Molecular Typing of Enterococcus faecalis from Persistent Endodontic Infections / Tipificación Molecular de Enterococcus faecalis Provenientes de Infecciones Endodónticas Persistentes

ABSTRACT: Molecular techniques that provide valuable information about the epidemiology of oral strains. The purpose of this study was to determine the genetic relatedness of 83 Enterococcus faecalis strains isolated from treated root canals. These strains were obtained from patients who were treated for persistent endodontic infections. E. faecalis isolates were molecular typed by Pulsed Field Gel Electrophoresis using Smal. Ten clonal groups and 13 pulse types with 38.7 % similarity for the less related strains were identified. Genetic heterogeneity among strains from different patients and a high level of genetic homogeneity among intrapatient strains were observed. Therefore, restriction endonuclease fingerprinting of genomic DNA from E. faecalis strains confirmed the polyclonality of the isolates obtained from the root canals of patients diagnosed with persistent endodontic infections, compared with other reports. These results provide additional data for a better understanding of the epidemiological aspects of root canal infections by E. faecalis.

RESUMEN: Las técnicas moleculares proporcionan información valiosa sobre la epidemiología de aislados orales. El propósito de este estudio fue determinar la relación genética de 83 cepas de Enterococcus faecalis aisladas de conductos radiculares tratados. Estas cepas se obtuvieron de pacientes que fueron tratados por infecciones endodónticas persistentes. Los aislados de E. faecalis se tipificaron molecularmente por electroforesis en gel de campo pulsado usando Smal. Se identificaron diez grupos clonales y 13 pulsotipos con un 38,7 % de similitud para las cepas menos relacionadas. Se observó heterogeneidad genética entre las cepas de diferentes pacientes y un alto nivel de homogeneidad genética entre las cepas intrapacientes. Por lo tanto, la toma de huellas dactilares a traves de restricción de ADN genómico de cepas de E. faecalis confirmó la policlonalidad de los aislados obtenidos de los conductos radiculares de pacientes diagnosticados con infecciones endodónticas persistentes, en comparación con otros informes. Estos resultados proporcionan datos adicionales para una mejor comprensión de los aspectos epidemiológicos de las infecciones del conducto radicular por E. faecalis.

Apical extrusion of Enterococcus faecalis using three different rotary instrumentation techniques: An in vitro study.

Aims: To compare the apical extrusion of Enterococcus faecalis after instrumentation with three different Ni-Ti rotary instruments- An in vitro study. Settings and Design: In vitro study Methods and Material: Forty freshly extracted mandibular premolars were mounted in bacteria collection apparatus and root canals were contaminated with a suspension of Enterococcus faecalis. The contaminated teeth were divided into 4 groups of 10 teeth each according to rotary system used for instrumentation: Group1: Hyflex files, Group 2: GTX files, Group 3: Protaper files and Group 4: control group (no instrumentation). Bacteria extruded after preparations were collected into vials and microbiological samples were incubated in BHI broth for 24 hrs. The colony forming units were determined for each sample. Statistical Analysis Used: Statistical analysis was done using one way ANOVA followed by post hoc independent “t” test. Results: GTX files extruded least amount of bacteria followed by Hyflex files. Maximum extrusion of E. faecalis was seen in rotary Protaper group. Conclusion: Least amount of extrusion was seen with GTX files followed by Hyflex files and then rotary Protaper system.

Evaluation of Apical Contamination in Teeth with Prefabricated Posts Fixed with Different Dental Cements

To assess the sealing capacity of different dental cements regarding apical microleakage on teeth with prefabricated posts. Material and Methods:Forty-eight single-rooted teeth were selectedand, after having their coronal part removed at 10mm standard, underwent endodontic cleaning and preparation. The space for the post was prepared with # 3 Largo bur at 7 mm standard value. The study included the following groups: Group I, post prefabricated with # 1 intracanal glass fiber cemented with zinc phosphate cement (n = 12); Group II, post prefabricated with # 1 intracanal glass fiber cemented with conventional glass ionomer cement, Vidrion C (n = 12); Group III, post prefabricated with # 1 intracanal glass fiber cemented with chemical action resin cement, Multilink (n = 12). Two groups of six teeth each were also included, one as negative control group and the other as positive control. After cementing, teeth were tested through a dual-chamber experimental model, using Enterococcus Faecalis for apical contamination. Results:The control groups behaved as expected: positive control group with total contamination in 11 days and negative control group without any contaminated specimen within observation time of 60 days. Group I showed microleakage in all specimens for up to 29 days (100%)...

Group II and Group III showed microleakage in 50 and 49 specimens (83.33% and 75%) respectively along the research time of 60 days. Group 1 showed microleakage in all specimens for up to 29 days (100%). Group 2 and Group 3 showed microleakage in 50 and 49 specimens (83.33% and 75%) respectively along the research time of 60 days. The Log-Rank test showed differences between Groups 1 and 2 (p<0.05) and between Groups 1and 3 (p<0.05). However, there was no difference between Groups 2 and 3 (p> 0.05). The results showed higher delay in bacterial infiltration in Groups 2 and 3 when compared to Group 1.Conclusion:No cement completely prevented infiltration during the experimental period. Zinc phosphate cement had the lowest apical sealing capacity while glass ionomer cement and resin cement showed similar results...

Microbial distribution in the root canal system after periapical lesion induction using different methods

The aim of this study was to evaluate the microbial distribution in the root canal system after periapical lesion induction in dogs' teeth using different methods. Fifty-two root canals were assigned to 4 groups (n=13). Groups I and II: root canals were exposed to the oral cavity for 180 days; groups III and IV: root canals were exposed for 7 days and then the coronal openings were sealed for 53 days. The root apices of groups I and III were perforated, while those of groups II and IV remained intact. After the experimental periods, the animals were euthanized and the anatomic pieces containing the roots were processed and stained with the Brown & Brenn method to assess the presence and distribution of microorganisms. The incidence of microorganisms at different sites of the roots and periapical lesions was analyzed statistically by the chi-square test at 5 percent significance level. All groups presented microorganisms in the entire root canal system. A larger number of microorganisms was observed on the root canal walls, apical delta and dentinal tubules (p<0.05), followed by cementum and cemental resorption areas. In spite of the different periods of exposure to the oral environment, the methods used for induction of periapical periodontitis yielded similar distribution of microorganisms in the root canal system.

O objetivo deste estudo foi avaliar a distribuição microbiana no sistema de canais radiculares após indução de lesões periapicais em dentes de cães por diferentes métodos. Cinqüenta e dois canais radiculares foram divididos em 4 grupos (n=13). Grupos I e II: canais radiculares foram expostos por 180 dias; grupos III e IV: canais radiculares foram expostos por 7 dias e então as aberturas coronárias foram seladas por 53 dias. Os ápices radiculares dos grupos I e III foram arrombados, enquanto os dos grupos II e IV foram mantidos intactos. Após os períodos experimentais, os animais foram mortos e as peças foram processadas e coradas pelo método de Brown e Brenn para avaliação da presença ou ausência e distribuição dos microrganismos. A incidência de microrganismos nas diferentes regiões das raízes e lesões periapicais foi analisada estatisticamente pelo Teste Qui-Quadrado em nível de 5 por cento de significância. Todos os grupos apresentaram microrganismos em todo o sistema de canais radiculares. Um maior número de microrganismos foi observado nas paredes do canal radicular, delta apical e túbulos dentinários, seguido pelo cemento e áreas de reabsorção cementária. Apesar de utilizar diferentes períodos de exposição dos canais radiculares ao meio bucal, os métodos usados para indução das lesões periapicais permitiram semelhante distribuição de microrganismos no sistema de canais radiculares (p>0,05).

Bacterial leakage in root canals filled with calcium hydroxide paste associated with different vehicles

This in vitro study evaluated, using a bacterial leakage model, whether intracanal medication with calcium hydroxide [Ca(OH)2]-based pastes prepared with different vehicles, has inhibitory effect on corono-apical leakage of bacteria. Forty instrumented human canines were dressed with Ca(OH)2 p.a. associated with: G1= distilled water; G2= polyethylene glycol (PG); G3= PG + CMCP; and G4= glycerin. Five teeth with intact crowns served as negative controls and 5 instrumented teeth without temporary dressing served as positive controls. All teeth were mounted in a 2-chamber apparatus and then exposed to human saliva for 63 days. Leakage was recorded when turbidity was observed in the lower chamber. Fifty percent of the samples of G1 and G2, 10 percent of G3 and 80 percent of G4 were fully contaminated after 9 weeks. Statistically significant differences were observed with paired comparisons G3 and G4 (p=0.0069), with G3 achieving better seal against bacterial leakage than G4.

Este estudo in vitro avaliou, por um modelo de infiltração bacteriano, se a medicação intracanal com hidróxido de cálcio associado a diferentes veículos, tem efeito inibitório na penetração coronária de bactéria. Quarenta caninos humanos instrumentados foram medicados com Ca(OH)2 p.a. associados à G1= água destilada; G2= polietilenoglicol (PG); G3= polietilenoglicol e paramonoclorofenol canforado (PMCP); e G4= glicerina. Cinco dentes hígidos foram utilizados como grupo controle negativo e cinco dentes instrumentados sem medicação intracanal serviram como grupo controle positivo. Todos os dentes foram montados em um aparato de duas câmaras e expostos a saliva humana por 63 dias. A infiltração foi verificada através da observação do turvamento do meio de cultura na câmara inferior. Cinqüenta por cento das amostras do G1 e G2, 10 por cento do G3 e 80 por cento do G4 foram totalmente contaminadas após 9 semanas. Diferenças estatisticamente significantes foram observadas quando foram realizadas comparações pareadas entre G3 e G4 (p=0,0069), com G3 alcançando um melhor selamento contra infiltração bacteriana do que G4.

Er: Yag laser irradiation of the microbiological apical biofilm

One problem in cases of healing-resistant periapical lesions is to eradicate the contamination at the periapical area. This contamination is due to the microbiological biofilm formed by microorganisms and their subproducts lodged in apical third of the root, on both cementum and dentin surface. Paraendodontic surgery consists of the mechanical removal of harmful agents to promote healing and periapical health. The purpose of this study was to assess the results of Er:YAG laser irradiation on the apical root third of newly extracted teeth to eliminate microbial contamination on root apex surface. Apical irradiation was performed with an Er:YAG laser device using an experimental contact tip, at 100 mJ, 10 Hz, 1 W, 39 J/cm², 3 times on the target area. SEM analysis showed the elimination of part of the irradiated cementum and the formation of small roughened without exposing the subjacent dentin. Vaporization of the remaining periodontal tissue and removal of microbiological apical biofilm (MAB) were also observed on the irradiated areas. Under the tested conditions and based on the findings of this study, Er:YAG laser may be considered effective for removal of microbiological apical biofilm.

A problemática dos casos envolvendo pacientes portadores de lesões periapicais resistentes é a eliminação da infecção que atinge a região periapical. Esta infecção é composta por microrganismos e seus subprodutos alojados no cemento e dentina do terço apical, sob forma de biofilme microbiano. A execução da cirurgia paraendodôntica com vistas à promoção da saúde do periápice, invariavelmente resume-se em remover mecanicamente os agentes causadores da doença, com objetivo de proporcionar a reparação. O propósito deste estudo foi avaliar o resultado da irradiação com laser de Er:YAG no terço apical de dentes recém extraídos com relação à infecção microbiana na superfície do ápice radicular. O laser Er:YAG foi empregado para irradiação de ápices radiculares, com ponteira experimental de contato (Chisel, Morita co.), utilizando energia de potência de 100 mJ, 10 Hz, por 3 vezes em área delimitada no terço apical das raízes. Os resultados do estudo em microscopia eletrônica de varredura mostraram a eliminação do tecido periodontal remanescente juntamente com quantidade significativa de microrganismos. Portanto, pode-se concluir que o laser de Er:YAG nas condições experimentais testadas mostrou-se efetivo na remoção de microrganismos do tecido periodontal contaminado e do cemento sem expor a dentina subjacente.

The importance of apical patency and cleaning of the apical foramen on root canal preparation

O limite apical de trabalho sempre constituiu um tema de muita controvérsia. Apesar dos vários trabalhos que já foram publicados sobre o assunto, ainda não existe uma definição sobre ele. A recente discussão sobre patência apical e limpeza do forame e a incorporação desses procedimentos ao tratamento endodôntico parece ter gerado uma polêmica maior ainda. É possível que essa polêmica tenha a sua causa maior na ausência de interrelação do conhecimento que se tem sobre o coto pulpar e tecidos periapicais e a realidade dos fatos da clínica. Através de uma discussão sobre os principais aspectos desse tema, este artigo pretende apresentar uma nova concepção a respeito da importância da patência apical e limpeza do forame no preparo do canal.