Can Antimicrobial Photodynamic Therapy (aPDT) Enhance the Endodontic Treatment?

Antimicrobial photodynamic effect of the photosensitizer riboflavin, alone and in combination with colistin, against pandrug-resistant Pseudomonas aeruginosa clinical isolates

INTRODUCTION

Development of multi-, extensively-, and pandrug-resistant (MDR, XDR, and PDR) strains of Pseudomonas aeruginosa remains a major problem in medical care. The present study evaluated the effect of antimicrobial photodynamic therapy (aPDT) as a monotherapy and in combination with colistin against P. aeruginosa isolates.

METHODS

Two P. aeruginosa isolates recovered from patients with respiratory tract infections were examined in this study. Minimum inhibitory concentration (MIC) of colistin was determined by the colistin broth disk elution (CBDE) and the reference broth microdilution (rBMD) methods. aPDT was performed using the photosensitizer (Ps) riboflavin at several concentrations and a light-emitting diode (LED) emitting blue light for different irradiation times with or without colistin at 1/2 × MIC concentration.

RESULTS

Both PA1 and PA2 isolates were identified as colistin-resistant P. aeruginosa with a MIC ≥4 μg/mL by the CBDE and MICs of 512 μg/mL and 256 μg/mL, respectively, by the rBMD. In aPDT, neither riboflavin nor LED light alone had antibacterial effects. The values of colony forming units per milliliter (CFU/mL) in both isolates were significantly reduced by LED + Ps treatments in a time-dependent manner (LED irradiation time) and dose-dependent manner (Ps concentration). In comparison with control, treatment with Ps (50 μM) + LED (120 s) and Ps (100 μM) + LED (120 s) resulted in 0.27 log10 CFU/mL and 0.43 log10 CFU/mL reductions in PA1, and 0.28 log10 CFU/mL and 0.34 log10 CFU/mL reductions in PA2, respectively, (P < 0.01). The best results were obtained after the combination of aPDT followed by colistin, which increased bacterial reduction, resulting in a 0.41-0.7 log10 CFU/mL reduction for PA1 and 0.35-0.83 log10 CFU/mL reduction for PA2 (P = 0.001).

CONCLUSIONS

This study suggests the potential implications of aPDT in combination with antibiotics, such as colistin for treatment of difficult-to-treat P. aeruginosa infections.

In vitro effects of Er: YAG laser-activated photodynamic therapy on Enterococcus faecalis in root canal treatment

OBJECTIVE

Photodynamic therapy (PDT) plays an important role for root canal disinfection. Nevertheless, the effect of photosensitizers penetrating dentin tubules is limited, which ultimately impedes the disinfection effect of PDT. The study implements an Er: YAG laser to activate methylene blue, the photosensitizer, to determine the bactericidal impact of PDT on Enterococcus faecalis in vitro root canals.

METHODS

We obtained 53 single root canal teeth with intact roots, standardized the root to 9 mm. The root canals were prepared using ProTaper rotary files. Subsequently, the teeth were sterilized, and Enterococcus faecalis was cultured for 3 weeks in vitro using brain heart infusion (BHI). The model of Enterococcus faecalis root canal infection of teeth was constructed by observing Enterococcus faecalis through electron microscope scanning. The teeth were randomly allocated to five treatment groups (n = 10): control, NaOCl, NaOCl + Er: YAG, PDT, and PDT + Er: YAG. Following treatment, the number of colony forming units (CFU)/ml was assessed for each group. Statistical analysis was conducted using one-way ANOVA, with post-hoc analysis using Tukey's test for multiple comparisons.

RESULTS

The colony counts in the remaining groups were significantly lower compared to the control group (P<0.001). Using PDT alone had the least impact on reducing colonies, while using PDT and Er: YAG laser together resulted in a significant reduction in colony counts (P<0.001). There was no significant difference in colony counts reduction between the NaOCl + Er: YAG group and the PDT + Er: YAG group (P = 1.000).

CONCLUSIONS

The combination of Er: YAG laser and PDT significantly enhanced the bactericidal efficacy of PDT against Enterococcus faecalis in root canals. It had a similar impact on eliminating Enterococcus faecalis when compared to the effect of using Er: YAG laser and NaOCl.

Influence of Passive Ultrasonic Irrigation of the Photosensitizer Used in Photodynamic Therapy on Microbial Reduction in the Root Canal System: An in Vitro Study

Introduction

The success of endodontic treatment is based on microbial reduction promoted by the interaction of chemical and mechanical procedures. Photodynamic therapy (PDT) is used as an adjunct to conventional treatment, with significant microbial reduction. This study aimed to evaluate the influence of passive ultrasonic irrigation (PUI) of the photosensitizer (PS) used in PDT on microbial reduction in the root canal system.

Materials and Methods

Forty-five mesiobuccal root canals from extracted human mandibular molars that were inoculated with standard strains of Enterococcus faecalis, Candida albicans, and Streptococcus mutans for 21 days were selected. The root canals were prepared using the ProTaper Next system and randomly divided into 3 groups (n=15): 1) PDT: PDT alone; 2) PUI+PDT: PUI followed by PDT; and 3) PUI/PS+PDT: PUI of the PS followed by PDT. Microbiological samples were collected from the canals before and after using the protocols described above. The data were analyzed by analysis of variance (Tukey's test) at a significance level of 5%.

Results

Microbial counts before PDT, PUI+PDT, and PUI/PS+PDT did not differ significantly (P>0.05), showing methodological standardization in the microbial contamination of the root canal system. There was a significant reduction in microbial counts after PDT (61.05%), PUI+PDT (65.04%), and PUI/PS+PDT (68.58%) (P<0.01), but with no statistically significant difference between the three groups (P>0.05).

Conclusion

Based on the present findings, it was concluded that the combination of PUI with PDT or PS activation did not influence microbial reduction achieved by PDT alone.

Nano-phototherapy: Favorable prospects for cancer treatment

Nanotechnology-based phototherapies have drawn interest in the fight against cancer because of its noninvasiveness, high flexibility, and precision in terms of cancer targeting and drug delivery based on its surface properties and size. Phototherapy has made remarkable development in recent decades. Approaches to phototherapy, which utilize nanomaterials or nanotechnology have emerged to contribute to advances around nanotechnologies in medicine, particularly for cancers. A brief overviews of the development of photodynamic therapy as well as its mechanism in cancer treatment is provided. We emphasize the design of novel nanoparticles utilized in photodynamic therapy while summarizing the representative progress during the recent years. Finally, to forecast important future research in this area, we examine the viability and promise of photodynamic therapy systems based on nanoparticles in clinical anticancer treatment applications and briefly make mention of the elimination of all reactive metabolites pertaining to nano formulations inside living organisms providing insight into clinical mechanistic processes. Future developments and therapeutic prospects for photodynamic treatments are anticipated. Our viewpoints might encourage scientists to create more potent phototherapy-based cancer therapeutic modalities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A Bibliometric Study on the Top 101 Most-Cited Articles of Dental Journals of the Middle East/North Africa Countries From 2011 to 2021

Introduction: This retrospective descriptive study evaluated the Scopus-indexed dental journals and their most-cited documents affiliated with the Middle East and North Africa (MENA) countries from 2011 to 2021. Methods: Dental journals affiliated with MENA countries, their bibliometric indicators (SJR, CiteScore, SNIP, and H-index), and the 101 most cited articles of the considered journals were extracted and studied through descriptive statistics. In addition, the "citation per year" of each top 101 articles was calculated. Spearman's rho test was used for pairwise comparisons of the correlation coefficient values between each two of the considered bibliometric indicators. Results: The number of citations of the 101 most-cited papers ranged from 35 to 203. The mean (SD) citations of studied articles were 61.33 (37.58) and the median was 46. Furthermore, CiteScore had the highest significant correlation with SJR (r=0.828, P˂0.001). Moreover, the citation per year of the top 101 documents had no significant relationship with any of the journals' bibliometric indicators. Conclusion: Because journal performance and citation rate are multi-dimensional concepts, a single metric cannot express them thoroughly despite correlations between indices. "European Journal of Dentistry" from Turkey, "Saudi Dental Journal" from Saudi Arabia, and "Iranian Endodontic Journal" and "Journal of Lasers in Medical Sciences" both from Iran had the highest ranks in the SCImago portal and the highest scores in bibliometric indices amongst the MENA dental journals.

Effect of Malachite green, Ocimum Sanctum, and Er, Cr: YSGG laser on antimicrobial activity against S.mutans and CAD disinfection bonded to resin restoration

AIMS

Evaluation of survival of S.mutans and shear bond strength (SBS) of adhesive restorative material bonded to carious affected dentin (CAD) after using cavity disinfectant i.e., Er, Cr: YSGG (ECYL), (Nd: YAG) (NYL), Malachite green (MG), Ocimum sanctum (OS) in comparison to the conventional control chlorhexidine gluconate (CHX).

MATERIALS AND METHODS

Seventy-five caries-affected mandibular third molars having ICDAS scores 4 and 5 were included. Carious infected dentin was eliminated and CAD surface was obtained. On twenty-five samples, an uncontaminated suspension of S. mutans strain ATCC 35668 in Brain-Heart Infusion broth (BHI) was obtained after 12 hours of incubation at 37°C. Based on the disinfection regime used to sterilize the CAD surface, all the specimens were allocated into five different groups. (n=15) Group 1: CAD disinfected with CHX, Group 2: CAD disinfected with ECYL, Group 3: CAD disinfected with NYL, Group 4: CAD disinfected with MG, and Group 5: CAD disinfected with OS. An assessment of the survival rate of S. mutans was performed. Fifty specimens were smeared with single-step adhesive bond followed by restoring the CAD surface using packable composite. SBS and failure mode were determined using a universal testing machine and stereomicroscope at 40x magnification. ANOVA and post-hoc Tukey-Kramer test was used for data analysis p=0.05 RESULTS: Group 1: CHX-treated specimens displayed the lowest bacterial viability (0.11±0.03 CFU/mL). However, group 4: MG exhibited the highest bacterial survival (0.15 ±0.09 CFU/mL). The highest and lowest SBS of resin adhesive bonded to disinfected CAD surface were exhibited by (group 5: OS) (21.48±1.39 MPa) and (group 3: NYL) (16.41±0.90 MPa) respectively (p>0.05).

CONCLUSION

Ocimum sanctum seems to be promising in terms of its antibacterial efficacy against S.mutans and positive impact on SBS of resin adhesive to CAD surface.

An easily achievable strategy to promote the penetration of methylene blue into dentinal tubules

BACKGROUND

One critical issue that impairs the therapeutic effects of antimicrobial photodynamic therapy (aPDT) in root canal disinfection is the insufficient penetration of photosensitizer into dentinal tubules. Therefore, this study aimed to compare the treatments in enhancing photosensitizers' penetrability for aPDT in root canal therapy.

METHODS

Thirty premolars with a single root canal were randomly divided into three groups (n = 10), using Methylene blue (MB) as a photosensitizer and treated with different approaches: sonic-assisted diffusing group, ultrasonic-assisted diffusing group and the control without treatment. All specimens were observed by stereomicroscope to measure the penetration depth of MB into dentinal tubules.

RESULTS

Both sonic and ultrasonic treatments substantially improved the penetrability of MB. The former achieved a deeper penetration depth than the latter did in the same region of root (P<0.05). Regarding the dye penetration depths at different root regions, the control group showed a declining trend from coronal to apical. In contrast, the penetration depths of sonic and ultrasonic-assisted diffusing groups from highest to lowest were middle > coronal > apical (P<0.05).

CONCLUSIONS

This study showed that both sonic and ultrasonic treatments remarkably promoted MB's penetration depth into dentinal tubules. Maximum penetration was achieved when treated with a sonic approach.

Antibacterial potential of riboflavin mediated blue diode laser photodynamic inactivation against Enterococcus faecalis: A laboratory investigation

OBJECTIVES

This study aimed to evaluate the inactivation potency of riboflavin-mediated blue diode laser photodynamic inactivation (PDI) against Enterococcus faecalis at planktonic and biofilm stages and also investigated its effect on the tooth color change.

MATERIALS AND METHODS

The antibacterial and antibiofilm activities of riboflavin mediated PDI against E. faecalis were investigated. The numbers of colony-forming units (CFUs)/mL were calculated. Teeth discoloration were evaluated using the CIE L*a*b* based color difference (ΔE).

RESULTS

Antibacterial analysis indicated that the blue diode laser irradiation at 12, 18, 24, and 30 J/cm² alone and different concentrations of riboflavin solution (6.25 to 100 μM) reduced the number of CFU/mL of E. faecalis, but the reduction was not statistically significant (P > 0.05). Depending on the riboflavin concentration and the light dose, there can be as much as a 1-log effect on CFU/mL. In addition, E. faecalis biofilm was more affected with 30 J/cm² irradiation dosage and 100 μM riboflavin than other groups. Meanwhile, bacterial suspensions treated with 5.25% sodium hypochlorite (NaOCl) showed maximum biofilm inhibition and colony number reduction, compared with the control. The teeth exhibited clinically acceptable color change after riboflavin treatment at concentration ranging from 6.25 to 50 μM (ΔE < 3.7).

CONCLUSIONS

The riboflavin mediated PDI process is somewhat less effective than NaOCl but perhaps less toxic to tissues. It might be feasible to repeat the riboflavin + light treatment to further promote efficacy.

[Potentialities of photoactivated disinfection in dentistry]

Infection control is an essential part of dental practice. Oral antiseptics should be highly effective against the most common oral pathogens without causing microbial resistance, biocompatible with the human tissues with no interaction with fillings materials. Photoactivated disinfection (PAD) is based on activation of photosensitizers - specific substances releasing active oxygen forms after absorption of the light. The active oxygen forms destroy bacterial cell structures without affecting human cells. The overwhelming majority of Russian and international researchers have reported high effectiveness of PAD in periodontics, implantology and endodontics, whereas the use of PAD in caries treatment and prevention is not so fully understood yet. Earlier studies have demonstrated high sensitivity of cariogenic bacteria to PAD, suggesting it as an additional minimally invasive caries therapy improving treatment effectiveness. PAD spares dental tissues without reduction in the effectiveness of disinfection. It is particularly important in treatment of deep carious lesions and disinfection of thin dentine layer near the pulp. Effectiveness of PAD in caries treatment has been demonstrated for both permanent and deciduous dentition. PAD doesn't affect bond strength to fillings, improves plasticity of dental pulp and dental hard tissues mineralization in children. Effective control of a wide range of bacteria without causing resistance makes PAD a prospective method of treatment and prevention of caries.

Comparison of bacterial disinfection efficacy using blue and red lights on dental implants contaminated with Aggregatibacter actinomycetemcomitans

OBJECTIVES

The purpose of this study was to determine the bacterial disinfection efficacy of four photosensitizers (PSs; curcumin, riboflavin, toluidine blue O, and phycocyanin) with blue diode laser (Blue DL) and blue light-emitting diode (Blue LED) or Red DL and Red LED in dental implants contaminated with Aggregatibacter actinomycetemcomitans.

MATERIALS AND METHODS

A total of 60 dental implants were contaminated with A. actinomycetemcomitans. All implants were then randomized into ten different disinfection modalities (n = 6 implants per group). The irradiation wavelength in Blue DL and Blue LED or Red DL and Red LED was 450, 430-460, 635, and 630 nm, respectively and its applied energy density was 60 J/cm² in all groups. Group IX was served as the control group and in group X disinfection was performed with 0.2% chlorhexidine. After the treatments, the colony forming units (CFUs)/ml were calculated to determine antimicrobial effects of each treatment.

RESULTS

All disinfection methods significantly reduced bacteria amounts of dental implants inoculated with A. actinomycetemcomitans compared to control group. The CFU/ml in LED group was significantly lower than the DL in all studied groups.

CONCLUSION

aPDT could be an effective supplement in dental implants disinfection. The LED, proved to be better in reducing CFU/ml of A. actinomycetemcomitans on dental implants surface than DL.

5-Aminolevulinic Acid and Red Led in Endodontics: A Narrative Review and Case Report

The present study aims to discuss the main factors involving the use of 5-aminolevulinic acid together with red LED light and its application in endodontic treatment through a narrative review and a case report. Persistence of microorganisms remaining on chemical-mechanical preparation or intracanal dressing is reported as the leading cause of failure in endodontics. Photodynamic therapy has become a promising antimicrobial strategy as an aid to endodontic treatment. Being easy and quick to apply, it can be used both in a single session and in several sessions, as well as not allowing forms of microbial resistance. 5-aminolevulinic acid in combination with red LED light has recently been studied in many branches of medicine, with good results against numerous types of bacteria including Enterococuss faecalis. The case report showed how bacterial count of CFU decreased by half (210 CFU/mL), after 45 min of irrigation with a gel containing 5% of 5-aminolevulinic acid compared to the sample before irrigation (420 CFU/mL). The subsequent irradiation of red LED light for 7 min, the bacterial count was equal to 0. Thus, it is concluded that the use of 5-aminolevulinic acid together with red LED light is effective in endodontic treatment.

Antimicrobial photodynamic therapy in endodontic reintervention: A systematic review and meta-analysis

BACKGROUND

To evaluate the effectiveness of the use of antimicrobial photodynamic therapy (aPDT) in root canals disinfection in cases of endodontic retreatments.

METHODS

This Systematic Review was registered in PROSPERO (CRD42021260013) and followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Searches were performed in the electronic databases PubMeb, Scopus, Web of Science, Embase, Web of Science, Clinical Trials and Cochrane Library. Methodological quality and risk of bias were assessed by the Cochrane Risk of Bias tool for randomized clinical trials (RCT) and by the Newcastle-Ottawa (NOS) qualifier for non-RCT (prospective) studies. Meta-analysis was performed using R software, version 3.6.3 with the "META" package assistant by the RStudio platform. The odds ratio (OR) measure of effect was calculated and the random effect model was applied with a 95% confidence interval, and heterogeneity tested by the I2 index. The certainty of evidence was rated using GRADE.

RESULTS

Regarding the 1513 studies screened, 10 met the eligibility criteria and were included, and 8 used in the quantitative synthesis. Meta-analysis showed that all of studies data presented a significant difference before and after of antimicrobial photodynamic therapy in the microbial load reduction in secondary endondontic infections (OR 0.15 [0.07; 0.32], p < 0.0001). Overall, the studies had a low risk of bias and, the analysis of evidence by GRADE assessment was rated as moderate.

CONCLUSION

It is suggested that aPDT is a beneficial and promising tool, showing efficacy in reducing the microbial load in cases of endodontic retreatment.

Effect of Ultrasonic and Diode Laser Irrigation Activation on Post-operative Pain and Microbial Reduction in Single Visit Endodontic Treatment of Necrotic Mandibular Molars

Aim: To clinically evaluate the effect of continuous ultrasonic and diode laser 810 wave length irrigation activation techniques on postoperative pain and bacterial reduction in single visit endodontic treatment of mandibular molars. Material and methods: Forty patients requiring root canal treatment therapy for necrotic mandibular molars teeth were included in this study with age ranges between 20 and 45 years. In all cases, single visit endodontic treatment was carried out using Revo-S rotary file system in crown down sequence. NaOCl 2.5% irrigation solution was used during treatment. Patients were randomly and equally assigned into two groups according to irrigation technique. Group (1): conventional syringe irrigation and group (2): continuous ultrasonic irrigation. Each group was subdivided into two sub groups (n = 10); subgroup 1A (conventional syringe irrigation with no laser), subgroup 1B (conventional syringe irrigation with diode laser), subgroup 2A (continuous ultrasonic irrigation with no laser) and subgroup 2B (continuous ultrasonic irrigation with diode laser). Postoperative pain evaluation was done using Visual Analogue Scale (VAS) at 6, 12, 24, 36, 48 hours and 7 days postoperatively. Microbiological detection of bacterial reduction was done by taking Samples (S1 and S2) for bacterial cultures. S1 after finishing access cavity and before mechanical preparation and S2 after finishing mechanical preparation and irrigation activation and before obturation. Samples were cultured on blood agar and determined as colony forming units (CFU/mL). Microbiological bacterial reduction was calculated accordingly.  Statistical analyses were analyzed using the Mann-Whitney U test.  The significance level was set at p < 0.05. Results: In all sub groups, postoperative pain decreased by time in all time intervals but pain was significantly lower in subgroup (2B) (continuous ultrasonic irrigation with diode laser) than subgroup (1A) (conventional syringe irrigation with no laser) in all time interval. Microbiological results showed the highest bacterial reduction was in subgroup (2B) (continuous ultrasonic irrigation with diode laser) and least bacterial reduction was in subgroup (1A) (conventional syringe irrigation with no laser). Conclusion: Using diode laser and continuous ultrasonic irrigation activation techniques as adjunctive methods showed improvement in postoperative pain records and enhanced bacterial reduction in root canal therapy. Keywords: Continuous ultrasonic irrigation, diode laser 810, post-operative pain, bacterial reduction, single visit endodontic treatment.

Investigating the Antibacterial Effect of Passive Ultrasonic Irrigation, Photodynamic Therapy and Their Combination on Root Canal Disinfection

Introduction: Enterococcus faecalis is a gram-positive, facultative anaerobic bacterium associated with persistent endodontic infections. Conventional disinfection methods may not completely eradicate the bacteria within the root canal system. Therefore, novel modalities have been suggested to optimize root canal disinfection. The aim of this study was to evaluate and compare the antibacterial effect of photodynamic therapy (PDT), passive ultrasonic irrigation (PUI) and their combination in addition to conventional endodontic irrigation against E. faecalis biofilms in root canals. Methods: Root canals of 50 single-rooted extracted human teeth were prepared and incubated with E. faecalis for 21 days. They were then divided into 4 treatment groups and a control group as follows: (1) NaOCl-Syringe irrigation with 2.5% NaOCl, (2) PUI-Passive ultrasonic irrigation with NaOCl, (3) NaOCl+PDT-Photodynamic therapy following syringe irrigation with NaOCl, (4) PUI+PDT, (5) Control-Syringe irrigation with saline. Colony-forming units were counted and bacterial reduction was calculated for each treatment group. Results: All treatments led to significant reductions in the bacterial load compared to the control group. PUI and PUI+PDT led to the complete elimination of the bacteria from the root canals. NaOCl and NaOCl+PDT treatments reduced the bacteria by 99.9% and 99.5% respectively. NaOCl+PDT was significantly less effective in reducing the bacteria compared to other treatment groups. There were no significant differences between the NaOCl, PUI, and PUI+PDT groups. Conclusion: Passive ultrasonic irrigation with or without the combination of Photodynamic therapy completely eradicated the bacteria. The use of PDT as an adjunction to NaOCl syringe irrigation and PUI did not enhance their antibacterial effect.

Blue Light Photodynamic Therapy With Curcumin and Riboflavin in the Management of Periodontitis: A Systematic Review

Introduction: The aim of this article was to evaluate reports in the scientific literature that used antimicrobial photodynamic therapy (aPDT) with a blue light source and curcumin and riboflavin as photosensitizers in the management of periodontitis. Methods: The search was conducted in electronic databases, including PubMed, Web of Science, and Scopus, with the keywords "photodynamic therapy", "antimicrobial photodynamic therapy", "laser activated disinfection", "photoactivated disinfection", "light activated disinfection" "LED", "Periodontitis", "Curcumin", "Riboflavin", and "periodontitis" from 2012 to 2020. Results: After evaluating a total of 24 relevant articles, 13 articles were selected, full texts were read, and the data were extracted and placed in a table. Conclusion: Reviewing articles showed that curcumin as a photosensitizer activated by a blue wavelength is effective in the elimination of the various bacterial species involved in periodontal disease, and to the best of our knowledge, there is no study that has shown this substance does not reduce bacteria. According to the result of the articles, riboflavin as a photosensitizer activated by blue light can reduce bacteria that are involved in periodontitis, but other studies have reported that blue light alone can also reduce bacteria significantly. Therefore, more in-vitro and clinical trial studies are needed to give a more conclusive opinion on the effectiveness of riboflavin as a photosensitizer in the treatment of periodontitis.

Effect of Apical Size and Taper on the Efficacy of Root Canal Disinfection With LED Photodynamic Therapy as an Adjunct to Irrigation With Sodium Hypochlorite

Introduction: This study assessed the effect of apical size and taper on the efficacy of root canal disinfection with LED photodynamic therapy (PDT) as an adjunct to irrigation with sodium hypochlorite. Methods: A total of 126 extracted human mandibular molars were divided into 4 groups. The mesiobuccal canal was prepared to size 25/4% in group 1, 25/6% in group 2, 30/4% in group 3, and 30/6% in group 4 using the iRaCe rotary system. A 21-day Enterococcus faecalis biofilm was prepared and used for inoculation of the canals. Each group was randomly divided into 3 subgroups for canal disinfection with 2.5% sodium hypochlorite, sodium hypochlorite plus LED PDT and saline (positive control). Samples from the root canals were obtained with rotary files and cultured. Microbiologic data were analyzed using the Poisson regression test. Results: The bacterial count significantly decreased following disinfection with sodium hypochlorite with/without PDT in all sizes and tapers of preparation compared with the control group (P<0.05). Increasing the apical taper or apical size and the use of PDT as an adjunct did not have a significant effect on the reduction of the bacterial count (P>0.05). However, the apical size and PDT had a significant effect on the number of residual bacteria (P<0.05), and increasing the apical size and conduction of PDT significantly decreased the number of residual bacteria. Conclusion: The apical size and taper and the use of PDT as an adjunct did not have a significant effect on the reduction of the bacterial count. However, increasing the apical size and conduction of PDT as an adjunct to sodium hypochlorite irrigation significantly decreased the number of residual bacteria in the root canal system.

Antimicrobial action of photodynamic therapy on Enterococcus faecalis biofilm using curing light, curcumin and riboflavin

The aim of this study was to assess the effect of antimicrobial photodynamic therapy (aPDT) with curcumin and riboflavin on three-week Enterococcus faecalis biofilm. At first the 15-mm root canals of 65 single rooted extracted human teeth (including maxillary incisors, mandibular and maxillary canines and mandibular premolars) were separated from the crown and were prepared with ProTaper instruments. After autoclave sterilisation, samples were inoculated with E. faecalis suspension, and incubated for three weeks. After ensuring biofilm formation by scanning electron microscopy (SEM) in two teeth, the remaining 63 teeth were randomly divided into seven groups (n = 9): aPDT + curcumin, aPDT + riboflavin, LED, curcumin, riboflavin, 5.25% NaOCl (positive control) and no intervention (negative control). For light source a LED unit with 390-480 nm wavelength (peak of 460 nm), power density of 1000 ± 100 mW cm^-2 and mean energy density of 60 J cm^-2 was used. The roots were horizontally sectioned into coronal, middle and apical thirds each with 5 mm thicknesses. Dentin chips with equal weight (1 ± 0.005 g) were collected from the root canal walls with Gates Glidden drills and were transferred into microtubes containing 1 mL of sterile saline and vortexed for 30 s. Next, 10 µL of the contents of each tube was serially diluted and eventually, 10 µL of each solution was cultured on BHI agar. The number of colony-forming units was determined. Data were analysed using the Kruskal-Wallis and Friedman tests. The colony reduction was not significantly different between NaOCl and either riboflavin + LED or Curcumin + LED. The 5.25% NaOCl group showed maximum reduction in colony count, compared with the negative control (P = 0.00). Groups with aPDT with Curcumin + LED (P = 0.005), and with riboflavin + LED (P = 0.011) showed significant reduction in colony count in all three canal thirds (P < 0.05) without any difference with one another. With significant reduction of E. faecalis colony count, aPDT with Curcumin and riboflavin can serve as an adjunct to routine root canal disinfection method.

Photodynamic Inactivation of an Endodontic Bacteria Using Diode Laser and Indocyanine Green-Loaded Nanosphere

Apical periodontitis, an inflammatory lesion causing bone resorption around the apex of teeth, is treated by eradicating infectious bacteria from the root canal. However, it has a high recurrence rate and often requires retreatment. We investigated the bactericidal effect of antimicrobial photodynamic therapy (aPDT)/photodynamic antimicrobial chemotherapy (PACT) using indocyanine green (ICG)-loaded nanospheres coated with chitosan and a diode laser on a biofilm of Enterococcus faecalis, a pathogen of refractory apical periodontitis. Biofilm of E. faecalis was cultured in a porcine infected root canal model. ICG solution was injected into the root canal, which was then irradiated with a laser (810 nm wavelength) from outside the root canal. The bactericidal effect was evaluated by colony counts and scanning electron microscopy. The result of the colony counts showed a maximum 1.89 log reduction after irradiation at 2.1 W for 5 min. The temperature rise during aPDT/PACT was confirmed to be within a safe range. Furthermore, the light energy transmittance through the root was at a peak approximately 1 min after the start of irradiation, indicating that most of the ICG in the root canal was consumed. This study shows that aPDT/PACT can suppress E. faecalis in infected root canals with high efficiency.

Effects of curcumin-mediated antimicrobial photodynamic therapy associated to different chelators against Enterococcus faecalis biofilms

BACKGROUND

The aim of this study was to evaluate curcumin-mediated antimicrobial photodynamic therapy (aPDT) action combined or not with ethylenediaminetetraacetic acid (EDTA) and hydroxyethylidene bisphosphonate (HEBP) on Enterococcus faecalis biofilms.

METHODS

Enterococcus faecalis biofilms were grown on dentin bovine discs in brain heart infusion (BHI) medium with 1% glucose, in aerobic conditions at 37°C for 7 days. Then, they were randomly distributed to one of experimental conditions, as follows: control, 75 J.cm^-2 LED, 600 μmol.L^-1 curcumin, 17% EDTA, 18% HEBP, 600 μmol.L^-1 curcumin plus 75 J.cm^-2 LED, 600 μmol.L^-1 curcumin plus 17% EDTA, 600 μmol.L^-1 curcumin plus 18% HEBP, 600 μmol.L^-1 curcumin plus 17% EDTA and 75 J.cm^-2 LED or 600 μmol.L^-1 curcumin plus 18% HEBP and 75 J.cm^-2 LED. The viability of microorganisms and the vitality of biofilms were determined by colony forming unit counts and confocal scanning laser microscopy (CSLM), respectively. Statistical analysis was conducted by Kruskal Wallis and Dunn's post-hoc tests (α = 0.05).

RESULTS

The results showed that all combinations of aPDT with chelators significantly reduced the viability of microbial cells and the vitality of biofilms in comparison to control, even when considering deeper layers of biofilms.

CONCLUSION

The combination of curcumin with EDTA and HEBP similarly improved the effect of aPDT on E. faecalis biofilms.

Comparing the Efficacy of Toluidine Blue, Methylene Blue and Curcumin in Photodynamic Therapy Against Enterococcus faecalis

Introduction: Antimicrobial photodynamic therapy (aPDT) as a supplement to the conventional root canal preparation has shown promising results. Previous studies have adopted various combinations of light sources and photosensitizers, which makes it difficult to compare the disinfection efficacy of different PDT protocols. The aim of the present study was to compare the efficacy of three photosensitizers (toluidine blue, methylene blue, and curcumin) in PDT using LED against Enterococcus faecalis in root canal disinfection. Methods: Root canals of 54 single-rooted extracted teeth were prepared using the ProTaper Gold rotary system and were incubated with E. faecalis for three weeks. They were then randomly divided into five experimental groups and a control group: (1) Irrigation with 2.5% NaOCl for 30 seconds, (2) NaOCl irrigation followed by TB-PDT, (3) NaOCl irrigation followed by MB-PDT, (4) NaOCL irrigation followed by curcumin-PDT, (5) Curcumin solvent (1% ethanol+1% BSA), (6) Control (irrigation with normal saline). Sampling was done by collecting dentin shavings from the root canals, and colony-forming units were determined for each treatment group. The data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. The significance level was set at P<0.05. Results: In all treatment groups, the mean values of colony forming unit (CFU) decreased by 99% compared to the control group. The lowest mean values of CFU were observed in groups 2 and 4, followed groups 3, 1, and 5 respectively. The mean CFU count in group 2 was significantly lower than that of group 1 (P value=0.011), while there were no significant differences among groups 1, 3, and 4 (P value >0.05). Conclusion: The adjunction of toluidine blue-mediated PDT by means of a light-emitting diode to NaOCl irrigation increased its antibacterial efficacy against E. faecalis and could be an effective complementary method in root canal disinfection.

Final Endodontic Irrigation with 2% Peracetic Acid: Antimicrobial Activity and Cytotoxicity

OBJECTIVE

 The aim of present study was to assess the cytotoxicity and antimicrobial efficacy of 2% peracetic acid (PAA) compared with 5.25% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX).

MATERIAL AND METHODS

 For the cytotoxicity test, 100 µl of the tested solutions were added in 12 wells with ECV 304 endothelial cells in each group: NaOCl, CHX, and PAA, in addition to the control group. Each solution was evaluated after 24 hours of contact in four dilutions: 0.2, 0.1, 0.05 and 0.025 through mitochondrial function using MTT colorimetric assay. In the antimicrobial evaluation, 40 dentin blocks 5 mm in length and 0.2 g in weight were incubated with 400 µl of Enterococcus faecalis suspension for 21 days at 37°C. The contaminated samples were divided into three experimental groups within 5 minutes of contact: NaOCl group, CHX group, PAA group, as well as the positive control group. The specimens received treatment and were transferred to a tube with saline for serial dilution of the solution and seeding for isolation and colony forming unit (CFU) count.

STATISTICAL ANALYSIS

 The results obtained were expressed as mean (A570 nm) ± standard deviation (SD) and in a multiple linear regression model and multiple comparisons conducted.

RESULTS

 The antimicrobial evaluation revealed that the NaOCl and CHX groups showed a statistically significant difference compared with the control group (p < 0.001), while the PAA reduced only the CFU growth. It can be concluded that, among the agents tested, PAA expressed greater cell viability, followed by CHX and NaOCl. However, it did not show greater antimicrobial activity in vitro in the mature biofilm of Enterococcus faecalis.

Photodynamic therapry with curcumin in the reduction of enterococcus faecalis biofilm in bone cavity: rMicrobiological and spectral fluorescense analysis

BACKGROUND

Antimicrobial photodynamic therapy (PDT) has emerged as a therapeutic strategy to conventional procedures using antibiotics.

OBJECTIVE

To evaluate the antimicrobial effectiveness of PDT using blue light emitting diode (LED) associated with curcumin on biofilms of Enterococcus faecalis in bovine bone cavities and also to analyze the presence of these biofilms through spectral fluorescence.

MATERIALS AND METHODS

Standardized suspensions of E. faecalis (ATCC 29212) were incubated in artificial bone cavities for 14 days at 36 °C ± 1 °C for biofilm formation. The test specimens were distributed among the four experimental groups (n = 10): L-C- (control), L + C- (LED for 5 min), L-C+ (curcumin for 5 min) and L + C+ (PDT). Aliquots were collected from the bone cavities after treatments and seeded on BHI agar for 24 h at 36 °C ± 1 °C for CFU count. Before and after each treatment the specimens were submitted to spectral fluorescence, whose images were compared in the Image J program. The log10 CFU/mL results were submitted to the Kruskal-Wallis test (5%) and the biofilm fluorescence spectroscopy results were submitted to the Wilcoxon test (5%).

RESULTS

All treatments presented statistical difference when compared to the control, and PDT was responsible for the largest reduction (1.92 log10 CFU/mL). There was a reduction in the fluorescence emitted after the treatments, with greater statistical difference in the PDT group.

CONCLUSION

PDT was efficient in the reduction of E. faecalis biofilms. In all groups post treatment there was a significant reduction of biofilms in the fluorescence spectroscopy images with greater reduction in the PDT group.

Photosensitizers attenuate LPS-induced inflammation: implications in dentistry and general health

Antimicrobial photodynamic therapy (aPDT) is a complementary therapeutic modality for periodontal and endodontic diseases, in which Gram-negative bacteria are directly involved. Currently, there are few evidences regarding the effects of aPDT on bacterial components such as lipopolysaccharide (LPS) and it would represent a major step forward in the clinical use of this therapy. In this context, this study aimed to evaluate the efficacy of different photosensitizers (PSs) used in aPDT in LPS inhibition. Four PSs were used in this study: methylene blue (MB), toluidine blue (TBO), new methylene blue (NMB), and curcumin (CUR). Different approaches to evaluate LPS interaction with PSs were used, such as spectrophotometry, Limulus amebocyte lysate (LAL) test, functional assays using mouse macrophages, and an in vivo model of LPS injection. Spectrophotometry showed that LPS decreased the absorbance of all PSs used, indicating interactions between the two species. LAL assay revealed significant differences in LPS concentrations upon pre-incubation with the different PSs. Interestingly, the inflammatory potential of LPS decreased after previous treatment with the four PSs, resulting in decreased secretion of inflammatory cytokines by macrophages. In vivo, pre-incubating curcumin with LPS prevented animals from undergoing septic shock within the established time. Using relevant models to study the inflammatory activity of LPS, we found that all PSs used in this work decreased LPS-induced inflammation, with a more striking effect observed for NMB and curcumin. These data advance the understanding of the mechanisms of LPS inhibition by PSs.

Efficacy of antimicrobial photodynamic therapy administered using methylene blue, toluidine blue and tetra 2-mercaptopyridine substituted zinc phthalocyanine in root canals contaminated with Enterococcusaecalis

BACKGROUND

Traditional chemomechanical treatment procedures are an indispensable part of endodontic treatment, however, additional treatment approaches such as antimicrobial photodynamic therapy (aPDT) may also be recommended for the elimination of residual microorganisms. In this study, the disinfection efficiency of aPDT performed using methylene blue (MB), toluidine blue (TB), and tetra 2-mercaptopyridine substituted zinc phthalocyanine (TM-ZnPc) was compared in the roots contaminated with Enterococcus faecalis (E. faecalis).

MATERIALS AND METHODS

Forty-nine teeth with a single root and canal were included in this study. The roots were sterilized, and inoculated with E. faecalis. The roots were kept in an incubator for 30 days to form the biofilm. Forty-five teeth were prepared up to the F3 file of the ProTaperNext system under 2.5 % NaOCL irrigation. The samples were divided into three groups according to the type of used photosensitizer (PS) (n = 15); MB (313 μM), TB (327 μM), and TM-ZnPc (6μM). All PSs were irradiation with a light-emitting diode (LED) lamp (630 nm, 2-4 mW/cm²) for the 60 s. Two microbiological samples of the intracanal content were taken (one before and one immediately after additional aPDT in all groups) using sterile paper points. The colony-forming units per milliliter (CFU/mL) were calculated after 24 h of incubation at 37 °C.

RESULTS

After all aPDT protocols, intracanal bacterial load decreased significantly compared to the amount after chemomechanical preparation (P < 0.05). No significant difference in the reduction in intracanal bacterial load was found between the PSs (P < 0.05).

CONCLUSIONS

In the current study, the aPDT protocol performed with TM-ZnPc provided similar antimicrobial efficacy, although it was used at a lower concentration compared to MB and TB. Therefore, the use of TM-ZnPc in intra-canal disinfection in endodontics seems promising.

Antimicrobial effect of photodynamic therapy on intracanal biofilm: A systematic review of in vitro studies

BACKGROUND

Antimicrobial photodynamic therapy (A-PDT), is one of the adjunctive therapies developed to improve the effectiveness of root canal disinfection.. The aim of this study was to analyze the antimicrobial effect of PDT on intracanal biofilm.

METHODS

Two reviewers conducted a literature search in PubMed, MEDLINE, Lilacs, SciELO, EMBASE and Google Scholar using the following search strategy: photochemotherapy "[Mesh] OR (photodynamic therapy) AND" dental plaque "[Mesh] OR (dental biofilm) AND (root canal). The following data were collected: publication year, author's name, study site, type of study, participant number, type of photosensitizer, type of laser, method of data collection, application time and results. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS).

RESULTS

After selection based on title, abstract and full text, 27 studies were included in this systematic review. PDT reduced bacterial viability in most studies when combined with conventional endodontic techniques.

CONCLUSION

PDT reduced bacterial counts in most studies, especially when used as an adjunct to the conventional endodontic technique to treat refractory infection. However, PDT effects on in vitro bacterial biofilm were not accurately quantified because of the numerous biases in the studies reviewed.

Systematic Review on the Role of Lasers in Endodontic Therapy: Valuable Adjunct Treatment?

(1) Background: Adjunctive instruments, such as lasers have been investigated to address the risk of failure of endodontic therapy due to the complexity of the root canal system. Lasers have been used therapeutically, in direct irradiation of the root canals or adjunct to irrigants placed into the canals, in combination with a photosensitizer (antimicrobial photodynamic therapy) and in pain management (photobiomodulation). The purpose of this systematic review was to evaluate the evidence in clinical use within these three areas of therapy. (2) Methods: PubMed, Cochrane and Scopus search engines were used to identify human clinical trials regarding the use of lasers in endodontic therapy. (3) Results: After applying the keywords and additional filters, inclusion and exclusion criteria, the initial number of 1486 articles was reduced to 17. It was revealed that almost all studies (14/17) presented a statistically significant improved outcome in laser-assisted endodontic therapy, with the remaining three not showing any adverse effects. (4) Conclusions: The use of laser photonic energy of appropriate delivered parameters can be proposed as useful adjunctive when considering optimal treatment modalities in orthograde endodontics. Additionally, a tendency of research towards pain modulation in this field is developing.

The Effect of Antimicrobial Photodynamic Therapy Using Chlorophyllin–Phycocyanin Mixture on Enterococcus faecalis: The Influence of Different Light Sources

The purpose of this study was to evaluate the in vitro effect of the chlorophyllin–phycocyanin mixture (Photoactive+) as a photosensitizer (PS) during antimicrobial photodynamic therapy (aPDT) on the count of Enterococcus faecalis (E. faecalis) using different light sources. The antimicrobial effect of aPDT with chlorophyllin–phycocyanin mixture using different light sources including diode laser (λ = 660 nm), diode laser (λ = 635 nm), LED (λ = 450 ± 30 nm) alone or in combination was assessed using microbial cell viability assay against E. faecalis. In addition, the cell cytotoxicity of Photoactive+ was assessed on human gingival fibroblast (HuGu) cells by MTT assay; E. faecalis growth when treated by both red wavelengths (635 nm, 660 nm) and combination of LED (420–480 nm) and red wavelengths (635 nm, 660 nm), significantly reduced compared to the control group (p < 0.05). There was no significant reduction in the number of viable cells exposed to Photoactive+ compared to the control group (p < 0.05). This study shows that the application of chlorophyllin–phycocyanin mixture and irradiation with emission of red light achieved a better result for bacterial count reduction, compared to a control. This component can be applied safely due to very negligible cytotoxicity.

In vitro antimicrobial photodynamic inactivation of multidrug-resistant Acinetobacter baumannii biofilm using Protoporphyrin IX and Methylene blue

BACKGROUND

Acinetobacter baumannii is a challenging pathogen due to the rapid development of antimicrobial resistance and biofilm formation. The objective of this study was to evaluate the effect of antimicrobial photodynamic inactivation against biofilms of multidrug-resistant A. baumannii isolated from clinical, abattoir and aquatic sources.

METHODS

The isolates were tested for susceptibility to imipenem, meropenem, tigecycline and colistin using autoSCAN-4 automated system and rechecked by the E-test. Methylene blue, Protoporphyrin IX, and a halogen lamp were used in the in vitro assay against biofilms of the isolates. The antimicrobial photodynamic inactivation was assessed by counting colony-forming units (CFU).

RESULTS

The isolates from abattoir and aquatic sources were resistant to carbapenems (>64 μg/mL) but susceptible to tigecycline (2 μg/mL) and colistin (Abattoir, 0.35 μg/mL and Aquatic, 0.24 μg/mL), whereas the clinical isolate was susceptible to only colistin (0.5 μg/mL) using the E-test. The log survival percentages of the control group at a concentration of 20 μM were 5 × 10^-6 % for Protoporphyrin IX and 2 × 10^-6 % for Methylene blue. Therefore, Methylene blue showed higher bacterial reduction of 7.0 log₁₀ colony forming units than 6.0 log₁₀ for Protoporphyrin IX. No significant difference was observed with respect to the origin of isolates and the minimum inhibitory concentrations.

CONCLUSION

The results indicate that antimicrobial photodynamic inactivation could be an alternative strategy for the control of infections caused by multi-drug resistant A. baumannii by significantly reducing biofilm growth at a sub-lethal concentrations.

Ex vivo comparison of antibacterial efficacy of conventional chemomechanical debridement alone and in combination with light-activated disinfection and laser irradiation against Enterococcus faecalis biofilm

BACKGROUND AND OBJECTIVES

Intracanal disinfection plays an important role in endodontic treatment success. Enterococcus faecalis (E. faecalis) is a resistant microorganism responsible for endodontic infections. We aimed to assess the bactericidal effects of three disinfection methods on E. faecalis biofilm.

MATERIALS AND METHODS

Fifty-five freshly extracted single-rooted human teeth were evaluated. A barbed broach was used to extract the pulp tissue. No further root canal preparation was performed. Specimens were sterilized with gamma radiation, and inoculated with E. faecalis suspension. They were then incubated for 4 days and 4 weeks. Biofilm formation was confirmed using a scanning electron microscope (SEM). The teeth were randomly assigned to three subgroups (n = 7) to assess the antimicrobial efficacy of the following three disinfection methods against immature (4-day) and mature (4-week) biofilms: the conventional chemomechanical debridement (CCMD), CCMD + light-activated disinfection (LAD; 810 nm, 0.3 W, 120 J/cm²) with indocyanine Green (EmunDo) as photosensitizer and CCMD + diode laser irradiation (810 nm, 2 W). The teeth were then longitudinally split into two halves and the colony count was reported as colony forming units (CFUs) to assess bacterial viability after each disinfection protocol.

RESULTS

None of the disinfection methods could completely remove the biofilm. CCMD + LAD caused the highest and CCMD + diode laser caused the lowest reduction in biofilm. Antibacterial efficacy was significantly lower against the mature (4-week) biofilm compared with immature (4-day) biofilm in all groups (P < 0.05).

CONCLUSION

All three disinfection methods were effective for partial elimination of E. faecalis biofilm. But CCMD + LAD was significantly more efficacious in decreasing both mature and immature biofilms.

In vitro Evaluation of the Antimicrobial Effect of N-acetylcysteine and Photodynamic Therapy on Root Canals Infected with Enterococcus faecalis

Introduction

This study aimed to evaluate the in vitro effectiveness of N-acetylcysteine (NAC), photodynamic therapy (PDT) and NAC with supplemental PDT in optimizing the removal of bacteria from infected dentinal tubules of root canals infected with Enterococcus (E.) faecalis biofilm.

Methods and Materials

Eighty human teeth were randomly divided into 5 groups (n=16) according to the intracanal medication used: saline solution (control); calcium hydroxide (CH); NAC; PDT; NAC+PDT. Ten samples from each group were prepared for microbiological culture analysis (CFU/mL) and were inoculated with E. faecalis suspension for 21 days for biofilm development; the other six samples from each group were prepared for scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) and submitted to a 5-days contamination protocol including eight centrifugation cycles on every other day for dentinal tubules infection. For antimicrobial activity analysis by microbiological culture (CFU/mL), the root canals were contaminated with E. faecalis biofilm, instrumented and then medicated according to the experimental groups. Three samples were collected from the root canals: after 21-days of contamination, immediately after the instrumentation and 14-days after the medication according to the experimental groups. The morphology of E. faecalis biofilm on the root canal walls and bacterial cells viability were assessed by means of SEM and CLSM, respectively. One-way ANOVA and Repeated Measures ANOVA tests were used to analyze the obtained data statistically.

Results

CFU/mL analysis showed that CH, NAC and NAC+PDT promoted greater antibacterial activity with statistically significant difference compared to saline solution and PDT (P<0.0001). However, saline solution and PDT were statistically similar (P>0.07). Illustrative images by SEM confirmed partially the CFU/mL results. CLSM showed that all groups were effective eliminating E. faecalis except for the saline solution group.

Conclusions

Based on this in vitro study NAC was bactericidal against E. faecalis biofilms regardless PDT stimulation, presenting similar antimicrobial activity to CH.

Modulation of virulence in Enterococcus faecalis cells surviving antimicrobial photodynamic inactivation with reduced graphene oxide-curcumin: An ex vivo biofilm model

BACKGROUND

Enterococcus faecalis, as a major microorganism in persistent/secondary infections of endodontically treated teeth, is less likely to be eliminated during endodontic therapy. In this study, the effect of root canal disinfection and anti-virulence activities of photodynamic inactivation (PDI) of E. faecalis utilizing reduced graphene oxide-curcumin (rGO-Cur) as a photosensitizing agent following irradiation with light-emitting diode (LED), as well as intracellular ROS production were evaluated on ex vivo biofilms of E. faecalis in comparison with sodium hypochlorite (NaOCl) as the traditional endodontic irrigation solution.

MATERIALS AND METHODS

After formulation and confirmation of synthesized rGO-Cur using scanning electron microscopy (SEM), Fourier transformation infrared (FT-IR), UV-Vis spectra, dynamic light scattering (DLS), and Zeta potential, the minimum biofilm inhibitory concentrations (MBICs) and in vitro anti-biofilm activity of rGO-Cur, light-emitting diode (LED) at the wavelength of 435 ± 20 nm, and rGO-Cur-PDI were determined against 4-week-old pre-formed biofilms of E. faecalis. After preparation of ex vivo biofilm model in root canals, the ex-vivo anti-biofilm potential of rGO-Cur, LED, and rGO-Cur-PDI against E. faecalis were analyzed using the XTT assay and scanning electron microscopy (SEM) in comparison with NaOCl. The effects of sub-MBIC of rGO-Cur and NaOCl, sub-lethal dose of LED, and sub-significant inhibitory (SSI) potential of rGO-Cur-PDI for E. faecalis biofilms on virulence genes (efa, esp, gel, and fsr) expression of E. faecalis were analyzed using real-time polymerase chain reaction (qRT-PCR) assay. Intracellular reactive oxygen species (ROS) level was measured in rGO-Cur-PDI-treated bacterial cells compared to control cells with 2',7'-dichlorfluorescein-diacetate (DCFH-DA) fluorescent probe.

RESULTS

The FTIR, DLS, Zeta potential, SEM, and UV-Vis spectra analysis indicated the successful synthesis of rGO-Cur. The MBIC of rGO-Cur was 250 μg/ml, which inhibited the growth ofE. faecalis. LED showed insignificant anti-biofilm activity against E. faecalis even after treating for a long irradiation time (300 s). According to checkerboard assay, the MBIC value of rGO-Cur-PDI was reduced noticeably compared to the individual MBIC values of rGO-Cur and LED for E. faecalis. The expression levels of efa, esp, gel, and fsr genes in pre-formed E. faecalis biofilms were markedly reduced after rGO-Cur, rGO-Cur-PDI, and NaOCl treatment in comparison with the control group. Conversely, LED revealed no significant change in the expression of the virulence genes. The intracellular ROS assay showed a significant increase (8.3-fold) in rGO-Cur-PDI when compared to the control.

CONCLUSION

Our data support that rGO-Cur-PDI showed dual inhibitory effects on biofilm formation ability and virulence activity of E. faecalis with potential clinical applications for infection control in endodontics.

Dual wavelength irradiation antimicrobial photodynamic therapy using indocyanine green and metformin doped with nano-curcumin as an efficient adjunctive endodontic treatment modality

BACKGROUND

Indocyanine green (ICG) doped with nano-curcumin (N-CUR) can increase photosensitivity in antimicrobial photodynamic therapy (aPDT). Since metformin (Met) provides a synergistic advantage with photosensitivity, it was conjugated with N-CUR@ICG. Aim of the study was to evaluate the photosensitizing effect of N-CUR@ICG-Met used as a new photosensitizer in dual wavelengths irradiation (diode laser and light-emitting diode, LED) aPDT in root canals infected with Enterococcus faecalis biofilm.

MATERIALS AND METHODS

Following synthesis and confirmation of N-CUR@ICG-Met by Scanning electrone microscope (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Zetasizer analysis, the mature microbial biofilm was formed. The quantitative and qualitative evaluations of E. faecalis biofilm were made using microbial viability and SEM analysis of the following groups of treatment modalities (n = 5): 1- N-CUR, 2- ICG, 3- Met, 4- N-CUR@ICG, 5- N-CUR@ICG-Met, 6- Diode laser, 7- LED, 8- aPDT/diode, 9- aPDT/LED, 10- aPDT/diode laser + LED, 11- aPDT/LED + diode laser, 12- 2.5 % sodium hypochlorite (NaOCl). In addition, E. faecalis not treated served as negative control. Data were statistically analyzed using One-way Analysis of Variance (ANOVA) and the post-Hoc Bonferroni tests with a level of significance set at P < 0.05.

RESULTS

SEM, FT-IR, XRD, Zetasizer analysis confirmed successful doping of ICG-Met onto/into N-CUR. The treatment modality of N-CUR@ICG-Met mediated aPDT/diode laser, aPDT/LED, aPDT/diode laser + LED, and aPDT/LED + diode laser statistically decreased the cell viability of E. faecalis for 69.40 %, 75.52 %, 82.74 %, and 83.84 %, respectively compared with the negative control group (P < 0.05). The double wavelengths irradiation technique, which exposed the N-CUR@ICG-Met with diode laser irradiation and immediately after with LED (i.e. group No. 10), as well as, N-CUR@ICG-Met with LED irradiation and immediately after with diode laser (i.e. group No. 11) reduced the viable E. faecalis count in biofilm structures statistically more than the other treatment modalities (P < 0.05).

CONCLUSIONS

N-CUR@ICG-Met as a new photosensitizer in dual wavelengths irradiation method may improve anti-biofilm activity of aPDT against E. faecalis.

Evaluation of the outcome of various laser therapy applications in root canal disinfection: A systematic review

BACKGROUND

Any successful endodontic therapy requires elimination of the endodontic biofilms through meticulous root canal disinfection methods. Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are the most common effective irrigants, in removing smear-layer from the coronal and middle thirds of the dental canals but reduced considerably towards the apical one third. In recent years, newly alternative treatment modalities have been proposed, including high-power lasers and antimicrobial photodynamic therapy (aPDT). Our work was conducted to evalaute the outcome of root canal disinfection in relation to the efficacy of various treatment modalities. Furthermore, every effort was made to present an overview of the aPDT outcomes, as a model for this application, and to propose laser parameters protocol with positive results.

METHODS

The electronic databases PubMed was searched from January 2013- January 2019. Our inclusive criteria based on laser therapy applications, as a model for root canal disinfection. The search terms utilised various combinations as follows: photodynamic therapy or antimicrobial photodynamic therapy or photoactivated disinfection or light activated disinfection or laser activated disinfection or laser therapy, and endodontic.

RESULTS

The results of this systematic review concluded that the effectiveness of aPDT and various laser wavelengths protocols, in removing endodontic biofilms from infected root canals, remains unattainable.

CONCLUSIONS

Study concluded that the combination of aPDT with antimicrobial irrigants could provide a synergetic effect. However, due to the heterogeneity of the selected studies and their limitations, in terms of lack of standardised protocol or discrepancy in the methodology, authors suggest further validated approaches to achieve optimal outcomes.

Inactivation of oral biofilms using visible light and water-filtered infrared A radiation and indocyanine green

Aim: To investigate the antimicrobial photodynamic therapy (aPDT) of visible light and water-filtered infrared A radiation in combination with indocyanine green (ICG) on planktonic oral microorganisms as well as on oral biofilm. Methods: The irradiation was conducted for 5 min in combination with ICG. Treatment with chlorhexidine served as a positive control. The number of colony forming units and bacterial vitality were quantified. Results: All tested bacterial strains and salivary bacteria were killed at a level of 3log_10. The colony forming units of the initial mature oral biofilms were strongly reduced. The high bactericidal effect of aPDT was confirmed by live/dead staining. Conclusion: The aPDT using visible light and water-filtered infrared A radiation and ICG has the potential to treat periodontitis and peri-implantitis.

Photosensitizers in antibacterial photodynamic therapy: an overview

Antibacterial Photodynamic therapy (APDT) is a process utilizing light and light sensitive agents (named photosensitizer (PS)) and is usually applied in an oxygen-rich environment. The energy of the photons is absorbed by the photosensitizer and subsequently transferred to surrounding molecules. Consequently, reactive oxygen species and free radicals are formed. These oxidative molecules can damage bacterial macromolecules such as proteins, lipids and nucleic acids and may result in bacterial killing. Unlike antibiotics, APDT as a novel technique does not lead to the selection of mutant resistant strains, hence it has appealed to researchers in this field. The type of PS used in APDT is a major determinant regarding outcome. In this review, various types of PS that are used in antimicrobial Photodynamic therapy will be discussed. PSs are classified based on their chemical structure and origin. Synthetic dyes such as methylene blue and toluidine blue are the most commonly used photosensitizers in Antibacterial Photodynamic therapy (APDT). Other photosensitizers including natural PSs (e.g. curcumin and hypericin) and tetra-pyrrole structures like phthalocyanines and porphyrins have also been studied. Furthermore, nanostructures and their probable contribution to APDT will be discussed.

Photodynamic therapy in endodontics

Photodynamic therapy (PDT) is a treatment modality that was initiated in 1900; however, it was not until the last decade that PDT regained attention for its several favourable features during the treatment of microbial infections in endodontics. Recently, several papers advocated its use for root canal treatment. The concept of photodynamic inactivation requires microbial exposure to either exogenous or endogenous photosensitizer molecules, followed by visible light energy, typically wavelengths in the red/near-infrared region that cause the excitation of the photosensitizers resulting in the production of singlet oxygen and other reactive oxygen species that react with intracellular components and consequently produce cell inactivation and death. Recently, PDT has been suggested as a promising effective adjunct to standard antimicrobial intracanal cleaning and shaping for the treatment of periapical lesions. Current publications tested PDT in terms of bacterial load reduction in vivo, in vitro and ex vivo, showing promising results. The purpose of this article was to review the existing literature on PDT in the endodontic field regarding its mechanism of action, photosensitizers and light sources, limitations and clinical procedures. Although positive results have been demonstrated in vitro, there are considerably fewer in vivo investigations. In conclusion, more in vivo studies are needed on the use of antimicrobial PDT in root canal treatment.

Antimicrobial photodynamic therapy of Lactobacillus acidophilus by indocyanine green and 810-nm diode laser

This study investigated the efficacy of photodynamic therapy (PDT) using EmunDo as a photosensitizer against Lactobacillus acidophilus. A gallium aluminum arsenide diode laser was used in this experiment (810 nm, CW). Standard suspensions of Lactobacillus acidophilus were divided into six groups by treatment: 1) EmunDo, 2) diode laser (100 mW, 90 s), 3) diode laser (300 mW, 30 s); 4) EmunDo + diode laser (100 mW, 90 s), 5) EmunDo + diode laser (300 mW, 30 s), 6) control (no treatment). Bacterial suspensions from each group were subcultured onto the surface of MRS agar plates immediately and 24 h after treatment, and the viable microorganisms of Lactobacillus acidophilus were counted. The data were analyzed by ANOVA and student's t-test at p < 0.05. There was a significant between-group difference in the number of Lactobacillus acidophilus colonies in cell cultures obtained at 24 h after treatment (p < 0.001). The viable counts were significantly lower in EmunDo and both PDT groups, as compared to the other groups (p < 0.05). In the control and laser-irradiated groups, the number of colonies increased significantly at 24 h compared to the immediately after treatment (p < 0.05), whereas in both PDT groups, the number of colonies showed a significant reduction after 24 h of therapy (p < 0.05). Under the conditions used in this study, L. acidophilus colonies were susceptible to PDT after sensitization with EmunDo and exposure to diode laser. These findings imply that PDT is capable to reduce cariogenic bacteria, potentially leading to more conservative cavity preparation.

Evaluation of the antibacterial efficacy of various root canal disinfection methods against Enterococcus faecalis biofilm. An ex-vivo study

BACKGROUND

Complete elimination of bacteria and their by-products from the root canal system is very difficult with current techniques. The purpose of this study was to compare the antibacterial efficacy of different disinfection protocols against Enterococcus faecalis (E. faecalis) biofilms.

METHODS

Seventy-six extracted single-rooted human teeth were selected. Root canal preparation was done by proTaper rotary instruments. The smear layer was removed by 17% EDTA, followed by 5.25% sodium hypochlorite. After sterilization using gamma irradiation, sterilized specimens were inoculated with an E. faecalis suspension, incubated for 4 days and 4 weeks and then randomly divided into two experimental groups (4 days, 4 weeks old biofilms). After the confirmation of biofilm formation with SEM, the specimens in the experimental groups were randomly divided into five experimental subgroups according to the method of disinfection applied, which included: Diode laser irradiation (810 nm, 2 W), Light activated disinfection (LAD) with Indocyanine Green, 0.2% Chlorhexidine gluconate (0.2% CHX), 0.2% CHX + LAD and 0.2% CHX + Diode groups.

RESULTS

Complete biofilm bacterial elimination was not observed in either of the experimental groups. CHX + LAD (0.2%) method exhibited the highest reduction value in biofilm and only Diode alone revealed the lowest in all the root canal portions. Disinfection protocols also showed significantly lower antibacterial efficacy against 4-week old than the 4-day old matured biofilms (P < 0.05).

CONCLUSION

All the evaluated methods in this study were effective in the relative elimination of the E. faecalis biofilms except diode laser alone. Nevertheless, 0.2% CHX + LAD exhibited significantly higher efficacy in reducing both 4-day and 4-week old biofilms.

Antibacterial and Antibiofilm Efficacy of Antimicrobial Photodynamic Therapy Against Intracanal Enterococcus faecalis: An In Vitro Comparative Study with Traditional Endodontic Irrigation Solutions

OBJECTIVES

Enterococcus faecalis (E. faecalis), an infecting microorganism of the root canals, is difficult to eliminate during endodontic therapy. In this study, the effect of root canal disinfection with sodium hypochlorite (NaOCl) and chlorhexidine (CHX) was evaluated on planktonic and biofilm forms of E. faecalis in comparison with antimicrobial photodynamic therapy (aPDT) as an alternative strategy for root canal disinfection.

MATERIALS AND METHODS

In this study, E. faecalis (ATCC 29212) was used. The experimental procedures included aPDT with curcumin (CUR) and indocyanine green (ICG) as photosensitizers, irrigation with 5.25% NaOCl, 0.2% and 2.0% CHX solutions as traditional endodontic irrigating solutions, and the control group. The antibacterial and anti-biofilm potentials were assessed by counting the colony forming units and also using the crystal violet assay, respectively.

RESULTS

According to the results, E. faecalis biofilm was disrupted by 65.3%, 81.0% and 92.6% using 0.2% CHX, 2.0% CHX, and 5.25% NaOCl, respectively (P<0.05). In addition, CUR- and ICG-mediated aPDT displayed a significant reduction in E. faecalis count (90.2% and 82.5%, respectively) and its biofilm (83.6% and 75.2%, respectively) in comparison to the control group (P<0.05).

CONCLUSIONS

APDT has a high potential for elimination of E. faecalis and is almost equivalent to NaOCl and CHX. It can be used as an adjucnt to conventional endodontic irrigating solutions.

Expression patterns of oxyR induced by oxidative stress from Porphyromonas gingivalis in response to photo-activated disinfection

Introduction

Porphyromonas gingivalis, an important endodontic pathogen, may be exposed to sublethal doses of photo-activated disinfection (sPAD) during root canal therapy. Such an exposure can affect bacterial survival and virulence features. In this study, we evaluated the effect of sPAD-related oxidative stresses on the expression of oxidative stress response gene (oxyR) in P. gingivalis clinical isolates surviving in vitro photodynamic treatment.

Materials and methods

To determine the sPAD, 16 clinical P. gingivalis isolates photosensitized with toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) were irradiated with specific wavelength and energy density of diode laser corresponding to the photosensitizers following bacterial viability measurements. The effects of sPAD on the expression ratio of oxyR of 16 clinical P. gingivalis isolates were then assessed using quantitative real-time PCR (qRT-PCR) assay.

Results

Maximum values of sPAD against P. gingivalis were 6.25, 15.6, and 25 μg/mL at fluencies of 171.87, 15.6, and 93.75 J/cm², respectively, for TBO-, ICG-, and MB-sPAD (P>0.05). ICG-, MB-, and TBO-sPAD could increase the oxyR gene expression of the clinical P. gingivalis isolates 12.3-, 5.6-, and 8.5-fold, respectively. ICG-sPAD increased the expression of oxyR gene in clinical isolates of P. gingivalis ~1.5- and 2-fold higher than TBO- and MB-sPAD, respectively.

Conclusion

Our results showed that upregulation of oxyR during sPAD may lead to better survival and increased pathogenicity of P. gingivalis isolates. Therefore, selection of appropriate photo-activated disinfection dosage should be considered for the successful treatment of endodontic infection.

Ex vivo assessment of synergic effect of chlorhexidine for enhancing antimicrobial photodynamic therapy efficiency on expression patterns of biofilm-associated genes of Enterococcus faecalis

BACKGROUND

It has clearly been demonstrated that Enterococcus faecalis, as a persistent microorganism, is the major agent in the etiopatogeny of endodontic infections. Recently, the limitations of conventional endodontic therapy have given rise to many attempts to introduce antimicrobial photodynamic therapy (aPDT) as an alternative treatment. The aim of this study was to analyze the ex vivo effect of aPDT in combination with 2.0% chlorhexidine (CHX) as a conventional therapy on colony count and expression patterns of genes associated with biofilm formation of E. faecalis.

MATERIALS AND METHODS

A total of 125 extracted human single-rooted teeth were divide into six groups (A-F; n = 20) and were incubated with E. faecalis. Group A- photosensitizer (indocyanine green [ICG]); B- diode laser; C- aPDT; D- 2.0% CHX; E- aPDT with photosensitizer modified by 2.0% CHX; and F- control group (no procedure was performed). Five remaining teeth were used to confirm the presence of E. faecalis biofilm via scanning electron microscope. Counts of colony forming units (CFUs) in each group were evaluated separately and quantitative real-time PCR (qRT-PCR) was then applied to monitor genes expression of fsrC, efa, and gelE involved in E. faecalis biofilm.

RESULTS

The results showed that none of the tested groups achieved eradication or inhibition of biofilm. On the other hand, aPDT + 2.0% CHX, 2.0% CHX, and ICG- mediated aPDT groups showed significantly less CFU/mL than ICG and diode laser groups. The group with the lowest CFU/mL count was the aPDT + 2.0% CHX, being statistically different from all other groups that could decrease the expression levels of efa, gelE, and fsrC genes 6.8-, 8.3-, and 12.1-fold, respectively.

CONCLUSION

Based on the results, the synergism effect of ICG-aPDT with 2.0% CHX leads to modulation of the virulence of E. faecalis strains biofilm model by suppressing the expression of the genes associated with biofilm formation.

Diagnostic accuracy of multiplex real-time PCR approaches compared with cultivation -based detection methods: Monitoring the endopathogenic microbiota pre and post photo-activated disinfection

BACKGROUND

Several microbial species have been implicated in the pathogenesis of endodontic diseases that colonize the infected root canal system. Since the complete removal of endopathogenic agents is essential in endodontic infection therapy, photo-activated disinfection (PAD) is suggested as an alternative method to traditional antimicrobial therapy. Recent studies reported that the molecular methods with low sensitivity and high efficiency to identify fastidious anaerobic endopathogenic microbiota can be replaced by the cultivation-based approaches. This study aimed to validate the multiplex real-time PCR in order to identify six common microorganisms associated with the endodontic infections before and after the PAD.

MATERIALS AND METHODS

Microbial specimens from the root canals of 50 patients with primary and secondary endodontic infections were collected before PAD treatment using sterile paper points. Toluidine blue O (TBO)-mediated PAD was performed on the root canals, followed by resampling. The prePAD- and postPAD-treatment endodontic samples were transferred to a transport medium and six target microorganisms were then identified from the samples using the microbiological culture techniques and multiplex real-time PCR approach.

RESULTS

Multiplex real-time PCR could represent the presence of all target microorganisms in 100% cases before and after the PAD. Before PAD, using the culture method, Enterococcus faecalis (100%) was found to be the most frequent, followed by Veillonella parvula (97.5%), Aggregatibacter actinomycetemcomitans (94.7%), Porphyromonas gingivalis (84.3%), Lactobacillus rhamnosus (84.3%), and Actinomyces naeslundii (66.6%); whereas, after PAD these microbial frequencies changed to 80%, 83.3%, 66.6%, 80%, 66.6%, and 33.3%, respectively. The sensitivity and negative predictive value of the multiplex real-time PCR were 100% before and after the PAD, whereas the highest and the lowest specificities were 100% and 82% before PAD, and 97% and 89% after PAD for E. faecalis and P. gingivalis, respectively. The highest (100%) and the lowest (66%) positive predictive values were for V. parvula and A. naeslundii before and after the PAD, respectively.

CONCLUSION

As observed from the results, multiplex real-time PCR demonstrated high sensitivity and specificity when compared to the culture technique. Therefore, it can prove to be a highly sensitive technique to detect the endodontic infections microflora.

An experimental study for rapid detection and quantification of endodontic microbiota following photo-activated disinfection via new multiplex real-time PCR assay

BACKGROUND

The infected root canal system harbors one of the highest accumulations of polymicrobial infections. Since the eradication of endopathogenic microbiota is a major goal in endodontic infection therapy, photo-activated disinfection (PAD) can be used as an alternative therapeutic method in endodontic treatment. Compared to cultivation-based approaches, molecular techniques are more reliable for identifying microbial agents associated with endodontic infections. The purpose of this study was to evaluate the ability of designed multiplex real-time PCR protocol for the rapid detection and quantification of six common microorganisms involved in endodontic infection before and after the PAD.

MATERIALS AND METHODS

Samples were taken from the root canals of 50 patients with primary and secondary/persistent endodontic infections using sterile paper points. PAD with toluidine blue O (TBO) plus diode laser was performed on root canals. Resampling was then performed, and the samples were transferred to transport medium. Then, six target microorganisms were detected using multiplex real-time PCR before and after the PAD.

RESULTS

Veillonella parvula was found using multiplex real-time PCR to have the highest frequency among samples collected before the PAD (29.4%), followed by Porphyromonas gingivalis (23.1%), Aggregatibacter actinomycetemcomitans (13.6%), Actinomyces naeslundii (13.0%), Enterococcus faecalis (11.5%), and Lactobacillus rhamnosus (9.4%). After TBO-mediated PAD, P. gingivalis strains, the most resistance microorganisms, were recovered in 41.7% of the samples using molecular approach (P > 0.05).

CONCLUSION

As the results shown, multiplex real-time PCR as an accurate detection approach with high-throughput and TBO-mediated PAD as an efficient antimicrobial strategy due to the significant reduction of the endopathogenic count can be used for detection and treatment of microbiota involved in infected root canals, respectively.

Comparison of the Antimicrobial Efficacy of Calcium Hydroxide and Photodynamic Therapy Against Enterococcus faecalis and Candida albicans in Teeth With Periapical Lesions; An In Vivo Study

Introduction: Elimination of pathological microflora of root canal systems is a major goal in endodontic treatment. This study aimed to compare the antimicrobial efficacy of calcium hydroxide as an intracanal medication and antibacterial photodynamic therapy (aPDT) against Enterococcus faecalis and Candida albicans in teeth with periapical (PA) lesions. Methods: This in vivo study was conducted on 20 patients with single-rooted mandibular premolar with previously failed endodontic treatment. This study was performed as a clinical trial (IRCTID: IRCT2016090429686N1). After conventional chemo-mechanical root canal preparation (hand and rotary instruments and 2.5% NaOCl), microbiological samples were obtained using sterile paper points, then stored in thioglycolate solution and transferred to a microbiology laboratory. Group 1 (n = 10) specimens underwent aPDT (diode laser 808 nm + 50 mg/mL methylene blue), while creamy calcium hydroxide paste was used in group 2 for a duration of 1 week. A control sample was taken with sterile paper points and F3 Protaper rotary file. The samples were dispersed in transport medium, serially diluted, and cultured on selective mediums to determine the number of colony forming units (CFUs). Data were analyzed by Mann-Whitney U test at 5% significance level. The significance level for all analyses was set at P < 0.05. Results: Number of CFU significantly decreased in both groups after the interventions (P < 0.001); however, there was no significant difference in the colony count between the 2 groups. Conclusion: aPDT and calcium hydroxide therapy showed the same antimicrobial efficacy on E. faecalis and C. albicans.