos, quinze americanos, catorze africanos e quatro da zona do Pacífico. Em termos de representação individual, a Europa, com mais de 57% de presenças, foi a zona do globo mais visível. De salientar, contudo, a presença significativa de um elevado número de representantes de países em busca de desenvolvimento, de todos os continentes, da Letónia à Eslováquia, da Mongólia ao Vietname, da República Dominicana ao Equador, do Botswana à Tunísia, passando pelo Chade e pelo Togo

Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG),Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract fromCasearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response

A new improved protocol for in vitro intratubular dentinal bacterial contamination for antimicrobial endodontic tests: standardization and validation by confocal laser scanning microscopy

Objectives To compare three methods of intratubular contamination that simulate endodontic infections using confocal laser scanning microscopy (CLSM). Material and Methods Two pre-existing models of dentinal contamination were used to induce intratubular infection (groups A and B). These methods were modified in an attempt to improve the model (group C). Among the modifications it may be included: specimen contamination for five days, ultrasonic bath with BHI broth after specimen sterilization, use of E. faecalisduring the exponential growth phase, greater concentration of inoculum, and two cycles of centrifugation on alternate days with changes of culture media. All specimens were longitudinally sectioned and stained with of LIVE/DEAD® for 20 min. Specimens were assessed using CLSM, which provided images of the depth of viable bacterial proliferation inside the dentinal tubules. Additionally, three examiners used scores to classify the CLSM images according to the following parameters: homogeneity, density, and depth of the bacterial contamination inside the dentinal tubules. Kruskal-Wallis and Dunn’s tests were used to evaluate the live and dead cells rates, and the scores obtained. Results The contamination scores revealed higher contamination levels in group C when compared with groups A and B (p;0.05). The volume of live cells in group C was higher than in groups A and B (

Antimicrobial susceptibility and RNA purification protocol for gene expression analysis of clinical isolates of Fusobacterium nucleatum

Fusobacterium nucleatum é uma espécie bacteriana Gram-negativa, anaeróbia estrita e uma das espécies frequentemente encontradas nas infecções primárias do sistema de canais radiculares. Esta espécie tem grande importância na formação de biofilmes por ser uma ponte de união entre espécies que não são capazes de interagir. Os micro-organismos constituintes de biofilmes trocam material genético, aumentando a tolerancia dos mesmos e é quase impossível um isolado clínico ter os genes totalmente iguais à cepa padrão de coleções de cultura como da ATCC (American Type Culture Colection). O presente estudo investigou a espécie bacteriana anaeróbia Fusobacterium nucleatum isolada de canais radiculares, comparando-a com sua cepa de referência. Foi feito a comparação da suscetibilidade microbiana in vitro por meio de cultura microbiológica pelo método do E-test, com as cepas em crescimento planctônico e em biofilme. Também foi definido um protocolo de Purificação de RNA para esta espécie em ambas as condições de crescimento. As cepas clínicas de F. nucelatum foram isoladas por meio da cultura microbiológica de 23 pacientes que apresentavam dentes com infecção primária e periodontite apical visível em radiografia. Foi feito isolamento e identificação da espécie por série bioquímica com testes comerciais (Sistema Api, Bio-Meriéux, França) e PCR convencional, sendo no total 4 isolados clínicos investigados. Foi verificada a suscetibilidade antimicrobiana dos seguintes antibióticos: Amoxicilina, Amoxicilina + ácido clavulânico, Ampicilina, Azitromicina, Clindamicina, Eritromicina e Metronidazol. O protocolo para purificação de RNA foi feito com microesferas de zircônia, dispositivo bead beater, kit comercial RNeasy (Qiagen) e transcrição para DNA complementar (cDNA). A qualidade da purificação foi testada quanto a sua capacidade de amplificação pela reação em cadeia da polimerase em tempo real (qPCR) utilizando primer para o gene 16s RNA específico para F. nucelatum. Todas as cepas testadas foram 100% suscetíveis a Amoxicilina + ácido clavulânico, Ampicilina, Azitromicina, Clindamicina e Metronidazol. Ambos os tipos de crescimento bacteriano demonstraram resistência somente à eritromicina. O protocolo proposto para a purificação do RNA de F. nucelatum dos isolados em crescimento planctônico e em biofilme foi eficaz. A média do rendimento do RNA das amostras para as bactérias em crescimento planctônico foi de 514,2 ng/μL (DP ± 397,7) e para as amostras em biofilme foi de 377,1 ng/μL (DP± 144,1). Os valores encontrados sugerem uma boa qualidade de RNA, livre de contaminação por proteínas. Todas as cepas de Fusobacterium nucleatum isoladas de canais radiculares, assim como a cepa ATCC foram suscetíveis aos antibióticos testados, com exceção do antibiótico eritromicina em ambos os tipos de crescimento bacteriano. As bactérias em biofilme apresentaram aumento na tolerância frente aos agentes antimicrobianos, com diferença estatística. O protocolo estabelecido para a purificação do RNA de cepas de Fusobacterium nucleatum cultivadas em fase planctônica e em biofilmes teve êxito com amplificação por qPCR.Fusobacterium nucleatum is a Gram-negative bacterial species, strict anaerobic and one of the species often found in primary infection of the root canal system. This species has great importance in biofilm formation to be a union bridge between species which are not able to act alone. The constituent microorganisms of the biofilm exchange each tother genetic material, increasing the strength of them. It is almost impossible for a clinical isolate have genes totally equal to a standard strain, such as strains of culture collections like ATCC (American Type Culture Collection). The present study investigated anaerobic bacterial species Fusobacterium nucleatum isolated from root canals, comparing them to the ATCC strain. The microbial in vitro susceptibility of biofilm and planktonic growth of the strains was compared by means of microbiological culture and the E-test method, with the antibiotics Amoxicillin, Amoxicillin + clavulanic acid, Ampicillin, Azithromycin, Clindamycin, Eritromycin and Metronidazole.. Also, a RNA Purification protocol for the strains under the same growth conditions was defined. Clinical isolates were obtained by microbiological samples of patients with teeth with pulp necrosis and apical periodontitis visible on radiographs. The species isolation and identification were performed using commercial biochemical tests (Sistema Api, Bio-Meriéux, France) and conventional PCR, obtaining four clinical isolates. The protocol for RNA purification was done with zirconia beads, bead beater device and commercial kit RNeasy (Qiagen) and transcribed into complementary DNA (cDNA). The quality of purification was tested for its ability of amplification by real time polymerase chain reaction (qPCR) using primer for the gene 16s RNA specific for F. nucleatum. All tested trains were 100% susceptible to amoxicillin + clavulanic acid, ampicillin, azithromycin, clindamycin and metronidazole. Both types of bacterial growth showed resistance to Erythromycin. Bacteria in biofilm showed a decrease in susceptibility to all antibiotics, but without statistical difference. The protocol proposed for the purification of RNA of F. nucleatum was effective, in the planktonic and the biofilm growth. The average yield of RNA samples for bacteria in planktonic growth was 514.2 ng /μL (SD ± 397.7) and the samples in biofilm was 377.1 ng / μL (SD ± 144.1). These found values suggest a good quality of RNA, free of protein contamination. The established protocol for the purification of the RNA of the Fusobacterium nucleatum strains, grown in biofilm and planktonic phase, had successfully amplified by qPCR

Analysis of the reaction of rat subcutaneous tissue to the implantation of calcium hydroxide pastes associated with different substances

O presente estudo teve como objetivo avaliar e comparar, morfologicamente, a resposta do tecido subcutâneo de ratos frente ao de hidróxido de cálcio associado a diferentes substâncias, sendo elas: clorexidina 0,2% em propilenoglicol, clorexidina 0,4% em propilenoglicol, Casearia sylvestris Sw (Guaçatonga) em propilenoglicol e propilenoglicol (que serviu como grupo controle). Para isso, foram utilizados 72 ratos Wistar. As pastas foram preparadas e colocadas em tubos de polietileno, que foram implantados no tecido subcutâneo do dorso de cada animal. Os períodos experimentais foram de 7, 14 e 30 dias após o procedimento cirúrgico, quando então, os animais foram mortos. As amostras coletadas passaram por processamento histotécnico e foram feitos cortes de 5µm de espessura e coloração com Hematoxilina e Eosina (H.E.). A avaliação das respostas do tecido conjuntivo em contato com as pastas testadas foirealizada de forma descritiva e quantitativa subjetiva.Os dados obtidos após análise quantitativa foram submetidos ao teste estatístico de Kruskal-Wallis e Dunn com nível de significância p<0,05. Os resultados mostraram que a clorexidina 0,4%, de modo geral, se mostrou mais irritante que os demais grupos. O extrato de Casearia sylvestris Sw apresentou comportamento satisfatório em relação à intensidade da reação inflamatória, igualando-se aos grupos 1 e 4. Com base na metodologia aplicada, foi possível concluir que aos 30 dias todos os grupos mostraram não interferir no processo de reparo e que todas as substâncias experimentais (clorexidina a 0,4%, a 0,2% e o extrato de Casearia sylvestris Sw) podem ser associadas ao hidróxido de cálcio.This study aimed to evaluate the response of rat subcutaneous tissue against calcium hydroxide associated with different substances: chlorhexidine 0.2% in propylene glycol, 0,4% chlorhexidine in propylene glycol, Casearia sylvestris (guaçatonga) in propylene glycol and propylene glycol (control group). The pastes were prepared and placed in polyethylene tubes, which were implanted in the dorsum of each animal (N=18). The experimental periods were 7, 14 and 30 days after surgery, at which time the animals were killed. The samples were histologically processed and stained with hematoxylin and eosin. The evaluation of the responses of connective tissue in contact with the pastes was performed using descriptive and quantitative analyses. The data obtained after the quantitative analysis were subjected to statistical test of Kruskal-Wallis and Dunn with significance level p <0.05. In overall, chlorhexidine 0,4%/calcium hydroxide showed the more intense inflamatory reaction in comparison to the other groups. The extract of Casearia sylvestris showed satisfactory performance in relation to the intensity of the inflammatory reaction, similar to groups 1 and 4. Based on the methodology, it was concluded that at 30 days all the materials do not to interfere with the repair process and that all experimental substances (chlorhexidine 0.4%, 0.2% and the extract of Casearia sylvestris) can be associated with calcium hydroxide

Effect of ultrasound streaming on the disinfection of flattened root canals prepared by rotary and reciprocating systems

New technical and scientific developments have been advocated to promote the success of the endodontic treatment. In addition to rotary and reciprocating systems, irrigating solution agitation has been suggested and passive ultrasonic irrigation (PUI) is the most used. Objective: To evaluate, in vitro, the effect of ultrasound streaming (US) in the disinfection of flattened root canal systems prepared by the ProTaper, BioRaCe and Reciproc systems, utilizing the microbiological culture. Methodology: Extracted human mandibular incisors (n=84) were used. Suspensions of Enterococcus faecalis (ATCC 29212) were standardized and inserted along with the teeth immersed in brain-heart infusion (BHI) broth. The contamination was made following a protocol during 5 days. The teeth were randomly divided into six groups: G1, ProTaper Universal; G2, ProTaper Universal with US; G3, BioRaCe; G4, BioRaCe with US; G5, Reciproc; and G6, Reciproc with US. Irrigation was performed with saline solution. After biomechanical preparation, microbiological samples were performed with sterilized paper points, which were diluted and spread on BHI agar; after 48 h, the colony forming units (CFU/mL) were counted for each sample. Results: Groups using ultrasonic agitation presented a greater antibacterial effect than the other ones, even using saline solution as irrigant. The ProTaper Universal system showed the best antibacterial activity of the tested systems (median of 0 CFU/mL with and without surfactant or ultrasonic activation [PUI]). Even with PUI, Reciproc (median of 2.5 CFU/mL with PUI and 5 without it) could not reduce as many colonies as ProTaper Universal without US. The BioRaCe system had greater bacterial reduction when using US (median of 0 CFU/mL with PUI and 30 without it). Conclusions: US promoted greater reduction in the number of bacteria in the flattened root canals prepared with nickel-titanium mechanized systems. Regarding the instruments used, the ProTaper Universal system was the most effective in reducing the bacterial number