Photodynamic Therapy with Pyoktanin Blue and Diode Laser for Elimination of Enterococcus faecalis

The Effect of Photodynamic Therapy on Enterococcus spp. and Its Application in Dentistry: A Scoping Review

Enterococci spp. are Gram-positive bacteria that cause mild to severe infections, many associated with the oral cavity, such as periapical infections and healthcare-associated infections (HAIs). Many of these infections become serious diseases that are difficult to resolve, specifically when multidrug-resistant (MDR) strains cause them. In recent years, the number of MDR strains of Enterococcus spp. has increased significantly. This increased prevalence of MDR strains produces significant pressure to generate more antimicrobial therapies, but there is a decline in the production of new antibiotics, driving the development of complementary therapies, such as photodynamic therapy (PDT). PDT combines a photosensitizer agent (PS), light, and oxygen to cause photooxidative stress in bacterial cells. PDT can eradicate Enterococcus spp. contaminations, improve the classic cleaning processes, and eradicate the bacteria in dental pieces. PDT's effectiveness can be improved with nanoparticles that function as carriers. Our work aims to describe the advances in PDT against Enterococcus spp. as a complement to antibiotic therapy, focusing on infections by Enterococcus faecium and Enterococcus faecalis, dental hygiene, and using nanoparticles to improve the antimicrobial effect. A systematic bibliographic search without a meta-analysis was conducted on various databases, using inclusion and exclusion criteria to identify the most relevant research. Of the 193 non-redundant articles found, 65 were selected for a systematic review, from which a summary table was created and a manual description was made. Photodynamic therapy for treating E. faecium and E. faecalis is a widely studied area, with promising results concerning bactericidal effectiveness and reductions in biofilm formation, particularly in regard to dental hygiene. Because most of the studies were conducted in vitro or ex vivo, the results indicated that there were not sufficient data to initiate clinical trials for safety and efficacy studies on humans.

Photodynamic Therapy With Resveratrol and an Nd:YAG Laser for Enterococcus faecalis Elimination

BACKGROUND/AIM

Enterococcus faecalis is the leading cause of endodontic treatment failures. Despite various conventional disinfection approaches, microorganisms often persist in root canals. Photodynamic therapy (PDT) is an adjunct antimicrobial strategy employing a nontoxic photosensitizer (PS) and light source. This study evaluated the antimicrobial effect of PDT using an Nd:YAG laser and resveratrol (RSV) with or without pigment, and confirmed that RSV is nontoxic as a PS.

MATERIALS AND METHODS

We employed laser irradiation at a 3W output power, using RSV and red pigment as the PS, on an E. faecalis bacterial solution. Subsequently, colony-forming units were quantified. The impact of RSV on osteoblasts was measured using an MTT assay.

RESULTS

E. faecalis counts declined after laser irradiation. The combined application of laser irradiation with RSV, red pigment, or both showed a reduction compared to no irradiation and control groups without RSV and red pigment. The 50% cytotoxic concentration against osteoblast cells from mice incubated with RSV for 48 h was 162 μM. The value with RSV and laser was 201 μM and that with RSV and red pigment was 199 μM. The value with RSV, laser and red pigment was 357 μM.

CONCLUSION

The combination of Nd:YAG laser irradiation and RSV as the PS with pigment was efficacious for E. faecalis elimination without inducing any toxic effects on osteoblasts. This combination holds potential as a root canal irrigation strategy.

Application of Photodynamic Therapy in Pediatric Dentistry: Literature Review

Microbiological control of dental pathologies presents a significant clinical challenge for dental surgeons, particularly considering drug-resistant microorganisms. To address this issue, Antimicrobial Photodynamic Therapy (PDT) has emerged as an effective and complementary technique for microbial reduction. This therapy involves the application of a photosensitizer dye (PS) either topically or systemically, followed by exposure to low-power lasers with appropriate visible light wavelengths. PDT has found a valuable place in dentistry across various specialties, including surgery, periodontics, endodontics, dentistry, implantology, orthodontics, and pediatrics. In the realm of pediatric dentistry, managing microorganisms during dental treatments has become a major challenge. Considering its promising results and ease of application, Photodynamic Therapy presents an interesting alternative for clinical practice. However, it is important to note that specific protocols must be followed for each application, encompassing the type of photosensitizer, concentration, pre-irradiation time, light type, wavelength, energy, power, and mode of light delivery. Researchers have been steadily refining these protocols to facilitate PDT's integration into clinical practice. The objective of this review is to describe in which procedures and oral health problems in children PDT can be applied. In this sense, we list what the literature brings about the possibilities of applying PDT in a pediatric dentistry clinic.

Antibacterial Effect of Red Laser Therapy on Enterococcus faecalis Using Different Photosensitizers: An In Vitro Study

Objective

To assess the antibacterial effect of red laser using different photosensitizers such as methylene blue and malachite green on monoradicular premolars contaminated with E. faecalis ATCC 29212.

Methods

This was an in vitro experimental study. Monoradicular premolars (44, 45, 34, and 35) were used, which were treated with ProTaper Next. After instrument change, irrigation, disinfection, and aspiration were performed with 2 ml of 4% NaOCl with a NaviTip 30°G needle (Ultradent, South Jordan, UT, USA). Group 1: RL + MB (red laser associated with methylene blue photosensitizer), group 2: RL + MG (red laser associated with malachite green photosensitizer), and group 3: control (no treatment). The E. faecalis strain was cultured on trypticase soy agar (TSB) (Difco, Detroit, MI, USA) and incubated at 37°C for 24 h. After the incubation period, colony-forming units (CFU/ml) of each group were counted using the plate count method. The ANOVA test was used with a significance level of p < 0.05.

Results

Group 1 had the lowest antibacterial contamination as it averaged only 530 ± 581.3 CFU/ml, while group 2 had the highest contamination with an average of 1990 ± 542.5 CFU/ml. Comparison revealed that there were statistically significant differences between the RL + MB and RL + MG groups (p < 0.001).

Conclusions

Group 1 had the best antimicrobial potential because it presented the lowest contamination in CFU/ml of E. faecalis compared to group 2 and group 3.

Re-Evaluation of Chemotherapeutic Potential of Pyoktanin Blue

Background: Pyoktanin blue (PB) is used for staining tissues and cells, and it is applied in photodynamic therapy due to its potent bactericidal activity. However, clinical application of PB as an antiviral and antitumor agent has been limited due to its potent toxicity. For clinical application, the antitumor and antiviral activity as well as the neurotoxicity of PB were re-evaluated with a chemotherapeutic index. Methods: Tumor-specificity (TS) was determined by the ratio of CC₅₀ against normal oral cells/oral squamous cell carcinoma (OSCC); neurotoxicity by that of normal oral/neuronal cells; antiviral activity by that of mock-infected/virus-infected cells; and potency-selectivity expression (PSE) by dividing TS by CC₅₀ (OSCC). Results: Antitumor activity of PB (assessed by TS and PSE) was comparable with that of DXR and much higher than that of 5-FU and melphalan. PB induced caspase-3 activation and subG1 cell accumulation in an OSCC cell line (Ca9-22). PB and anticancer drugs showed comparable cytotoxicity against both neuronal cells and OSCC cell lines. PB showed no detectable anti-HIV/HSV activity, in contrast to reverse transferase inhibitors, sulfated glucans, and alkaline extract of leaves of S.P. Conclusions: PB showed first-class anticancer activity and neurotoxicity, suggesting the importance of establishing the safe treatment schedule.

Antibiofilm activity of laser ablation with indocyanine green activated by different power laser parameters compared with photodynamic therapy on root canals infected with Enterococcus faecalis

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) is used as an adjunct to endodontic treatment to enhance microbial reduction in the root canal system. However, studies evaluating the impact of laser ablation with Indocyanine Green (ICG) are scarce. Thus, this in vitro study aimed to evaluate the efficiency of laser ablation with ICG using different laser parameters compared with aPDT using photosensitizer methylene blue (MB) and curcumin (CUR) on the reduction of E. faecalis biofilms on root canals.

METHODS

Forty-nine human premolars were used after biomechanical instrumentation for standardization. The root canals were contaminated with E. faecalis for 10 days to form biofilms, and divided into 7 groups (n = 7): 0.01% MB activated by red laser - MB+RL; 0.05% CUR activated by blue LED - CUR+BL; 0.05% ICG activated by infrared diode laser (2.5 W power, 30 ms interval, and 30 ms duration) - ICG+DL 2.5/30/30; 0.05% ICG activated by infrared diode laser (2.5 W power, 300 ms interval, and 100 ms duration) - ICG+DL 2.5/300/100; 0.05% ICG activated by infrared diode laser (3 W power, 300 ms interval, and 100 ms duration) - ICG+DL 3/300/100; sterile saline solution (negative control) - NC; and 2.5% NaOCl (positive control) - PC. Root canal sampling was performed prior to and immediately after the different treatment protocols. Data were submitted to One- and Two-Way ANOVA, followed by Student-Newman-Keuls test or Fisher LSD's test (α = 0.05).

RESULTS

All aPDT protocols promoted significant CFU reductions compared with the NC; the highest CFU reduction was observed for PC (p < 0.05). Among the protocols the highest CFU reduction was promoted by laser ablation with ICG+DL 3/300/100 (p < 0.05) except compared with aPDT using CUR+BL (p > 0.05).

CONCLUSIONS

Laser ablation protocol using ICG+DL proved to be efficient in reducing E. faecalis biofilms, especially when activated at 3/300/100 configuration.

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.

Biofilm Inactivation using Photodynamic Therapy in Dentistry: a review of literature

Introduction: Photodynamic therapy (PDT) is a therapy involving light and a photosensitising chemical substance, used in conjunction with molecular oxygen in order to elicit cell death (photo-toxicity) and thus ability to kill microbial cells, including bacteria, fungi and viruses. Photodynamic therapy is an alternative method of biofilm disruption and it is considered a new way of microorganism inactivation. It is also an additional procedure to reduce the infection rate in patients, caused by the increasing antimicrobials resistance of bacteria. The aim of this literature review was to evaluate the specific effects and the antibacterial effectiveness of photodynamic therapy using different types of photosensitizers (Erythrosine, Rose Bengal, Toluidine blue, Methylene blue, Ozone, Riboflavin, Curcumin, Chlorhexidine, SAPYR) and a visible light of a specific wavelength for each photosensitizer and to reveal the applications of PDT in periodontics, endodontics, prosthodontics and dental caries. Methods: A research of literature was performed in an attempt to find all the articles published on this topic in the last 10 years. The articles was searched by using a certain combination of different keywords (photodynamic therapy ) and (diode laser ) and (teeth) in PubMed database. Results: A total number of 83 articles were found. After applying inclusion and exclusion criteria, 35 articles were taken into consideration for our study and among them 4 were a manuscript, 3 was a review of literature, 1 was an in vivo evaluation and 27 were in vitro studies. Conclusion: Considering that none of the disinfection methods can completely remove the biofilm, PDT is a therapeutic tool complementary to conventional disinfection, with great applicability in dentistry. PDT showed significantly efficacy in reduction of biofilms. Exposure to light in the presence of a photosensitizing chemical substance helps in the reduction of microbes and the protocols could be recommended for clinical usage, but only together with ‘classic ‘ disinfection.