Effect Of Antimicrobial Photodynamic Therapy Research Articles

LASER in periodontal treatment: is it an effective treatment or science fiction?

There are several studies that evaluate the use of lasers in periodontal treatment in non-surgical or surgical therapy. However, while several studies showed clinically beneficial effects of some lasers in periodontal treatment, there are few clinical reports of additional advantages of lasers as adjunctive treatments in periodontology. The aim of this paper is to demonstrate and critically analyze the level of scientific evidence of effects of low-level lasers and high-power lasers in periodontology. A narrative review of the studies was carried out in each topic and type of laser or periodontal treatment. In nonsurgical periodontal therapy the results showed that there is an additional clinical benefit when using a diode laser (DL) associated with scaling and root planing (SRP) in patients with moderate to severe periodontitis. The Er:YAG laser seems to be the most suitable for nonsurgical periodontal therapy and promotes the same clinical effects as conventional therapy. In periodontal surgery vaporization of the gingival or mucosal tissue can be carried out with DL, CO2, Nd:YAG, Er:YAG and Er,Cr:YSGG lasers. Photobiomodulation (PBM), mediated by low-level lasers associated with non-surgical periodontal therapy, promotes additional benefits in the short term and accelerates the bone and gingival tissue repair process and also reduces postoperative symptoms of periodontal surgery. The effect of antimicrobial Photodynamic Therapy is relevant in the initial reevaluation periods. Studies have shown controversial results of the use of lasers in periodontics, and this fact may be due to the lack of standard parameters of irradiation in each clinical application.

Efficacy of antimicrobial photodynamic therapy with Rose Bengal and blue light against cariogenic bacteria

ObjectiveWe evaluated the effect of antimicrobial photodynamic therapy (a-PDT) with Rose Bengal and blue light LED on bacteria that initiate and promote dental caries. DesignColony forming units of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis, and Lactobacillus salivarius under planktonic and biofilm conditions were counted after a-PDT treatment using Rose Bengal and blue light LED. In addition, cariogenic bacteria from saliva and dental plaques from ten volunteers were used for evaluation of a-PDT treatment. ResultsWe found that a-PDT using Rose Bengal at > 10 μg/mL had antimicrobial effects on oral Gram-positive S. mutans, S. sobrinus, S. sanguinis, and L. salivarius under both planktonic and biofilm conditions. The effect was also observed for cariogenic bacteria that formed biofilms containing water-insoluble glucans, through which the bacteria are firmly attached to the tooth surface. Moreover, a-PDT led to a marked reduction in cariogenic bacteria in saliva and dental plaques. Conclusiona-PDT could be a useful approach for controlling dental caries in dental surgery.

Evaluation of antimicrobial photodynamic therapy on wounds infected by Staphylococcus aureus in animal models.

Antibiotic-resistant Staphylococcus aureus bacteria are one of the expanding challenges. The purpose of current study is to evaluate the antimicrobial effect of photodynamic therapy (aPDT) on wounds infected to Staphylococcus aureus. In this study, 40 six-month-old rats were divided into 4 groups: control, photosensitizer (PS), laser, and aPDT. A full-thickness wound was created on their skin and it was infected by Staphylococcus aureus. For aPDT, the Indocyanine Green (Germany, Nürnberg, A.R.C. Laser, EmunDo) photosensitive agent and laser diod 810 nm (Germany, Nürnberg, A.R.C. Laser) was utilized. The wound healing procedure was monitored every 24 h until the 12th day with photography. The number of the bacteria was counted on the 12th day also. All results were compared using ANOVA and Tukey post hoc tests. Significance level was considered P-Value < 0.05. The average area of wound reduced in days 5-11th in photosensitizer, laser, and aPDT, respectively. The absolute colonization rate of bacteria in the wounds showed a significant decrease in two groups laser and aPDT compared to the control group. However, the lowest value was for the aPDT. In the conditions of this study, it emerged that aPDT and laser have an antimicrobial effect against antibiotic-resistant bacteria (particularly Staphylococcus aureus) and improve wound healing.

Effectiveness of antimicrobial photodynamic therapy as an adjunct to open flap debridement in patients with aggressive periodontitis

The aim of the present clinical trial was to evaluate the clinical efficacy of photodynamic therapy (PDT) as an adjunct to open flap debridement (OFD) in the treatment of generalized aggressive periodontitis (GAP). The subjects recruited for the study were divided into two groups: 'control group' received treatment through OFD, whereas the test participants were treated with OFD and adjunctive PDT. The clinical periodontal parameters were plaque index (PI), full mouth probing depth (FMPD) and full mouth relative attachment loss (FMRA). The microbial levels of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannarella forsythia (Tf) were analyzed. All parameters were assessed at baseline and 3 months. The observed values for all the parameters were reported in mean and standard deviation (mean ± SD). In order to analyse the mean values and inter-group comparisons, the Mann-Whitney U test was employed. The p-value was set at <0.05 to establish a significant difference among the reported values. A statistically significant improvement for BOP was observed in PDT group in comparison to the control group at 3 months only (p < 0.05). A significant reduction in the microbiological levels for Aa, Pg and Tf in both the study groups was observed. However, no significant differences in microbial levels were observed at any time point when the control and test groups were compared to each other. PDT in conjuction with OFD plays a significant role in reducing the microbial load and improving the clinical periodontal parameters in patients with GAP. Moreover, it is regarded as a safe treatment regimen as no side effects have been reported regarding its use in GAP.

The Effect of Antimicrobial Photodynamic Therapy in the Osseointegration of Immediately Placed Implants in Sites with Ligature-Induced Periodontitis in Dogs.

This study evaluated the effect of the antimicrobial photodynamic therapy (aPDT) on the osseointegration of immediate implants in a healing situation with greater challenges. The mandibular premolars of eight beagle dogs were submitted to ligature-induced periodontal disease. After 3 months, teeth were extracted and immediate implants were placed in the sockets previously decontaminated by mechanical debridement (MD) or MD+aPDT. Following 12 weeks, the dogs were euthanized and the specimens were analyzed. Histologic and histomorphometric analyses demonstrated significantly better results for the immediate implants decontaminated by debridement associated with aPDT. The sites treated with MD+aPDT led to osseointegration of the immediate implants without evidence of inflammation; conversely, evidence of peri-implantitis was observed where aPDT was not used.

The effect of combined curcumin-mediated photodynamic therapy and artificial skin on Staphylococcus aureus-infected wounds in rats.

Healing wounds represent a major public health problem, mainly when it is infected. Besides that, the antibiotics misuse and overuse favor the development of bacterial resistance. This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) combined with artificial skin on disinfection of infected skin wound in rats. Twenty-four Wistar rats were randomly distributed into 4 groups (n = 6): (i) control-untreated; (ii) aPDT-treated with curcumin-mediated aPDT (blue light); (iii) artificial skin-treated with artificial skin alcohol-based; and (iv) aPDT plus artificial skin-treated with aPDT associated with artificial skin alcohol-based. For the in vivo model, a full-thickness biopsy with 0.80 cm was performed in order to inoculate the microorganism Staphylococcus aureus (ATCC 25923). The aPDT was performed with a curcumin gel and a blue LED light (450 nm, 80 mW/cm2) at the dose of 60 J/cm2 and the treatment with alcohol-based artificial skin was done with the topical application of 250 μL. Additional animals were submitted to aPDT combined with the artificial skin. After treatments, the number of colony-forming units (CFU) and the damage area were determined. Data were analyzed by two-way repeated measures ANOVA and Tukey tests. The highest reduction of the bacterial viability was observed in the PDT plus artificial skin group (4.14 log10), followed by artificial skin (2.38 log10) and PDT (2.22 log10) groups. In addition, all treated groups showed higher relative area of wound contraction (36.21% for the PDT, 38.41% for artificial skin, and 35.02% for PDT plus artificial) in comparison with the control group. These findings provide evidence for the positive benefits of aPDT with blue light and curcumin associated with artificial skin to decontaminate and accelerate the wound contraction.

In vitro effect of antimicrobial photodynamic therapy with phycocyanin on Aggregatibacter actinomycetemcomitans biofilm on SLA titanium discs.

The aim of this in vitro study was to evaluate antimicrobial photodynamic therapy (aPDT) with phycocyanin on Aggregatibacter actinomycetemcomitans biofilm formed on sandblasted, large-grit, and acid-etched (SLA) titanium discs. In this in vitro experimental study, the minimum inhibitory concentration (MIC), sublethal dose of diode laser irradiation time, and sublethal dose of aPDT were first determined. Next, 30 SLA titanium discs with 8 mm diameter and 2 mm thickness were incubated with A. actinomycetemcomitans in order for the bacterial biofilm to form, and were randomly divided into 5 groups (n = 6): (I) negative control with no treatment, (II) positive control, immersed in 0.2 % chlorhexidine (CHX) for 5 min, (III) phycocyanin alone with ×2 MIC concentration for 5 min, (IV) diode laser alone (635 nm wavelength, 220 mW power), and (V) PDT with diode laser and phycocyanin. The samples were then sonicated, and the number of colony-forming units (CFUs) on each disc was calculated. Data were analyzed using one-way ANOVA, t-test, and a post-hoc test. aPDT with 125 μg/mL phycocyanin and 4 min irradiation of 635 nm diode laser decreasedA. actinomycetemcomitans biofilm by 40.07 %. The lowest mean colony count (CFUs/mL) was noted in 0.2 % CHX group (0.0 × 105 CFU/mL) while the highest mean was observed in the negative control group (4.55 ± 0.08 × 105 CFUs/mL). Using phycocyanin alone significantly decreased the A. actinomycetemcomitans count by 27.54 % (3.29 ± 0.06 × 105 CFUs/mL) compared with the negative control group (P < 0.0001). Significant differences were noted between the negative control and other groups (P < 0.0001). aPDT with phycocyanin and diode laser can decrease the A. actinomycetemcomitans biofilm on SLA titanium implant surfaces and can be used as a safe and non-invasive decontamination method for reduction of A. actinomycetemcomitans biofilm on implant surfaces.

Antimicrobial effects of photodynamic therapy on Staphylococcus aureus biofilm grown on a specific acrylic resin surface for ocular prostheses.

Photodynamic therapy (PDT) is a treatment for the specific control of oral biofilms. However, its effects on maxillofacial prostheses have been barely explored. In this study, we evaluated the antimicrobial effect of PDT using methylene blue (MB) and laser against a Staphylococcus aureus biofilm developed on the surface of scleral acrylic resin. Sixty-six specimens of acrylic resin designed for ocular prostheses were fabricated in a disk-shaped format (3 × 10 mm). S. aureus biofilm was grown on the surface of the specimens for 24 h and the disks were then treated with MB at different concentrations (25, 50, 75 or 100 μg/mL), with or without PDT (GaAlAs diode laser; 660 nm; 100 mW; 9 J; 321.4 J.cm-2; 3.5 W.cm-2 and 90 s). Control groups were treated with 2% chlorhexidine gluconate (CHX) or phosphate buffered saline. After the treatments, colony forming units (CFU) were counted and the samples were qualitatively evaluated by scanning electron microscopy (SEM). Data were analyzed descriptively and by nested ANOVA and the Tukey test (α = .05). PDT groups with MB concentrations at 75 and 100 μg/mL formed fewer CFU compared to the other groups (P < 0.001) and the 2% CHX group did not form any CFU. SEM images revealed that the surface of the polymers in these groups did not show bacterial colonies. PDT significantly reduced S. aureus biofilm in the scleral acrylic resin when associated with an MB dilution of 75 μg/mL or higher. Thus, PDT can be a promising candidate for disinfecting ocular prostheses.

Evaluation of antimicrobial photodynamic therapy with toluidine blue against Enterococcus faecalis: Laser vs LED.

This study aimed to compare the antibacterial effect of antimicrobial photodynamic therapy (aPDT) by use of light emitting diode (LED) and diode laser light sources with toluidine blue (TBO) photosensitizer on Enterococcus faecalis (E. faecalis) biofilm in root canals of extracted single-canal human teeth. Eighty-five sound human single-canal teeth were chosen for this study and standardized to have 15 mm of root length. The root canals were prepared with ProTaper rotary files and inoculated and incubated with E. faecalis for one week. Samples were divided into five experimental (n = 15) groups of PDT with TBO/LED, TBO/diode laser, LED, TBO and diode laser and one negative (NaOCl) and one positive (no treatment) control group. Dentin chip samples were collected from inside the canals using size 40 hedstrom file. The number of colony forming units (CFUs) in each group was calculated. Irrespective of the light source used for activation of photosensitizer (diode or LED), PDT was significantly more effective than other experimental groups (P < 0.001). No significant difference was noted between aPDT with diode laser or LED (P > 0.05). No significant difference was noted in colony count among other groups (LED, TBO, diode; P > 0.05). The results showed that aPDT significantly decreased residual bacteria in the canal. Thus, it may be used as an adjunct for root canal disinfection. Both diode and LED are suitable light sources for this purpose and can be used alternatively.

The effect of antimicrobial photodynamic therapy using yellow-green LED and rose bengal on Porphyromonas gingivalis.

This study aimed to investigate the effects of a new antimicrobial photodynamic therapy (aPDT) system using yellow-green light-emitting diode (YGL) and rose bengal (RB) on Porphyromonas gingivalis (Pg) in vitro. Pg suspension mixed with RB was irradiated with YGL (565 nm) or blue light-emitting diode (BL, 470 nm) at 428 mW/cm2 in comparison with chlorhexidine (CHG) treatment. The cells were cultured anaerobically on agar plates, and the number of colony-forming units (CFU) was determined. The treated suspension was anaerobically incubated, and the cell density (OD600nm) was monitored for 24 h. Also, the viability of treated human gingival fibroblast (HGF-1) was measured using WST-8 assay. Pg morphology was observed with a scanning electron microscope. The RNA integrity number of aPDT-treated Pg was determined and gene expressions were evaluated by quantitative real-time polymerase chain reaction. RB + YGL (aPDT) demonstrated a significantly higher reduction of CFU, compared to RB + BL (aPDT) and CHG, furthermore the OD value rapidly decreased. Morphological changes of Pg with RB + YGL were more severe than with CHG. Although RB + YGL reduced HGF-1 viability, aPDT's impact was significantly lower than CHG's. With RB + YGL treatment, RIN values decreased; furthermore, gene expressions associated with DNA replication and cell division were remarkably decreased after 12 h. The results of this study demonstrated that a novel aPDT system using RB + YGL may have potential as a new technical modality for bacterial elimination in periodontal therapy.

The effect of antimicrobial photodynamic therapy in the osseointegration of immediately implants placed in a more compromised healing situation such as ligature‐induced periodontitis in dogs

The effect of antimicrobial photodynamic therapy in the osseointegration of immediately implants placed in a more compromised healing situation such as ligature‐induced periodontitis in dogs

Antimicrobial photodynamic therapy fighting polymicrobial infections – a journey from in vitro to in vivo

Rapidly evolving multidrug resistance renders conventional antimicrobial strategies increasingly inefficient. This urges the exploration of alternative strategies with a lower potential of resistance development to control microbial infections. A promising option is antimicrobial photodynamic therapy (aPDT), especially in the setting of wound infections. In this study its effectiveness was tested as a treatment option for polymicrobially infected wounds in both in vitro and in vivo models. First, aPDT was applied to wound-relevant Gram-positive and Gram-negative bacteria in planktonic culture as the standard in vitro test system and compared different media to show a possible dependency of the therapy on the surrounding environment. In a second step, aPDT was investigated in an in vitro model mimicking the wound bed conditions using fibrin-coated culture plates. Finally, we tested aPDT in vivo in a polymicrobial infected wound healing model in immunocompromised BALB/c mice. In vitro, it was shown that the bactericidal effectiveness of aPDT was strongly dependent on the surrounding environment of the phototoxic reaction. In vivo, the significant delay in wound healing induced by polymicrobial infection was drastically diminished by a two-times application of aPDT using 100 μM methylene blue (generally regarded as safe for topical application on human skin) and 24 J cm-2 pulsed red LED light. Our experiments suggest that aPDT is capable of significantly improving wound healing also in complicated polymicrobially infected wound situations.

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

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. 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). 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. 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.

Effects of antimicrobial photodynamic therapy on antibiotic-resistant Escherichia coli.

This study used Electron Cryo-tomography (ECT) and fluorescent images to evaluate antimicrobial photodynamic therapy (aPDT) on the envelope architecture of a Gram-negative bacteria and the effects of combined therapy of aPDT and antibiotics. Standard and clinical suspension of Escherichia coli were submitted to photodynamic treatment with methylene blue solution (100μM) and a 100 mW LED emitting at 660 nm with 3 and 18 J of energy. As a control group, a suspension of E. coli was submitted to penicillin V for 60 min at 30 °C, to compare the damage in cell wall structure. After treatment, ECT images were collected and E. coli biofilms were grown in glass-cover slides and stained with live/dead staining for fluorescence analysis before and after treatments. Bacteria were also submitted to disc diffusion and MIC50 tests with Ampicillin, Amoxicillin + Clavulanic acid, Clindamycin and Erythromycin. For in vivo experiment Galleria mellonella larvae were infected with E. coli and treated with antibiotics, aPDT or combined therapy. ECT images presented damage to cell walls and vesicles structures inside and outside the bacteria and fluorescent images showed dose dependent effect of aPDT. Antibiotic or aPDT alone did not improve the survival of caterpillars, but the combined therapy significantly increased survival curve. ECT and fluorescent images shows that aPDT seems to promote micro-damages to cell envelope and causes the production of membrane vesicles permeabilizing cell membranes. The results showed that pre-treating bacterial cells with a photosensitizer and light make them more susceptible to antibiotics and could be an alternative to local infection treatment by resistant bacteria.

Effectiveness of antimicrobial photodynamic therapy in restoring clinical, microbial, proinflammatory cytokines and pain scores in adolescent patients having generalized gingivitis and undergoing fixed orthodontic treatment.

The aim of the present study was to evaluate the effectiveness of photodynamic therapy (PDT) on clinical gingival inflammatory parameters, bacterial load, proinflammatory cytokine status, and pain scores in adolescent patients undergoing fixed orthodontic treatment with gingivitis. Thirty adolescent undergoing fixed orthodontic treatment with gingivitis were randomly divided into two groups: Group A - patients undergoing dental scaling (DS) with adjunctive photodynamic therapy (PDT) and Group BDS alone. Clinical gingival parameters including plaque scores, (PS), bleeding on probing (BOP) and probing depth (PD) were assessed. Visual analogue scale (VAS) and McGill Pain Questionnaire (MPQ) were used to report the values of present pain intensity. Crevicular fluid was sampled to quantify the levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α using enzyme-linked immunosorbent assay. The total bacterial counts for Porphyromonas gingivalis (P. gingivalis) and Tannerella forsythia (T. forsythia) were assessed. All examinations were performed at baseline, 1 week and 4 weeks. Both the treatment regimens reported statistically significant reduction in PS and BOP (p < 0.05). However, no significant difference was observed in PS and PD values when Group B was compared with Group A (p > 0.05). There was a statistically significant reduction noted for BOP in Group B when compared to Group A (p < 0.05). There was a statistically significant reduction in the microbial counts of T. forsythia in Group A when compared to Group B at week-1 (p < 0.05). During the 4-week follow-up, the counts for T. forsythia significantly increased. No significant changes could be seen in either of the pain scores in both the groups (p > 0.05). Both groups showed statistically significant reduction in the IL-6 and TNF-α levels. However, IL-6 was significantly reduced at 1 week, while TNF-a significantly reduced at 4 weeks of follow up among the participants in Group B. PDT has a positive effect in significantly reducing the periodontal microbial load in established gingivitis in adolescent patients undergoing fixed orthodontic treatment.

Effect of antimicrobial photodynamic therapy with Radachlorin and a 660 nm diode laser on Pseudomonas aeruginosa: An in vitro study.

Pseudomonas aeruginosa is one of the most life-threatening pathogens in nosocomial environments. This study aimed to explore whether photodynamic therapy using a 660 nm diode laser and Radachlorin is an effective in vitro inhibitor of P. aeruginosa and determine what energy density and rate of delivery are the most impactful. Suspensions ofP. aeruginosa were obtained, inoculated in petri dishes with Radachlorin, and incubated for 30 min. Then, the laser light of a 660 nm diode laser was irradiated at varying energy densities and rates of delivery. Cell viability was evaluated after culturing. The combination of Radachlorin and the laser was more effective than Radachlorin or the laser alone (P < 0.05) in reducingP. aeruginosa and showed a killing rate of 95.8 % at an energy density of 5 J/cm2. In addition, the low rate of photodynamic therapy delivery group was more effective in inhibiting P. aeruginosa compared to the high rate of photodynamic therapy delivery group (P < 0.05). Within the limitations of thisin vitro study, we found that photodynamic therapy using a 660 nm diode laser and Radachlorin was effective for the inhibition of P. aeruginosa. In addition, energy density and rate of delivery are important factors to consider when using a 660 nm diode laser and Radachlorin to inhibit the growth of this organism.

Antimicrobial Photodynamic Therapy in the Control of Pseudomonas syringae pv. actinidiae Transmission by Kiwifruit Pollen.

Pseudomonas syringae pv. actinidiae (Psa) is a phytopathogen responsible for bacterial canker in kiwifruit plants and can be disseminated through pollen. This study aimed to evaluate the effectiveness of antimicrobial photodynamic therapy (aPDT) in the inactivation of Psa on kiwifruit pollen using New Methylene Blue (NMB) and Methylene Blue (MB) in the presence/absence of potassium iodide (KI). Pollen germination assays were also performed to evaluate if it was affected by aPDT. Higher reduction of Psa was achieved using NMB (5.0 μM) combined with KI (100 mM) in vitro (ca. 8 log CFU mL−1 after 90 min of irradiation), while NMB alone promoted a lower reduction (3.7 log CFU mL−1). The most efficient NMB concentration with KI was used to study the photodynamic efficiency of MB (5.0 μM). MB with KI photo-inactivated Psa more efficiently than NMB, causing the same bacterial reduction (ca. 8 log CFU mL−1) in half the irradiation time (45 min). Therefore, MB was selected for the subsequent ex vivo aPDT assays in pollen. Almost all the Psa cells added artificially to the pollen (3.2 log CFU mL−1) were photo-inactivated (3.1 log CFU mL−1), whereas aPDT had a low effect on pollen natural microorganisms. When KI was added, a significant increase in aPDT effectiveness was observed (4.5 log CFU mL−1). No negative effects were observed in the pollen germination after aPDT. The results show aPDT is an effective and safe method to Psa inactivation on kiwifruit pollen, and MB use is a promising alternative in the control of Psa transmission.

Antimicrobial effect of photodynamic therapy using sinoporphyrin sodium and 390-400nm light-emitting diode on Porphyromonas gingivalis in vitro.

This study aims to investigate the effect of antimicrobial photodynamic therapy (a-PDT) using a novel combination of sinoporphyrin sodium (DVDMS) and light-emitting diode (LED) with a wavelength of 390-400nm on Porphyromonas gingivalis in vitro. Absorption spectrum of DVDMS was determined by spectrometer for selecting suitable wavelength light source. The uptake of DVDMS by P. gingivalis was evaluated according to fluorescence intensity detected by a spectrometer. Then effects of DVDMS alone, 390-400nm LED alone, and photodynamic therapy produced by 10, 20, 40, and 80μg/mL DVDMS and 390-400nm LED on the suspension of P. gingivalis were evaluated by counting the number of colony forming units (CFU) after incubation. In the experiment, the LED illumination time was 30, 60, 90, 120, 180, 240, and 360s, respectively, and the corresponding energy density was 1, 2, 3, 4, 6, 8, and 12J/cm2, respectively. According to the absorption spectrum of DVDMS, the 390-400-nm light emitted by the LED was selected as the light source. The fluorescence intensity of DVDMS on P. gingivalis increased significantly at 5min, and with the extension of time, it decreased at 30min. DVDMS alone did not produce a significant toxicity on P. gingivalis compared with PBS (p = 0.979). While 390-400nm LED alone had a certain bactericidal effect on P. gingivalis, the bactericidal effect was more obvious as the light dose increased (p < 0.001). The effect of a-PDT produced by 20, 40, and 80μg/mL DVDMS and 390-400nm LED were significantly better than that of 390-400nm LED alone (p < 0.05). Both DVDMS concentration and light dose could enchance the bactericidal effect. The strongest photo-killing effect was generated by 80μg/mL DVDMS with 360s illumination (energy density is 12J/cm2), and the log reduction of bacteria was 5.69 ± 1.70. a-PDT using the combination of DVDMS with 390-400nm LED shows promise as a new treatment modality for pathogens elimination in periodontal therapy.

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 &lt; 0.05). There was no significant reduction in the number of viable cells exposed to Photoactive+ compared to the control group (p &lt; 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.

Bactericidal effect of antimicrobial photodynamic therapy (aPDT) on dentin plate infected with Lactobacillus acidophilus.

This study aimed to examine bactericidal effects of a new antimicrobial photodynamic therapy (aPDT) on dentin plates infected with Lactobacillus acidophilus (L. acidophilus). First, we measured the amount of reactive oxygen species (ROS) produced when new photosensitizer (PS), acid red (AR), and brilliant blue (BB) were irradiated with a semiconductor laser. ROS generated from each PS solution by laser irradiation was calculated as the total light emission amount (Relative Light Unit, RLU) using a chemiluminescence measuring device. Second, we examined bactericidal effects of the aPDT on dentin plates infected with L. acidophilus. The bactericidal effects on each group were evaluated by colony count assay and adenosine triphosphate assay. The experimental groups comprised two laser irradiation groups (650nm laser, 650laser; and 940nm laser, 940laser), two PS groups (BB and AR), four aPDT groups (650nm laser irradiation with BB, 650laser-BB; 650nm laser irradiation with AR, 650laser-AR; 940nm laser irradiation with BB, 940laser-BB; 940nm laser irradiation with AR, 940laser-AR), and a control. The ROS in all aPDT groups was significantly higher than in the control. RLU in all groups applied with laser irradiation was significantly lower than that in the control. However, only 650laser-BB showed significantly lower colony counts than the control. 650laser-BB was the most effective in sterilizing the infected dentin plates.