In vivo killing of Porphyromonas gingivalis by toluidine blue-mediated photosensitization in an animal model

Biofilm inhibition/eradication: exploring strategies and confronting challenges in combatting biofilm

Biofilms are complex communities of microorganisms enclosed in a self-produced extracellular matrix, posing a significant threat to different sectors, including healthcare and industry. This review provides an overview of the challenges faced due to biofilm formation and different novel strategies that can combat biofilm formation. Bacteria inside the biofilm exhibit increased resistance against different antimicrobial agents, including conventional antibiotics, which can lead to severe problems in livestock and animals, including humans. In addition, biofilm formation also imposes heavy economic pressure on industries. Hence it becomes necessary to explore newer alternatives to eradicate biofilms effectively without applying selection pressure on the bacteria. Excessive usage of antibiotics may also lead to an increase in the number of resistant strains as bacteria employ an advanced antimicrobial resistance mechanism. This review provides insight into multifaceted technologies like quorum sensing inhibition, enzymes, antimicrobial peptides, bacteriophage, phytocompounds, and nanotechnology to neutralize biofilms without developing antimicrobial resistance (AMR). Furthermore, it will pave the way for developing newer therapeutic agents to deal with biofilms more efficiently.

Photodynamic Inactivation of Bovine Coronavirus with the Photosensitizer Toluidine Blue O

Coronaviruses (CoVs) belong to the group of enveloped positive-sense single-strand RNA viruses and are causative agents of respiratory, gastro-intestinal, and central nervous systems diseases in many host species, i.e., birds, mammals, and humans. Beta-CoVs revealed a great potential to cross the barrier between species by causing three epidemics/pandemics among humans in the 21st century. Considering the urgent need for powerful antiviral agents for decontamination, prevention, and treatment of BCoV infections, we turned our attention to the possibility of photodynamic inactivation with photosensitizers in combination with light irradiation. In the present study, we evaluated, for the first time, the antiviral activity of toluidine blue O (TBO) against Beta-coronavirus 1 (BCoV) in comparison to methylene blue (MB). First, we determined the in vitro cytotoxicity of MB and TBO on the Madin-Darby bovine kidney (MDBK) cell line with ISO10993-5/Annex C. Thereafter, BCoV was propagated in MDBK cells, and the virus titer was measured with digital droplet PCR, TCID50 assay and plaque assay. The antiviral activity of non-toxic concentrations of TBO was estimated using the direct inactivation approach. All effects were calculated in MAPLE 15® mathematical software by developing programs for non-linear modeling and response surface analysis. The median inhibitory concentration (IC50) of TBO after 72 h of incubation in MDBK cells was 0.85 µM. The antiviral activity of TBO after the direct inactivation of BCoV (MOI = 1) was significantly stronger than that of MB. The median effective concentration (EC50) of TBO was 0.005 µM. The cytopathic effect decreased in a concentration-dependent manner, from 0.0025 to 0.01 µM, and disappeared fully at concentrations between 0.02 and 0.3 µM of TBO. The number of virus particles also decreased, depending on the concentration applied, as proven by ddPCR analysis. In conclusion, TBO exhibits significant potential for direct inactivation of BCoV in vitro, with a very high selectivity index, and should be subjected to further investigation, aiming at its application in veterinary and/or human medical practice.

Evaluation of antimicrobial photodynamic therapy and minimal intervention associated with deproteinisation in permanent teeth with molar incisor hypomineralisation: study protocol for a clinical, controlled, blinded trial

INTRODUCTION

Molar incisor hypomineralisation (MIH) is a qualitative defect of enamel development that occurs in the mineralisation phase. MIH affects one or more permanent molars and, occasionally, permanent incisors. The aim of the proposed study is to evaluate the clinical effect of antimicrobial photodynamic therapy (aPDT) on permanent teeth with MIH through decontamination and sensitivity control.

METHODS AND ANALYSIS

Patients from 8 to 12 years of age with permanent molars will be randomly allocated to three groups. Group 1: selective chemical-mechanical removal of carious dentinal tissue around the walls of the cavity with Papacárie Duo and a curette followed by the application of aPDT and deproteinisation with Papacárie Duo; group 2: selective removal of carious dentinal tissue around the walls of the cavity with a curette, followed by the application of aPDT and deproteinisation with a 5% sodium hypochlorite solution; group 3: selective removal of carious dentinal tissue using a curette. The selected teeth must have a carious lesion in the dentin and posteruptive enamel breakdown on one or more surfaces with an indication for clinical restorative treatment. The teeth will subsequently be restored using a mixed technique with resin-modified glass ionomer cement and bulk-fill composite resin. The data will be submitted to descriptive statistical analysis. Associations with age and sex will be tested using either the χ2 test or Fisher's exact test. Pearson's correlation coefficients will be calculated to determine the strength of correlations between variables. Comparisons of the microbiological results (colony-forming units) will be performed using analysis of variance and the Kruskal-Wallis test. Kaplan-Meier survival analysis will be performed to assess the performance of the restorations.

ETHICS AND DISSEMINATION

This protocol has been approved by the Human Research Ethics Committee of Nove de Julho University (certificate number: 61027522.0.0000.5511/approval date: 23 August 2022). The findings will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT05443035.

Effects of various light-emitting diode wavelengths on periodontopathic bacteria and gingival fibroblasts: An in vitro study

BACKGROUND

In recent years, light has been used for bacterial control of periodontal diseases. This in vitro study evaluated the effects of light-emitting diode (LED) irradiation at different wavelengths on both Porphyromonas gingivalis and human gingival fibroblasts (HGF-1).

METHODS

P. gingivalis suspension was irradiated with LEDs of 365, 405, 450, 470, 565, and 625 nm at 50, 100, 150, and 200 mW/cm2 for 3 min (radiant exposure: 9, 18, 27, 36 J/cm2, respectively). Treated samples were anaerobically cultured on agar plates, and the number of colony-forming units (CFUs) was determined. Reactive oxygen species (ROS) levels were measured after LED irradiation. The viability and damage of HGF-1 were measured through WST-8 and lactate dehydrogenase assays, respectively. Gene expression in P. gingivalis was evaluated through quantitative polymerase chain reaction.

RESULTS

The greatest reduction in P. gingivalis CFUs was observed on irradiation at 365 nm with 150 mW/cm2 for 3 min (27 J/cm2), followed by 450 and 470 nm under the same conditions. While 365-nm irradiation significantly decreased the viability of HGF-1 cells, the cytotoxic effects of 450- and 470-nm irradiation were comparatively low and not significant. Further, 450-nm irradiation indicated increased ROS production and downregulated the genes related to gingipain and fimbriae. The 565- and 625-nm wavelength groups exhibited no antibacterial effects; rather, they significantly activated HGF-1 proliferation.

CONCLUSIONS

The 450- and 470-nm blue LEDs showed high antibacterial activity with low cytotoxicity to host cells, suggesting promising bacterial control in periodontal therapy. Additionally, blue LEDs may attenuate the pathogenesis of P. gingivalis.

Superhydrophobic Tipped Antimicrobial Photodynamic Therapy Device for the In Vivo Treatment of Periodontitis Using a Wistar Rat Model

Limited options exist for treatment of periodontitis; scaling and root planing (SRP) are not sufficient to eradicate P. gingivalis and the resulting inflammatory disease. Chlorhexidine (CHX), used as an adjuvant to SRP, may reduce bacterial loads but leads to pain and staining, while evidence for its efficacy is lacking. Antibiotics are effective but can lead to drug-resistance. The rising concern of antibiotic resistance limits the future use of this treatment approach. This study evaluates the efficacy of a novel superhydrophobic (SH) antimicrobial photodynamic therapy (aPDT) device as an adjuvant to SRP for the treatment of periodontitis induced in a Wistar rat in vivo model relative to CHX. The SH-aPDT device comprises an SH silicone rubber strip coated with verteporfin photosensitizer (PS), sterilized, and secured onto a tapered plastic optical fiber tip connected to a red diode laser. The superhydrophobic polydimethylsiloxane (PDMS) strips were fabricated by using a novel soluble template method that creates a medical-grade elastomer with hierarchical surface roughness without the use of nanoparticles. Superhydrophobicity minimizes direct contact of the PS-coated surface with bacterial biofilms. Upon insertion of the device tip into the pocket and energizing the laser, the device generates singlet oxygen that effectively targets and eliminates bacteria within the periodontal pocket. SH-aPDT treatment using 125 J/cm2 of red light on three consecutive days reduced P. gingivalis significantly more than SRP-CHX controls (p < 0.05). Clinical parameters significantly improved (p < 0.05), and histology and stereometry results demonstrated SH-aPDT to be the most effective treatment for improving healing and reducing inflammation, with an increase in fibroblast cells and extracellular matrix and a reduction in vascularization, inflammatory cells, and COX-2 expression. The SH-aPDT approach resulted in complete disease clearance assessed 30 days after treatment initiation with significant reduction of the periodontal pocket and re-formation of the junctional epithelium at the enamel-cementum junction. PS isolation on a SH strip minimizes the potential for bacteria to develop resistance, where the treatment may be aided by the oxygen supply retained within the SH surface.

Low-energy LED red light inhibits the NF-κB pathway and promotes hPDLSCs proliferation and osteogenesis in a TNF-α environment in vitro

There are few studies on the effect of low-energy LED red light on periodontal tissue regeneration in an inflammatory environment. In this study, Cell Counting Kit-8 (CCK-8) assays were used to detect the effects of TNF-α at three different concentrations (0, 10 ng/ml, and 20 ng/ml) on the proliferation of human periodontal ligament stem cells (hPDLSCs), and 10 ng/ml was selected as the subsequent experimental stimulation concentration. CCK-8 assays were used to detect the effect of LED red light with energy density of 1 J/ cm2, 3 J/ cm2, and 5 J/cm2 on the proliferation of hPDLSCs. The promotion effect of energy density of 5 J/cm2 on the proliferation of hPDLSCS was the most obvious (p < 0.05). Set CON group, ODM group, ODM + 10 ng/ml TNF-α group, and ODM + 10 ng/ml TNF-α + 5 J/ cm2 LED red light group. Alkaline phosphatase staining and activity detection, alizarin red staining and calcium nodules quantitative detection of osteoblast differentiation products, real-time fluorescence quantitative PCR detection of osteoblast gene expression (Runx2, Col-I, OPN, OCN). The results showed that ODM showed the strongest osteoblast ability, followed by ODM + 10 ng/ml TNF-α + 5 J/ cm2 LED red light group. The osteoblast ability of ODM + 10 ng/ml TNF-α was decreased, but was not found in CON group. Western blot was used to detect the expression of NF-κB pathway protein and osteoblast-related proteins (Runx2, Col-I, OPN, OCN) after addition of PDTC inhibitor. The results showed that the expression of p-IκBα was increased and the expression of IκBα was decreased (p < 0.05). The expression of osteoblast protein increased after the addition of inhibitor (p < 0.05). Therefore, in an inflammatory environment constructed by 10 ng/ml TNF-α, 5 J/cm2 LED red light can upregulate the proliferation and osteogenesis of hPDLSCs by inhibiting NF-κB signaling pathway.

Photoinactivation and Photoablation of Porphyromonas gingivalis

Several types of phototherapy target human pathogens and Porphyromonas gingivitis (Pg) in particular. The various approaches can be organized into five different treatment modes sorted by different power densities, interaction times, effective wavelengths and mechanisms of action. Mode 1: antimicrobial ultraviolet (aUV); mode 2: antimicrobial blue light (aBL); mode 3: antimicrobial selective photothermolysis (aSP); mode 4: antimicrobial vaporization; mode 5: antimicrobial photodynamic therapy (aPDT). This report reviews the literature to identify for each mode (a) the putative molecular mechanism of action; (b) the effective wavelength range and penetration depth; (c) selectivity; (d) in vitro outcomes; and (e) clinical trial/study outcomes as these elements apply to Porphyromonas gingivalis (Pg). The characteristics of each mode influence how each is translated into the clinic.

Effect of photodynamic therapy as an adjunctive to mechanical debridement on the nonsurgical treatment of peri-implant mucositis: A randomized controlled clinical trial

Background

The use of photodynamic therapy (PDT) has been evaluated as an adjunctive technique for bacterial decontamination of implants with peri-implantitis. Given the controversies over the efficacy of the application of PDT to treat peri-implant diseases, the present clinical study aimed to evaluate the posttherapeutic clinical parameters and cytokine levels in peri-implant crevicular fluid in patients with peri-implant mucosal inflammation, receiving mechanical debridement (MD) alone or in association with PDT.

Materials and Methods

In this double-blinded randomized clinical trial, 52 patients with peri-implant mucosal inflammation were selected and they were randomly assigned to 2 treatment groups: a MD group and an MD + PDT group using an 805 nm laser and indocyanine green (ICG). Although the decrease in bleeding on probing was the primary outcome, pocket depth, PUS, pain on probing, clinical attachment level, gingival recession, tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and matrix metalloproteinase-8 were also evaluated at baseline, 2-week, and 3-month postintervention. Repeated measure analysis of variance was used to analyze inter-group differences and a P ≤ 0.05 was considered for significant differences between tested parameters.

Results

Statistically significant improvements (P < 0.001) were detected for all variables after comparison of baseline data with those collected at each time interval of the study. Nevertheless, the inter-group comparisons of these variables between the baseline, 2-week, and 3-month intervals did not reveal any significant decrease in sites treated with either MD alone or MD + PDT.

Conclusion

The application of PDT using 805-nm laser and ICG as an adjunct therapy to MD did not provide any additional improvements in the clinical or biologic parameters of peri-implant mucosal inflammation.

The Efficiency of Photodynamic Therapy in the Bacterial Decontamination of Periodontal Pockets and Its Impact on the Patient

Research in the field of periodontal disease continues to focus on disease-associated microorganisms, as the microbial plaque and the host immune responses are considered to be important causative factors, that are highly responsible for the progression of this disease. The purpose of this article is to compare the reduction in the number of specific periodontopathogens in two test groups according to different therapeutic approaches in periodontal disease and to show possible differences. This article is based on a prospective clinical study involving eighteen subjects with forty-four average periodontal pockets assigned to study groups treated by two different methods, SRP and SRP followed by a single PDT application. Efficiency in removing specific bacterial species was evaluated by PCR testing, at baseline and immediately after treatment. The hypothesis that using SRP + aPDT results in an increased decontamination potential was confirmed statistically, when all five specific bacterial pathogens were investigated together. When the pathogens were considered separately, two of the five microorganisms tested were significantly lower in the SRP + PDT group (p < 0.00), and important germ counts reductions were also observed for the other three. There is also a statistically significant relation between the pain at 48 h postoperatively and the type of treatment the patients received, as resulted from the Questionnaire Form. Our results demonstrate that aPDT, as an adjunctive treatment to conservative mechanical cleaning of root surfaces at sites affected by periodontitis, represents an effective tool in terms of reducing specific periodontopathogen germs.

Clinical attachment loss in the use of adjunctive antimicrobial photodynamic therapy in Stages II-IV Grade C molar-incisor periodontitis: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to assess the extent of clinical attachment loss (CAL) as a clinical parameter in the efficacy of antimicrobial photodynamic therapy (aPDT) in non-surgical management of stage II-IV grade C molar-incisor pattern Periodontitis. This review protocol was conducted in accordance with PRISMA statements and is registered in PROSPERO (CRD42022321211). An electronic and manual search was conducted for relevant articles comparing the efficacy of aPDT versus scaling and root planning (SRP) alone or with amoxicillin/metronidazole (AMX/MET) published up until December 2021. The mean clinical attachment loss (CAL), probing depth (PD) reduction, and bleeding on probing (BOP) with a 95% confidence interval (CI) were pooled and compared between the two groups with CAL < and > 7 mm using a random-effect model after 3 and 6 months. To assess the heterogeneity of the findings, the I2 test was applied and Publication bias was evaluated by visual examination of the funnel plot symmetry. Analysis of 9 studies indicated a significant difference in clinical attachment gain in patients with CAL > 7 mm between the aPDT group and the SRP alone (mean difference=0.92, 95% CI=0.01-1.84, P=0.05) and SRP + AMX/MET (mean difference=0.91, 95% CI=-0.14-1.68, P=0.02) control groups. However, this difference was not significant in patients with CAL < 7 mm. Despite the limitations of the included studies, aPDT can be suggested for the improvement of clinical parameters in grade C molar-incisor pattern Periodontitis with CAL > 7 mm. However, its application in milder cases requires further investigation.

A Novel Technique for Disinfection Treatment of Contaminated Dental Implant Surface Using 0.1% Riboflavin and 445 nm Diode Laser—An In Vitro Study

Background: Antimicrobial photodynamic therapy (PDT) has been introduced as a potential option for peri-implantitis treatment. The aim of this study is to evaluate the antimicrobial effect of a novel technique involving a combination of 445 nm diode laser light with 0.1% riboflavin solution (used as a photosensitizing dye) as applied on a bacterial–fungal biofilm formed on implants and to compare the performance of this technique with that of the commonly used combination of 660 nm diode laser with 0.1% methylene blue dye. Methods: An in vitro study was conducted on 80 titanium dental implants contaminated with Staphylococcus aureus (SA) and Candida albicans (CA) species. The implants were randomly divided into four groups: negative control (NC), without surface treatment; positive control (PC), treated with a 0.2% chlorhexidine (CHX)-based solution; PDT1, 660 nm (EasyTip 320 µm, 200 mW, Q power = 100 mW, 124.34 W/cm2, 1240 J/cm2) with a 0.1% methylene blue dye; and PDT2, 445 nm (EasyTip 320 µm, 200 mW, Q power = 100 mW, 100 Hz, 124.34 W/cm2, 1.24 J/cm2) with a 0.1% riboflavin dye. Results: The PDT1 and PDT2 groups showed greater reduction of SA and CA in comparison to the NC group and no significant differences in comparison to the PC group. No statistically significant differences between the PDT1 and PDT2 groups were observed. Conclusions: A novel antimicrobial treatment involving a combination of 445 nm diode laser light with riboflavin solution showed efficiency in reducing SA and CA biofilm formation on dental implant surfaces comparable to those of the more commonly used PDT treatment consisting of 660 nm diode laser light with methylene blue dye or 0.2% CHX treatment.

The Effect of Photodynamic Therapy on the Early Outcome of Implants Placed on Patients with Periodontitis

Background: Immediate implant is a subtype of implant that is placed following tooth extraction within the socket without further delay. These implants are known to preserve the alveolar bone and minimize the total number of surgical interventions in a patient. 4 Photodynamic therapy (PDT) augments nonsurgical periodontal therapy using antibacterial mechanisms. PTD can be more effective in conjunction with scaling and root planing (SRP). The aim of this study is to assess the effects of PDT on the early outcomes of implants placed on patients with periodontitis with and without SRP at 9 months of follow-up. Materials and methods: A total of 23 implants were placed in 14 patients, with 11 in the test group and 12 in the control group. SRP was carried out prior to immediate implant placement in control sites, and PDT adjunctive to SRP (SRP + PDT) was performed in test sites before immediate implant placement. Plaque index, gingival index, probing pocket depth, clinical attachment level, and radiovisiographs were procured at baseline, 3 months, 6 months, and 9 months. Primary stability was examined at the time of implant placement, and the healing index was recorded a week later. Results: At the end of the 9 months of the study period, (SRP + PDT) group had a mean marginal bone loss of 0.95 mm, and the control group had 1.08 mm. Clinical parameters such as plaque index, gingival index, clinical attachment level, and probing depth showed definitive improvement after 9 months, compared with the baseline, but when the test and control groups were compared, the difference was statistically significant for plaque index and probing depth. The implants in both groups were followed up for a period of 9 months. There was an improvement in marginal bone loss but was not statistically significant. The survival of immediate implants in the PDT group was not different from those in the scaling and root planing group. Conclusion: The effect of PTD can be beneficially used as an adjunct to SRP. However, the effects were not significant. Photodynamic therapy can be effectively used as an adjunct to SRP owing to the better outcomes using PDT.

Light-emitting-diode-based antimicrobial photodynamic therapies in the treatment of periodontitis

The use of light-emitting diode (LED)-based photodynamic therapies in the treatment of periodontitis is increasing because these modalities are effective, safe, and painless. They are not subject to acquired drug resistance or environmental issues and are associated with no complications when used appropriately. These light sources have also been used in combination with pharmacological measures to synergize their effects and optimize therapeutic outcomes. This review focuses on optical devices used in treating periodontitis and delineates the current applications of various methods, including their utility and efficacy. The application of LEDs in periodontology is described.

Photodynamic Therapy with Natural Photosensitizers in the Management of Periodontal Disease Induced in Rats

This study aims to investigate the effect of new natural photosensitizers (PS) (based on oregano essential oil, curcuma extract, and arnica oil) through in vitro cytotoxicity and biological tests in rat-induced periodontal disease, treated with photodynamic therapy (aPDT). The cytotoxicity of PS was performed on human dental pulp mesenchymal stem cells (dMSCs) and human keratinocyte (HaCaT) cell lines. Periodontal disease was induced by ligation of the first mandibular molar of 25 rats, which were divided into 5 groups: control group, periodontitis group, Curcuma and aPDT-treated group, oregano and aPDT-treated group, and aPDT group. The animals were euthanized after 4 weeks of study. Computed tomography imaging has been used to evaluate alveolar bone loss. Hematological and histological evaluation showed a greater magnitude of the inflammatory response and severe destruction of the periodontal ligaments in the untreated group.. For the group with the induced periodontitis and treated with natural photosensitizers, the aPDT improved the results; this therapy could be an important adjuvant treatment. The obtained results of these preliminary studies encourage us to continue the research of periodontitis treated with natural photosensitizers activated by photodynamic therapy.

Repeated irradiation by light-emitting diodes may impede the spontaneous progression of experimental periodontitis: a preclinical study

PURPOSE

We investigated whether repeated irradiation with light-emitting diodes (LEDs) at a combination of 470 nm and 525 nm could suppress the progression of experimental periodontitis.

METHODS

A experimental periodontitis model was established in the second, third, and fourth premolars of the mandible in beagle dogs for 2 months. The spontaneous progression of periodontitis was monitored under the specified treatment regimen for 3 months. During this period, the animals were subjected to treatments of either plaque control only (control) or plaque control with LED application (test) at 2-week intervals. The clinical parameters included the probing pocket depth (PPD), gingival recession (GR), and the clinical attachment level (CAL). Histomorphometric analysis was performed using measurements of the length of the junctional epithelium, connective tissue (CT) zone, and total soft tissue (ST).

RESULTS

There were significant differences in PPD between the control and test groups at baseline and 12 weeks. When the change in PPD was stratified based on time intervals, it was shown that greater differences occurred in the test group, with statistical significance for baseline to 12 weeks, 6 to 12 weeks, and baseline to 6 weeks. There was no significant difference in GR between the control and test groups at any time points. Likewise, no statistically significant differences were found in GR at any time intervals. CAL showed a statistically significant difference between the control and test groups at baseline only, although significant differences in CAL were observed between baseline and 12 weeks and between 6 and 12 weeks. The proportion of CT to ST was smaller for both buccal and lingual areas in the control group than in the test group.

CONCLUSIONS

Repeated LED irradiation with a combination of 470-nm and 525-nm wavelengths may help suppress the progression of periodontal disease.

Phototherapy and optical waveguides for the treatment of infection

With rapid emergence of multi-drug resistant microbes, it is imperative to seek alternative means for infection control. Optical waveguides are an auspicious delivery method for precise administration of phototherapy. Studies have shown that phototherapy is promising in fighting against a myriad of infectious pathogens (i.e. viruses, bacteria, fungi, and protozoa) including biofilm-forming species and drug-resistant strains while evading treatment resistance. When administered via optical waveguides, phototherapy can treat both superficial and deep-tissue infections while minimizing off-site effects that afflict conventional phototherapy and pharmacotherapy. Despite great therapeutic potential, exact mechanisms, materials, and fabrication designs to optimize this promising treatment option are underexplored. This review outlines principles and applications of phototherapy and optical waveguides for infection control. Research advances, challenges, and outlook regarding this delivery system are rigorously discussed in a hope to inspire future developments of optical waveguide-mediated phototherapy for the management of infection and beyond.

Comparative Evaluation of the Effects of Antimicrobial Photodynamic Therapy With an LED and a Laser on the Proliferation of Human Gingival Fibroblasts on the Root Surface: An In Vitro Study

Introduction: This study aimed to compare the effects of root biomodification by citric acid and antimicrobial photodynamic therapy (aPDT) with LED and laser on the proliferation of human gingival fibroblasts (HGFs). Methods: This in vitro experimental study evaluated 60 single-rooted teeth extracted due to periodontal disease. The teeth underwent scaling and root planing (SRP), and then 5 × 5 mm blocks were prepared from the cervical area of the teeth 1 mm apical to the cementoenamel junction. The blocks were divided into 4 groups (n=15 blocks): SRP alone (control), SRP + citric acid, SRP + toluidine blue (TBO) + LED light, and SRP + TBO + laser. HGFs were seeded on the surface of the samples, and the methyl thiazolyl tetrazolium (MTT) assay was performed after 24, 48 and 72 hours. Group comparisons were performed using repeated measures ANOVA, while pairwise comparisons of the time points were performed by an LSD test. Results: Cell proliferation was higher in all experimental groups at 48 and 72 hours, compared with 24 hours (P < 0.05). Cell proliferation was significantly different in the citric acid group at 24 hours (P = 0.016) and 48 hours (P = 0.015), compared with other groups. However, cell proliferation was not significantly different in the aPDT group with LED Photosan and a diode laser at 24 and 48 hours (P > 0.05). Conclusion: aPDT and citric acid can enhance the proliferation of HGFs on dentin blocks. Further studies can pave the way for their future use in the clinical setting.

Organic Photo-antimicrobials: Principles, Molecule Design, and Applications

The emergence of multi-drug-resistant pathogens threatens the healthcare systems world-wide. Recent advances in phototherapy (PT) approaches mediated by photo-antimicrobials (PAMs) provide new opportunities for the current serious antibiotic resistance. During the PT treatment, reactive oxygen species or heat produced by PAMs would react with the cell membrane, consequently leaking cytoplasm components and effectively eradicating different pathogens like bacteria, fungi, viruses, and even parasites. This Perspective will concentrate on the development of different organic photo-antimicrobials (OPAMs) and their application as practical therapeutic agents into therapy for local infections, wound dressings, and removal of biofilms from medical devices. We also discuss how to design highly efficient OPAMs by modifying the chemical structure or conjugating with a targeting component. Moreover, this Perspective provides a discussion of the general challenges and direction for OPAMs and what further needs to be done. It is hoped that through this overview, OPAMs can prosper and will be more widely used for microbial infections in the future, especially at a time when the global COVID-19 epidemic is getting more serious.

Influence of antibacterial effects of tetracycline, laser, and photodynamic therapy on cell viability, cell damage, and virulence of Porphyromonas gingivalis

INTRODUCTION

This study compares and evaluates the efficacy of tetracycline, laser and photodynamic therapy on bacterial counts, cell damage, cell viability and neutralization of gingipains.

MATERIAL AND METHODS

P.gingivalis (ATCC 33,277) was cultured anaerobically. The minimal inhibitory concentration (MIC) for 50% inhibition of P.gingivalis by tetracycline, laser, and toluidine blue (TB) was determined using spectrophotometry. The antibacterial effects, cell viability, cell damage and neutralization of gingipains of the treated groups was evaluated by microbial culture and counting, 2,3 Bis 2 Methyloxy-4 Nitro-5 Sulphophenyl 2 H tetrazolium-5-Carboxaanilide (MTT) assay, lactate dehydrogenase (LDH) assay, and gingipain assay (BAPNA).

RESULTS

The MIC of tetracycline, toulidine, diode laser (810nmm; 0.5 Watts) is 1 µg/mL, 50 µg/mL and 15 s respectively. Comparative analysis for bacterial colony reduction was highest in tetracycline followed by PDT and then laser group at p < 0.01. MTT assay shows a significantly lesser number of viable cells in the tetracycline and PDT group when compared to laser group p < 0.01. Comparative analysis for cell damage using LDH shows the highest results for PDT followed by tetracycline and laser at p < 0.01. The highest neutralization of the gingipains is seen in the PDT group followed by tetracycline and laser groups at p < 0.01.

CONCLUSION

PDT shows highest antibacterial activity, gingipain neutralization, cell damage, and least number of viable cells in comparison with tetracycline and laser.

New tendencies in non-surgical periodontal therapy

The aim of this review was to update the evidence of new approaches to non-surgical therapy (NSPT) in the treatment of periodontitis. Preclinical and clinical studies addressing the benefits of adjunctive antimicrobial photodynamic therapy, probiotics, prebiotics/synbiotics, statins, pro-resolving mediators, omega-6 and -3, ozone, and epigenetic therapy were scrutinized and discussed. Currently, the outcomes of these nine new approaches, when compared with subgingival debridement alone, did not demonstrate a significant added clinical benefit. However, some of these new alternative interventions may have the potential to improve the outcomes of NSPT alone. Future evidence based on randomized controlled clinical trials would help clinicians and patients in the selection of different adjunctive therapies.

Efficacy and acceptability of different anti-fungal interventions in oropharyngeal or esophageal candidiasis in HIV co-infected adults: a pilot network meta-analysis

Background: Oropharyngeal/esophageal candidiasis are the most common opportunistic infections observed in patients with human immunodeficiency virus (HIV). While the commonly recommended treatment is fluconazole, relapse of oropharyngeal or esophageal candidiasis has been gradually increasing in recent decades.Methods: The current network meta-analysis (NMA) included randomized controlled trials (RCTs) investigating the efficacy and acceptability (i.e. drop-out rate) of different anti-fungal interventions against oropharyngeal or esophageal candidiasis in adults with HIV. All NMA procedures were conducted using the frequentist model.Results: Twenty-seven RCTs and 6277 participants were included. For oropharyngeal candidiasis, photosensitizer-based antimicrobial photodynamic therapy (aPDT) with laser irradiation plus methylene blue was associated with the highest cure rate and the lowest relapse rate among the investigated interventions [odds ratio (OR) = 6.82, 95% confidence intervals (95%CIs) = 0.19 to 244.42, p = 0.293, and OR = 0.03, 95%CIs = 0.00 to 0.77, p = 0.034, compared to fluconazole]. None of the investigated anti-fungal interventions were superior to fluconazole for esophageal candidiasis in respect of cure rates/relapse rates. All investigated anti-fungal interventions were well-accepted.Conclusions: aPDT could be the preferred strategy to manage oropharyngeal candidiasis; however the evidence for esophageal candidiasis still remained inconclusive.

Antimicrobial photodynamic therapy effectively reduces Porphyromonas gingivalis infection in gingival fibroblasts and keratinocytes: An in vitro study

BACKGROUND

Porphyromonas gingivalis possess the ability to invade host cells which prevents this pathogen from eradication by conventional periodontal therapy. Recently, antimicrobial photodynamic therapy (aPDT) was introduced to periodontal treatment as a complementary antibacterial method. The aim of this study was to evaluate the effect of toluidine blue-O (TBO) mediated aPDT on the viability of P. gingivalis invading gingival fibroblasts and keratinocytes in an in vitro model of infection.

METHODS

Primary human gingival fibroblasts (PHGF) and telomerase immortalized gingival keratinocytes (TIGK) were infected with Pg ATCC 33277. Two concentrations of TBO (0.01 mg/mL, TBO-c1 and 0.001 mg/mL, TBO-c2) and a non-laser red light source (λ = 630 nm) were applied to treat both cell-adherent/intracellular Pg (the adhesion/invasion model) or exclusively the intracellular bacteria (the intracellular infection model).

RESULTS

The median viability of cell-adherent/intracellular Pg in infected keratinocytes declined from 1.88 × 10⁵ cfu/mL in infected cells treated with TBO without irradiation to 40 cfu/mL upon irradiation for 10 s with TBO-c1. At higher light doses a complete photokilling of P. gingivalis was observed. Pg from exclusively intracellular infection model was also efficiently eradicated as the residual viability dropped from 1.44 × 10⁵ cfu/mL in control samples to 160, 20 and 10 cfu/mL upon irradiation for 10, 20 and 30 s, respectively. In the infected fibroblasts irradiation significantly reduced bacterial viability but did not completely eradicate the intracellular pathogen.

CONCLUSIONS

Antimicrobial PDT is effective in reducing the viability of intracellular periopathogens, however those residing within gingival fibroblasts seems to attenuate the photokilling effectiveness of this method.

Transgingival photodynamic therapy (tg-aPDT) adjunctive to subgingival mechanical instrumentation in supportive periodontal therapy. A randomized controlled clinical study

BACKGROUND

Recent data from preclinical studies and case series suggest that transgingival irradiation with diode lasers may represent a novel modality for antimicrobial photodynamic therapy (aPDT). However, at present, there is lack of data from controlled clinical studies on the use of transgingival antimicrobial photodynamic therapy (tg-aPDT) in the treatment of periodontitis.

OBJECTIVE

To evaluate the clinical effects of tg-aPDT used in conjunction with nonsurgical mechanical instrumentation during supportive periodontal therapy (SPT).

MATERIALS AND METHODS

Forty stage II and III periodontitis patients enrolled in SPT were randomly assigned to two groups of equal size. At baseline, study sites had to show sites with pocket probing depth (PPD) of ≥ 5 mm and Bleeding on Probing (BOP). Full mouth and site-specific Plaque-Index scores (PI), BOP, PPD, and Clinical Attachment Level (CAL) were recorded at baseline (BL), three months (3 M), and 6 months (6 M), respectively. The primary outcome variable was the change in the number of sites with BOP. Treatment was performed under local anaesthesia after random allocation to one of the following groups 1) Subgingival scaling and root planing (SRP) + tg-aPDT (test) or 2) SRP alone (control).

RESULTS

Thirty-nine patients completed the study. Full mouth PI and BOP improved over six month, however without statistically significant difference between the groups. At 6 M, BOP-levels were statistically significantly lower in test sites (25.0 %) compared to the control sites (65.0 %), (p < 0.025). PPD improved in both groups with comparable mean values at 3 M (PPD test: 5.21 ± 0.92 mm; PPD control: 4.45 ± 1.36 mm) and 6 M (PPD test: 5.11 ± 1.10 mm; PPD control: 4.35 ± 1.14 mm). Additionally, CAL slightly improved in both groups with comparable mean values at 3 M (CAL test: 6.79 ± 1.72 mm; CAL control: 5.30 ± 2.43 mm) and 6 M (CAL test: 6.26 ± 1.70 mm; CAL control: 5.50 ± 2.33 mm).

CONCLUSIONS

Within its limits, the present results appear to indicate that the use of tg-aPDT adjunctive to SRP may represent a new modality for controlling inflammation and further bleeding in residual periodontal pockets.

The role of periodontal treatment associated with photodynamic therapy on the modulation of systemic inflammation in the experimental model of asthma and periodontitis

BACKGROUND

The association of Periodontitis (P) with several systemic diseases, among them asthma (A), has been previously studied. As periodontal treatment (TTO) associated with photodynamic therapy (PDT) is able to treat P, the aim of this study is to verify whether periodontitis exerts systemic effects on asthma, and whether TTO, associated or not with PDT, is capable of altering the systemic course of both pathologies.

METHODS

64 male Balb/c mice were divided into 8 groups (n = 8): Basal (B), P, P + TTO, P + TTO + PDT, Asthma, A + P, A + P + TTO, A + P + TTO + PDT. After 43 days, all animals were euthanized. The total and differential leukocyte count in serum, platelet count, alveolar bronchial lavage cell count, femoral lavage cell count in addition to the reactivity of the trachea, lung edema and gingiva cytokines were analyzed. The frequency of inflammatory cells was assessed via flow cytometry. One-way ANOVA test was used, followed by the Student-Newman-Keuls post-test.

RESULTS

There was an increase in the number of blood circulating eosinophils in group A when compared to group B (p < 0.01); this characterized the asthma experimental model. P (p < 0.05) presented a lower amount of cytokine TNF-α in the gingiva when compared to the Asthma group. Apart from that, there was no statistical difference found for the other analyzed parameters.

CONCLUSION

These data contributed to elucidate that P and A, associated or not with TTO and PDT, are not able to interfere with the systemic parameters of Balb/c mice.

Photoexcited Toluidine Blue Inhibits Tau Aggregation in Alzheimer's Disease

The aggregates of microtubule-associated protein Tau are considered as a major hallmark of Alzheimer's disease. Tau aggregates accumulate intracellularly leading to neuronal toxicity. Numerous approaches have been targeted against Tau protein aggregation, which include application of synthetic and natural compounds. Toluidine blue is a basic dye of phenothiazine family, which on irradiation with a 630 nm light gets converted into a photoexcited form, leading to generation of singlet oxygen species. Methylene blue is the parent compound of toluidine blue, which has been reported to be potent against tauopathy. In the present work, we studied the potency of toluidine blue and photoexcited toluidine blue against Tau aggregation. Biochemical and biophysical analyses using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, ThS fluorescence, circular dichroism spectroscopy, and electron microscopy suggested that toluidine blue inhibited the aggregation of Tau in vitro. The photoexcited toluidine blue potentially dissolved the matured Tau fibrils, which indicated the disaggregation property of toluidine blue. The cell biology studies including the cytotoxicity assay and reactive oxygen species (ROS) production assay suggested toluidine blue to be a biocompatible dye as it reduced ROS levels and cell death. The photoexcited toluidine blue modulates the cytoskeleton network in cells, which was supported by immunofluorescence studies of neuronal cells. The studies in a UAS Tau E14 transgenic Drosophila model suggested that photoexcited toluidine blue was potent to restore the survival and memory deficits of Drosophila. The overall finding of our studies suggested toluidine blue to be a potent molecule in rescuing the Tau-mediated pathology by inhibiting its aggregation, reducing the cell death, and modulating the tubulin levels and behavioral characteristics of Drosophila. Thus, toluidine blue can be addressed as a potent molecule against Alzheimer's disease.

Advancing antimicrobial strategies for managing oral biofilm infections

Effective control of oral biofilm infectious diseases represents a major global challenge. Microorganisms in biofilms exhibit increased drug tolerance compared with planktonic cells. The present review covers innovative antimicrobial strategies for controlling oral biofilm-related infections published predominantly over the past 5 years. Antimicrobial dental materials based on antimicrobial agent release, contact-killing and multi-functional strategies have been designed and synthesized for the prevention of initial bacterial attachment and subsequent biofilm formation on the tooth and material surface. Among the therapeutic approaches for managing biofilms in clinical practice, antimicrobial photodynamic therapy has emerged as an alternative to antimicrobial regimes and mechanical removal of biofilms, and cold atmospheric plasma shows significant advantages over conventional antimicrobial approaches. Nevertheless, more preclinical studies and appropriately designed and well-structured multi-center clinical trials are critically needed to obtain reliable comparative data. The acquired information will be helpful in identifying the most effective antibacterial solutions and the most optimal circumstances to utilize these strategies.

Clinical outcomes of adjunctive indocyanine green-diode lasers therapy for treating refractory periodontitis: A randomized controlled trial with in vitro assessment

BACKGROUND/PURPOSE

It is still challengeable to treat periodontal pockets refractory to mechanical debridement. This study is to evaluate the potential of indocyanine green (ICG)-diode laser-based photothermal therapy (PTT) for solving this dilemma.

METHODS

Bone marrow-derived mesenchymal stem cells (BMSCs) and periodontal ligament cells (PDLCs) were incubated with phosphate-buffered saline, chlorhexidine, or ICG, non-irradiated or irradiated with 810-nm diode lasers, and the cell viability was evaluated. Patients with teeth refractory to mechanical periodontal debridement on different quadrants were recruited. At baseline (T0), all examined teeth received scaling and root planing, and those on the test quadrant (PTT group) received ICG-diode laser treatment. The outcome was evaluated using clinical parameters and cytokines in the gingival crevicular fluids at 4-6 weeks (T1) and 6 months (T2).

RESULTS

In ICG-treated cultures, the viability of BMSCs and PDLCs was recovered on day 4, and laser irradiation inhibited the metabolic activities of BMSCs. 22 patients with 30 control teeth and 35 PTT-treated teeth were examined. All examined teeth showed modest reductions in probing pocket depth (PPD), clinical attachment loss (CAL), bleeding upon probing (BOP), and plaque score at T1 and T2 and significant reductions in IL-1β and MMP-8 at T2. Compared with controls, BOP was reduced more prominently, IL-1β and MMP-8 were significantly lower, and reductions in PPD and CAL were slightly greater in the PTT group at T1 (0.05-0.19 mm).

CONCLUSION

ICG-diode laser-based PTT is compatible to periodontium and assists in faster resolution of gingival inflammation in periodontal pockets refractory to mechanical debridement.

Susceptibility of oral bacteria to antibacterial photodynamic therapy

Effective methods for managing the oral microbiome are necessary to ensure not only the oral but also the systemic health of a human body. The purpose of this study was to determine the sensitivity of four photosensitizers (PSs) to blue light in six representative oral bacterial species that cause intraoral diseases. The following six strains were investigated: Actinomyces israelii, Enterococcus faecium, Fusobacterium nucleatum, Lactobacillus gasseri, Streptococcus mutans, Veillonella parvula. PS stock solutions (1 mg/ml) were prepared by dissolving curcumin and protoporphyrin-IX in dimethyl sulfoxide, and resazurin and riboflavin in distilled water. The inoculation of 20 ml of a bacterial suspension cultured for 24 hours was mixed with 1,980 ml of each test solution, and then a light source was placed in front of the mixture. The irradiation wavelength was 405 nm and its applied energy was 25.3 J. The independent-samples t-test and one-way analysis of variance within groups were performed to compare the antibacterial effects in the four PSs. The antibacterial susceptibility when using different PSs and visible blue-light irradiation differed between the bacterial strains. Antibacterial photodynamic therapy that includes light exposure and PSs can be used to control the oral bacteria strains related to oral disease.

Photodithazine-mediated antimicrobial photodynamic therapy against fluconazole-resistant Candida albicans in vivo

This study evaluated the efficacy of antimicrobial Photodynamic Therapy (aPDT) against fluconazole-resistant Candida albicans in a murine model of oral candidosis. Mice were inoculated with two clinical isolates (R10, R15) and one reference strain (ATCC) of resistant C. albicans to produce oral candidosis. After inoculation, aPDT mediated by Photodithazine® (PDZ) and LED light was performed. The use of PDZ or light only was also investigated. Additional animals were treated with Nystatin (NYS). Untreated or healthy mice were also evaluated. Microbiological evaluation was performed by recovering C. albicans from the tongue via colony-forming units. Animals were killed 24 hours after treatments, and the tongues were removed for histological analysis. Data were analyzed by one-way ANOVA and Tukey test (P < .05). The results demonstrated that all strains showed the same behavior after aPDT and NYS treatment. A significant reduction in C. albicans viability was achieved after both treatments for R15 and ATCC. No significant reduction was verified for C. albicans R10 submitted to aPDT or NYS. The histological analysis revealed that aPDT did not cause side effects on tissues. aPDT was effective for inactivation of two fluconazole-resistant C. albicans of the three strains evaluated.

Killing mechanism of bacteria within multi-species biofilm by blue light

Objectives: The aim of the study was to characterize the immediate and delayed effects of non-coherent blue-light treatment on the composition and viability of an in vitro biofilm composed of anaerobic multispecies, as well as the mechanisms involved. Methods: A multispecies biofilm was constructed of Streptococcus sanguinis, Actinomyces naeslundii, Porphyromonas gingivalis and Fusobacterium nucleatum, test groups were exposed to blue light. The multispecies biofilm was explored with a newly developed method based on flow cytometry and confocal microscopy. The involvement of the paracrine pathway in the phototoxic mechanism was investigated by a crossover of the supernatants between mono-species P. gingivalis and F. nucleatum biofilms. Results: Blue light led to a reduction of about 50% in the viable pathogenic bacteria P. gingivalis and F. nucleatum, vs that in the non-exposed biofilm. Biofilm thickness was also reduced by 50%. The phototoxic effect of blue light on mono-species biofilm was observed in P. gingivalis, whereas F. nucleatum biofilm was unaffected. A lethal effect was obtained when the supernatant of P. gingivalis biofilm previously exposed to blue light was added to the F. nucleatum biofilm. The effect was circumvented by the addition of reactive oxygen species (ROS) scavengers to the supernatant. Conclusion: Blue-light has an impact on the bacterial composition and viability of the multispecies biofilm. The phototoxic effect of blue light on P. gingivalis in biofilm was induced directly and on F. nucleatum via ROS mediators of the paracrine pathway. This phenomenon may lead to a novel approach for 'replacement therapy,' resulting in a less periodonto-pathogenic biofilm.

Photodynamic antimicrobial chemotherapy has an overt killing effect on periodontal pathogens? A systematic review of experimental studies

The periodontal disease (PD) etiology is mainly associated with some bacterial strains, such as Porphyromonas gingivalis (P. gingivalis). Nonsurgical root scaling (e.g., antibiotics) may achieve a temporary decrease in the P. gingivalis level, yet it cannot eradicate the microorganism. Moreover, antibiotics can lead to bacterial resistance and undesirable side effects. This systematic review was performed to identify animal data defining antimicrobial photodynamic therapy (PACT) role on experimental PD models in the treatment of P. gingivalis. Embase, MEDLINE, and PubMed were examined for studies published from January 1980 to August 2018. MeSH terms and Scopus data were used to find more related keywords. Four studies were selected and reviewed by two independent researches with a structured tool for rating the research quality. The beneficial effect of PACT included reductions in P. gingivalis counts, bleeding on probing, redness, and inflammation on multiple sites (i.e., first molar, dental implants; subgingival; and mandibular premolars). Although our results suggest that PACT displays antimicrobial action on P. gingivalis, thus improving the PD, a nonuniformity in the PACT protocol and the limited number of studies included lead to consider that the bactericidal efficacy of PACT against periodontal pathogens in PD remains unclear.

Clinical and microbiological effects of multiple applications of antibacterial photodynamic therapy in periodontal maintenance patients. A randomized controlled clinical study

BACKGROUND

At present, very limited data are available on the clinical and microbiological outcomes obtained following repeated application of aPDT following one single mechanical debridement.

OBJECTIVE

To evaluate clinically and microbiologically the outcomes following one single session of subgingival mechanical debridement (scaling and root planing; e.g. SRP) followed by 1x immediate application of aPDT and 2 x subsequent use of aPDT without SRP.

MATERIALS AND METHODS

Forty patients diagnosed with generalized chronic periodontitis that were enrolled in periodontal maintenance (supportive periodontal therapy) program, were randomly assigned to one of the two treatments: 1. SRP by means of ultrasonic and hand instruments followed by one single session of SRP followed by 1x immediate application of aPDT and 2 x subsequent applications of aPDT without SRP (test) or 2. SRP alone (control). The following clinical parameters were recorded at baseline, at 3 and 6 months: Full-Mouth Plaque Scores (FMPS), Full-Mouth Bleeding Scores (BOP), Probing Pocket Depth (PPD), Clinical Attachment Level (CAL) and Gingival Recession (RC). Additionally, microbiological samples were evaluated at baseline and six months after treatment. The primary outcome variable was BOP.

RESULTS

Both treatments improved statistically significantly (p < 0.05) the FMPS, PPD and CAL values, while no statistically significant changes occurred in terms of RC. In the test group, BOP decreased statistically significantly (p < 0.05) after 3 and 6 months, while in the control group the respective values decreased statistically significantly only at 3 months. Both treatments reduced statistically significantly the total bacteria counts (TBC) after 6 months (p < 0.05). At 6 months, the use of SRP and aPDT resulted in a statistically significant decrease in the number of all tested bacteria except A. actinomycetemcomitans while the use of SRP alone resulted only in a statistically significant decrease in the numbers of P. gingivalis, T. denticola and T. forsythia.

CONCLUSIONS

In periodontal patients enrolled in a maintenance program one single session of SRP followed by 3x application of aPDT, enhanced the clinical and microbiological outcomes compared to SRP alone.

The effect of antimicrobial photodynamic therapy on infected dentin in primary teeth: A randomized controlled clinical trial protocol

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) has been used for the treatment of dental caries. Papacarie is a gel composed of papain and chloramine employed for the partial removal of carious tissue, effective against bacteria, however, some studies report that this antibacterial action is not quite so evident. The aim of this study is to evaluate the clinical effect of aPDT on infected dentin in dental caries lesion in primary teeth.

METHODS

Thirty-two primary molars with deep occlusal dental caries will be selected and divided in 2 groups: G1 - caries removal with a low-speed drill and G2 - application of aPDT with PapacarieMBlue. After treatment, all the teeth will be restored with glass ionomer cement and followed up clinically and radiographically, with evaluations at 3, 6, and 12 months. Dentin samples before and after treatment will be analyzed microbiologically. The data will be submitted to descriptive statistical analysis of the association between the categorical variables and both age and gender using the chi-square test and Fisher exact text. The Student t test and analysis of variance will be used for the comparison of mean signs and symptoms of reversible pulpitis. Pearson correlation coefficients will be calculated for the analysis of correlations among the continuous variables.

DISCUSSION

Adding methylene blue dye to the formula of PapacarieMBlue might potentiate the antimicrobial action of aPDT and work more effectively on the infected dentin combined with a conservative, minimally invasive treatment.

TRIAL REGISTRATION

NCT02734420 on 10 march 2016.

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.

Efficacy of an LED toothbrush on a Porphyromonas gingivalis biofilm on a sandblasted and acid-etched titanium surface: an in vitro study

Purpose

The aim of this study was to evaluate the antimicrobial effect of a newly devised toothbrush with light-emitting diodes (LEDs) on Porphyromonas gingivalis attached to sandblasted and acid-etched titanium surfaces.

Methods

The study included a control group, a commercial photodynamic therapy (PDT) group, and 3 test groups (B, BL, and BLE). The disks in the PDT group were placed in methylene blue and then irradiated with a diode laser. The B disks were only brushed, the BL disks were brushed with an LED toothbrush, and the BLE disks were placed into erythrosine and then brushed with an LED toothbrush. After the different treatments, bacteria were detached from the disks and spread on selective agar. The number of viable bacteria and percentage of bacterial reduction were determined from colony counts. Scanning electron microscopy was performed to visualize bacterial alterations.

Results

The number of viable bacteria in the BLE group was significantly lower than that in the other groups (P<0.05). Scanning electron microscopy showed that bacterial cell walls were intact in the control and B groups, but changed after commercial PDT and LED exposure.

Conclusions

The findings suggest that an LED toothbrush with erythrosine treatment was more effective than a commercial PDT kit in reducing the number of P. gingivalis cells attached to surface-modified titanium in vitro.

Evaluation of the effect of two types of laser on the growth of streptococcus mutans

Background and aims

This study was done to compare the antibacterial effect of Photodynamic therapy (PDT) on streptococcus mutans (S. mutans) using two different light sources and photosensitizers (PS).

Materials and methods

Five groups were studied in this research:no light and no toluidine blue ortho (TBO) as PS for control group, irradiation only (CO₂ laser or Nd:YAG laser), and irradiation with PS (CO₂ laser and TBO or Nd:YAG laser and TBO). Standard suspensions of S. mutans, based on the type of group, were used in different PDTs. Bacterial suspension from each treatment was subcultured onto the surface of Mueller-Hinton agar plates, and bacterial growth was assessed. The results were analyzed by analysis of variance (ANOVA).

Results

There was a statistically significant reduction in the viability of S. mutans in TBO with CO₂ laser and TBO with Nd:YAG laser groups (p value < 0.05). However, there was no significant difference between control and groups treated with lasers only. The highest number of the colonies of S. mutans in treated groups was observed in CO₂ laser irradiation only and the lowest number was seen in CO₂ laser with TBO. In the groups irradiated alone (without TBO), no significant reduction of colonies was observed. There was no significant difference between the experimental groups.

Conclusions

The colonies of S. mutans were susceptible to either CO₂ laser or Nd:YAG laser in the presence of TBO with no significant difference. So these lasers with this photosensitizer may be useful in prevention of dental caries and antimicrobial treatment protocols.

Effect of aPDT on Streptococcus mutans and Candida albicans present in the dental biofilm: Systematic review

To evaluate the effect of aPDT on S. mutans and C. albicans present in the dental biofilm, using methylene blue as a photosensitizer in different pre-irradiation times. The searches were made on Pubmed, Web of Science, Bireme, Scopus and Cochrane Library, and were complemented by screening the references of selected articles in the attempt to find any article that did not appear in the database search. The searches were performed by two researchers and limited to studies involving human subjects published in the English language. Inclusion criteria included in vitro studies with aPDT; studies that used methylene blue as a photosensitizer; studies that used low power laser; studies that evaluated S. mutans or C. albicans. Studies published in a non-English language, patents, in vivo or in situ studies; case reports, serial case, reviews and animal studies were not included. Studies published before 1996 were also not included. Initially, the search resulted in 68 published studies. 16 records were excluded because they were duplicated. The analysis of titles and abstracts resulted in the exclusion of 48 of the published studies, resulting in 4 studies included in the systematic review. The aPDT was effective in three of the four papers selected for the systematic review and the pre-irradiation time used was 5 or 15 min. This therapy had satisfactory results in both C. albicans and S. mutans when using methylene blue as a photosensitizer.

Treatment of severe periodontitis with a laser and light-emitting diode (LED) procedure adjunctive to scaling and root planing: a double-blind, randomized, single-center, split-mouth clinical trial investigating its efficacy and patient-reported outcomes at 1 year

Broad methodological heterogeneity makes the literature on the clinical effects of laser treatment in periodontitis, both as monotherapy and adjunct to non-surgical therapy, which is difficult to interpret. The present split-mouth study was performed: (i) to determine the efficacy and safety of a photoablative-photodynamic diode laser therapy, including antiseptic LED irradiation, in adjunct to scaling and root planing (iPAPD+SRP) vs. sham-treatment+SRP for the treatment of diffuse severe periodontitis and (ii) to estimate the patient-reported outcomes. Twenty-four patients with severe periodontitis were treated with iPAPD+SRP or sham-treatment+SRP. iPAPD+SRP consisted of the following: (1) intra-/extra-pocket de-epithelization with photoablative λ 810 nm laser, (2) disinfection with λ 405 nm LED, (3) SRP, and (4) 10 weekly antiseptic/anti-inflammatory photodynamic treatments with λ 635 nm laser and 0.1% toluidine blue as photosensitizer. Clinical and cytofluorescent periodontal markers and patient-reported results were analyzed. At 1-year follow-up, both groups showed a significant reduction of several severity markers of periodontitis, namely probing depth (PD) and bleeding on probing (BoP), as well as of bacteria, polymorphonuclear cells, erythrocytes and damaged epithelial cells in exfoliative samples, as compared with day 0. The quadrants subjected to iPAPD+SRP showed significantly better values of these parameters as well as of clinical attachment level (CAL) as compared with those undergoing sham-treatment+SRP. The patients' perceived pain/discomfort, and overall liking was also in favor of the iPAPD+SRP treatment. This study confirms the efficacy of combined phototherapy in adjunct to SRP which had emerged from previous clinical trials, extending its field of application to severe periodontitis.

Indocyanine green-mediated photothermal therapy in treatment of chronic periodontitis: A clinico-microbiological study

Background:

Photodynamic therapy (PDT) has developed as an alternative treatment modality in periodontitis patients. Different photosensitizers used over the years have shown contradictory results. Thus, recently indocyanine green (ICG)-mediated photothermal therapy has emerged for the treatment of chronic periodontitis.

Aim:

The present study aimed at comparing and evaluating the effects of photothermal therapy using ICG in the treatment of chronic periodontitis with scaling and root planing (SRP).

Materials and Methods:

This was a randomized, controlled, clinical trial where fifty participants were equally divided into two groups, i.e., control group (SRP) and test group (SRP + photothermal therapy). Clinical parameters were evaluated at baseline and 6-month follow-up. These were plaque index (PI), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL). Microbiological analysis of plaque sample was also done to check for anaerobic mixed flora.

Results:

Significant reduction was seen in PD, CAL, and BOP in the test group as compared to control group after 6 months (P < 0.05). However, intergroup comparison of PI showed nonsignificant results (P > 0.05). Anaerobic culture of plaque samples of test group also revealed a significant reduction of microorganisms in comparison with control group.

Conclusion:

ICG-mediated photothermal therapy can act as an alternative to antimicrobial PDT as an adjunct to SRP in the treatment of chronic periodontitis.

Clinical effects of photodynamic therapy as an adjunct to full-mouth ultrasonic scaling and root planing in treatment of chronic periodontitis

Background and aims

Photodynamic therapy (PDT) is a potential strategy to eliminate infection in the specific tissue. It uses lower-power laser to activate a photosensitizing agent. Studies have shown the benefit of PDT in the periodontal treatment. The aim of this study was to evaluate the periodontal changes after applying PDT as an adjunct to one visit full-mouth SRP (scaling and root planing) with subgingival piezoelectric ultrasonic scaler compared with full-mouth SRP alone.

Methods

A split-mouth randomized clinical trial was designed. Twenty patients with moderate to severe chronic periodontitis were treated with subgingival piezoelectric ultrasonic device alone in control group and adjunct treated with PDT in the test group. Probing pocket depth (PD), clinical attachment level (CAL), plaque index (PI), gingival bleeding index (GBI) and gingival inflammation index (GI) were evaluated at baseline, 1 month, 3 and 6 months after treatment. Only sites with PD ≥ 4 mm at baseline were calculated.

Results

All periodontal parameters were significantly improved in both groups at 1 month, 3 and 6 months after treatment. All parameters in test group were better than that control group, with statistically significant differences of GBI and GI (P < 0.05) at 3 and 6 months after treatment but no statistically significant differences of PD, CAL and PI.

Conclusions

One visit full-mouth ultrasonic SRP seems to have good enough effort for the periodontal status till 6 months. The adjunct treatment of PDT provided positive effect in term of GBI and GI.