Aspectos histomicrobiológicos do sistema de canais radiculares e das lesões periapicais em dentes de cães após instrumentação automatizada e medicação intracanal com pastas de Ca(OH)2

OBJECTIVE: The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OH)2]-based intracanal dressings. MATERIALS AND METHODS: Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH)2-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH)2 p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p;0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively. CONCLUSION: In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.OBJETIVO: Neste estudo avaliou-se a distribuição dos microrganismos no sistema de canais radiculares (SCR) e região periapical (RP) de cães após instrumentação automatizada e utilização de pastas à base de hidróxido de cálcio CaO(H)2. MATERIAL E MÉTODOS: Lesões periapicais crônicas foram induzidas em 80 raízes de pré-molares de quatro cães. Após a instrumentação com o sistema Profile auxiliado pela solução de hipoclorito de sódio a 5,25%, aplicou-se as seguintes pastas contendo Ca(OH)2: grupo 1-Calen (n=18), grupo 2-Calen/PMCC (n=20), grupo 3-hidróxido de cálcio p.a. + solução anestésica (n=16) e grupo 4-hidróxido de cálcio p.a. + solução de digluconato de clorexidina a 2% (n=18), por 21 dias. Oito canais radiculares sem tratamento endodôntico constituíram o grupo-controle. Nas secções histológicas coradas por Brown & Brenn, avaliou-se a presença de microrganismos nos 3mm apicais do SCR e RP, incluindo o canal radicular principal, deltas, cementoplastos, túbulos dentinários, reabsorções cementárias e lesão periapical. Os resultados foram analisados pelo teste de Mann-Whitney (p;0.05). Nos grupos 1, 2, 3, 4 e controle, os percentuais de sítios do SCR contendo microrganismos foram: 67.6%, 62.5%, 78.2%, 62.0% e 87.6%, respectivamente. CONCLUSÃO: Histomicrobiologicamente, os protocolos de anti-sepsia utilizados proporcionaram insignificativa redução dos microrganismos no SCR e na RP, embora, metabolicamente, muitas bactérias vistas nas secções histológicas podem ter sido inativadas irreversivelmente ou mesmo perdido a viabilidade em função dos procedimentos de anti-sepsia utilizados

Ação do preparo biomecânico e de pastas à base de hidróxido de cálcio na anti-sepsia do sistema de canais radiculares de cães

In the endodontic treatment of root canals with necrotic pulps associated with periapical radiolucent areas, one of the main objectives of treatment consists in eliminating the microorganisms spread throughout the ramifications of the root canal system. The scope of this study was to evaluate the antiseptic efficacy of biomechanical preparation and two calcium hydroxide-based pastes, in dogs' teeth with experimentally induced chronic periapical lesions. After initial microbiological sampling, instrumentation of the root canals was undertaken using the conventional technique, using K type files used in conjunction with a solution of 5.25% sodium hypochlorite. After ninety-six hours, further microbiological sampling was undertaken and Calen/CPMC or Calasept pastes were applied for 15 and 30 days. Ninety six hours after the removal of the medication, the third microbiological sampling was undertaken and finally histomicrobiological analysis followed using Brown & Brenn staining. The results were analyzed using the Kruskall-Wallis test, with a level of significance established at 5% (p;0.05), characterized by an elevated incidence of cocci, bacilli and filaments, predominantly gram-positive, in root canals, secondary canals and accessories, apical cementoplasts and dentinal tubules, but with a low incidence of microorganisms in areas of cementum resorption and the periapical lesion. The biomechanical preparation and intracanal dressing based on calcium hydroxide were important in the antisepsis of the root canal; however, both procedures did not produce significant changes in the microbiological aspects of the root canal system.No tratamento endodôntico dos canais radiculares com polpa necrótica associados à áreas radiolúcidas periapicais, um dos principais objetivos consiste em eliminar os microrganismos situados em todo o sistema de ramificações. Por conseguinte, o objetivo deste estudo foi avaliar a eficácia anti-séptica do preparo biomecanico e de duas pastas à base de hidróxido de cálcio, em dentes de cães com reações periapicais crônicas experimentalmente induzidas. Após amostragem microbiológica inicial, realizou-se a instrumentação dos canais radiculares pela técnica convencional, utilizando-se limas tipo Kerr coadjuvadas pela solução de hipoclorito de sódio a 5,25%. Noventa e seis horas após, obteve-se a segunda amostragem microbiológica e aplicou-se as pastas Calen/PMCC ou Calasept, por 15 e 30 dias. Noventa e seis horas após a remoção da medicação, obteve-se a terceira amostragem microbiológica e ulterior análise histomicrobiológica pela técnica de Brown & Brenn. Os resultados foram analisados pelo teste de Kruskall-Wallis, com nível de significância estabelecido em 5% (p;0,05), caracterizado por elevada incidência de cocos, bacilos e filamentosos, predominantemente gram-positivos, situados no canal radicular, canais secundários e acessórios, cementoplastos apicais e túbulos dentinários, mas com baixa incidência de microrganismos nas áreas de reabsorção cementária e lesão periapical. O preparo biomecânico e o curativo de demora à base de hidróxido de cálcio foram importantes na anti-sepsia do canal radicular principal, contudo, ambos os procedimentos não proporcionaram significativas mudanças nos aspectos histomicrobiológicos do sistema de canais radiculares

Comparison of the time required for removal of intraradicular cast posts using two Brazilian ultrasound devices

The aim of this in vitro study was to compare the time required for removal of intraradicular cast posts cemented with zinc phosphate (ZF) or glass ionomer cement (GIC), using two Brazilian ultrasound devices (BUD). Seventy two human inferior premolars with single root canals were sectioned transversally at the cementoenamel junction. In each specimen, the root canal was endodontically treated, the post space was prepared to a depth of 9 mm and the canal was molded to obtain a post impression. After the casting procedures, the posts were randomly distributed into 2 groups (n = 36) according to the luting material used: G1 - ZF and G2 - GIC. The tooth and luted post set was then embedded in an acrylic resin block. The groups were then divided into 3 subgroups (n = 12) according to the ultrasound device used: A - Enac (Osada Electric, Japan), used as a control group; B - Profi II Ceramic (Dabi Atlante, Brazil) and C - Jet Sonic Satelec (Gnatus, Brazil). The posts were submitted to the vibration process with maximum power set on all surrounding surfaces. Time of application was recorded with a chronometer until complete post dislodgment, and the data were analyzed by the ANOVA test (p < 0.05). The averages required for post removal in G1 and G2 were respectively 41.42 and 92.03 seconds, with significant statistical difference (p = 0.001). No statistical difference was observed among the three ultrasound devices (p = 0.088), and the BUD presented a performance similar to that of the international gold standard device (Enac). Moreover, the type of luting agent had a greater influence on the time required for post removal than the origin of the ultrasonic unit

Elimination of intracanal infection in dogs' teeth with induced periapical lesions after rotary instrumentation: Influence of different calcium hydroxide pastes

The aim of this study was to evaluate the antiseptic efficacy of rotary instrumentation associated with calcium hydroxide-based pastes prepared with different vehicles and antiseptics. Chronic periapical lesions were experimentally induced in 72 premolar root canals of four dogs. Under controlled asepsis, after initial microbiological sampling (A1), the root canals were instrumented using the ProFile system in conjunction with 5.25% sodium hypochlorite and the intracanal medication was placed. Four experimental groups were formed according to the pastes used: group 1- Calen (n=18), group 2- Calen+CPMC (n=20), group 3- Ca(OH)2 p.a.+ anaesthetic solution (n=16) and group 4- Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). After 21 days, the pastes were removed; the canals were emptied and 96 hours later a second microbiological sample was obtained (A2). The incidence of positive microbiological cultures and the number of cfus in stages A1 and A2 were compared statistically by the Wilcoxon test while the influence of the different treatments in intracanal infection was evaluated by Kruskal-Wallis test at 5% significance level (p<0.05). Large numbers of strict and facultative anaerobes, and viridans group streptococci were found in 100% of root canals of A1 samples. Among A2 samples, all treatments showed significant reduction of cfus and positive cultures (p<0.05), but only groups 3 and 4 showed 100% of root canals free of microorganisms. Rotary instrumentation plus NaOCl 5.25% associated with intracanal medication produced a drastic reduction or elimination of intracanal microbiota, whose performance was not influenced by the nature of the vehicle or the antiseptic added to the Ca(OH)2 p.a

Evaluation of cytotoxicity of two endodontic cements in a macrophage culture

Compared to gutta-percha, the endodontic cements are used in small quantity to seal root canals, but are indispensable to achieve hermetically sealed margins, where its biocompatibility depends on the sum of responses of each cell present in the periapical region. The object of this study was to evaluate the cytotoxicity of two endodontic cements, one based on epoxy resin (Sealer 26) and the other containing zinc oxide eugenol (Endofill) by using cultured peritoneal macrophages from Swiss mice to measure the induced production of nitric oxide. After solidification and pulverization, aliquots of 100mul of suspension containing 18mg/mL of the respective cements were added to 96-well tissue culture plates containing the tissue culture of macrophages at a concentration of 5.0X10(6) cells/ml. In the positive control group the cell culture was treated with 10mg/mL of lipopolyssaccharide from Escherichia coli 026:B6 and the cell culture alone represented the negative control. After 48 hours of incubation, at 37ºC, in 5% CO2, the cultures were placed in an ELISA automatic reader to evaluate the release of nitric oxide. The production of nitric oxide for cement Sealer 26 was between 36.1 and 313.0 mumols, with a mean of 143.82±111.03mumols, while for the Endofill these values were significantly less (p=0.01), varying from 50.8 to 125.7mumols, with a mean of 80.33±28.42 mumols. In the positive and negative control groups the mean release of nitric oxide was of 162.75mumols and 4.42mumols, respectively. There was no significant difference between the positive control group and cement Sealer 26 (p>0.05). Therefore, the cement Sealer 26 caused significantly greater toxicity to the macrophages, possibly due to the components from the epoxy resin and formaldehyde release during polymerization

Residual antibacterial activity of chlorhexidine digluconate and camphorated p-monochlorophenol in calcium hydroxide-based root canal dressings

The purpose of this study was to evaluate the residual antibacterial activity of several calcium hydroxide [Ca(OH) 2]-based pastes, placed in root canals of dogs' teeth with induced chronic periapical lesions. Root canals were instrumented with the ProFile rotary system and filled with 4 pastes: G1 (n=16): Ca(OH) 2 paste + anesthetic solution; G2 (n=20): Calen® paste + camphorated pmonochlorophenol (CMCP); G3 (n=18): Calen®; and G4 (n=18): Ca(OH) 2 paste + 2% chlorhexidine digluconate. After 21 days, the pastes were removed with size 60 K-files and placed on Petri plates with agar inoculated with Micrococcus luteus ATCC 9341. Pastes that were not placed into root canals served as control. After pre-diffusion, incubation and optimization, the inhibition zones of bacterial growth were measured and analyzed by Mann-Whitney U test at 5% significance level. All pastes showed residual antibacterial activity. The control samples had larger halos (p<0.05). The mean residual antibacterial activity halos in G1, G2, G3 and G4 were 7.6; 10.4; 17.7 and 21.4 mm, respectively. The zones of bacterial growth of G4 were significantly larger than those of G1 and G2 (p<0.05). In conclusion, regardless of the vehicle and antiseptic, all Ca(OH) 2-based pastes showed different degrees of measurable residual antibacterial activity. Furthermore, unlike CMCP, chlorhexidine increased significantly the antibacterial activity of Ca(OH) 2