Evaluation of photo-activated disinfection effectiveness with methylene blue against Porphyromonas gingivalis involved in endodontic infection: An in vitro study

BackgroundEradication or suppression of microbial pathogens is a major goal in endodontic infection therapy. Sub-lethal doses of photo-activated disinfection (sPAD) as a new treatment method might be able to control the microorganisms involved in endodontic infections normally treated with PAD. This study evaluated the effect of sPAD using methylene blue (MB) in combination with diode laser irradiation on the growth and biofilm formation ability of Porphyromonas gingivalis as an endodontic pathogen.Materials and methodsThe anti-microbial and anti-biofilm potential of sPAD against P. gingivalis were assessed at sub-lethal doses of MB and irradiation by diode laser on colony forming unit and crystal violet assays, respectively.ResultsMB-sPAD using 25 μg/mL at a fluency of 117.18 J/cm² and 50–100 μg/mL at a fluency of 93.75 J/cm² significantly P. gingivalis growth when compared to the control. MB at 100 μg/mL at a fluency of 117.18 J/cm² in MB-mediated PAD showed a significant inhibitory effect on biofilm formation in P. gingivalis compared with MB-sPAD.ConclusionHigh doses of MB-mediated sPAD exhibited anti-microbial and anti-biofilm potential activity, whereas lower doses of MB-mediated sPAD did not display this ability. Therefore, the dose of PAD used in vivo should be taken into account for endodontic treatment.     

Evaluation of temperature change during antimicrobial photodynamic therapy with two different photosensitizers in dental caries

IntroductionMany attempts have been made in elimination of bacteria in infected and demineralized dentin to not only provide efficient bactericidal potential, but to have minimal damage for tooth structure. The aim of this study was to assess the temperature change during aPDT with ICG and TBO compared with conventional Diode laser irradiation.Materials and methods48 premolar teeth which were selected for this study. A class I cavity was drilled in each teeth, with dimensions of 2 mm width, 4 mm length and depth of 2.5–3.5 mm, providing a dentinal wall of approximately 0.5 mm for pulp chamber. Then teeth were randomly allocated in 4 experimental groups (n = 12); Group 1: TBO + LED, Group 2: ICG + Diode Laser, Group 3: Diode laser with output power of 0.5 W, Group 4: Diode laser with output power of 1 W. Thermocouple device was held by experimenter hand and the sensor was in pulp chamber of the teeth. Heat generated during irradiation was reported on LCD screen by NUX Plus software. Repeated measure ANOVA was used in order to compare the temperature before and after laser application. Tukey HSD was used to compare the results between groups.ResultsTemperature was risen for about 0.54 ± 0.05 °C for group 1, 1.67 ± 0.14 °C for group 2, 4.21 ± 0.83 °C for group 3, and 4. 50 ± 0.32 °C for group 4. The difference between group 1 & 2, 1 & 3 and 1 & 4 was significant (p < 0.0001).ConclusionAccording to results of this study, Diode (with or without photosensitizer- 0.5 and 1 W) can be safely used as alternative approach for disinfection after caries removal in thermal point of view.     

Monitoring gene expression of rcpA from Aggregatibacter actinomycetemcomitans versus antimicrobial photodynamic therapy by relative quantitative real-time PCR

BackgroundAggregatibacter actinomycetemcomitans is an important pathogen that is frequently found in various infections, particularly aggressive periodontitis. In this study, we described the outcome of the expression level of A. actinomycetemcomitans virulence factor following treatment by antimicrobial photodynamic therapy (aPDT) with indocyanine green (ICG) as a photosensitizing agent.Materials and methodsTo determine the aPDT effect on the cell-surviving assay and expression ratio of the rcpA gene in A. actinomycetemcomitans by a colony-forming unit and relative quantitative (q) real-time PCR (qRT-PCR) assays, respectively, the proper dosing of sub-lethal aPDT was specified.ResultsThe results of the current study showed that ICG-mediated aPDT, using 250–1000 μg/mL, showed a significant reduction in A. actinomycetemcomitans growth when compared to the control group (P < 0.05). Also, a sub-lethal dose of aPDT against A. actinomycetemcomitans was 125 μg/mL ICG, with a 30 s diode laser irradiation time at fluency of 15.6 J/cm² that could reduce the expression of rcpA gene approximately 6-fold.DiscussionaPDT with ICG could reduce the cell survival and the virulence agent of A. actinomycetemcomitans. Thus, use of the appropriate aPDT dosage can be used for the successful treatment of periodontitis in vivo.     

The evaluation of cultivable microbiota profile in patients with secondary endodontic infection before and after photo-activated disinfection

BackgroundSecondary/persistent endodontic infection can be the outcome of failure of endodontic treatment. Photo-activated disinfection (PAD) can be a useful adjunct to mechanical and antimicrobial agents in eliminating endopathogenic microorganisms. In this study, we evaluated the effect of PAD on diversity and count of microbiota related to secondary/persistent endodontic infections.Materials and methodsRoot canal samples were taken using sterile paper points from the root canals of 14 patients with secondary/persistent endodontic infections after removing the root-canal filling materials. PAD was performed on teeth with toluidine blue O (TBO) in combination with diode laser. Then re-sampling was conducted from the canal root using sterile paper points and transferred to transport medium. The samples were plated and pure cultures of the target microorganisms were then isolated and identified by analytical profile index (API ^® 20A) assays and 16S ribosomal RNA gene sequencing.ResultsBefore TBO-PAD, a total of 31 cultivable isolates could be retrieved; 25.8% of the isolated species were obligate anaerobic or microphilics including Veillonella parvula, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Propionibacterium acnes, and Lactobacillus acidophilus, and 74.2% of the isolated species were facultative anaerobic such as Enterococcus faecalis, Actinomyces naeslundii, L. rhamnosus, L. casei, Streptococcus sanguinis, S. mitis, and Candida albicans. According to this in vivo study, the diversity and count of microbiota in root canal-treated teeth were decreased after TBO-PAD, so that E. faecalis, V. parvula, and C. albicans were the microorganisms that recovered after PAD.ConclusionTBO-PAD is an effective approach that exhibited anti-microbial potential activity against microbiota involved in secondary/persistent endodontic infection.