Monitoring the effectiveness of photodynamic therapy with periodic renewal of the photosensitizer on intracanal Enterococcus faecalis biofilms.

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) can eliminate microorganisms in a root canal. However, the parameters for disinfection remain undefined. This study assessed the effectiveness of a PDT protocol against intracanal Enterococcus faecalis biofilms. MATERIALS AND METHODS: Root canals were contaminated with E. faecalis for 21 days. The instrumentation was associated to irrigation with 0.85% saline or an alternate irrigation (AI) with 5.25% NaOCl and 17% EDTA. Complementary treatments included saline/PDT and AI/PDT. Four PDT cycles were performed using a diode laser (660nm, 40mW) delivered through a tapered optical fiber. In each cycle, the root canal was filled with 1.56µM/mL methylene blue and irradiated for 150s. Microbiological samples were collected before (S1) and after (S2) instrumentation; after PDT (S3); and daily over the course of 14 days (S4-S17). Colony-forming units (CFUs) were counted, positive cultures verified, and data subjected to parametric and proportion's tests. RESULTS: The highest bacterial load reduction was observed in S2. In regard to S3, Saline/PDT reduced 1.3 log(10) CFU counts (p=0.000 for S2) and no CFUs were recovered after AI/PDT treatment. All canals were CFU-free on the 14th day for saline/PDT, AI and AI/PDT. Positive cultures were observed in 60% of saline-irrigated canals on the 14th day, whereas the saline/PDT, AI and AI/PDT treatments resulted in germ-free canals after 10, 5 and 2 days, respectively. CONCLUSION: Our findings suggest immediate and delayed antibacterial effects using the PDT protocol tested.

The efficacy of a cervical barrier in preventing microleakage of Enterococcus faecalis in endodontically treated teeth.

The clinical failure of coronal restorations can compromise the healthy periapical status of endodontically treated teeth. The purpose of the present ex vivo study was to assess the effectiveness of the cervical barrier in preventing bacterial microleakage in the eventual loss of the coronal restoration. Following removal of the smear layer and obturation to the cementoenamel junction using gutta-percha, 70 single-rooted mandibular premolars were randomly divided into five different groups: Group 1 received no additional treatment; Groups 2 and 3 had 2 mm and 3 mm of the obturation removed, respectively, followed by placement of a cervical barrier that was the same thickness as the obturation. In Group 4 (positive control), the root canals were filled only with gutta-percha, while in Group 5 (negative control), the root canals were completely impermeabilized following obturation. The filled root canals were incorporated into a split-chamber model system using Enterococcus faecalis as a microbial marker. The apices were suspended in the lower chambers. Leakage was determined daily for 60 days and evaluated for turbidity. According to Fisher's exact test, the cervical barrier in Groups 2 and 3 prevented the microleakage of E. faecalis into the root canals when compared with Groups 1 and 4. This result was similar to that for the completely sealed samples in Group 5 (p = 0.001).

Influence of sodium hypochlorite-based irrigants on the susceptibility of intracanal microbiota to biomechanical preparation.

This study evaluated the microbiological conditions of root canals, using smears and culture from anterior teeth and premolars with necrotic pulps associated with chronic periapical pathologies, before and after biomechanical preparation (BMP). During double-flared instrumentation, 1, 2.5 and 5% sodium hypochlorite (NaOCl)-based irrigants were used in 3 groups: GI (n=39), GII (n=36) and GIII (n=36), respectively. Before BMP, all cultures were positive and the smears showed microbiologically diverse morphotypes, including fusiforms, pleomorphic, rods, cocci and filaments. Quantitatively, 20, 20 and 23 morphotypes were identified in GI, GII and GIII, respectively). After BMP, the percentages of negative cultures in GI, GII and GIII were 74.2%, 86.3% and 93.4% (p>0.05) and the number of morphotypes decreased to 14, 15 and 5, respectively. All teeth with 2 root canals and/or associated fistulas were microbiologically negative after BMP, regardless of irrigant concentration. Gram-negative morphotypes were more susceptible to the action of irrigants. After irrigation with 5% NaOCl, only structural arrangements consisting of Gram-positive cocci and bacilli persisted. Thus, BMP plus 5% NaOCl offered the best antiseptic potential because in the few positive cultures a significant reduction in the number of microbiological morphotypes was also shown (p<0.05).

Influence of sodium hypochlorite-based irrigants on the susceptibility of intracanal microbiota to biomechanical preparation

This study evaluated the microbiological conditions of root canals, using smears and culture from anterior teeth and premolars with necrotic pulps associated with chronic periapical pathologies, before and after biomechanical preparation (BMP). During double-flared instrumentation, 1, 2.5 and 5 percent sodium hypochlorite (NaOCl)-based irrigants were used in 3 groups: GI (n=39), GII (n=36) and GIII (n=36), respectively. Before BMP, all cultures were positive and the smears showed microbiologically diverse morphotypes, including fusiforms, pleomorphic, rods, cocci and filaments. Quantitetively, 20, 20 and 23 morphotypes were identified in GI, GII and GIII, respectively). After BMP, the percentages of negative cultures in GI, GII and GIII were 74.2 percent, 86.3 percent and 93.4 percent (p>0.05) and the number of morphotypes decreased to 14, 15 and 5, respectively. All teeth with 2 root canals and/or associated fistulas were microbiologically negative after BMP, regardless of irrigant concentration. Gram-negative morphotypes were more susceptible to the action of irrigants. After irrigation with 5 percent NaOCl, only structural arrangements consisting of Gram-positive cocci and bacilli persisted. Thus, BMP plus 5 percent NaOCl offered the best antiseptic potential because in the few positive cultures a significant reduction in the number of microbiological morphotypes was also shown (p<0.05).

Este estudo avaliou as condições microbiológicas dos canais radiculares, por meio de esfregaços e culturas de dentes anteriores e pré-molares com necrose pulpar associada à radiolucidezes periapicais, antes e após o preparo biomecânico (PBM). Utilizou-se a técnica de instrumentação biescalonada coadjuvada por soluções de hipoclorito de sódio (NaOCl) a 1, 2,5 ou 5 por cento nos grupos I (n=39), II (n=36) e III (n=36), respectivamente. Antes do PBM havia 100 por cento de culturas positivas e os esfregaços proveram diversificados morfotipos microbiológicos, sendo 20, 20 e 23 nos grupos I, II e III, respectivamente. Após o PBM, o percentual de culturas negativas nos grupos I, II e III foi 74,2 por cento, 86,3 e 93,4 por cento (p>0,05) e a incidência de morfotipos declinou para 14, 15 e 5, respectivamente. Todos os dentes birradiculados e/ou portadores de fístulas apresentaram-se microbiologicamente negativos após o PBM, independentemente do irrigante utilizado. Os morfotipos Gram-negativos foram mais suscetíveis à ação do PBM. Após o PBM persistiram apenas cocos e bacilos Gram-positivos no grupo III. Portanto, o PBM coadjuvado por solução de NaOCl a 5 por cento, proporcionou o melhor desempenho anti-séptico, pois, nas poucas culturas positivas, houve também significativa redução do número de morfotipos microbiológicos (p<0.05).

Influência da "Smear Layer" na reparaçäo periapical de dentes com necrose pulpar e patologias periapicais / Influence os Smear Layer on periapical repair of teeth with necrotic pulp and periapical lesions

O objetivo desse estudo foi averiguar se a "smear layer" influencia na desinfecçäo do canal radicular e no processo reparativo periapical de dentes molares humanos, permanentes, portadores de necrose pulpar associada a áreas radiolúcidas periapicais. Após o preparo biomecânico e aplicaçäo da pasta Calen/PMCC por sete dias, verificou-se maior incidência de cultura positiva no grupo sem "smear layer". Concluiu-se que a remoçäo da "smear layer", a cultura microbiológica positiva e as obturaçöes exatas ou ligeiras sobre obturaçöes associaram-se com lesöes periapicais parcialmente resolvidas