Effect of ultrasonic streaming on intra-dentinal disinfection and penetration of calcium hydroxide paste in endodontic treatment

ABSTRACT Objective The antimicrobial effect of ultrasonic agitation of calcium hydroxide (CH) pastes in infected bovine dentin and their penetrability were evaluated using confocal laser scanning microscopy (CLSM) and microbiological culture. Material and Methods Fifty-two bovine teeth were infected with Enterococcus faecalis using a new contamination protocol; then they received CH paste and were divided into groups with or without ultrasound. Ultrasonic agitation was conducted for 1 min with a plain point insert. After 15 d, the CLSM analyzed the viable and dead bacteria with Live and Dead assay. The dentinal wall debris was collected by burs, and the colony forming units (CFU/mL) were counted. The penetrability of the paste inside dentinal tubules was tested using the B-rodamine dye. Results The calcium hydroxide paste showed better results with the use of ultrasonic agitation (p<0.05). Conclusion The ultrasonic agitation of CH paste increased its antimicrobial action and was responsible for intradentinal penetration with the fulfilment of the tubules.

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). No differences were observed between group A and B (p>0.05). The volume of live cells in group C was higher than in groups A and B (p<0.05). Conclusion The new protocol for intratubular infection resulted in high and uniform patterns of bacterial contamination and higher cell viability in all specimens when compared with the current methods.

Efeitos de diferentes aditivos sobre as propriedades antimicrobianas, físicas e químicas do agregado trióxido mineral (MTA) / Effects of various additives on antimicrobial, physical and chemical properties of mineral trioxide aggregate (MTA)

Objetivo: verificar a ação antimicrobiana, solubilidade, tempo de presa, escoamento, pH, liberação de cálcio e característica da superfície do MTA associado as substancias hipoclorito de sodio gel a 1%, clorexidina gel a 2%, água destilada associada a 10% de propilenoglicol (CCPG), K-Y gel, solução salina e, por fim, água destilada. Métodos: para o teste antimicrobiano, utilizou-se o Streptococcus mutans, Lactobacillus casei, Enterococcus faecalis e Candida albicans, por meio do método de contato direto. Para avaliação do tempo de presa e escoamento, foram utilizadas as especificações ASTM 266/08 e ADA 57/2007. Para o pH e liberação de cálcio, os materiais foram inseridos em cavidades retrogradas de dentes de resina acrílica e imersos em água ultrapura, para avaliação em diferentes períodos, utilizando um pHmetro e um espectrofotômetro de absorção atômica. Para a analise das características de superfície, os dentes de acrílico foram analisados com microscopia eletrônica de varredura (MEV). Resultados: os resultados dos testes antimicrobianos mostraram que os diferentes aditivos associados ao MTA apresentaram maior propriedade inibitória do que bactericida, sendo que a clorexidina apresentou os melhores resultados. As amostras que utilizaram o K-Y gel como veiculo apresentaram maiores índices de solubilidade. Houve diferença estatística entre os grupos (p > 0,05) quanto ao escoamento. O grupo que utilizou o CCPG apresentou o menor tempo de presa. O grupo K-Y apresentou os menores pH e liberação de cálcio no período de três horas. Nos outros períodos, houve maior uniformidade entre os grupos. Com relação as características da superfície, o grupo CCPG apresentou a maior porosidade (p < 0,05). Conclusão: o único veiculo avaliado que proporcionou alguma melhora no efeito antimicrobiano foi a clorexidina gel a 2%. Ja o K-Y gel interferiu nas propriedades físico-químicas do MTA, e a adição de CCPG proporcionou a maior porosidade.