Proton Nuclear Magnetic Resonance Spectroscopy Analysis of Mixtures of Chlorhexidine with Different Oxidizing Agents Activated by Photon-Induced Photoacoustic Streaming for Root Canal Irrigation.

Objective: The aim of this in vitro study was to investigate the possible interactions between photon-induced photoacoustic streaming (PIPS™)-activated oxidizing agents and 2% chlorhexidine digluconate. Background data: There is no information about the safety of laser-activated oxidizing agents in combination usage with chlorhexidine gluconate. Materials and methods: Groups were designed as follows G1: 98% para-chloroaniline (PCA); G2: 2% chlorhexidine (CHX); G3: 5.25% sodium hypochlorite (NaOCl) +2% CHX; G4: 5.25% NaOCl (30 sec PIPS activated) +2% CHX; G5: 5.25% NaOCl (60 sec PIPS activated) +2% CHX; G6: 3.5% chlorine dioxide (ClO2) + 2% CHX; G7: 3.5% (ClO2) (30 sec PIPS activated) +2% CHX; G8: 3.5% (ClO2) (60 sec PIPS activated) +2% CHX. The laser-irrigation protocol was performed with an erbium:yttrium-aluminum-garnet laser with a wavelength of 2940 nm equipped with a 140 mm long endodontic fiber tip (PIPS) using 10 mJ at 15 Hz (0.15 W), per pulse operating outputs. Groups were analyzed with proton nuclear magnetic resonance spectroscopy, using PCA as an internal standard. Results: No free PCA was formed in any groups of mixtures or after PIPS activation. Conclusions: Mixing of 3.5% ClO2 and 2% CHX does not form bulky precipitates, unlike the mixture NaOCl + CHX. PIPS activation does not cause changes in reactions of oxidizing agents.

Effect of laser-activated irrigation of 1320-nanometer Nd:YAG laser on sealer penetration in curved root canals.

INTRODUCTION: The purpose of this study was to investigate the efficacy of laser-activated irrigation (LAI) of 1320-nm neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser on sealer penetration into dentinal tubules in the presence of 5.25% sodium hypochlorite (NaOCl) or 17% ethylenediaminetetraacetic acid (EDTA). METHODS: The curved root canals (>20°) from 63 extracted human molars (negative control, n = 3) were prepared to size #30.06 with NaOCl irrigation. Teeth were divided into 4 groups (n = 15) as follows: group N, NaOCl irrigation without LAI; group E, EDTA irrigation without LAI; group NL, LAI with NaOCl; group EL, LAI with EDTA. In all groups, the laser fiber was inserted and withdrawn 4 times for 5 seconds each. Teeth were obturated with gutta-percha and fluorescent-labeled sealer. Transverse sections at 2 and 5 mm from root apex were examined with confocal laser scanning microscopy, and the percentage of sealer penetration into dentinal tubules was measured. RESULTS: Groups E, NL, and EL showed higher percentage of sealer penetration than group N (P < .05). With NaOCl as irrigant, LAI (group NL) resulted in significantly higher amount of sealer penetration than nonactivated group (group N) in both levels (P < .05). However, with EDTA, no significant differences in sealer penetration were observed between the laser-activated group (group EL) and its nonactivated counterpart (group E) in both levels (P > .05). CONCLUSIONS: The 1320-nm Nd:YAG laser activation with either NaOCl or EDTA was much better than NaOCl irrigation alone and as effective as EDTA final flush for sealer penetration into dentinal tubules. Additional use of laser with EDTA did not improve the quality of obturation in the curved canals.

Utilização da terapia fotodinâmica associada ou não ao hipoclorito de sódio na instrumentação de canais radiculares contaminados com Enterococcus faecalis / The use of photodynamic therapy associated or not to sodium hypochlorite in the instrumentation of radicular canals contaminated by Enterococcus faecalis

O presente trabalho teve por objetivo avaliar a ação do laser de baixa intensidade associado ao corante azul de toluidina, como agente bactericida durante a fase de instrumentação dos canais radiculares, comparando sua utilização associada ou não ao hipoclorito de sódio 0,5%. Para tal, 90 caninos humanos foram instrumentados, autoclavados e 88 imersos em caldo TSB (Tryptcase Soy Broth). Em seguida foram inoculados com suspensão de E. faecalis e incubados em estufa a 37°C, por 72 horas, para permitir a formação do biofilme. As amostras foram randomicamente divididas em 4 grupos de 22 dentes cada e 1 grupo controle negativo com 2 dentes. Grupo I: reinstrumentados e irrigados com soro fisiológico com posterior aplicação de terapia fotodinâmica (PDT); Grupo II: reinstrumentados e irrigados com hipoclorito de sódio a 0,5% com posterior aplicação de PDT; Grupo III: reinstrumentados e irrigados com hipoclorito de sódio a 0,5%; Grupo IV controle positivo: não foi realizado nenhum tipo de tratamento antes da coleta do material e Grupo V controle negativo: não foram contaminados. Para a coleta da dentina intracanal utilizou-se uma broca Gates Glidden número 6. A atividade antimicrobiana foi avaliada por meio da contagem de UFCs (unidades formadoras de colônias). Os dentes foram então imersos em meio seletivo para enterococos, incubados em estufa a 37º C por 72 horas e avaliados quanto à alteração de coloração do meio. Todas as amostras, exceto o controle negativo, apresentaram-se positivas. Com a finalidade de certificar-se da formação do biofilme e da confirmação dos resultados das contagens das UFCs, 9 amostras foram avaliadas ao MEV (microscopia eletrônica de varredura)...

This current paper aims to assess the action of low-intensity laser together with toluidine blue as a bactericidal agent during the instrumentation phase of radicular canals, comparing its associated or non-associated use with sodium hypochlorite 0.5%. To do so, 90 human canines were instrumented, autoclaved, and 88 were immersed into TSB, and were then inoculated with an E. faecalis suspension and brought into an incubator at 37 degrees Celsius for 72 hours in order to allow the formation of biofilm. The samples were randomly divided into 5 groups, 4 of which composed of 22 samples each plus 1 negative control. Group I: reinstrumented and irrigated with saline solution and subsequent application of photodynamic therapy (PDT); Group II: reinstrumented and irrigated with sodium hypochlorite 0.5% and subsequent PDT application; Group III: reinstrumented and irrigated with sodium hypochlorite 0.5%; Group IV: positive control (no previous treatment before material collection); Group V: negative control (2 samples) with no contamination. The collection of intracanal dentin was obtained by using a Gates Glidden drill nr. 6. The antimicrobial activity was assessed by CFUs counting. The teeth were then immersed in a selected medium for Enterococcus, incubated at 37 degrees Celsius for 72 hours. They were then assessed for medium turbidity. All samples, with the exception of the negative control, showed positive. In order to make sure of the formation of biofilm and the confirmation of the CFUs counting, 9 samples were scavenged under the electron microscope...

Laser activation of endodontic irrigants with improved conical laser fiber tips for removing smear layer in the apical third of the root canal.

With a tube etching process, conical-ended optical fibers for middle infrared lasers that have lateral emissions can be produced, a feature of benefit for delivering laser energy onto the root canal walls. This study examined the ability of these improved laser tips when Er:YAG and Er,Cr:YSGG lasers were used in root canals in which thick smear layers had been created intentionally to provide a challenge for the laser system. Smear layer was assessed from scanning electron microscopy images with an objective digital method. Lasing improved the action of ethylene diamine tetraacetic acid with cetavlon (EDTAC) in removing smear layer. Conical fibers performed better than plain fibers, but there was no difference in performance between the 2 laser systems when matched for all other parameters. These results provide a "proof of concept" for lateral emitting fibers for endodontic procedures and illustrate the novel contribution of lasing to the action of EDTAC in dissolving smear layer.