Does potassium iodide help in the microbial reduction of oral microcosm biofilms after photodynamic therapy with methylene blue and red laser?

ObjectiveTo evaluate the efficacy of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) doped with potassium iodide (KI) against oral microcosms biofilms cultured in dentin.MethodsA saliva-glycerol stock formed from pooled human saliva was diluted in McBain artificial saliva with 1% sucrose (1:1), inoculated on bovine dentin blocks, and refreshed daily for 5 days. The biofilms were divided (n = 9/group) and treated with 0.9% NaCl (C), 0.2% chlorhexidine (CX), 0.01% MB + low-power laser 15 J, 88 mW, 180 s (PL), and 0.01% MB + 50 mM KI + laser (PKIL). Serial dilution was performed, and cellular viability (CFU/mL) was evaluated for total microorganisms, total lactobacilli, total streptococci, and S. mutans. Additional biofilms were cultured and treated (n = 4) for biomass determination (%BMR). The microscopic structure of the biofilms was observed by SEM. One-way ANOVA and Tukey tests were conducted (α=5%).ResultsTotal microorganisms and total streptococci significantly reduced in biofilms treated with CX and PKIL when compared to C, but the CX, PKIL, and PL treatments did not differ from each other. Total lactobacilli and S. mutans showed a significant reduction in the CX, PL, and PKIL groups when compared to C, but with no difference between them. Biomass analysis showed a significantly reduction for CX and PKIL compared to C. SEM micrographs showed noticeable changes in bacterial membrane integrity for the PKIL and CX groups.ConclusionThe addition of KI to methylene blue-mediated aPDT in microcosm biofilms was effective in reducing oral microorganisms, but the effect was group dependent.     

In vitro evaluation of EDTA combined with photodynamic therapy to reduce Streptococcus mutans in carious dentin

BackgroundThis in vitro study aimed to evaluate the use of EDTA combined with photodynamic therapy to reduce Streptococcus mutans in carious dentin.MethodsSixty third molars were sectioned to obtain flat dentin surfaces. All specimens were waterproofed, except for the coronal dentin, and subjected to cariogenic challenge in brain-heart infusion (BHI) broth supplemented with 0.5% yeast extract, 1% glucose, 1% sucrose, and standard strain of S. mutans (ATCC 25175). The specimens were divided into 6 groups (n = 10 each): (1) control – caries collection; (2) EDTA - 17% EDTA was actively applied with a microbrush for 1 min; (3) aPDT – antimicrobial photodynamic therapy with 0.01% methylene blue photosensitizer (wavelength of 660 nm, energy of 4 J, power of 100 mW, spot size of 0.028 cm², energy density of 142 J/cm² for 40 s); (4) EDTA+aPDT – 17% EDTA actively applied for 1 min plus aPDT; (5) (EDTA+PT) + L – application of EDTA compounded with photosensitizer plus laser irradiation; and (6) PT – photosensitizer alone. Collection of caries was performed after the different cavity disinfection protocols. Aliquots from each dilution were seeded for colony-forming unit (CFU) counts. The results were log₁₀-transformed and analyzed by the Kruskal-Wallis test (Student-Newman-Keuls).ResultsThere was a significant reduction in S. mutans after aPDT (p<0.05), EDTA+aPDT (p<0.001), and (EDTA+PT) + L (p<0.001). The percentage of microbial reduction in ascending order was as follows: EDTA: 1.65%; PT: 15.51%; aPDT: 38.28%; EDTA+aPDT: 75.24%; and (EDTA+PT) + L: 97.35%.ConclusionApplication of 17% EDTA prior to photosensitization or compounded with a photosensitizer increased the antimicrobial effect of aPDT on S. mutans in carious dentin.     

Antimicrobial photodynamic therapy on Streptococcus mutans is altered by glucose in the presence of methylene blue and red LED

BackgroundDental caries are a multifactorial disease that progressively produces tooth destruction as a result of bacterial colonization of enamel surface, especially Streptococcus mutans. The objective of this work was to investigate the role of glucose in antimicrobial photodynamic therapy (aPDT) on S. mutans.MethodsS. mutans ATCC 25175 were cultured on microaerophilia at 37 °C for 48 h, and we tested aPDT in the presence of 50 mM glucose. Bacterial suspension was used to investigate aPDT with 100 μM methylene blue (MB) under LED emitting radiation at ʎ = 660 nm and parameters as following (P = 473 mW; I = 166.8 mW/cm², and doses of 5, 10 and 20 J/cm²). A seventy-two hours biofilm was grown on 96 flat buttoned well-plate and irradiation was performed from 10 to 80 J/cm² at similar conditions.ResultsThere was no dark toxicity nor bacterial death regarding LED irradiation on suspension and on biofilm. Nevertheless, aPDT presented expressive bacterial inactivation following 1 and 2 min of irradiation on cell suspension. On the other hand, there was no inactivation in the presence of glucose under the same conditions. Biofilm was completely inactivated by MB-mediated aPDT after 6 min of irradiation. However, the presence of glucose delayed the complete inactivation of the biofilm.ConclusionThe presence of glucose in the suspension drastically delayed the effect of aPDT on S. mutans and this effect is more pronounced in bacterial suspension than on biofilm.     

Antimicrobial efficacy,optical properties and flexural strength following antimicrobial photodynamic therapy over vacuum-formed orthodontic retainers

Background and aimsVacuum-formed retainers (VFRs) are widely used in dental practices because of their superior esthetics. However, simultaneous maintenance of their hygiene, mechanical and optical properties is challenging. This study aimed to evaluate and compare the disinfection efficacy of antimicrobial photodynamic therapy (aPDT), chlorhexidine (CHX), sodium hypochlorite (NaOCl) and water over VFRs specimens, along with their effect on flexural strength and color stability.Materials and methodsFabricated VFRs of thicknesses 1 mm and 2 mm were contaminated with S. mutans and C. albicans. Brain Heart Infusion agar was used to seed Streptococcus Mutans whereas Candida Albicans was seeded in Sabourand Dextrose Agar. The contaminated retainers were divided into four groups and decontaminated using four different treatment protocols: aPDT, CHX, NaOCl and water, with 10 specimens per group. Microbial viability following decontamination, was assayed using MTT. To assess the color stability, pre and post decontamination color difference of 10 specimens was recorded using a spectrophotometer by blinding technique. The flexural strength of 10 specimens was measured using a universal testing machine by a standardized 3-point flexural strength (FS) test.ResultaPDT showed the highest reduction in the viability of S. mutans (28%) and C. albicans (20%) species in 1 mm thickness group while the second highest reduction following disinfection with CHX (40%) in followed by NaOCl disinfection (50%). On comparison between 1 mm and 2 mm, a statistically significant difference was noted for S. mutans in aPDT (p = 0.033) and NaOCl (p = 0.028) groups, and for C. albicans, a significant difference was noted within NaOCl (p = 0.001) and CHX (p = 0.043) groups. For FS, a statistically significant difference (p < 0.05) was observed between aPDT and the rest of the groups, whereas there was no statistically significant difference in the flexural strength between the CHX, NaOCl and water groups (p > 0.05) in both 1 mm and 2 mm specimens. Between 1 mm and 2 mm specimens, no statistically significant difference in the mean color difference was noted after any disinfection protocol (p > 0.05).ConclusionAntimicrobial photodynamic therapy showed a remarkable reduction in candidal and bacterial viability over VFRs. aPDT treated VFR specimens showed increased flexural strength and a higher color difference post treatment compared to other reagents.     

Plant extract incorporated into glass ionomer cement as a photosensitizing agent for antimicrobial photodynamic therapy on Streptococcus mutans

BackgroundA plant extract (EB) incorporated into glass ionomer cement (GIG) could be a potential photosensitizer for Antimicrobial PDT (aPDT) against caries-microorganisms, replacing methylene blue (MB), due to the presence of chlorophyll. GIC + EB + aPDT could be an therapeutic alternative to dentin decontamination and sealing, allowing reduction of operative time.ObjectiveEvaluate Dioscorea altissima (EB) incorporated into GIC as a photosensitizer for aPDT against Streptococcus mutans.MethodsGroups (n = 24; ntotal = 192): G1-GIC; G2-GIC + LASER; G3-GIC/EB; G4-GIC/EB + LASER; G5-GIC+MB; G6-GIC + aPDT; G7-GIC/EB + MB; and G8 – GIC/EB+aPDT. In aPDT groups, MB was the photosensitizer. In LASER groups, MB was not used. The irradiation protocol was 660 nm/100 mW/5 J/150 J/cm²/50 s, with a 5-min pre-irradiation time for the MB groups. Antibacterial assays were carried out in 24-well microplates. The wells were completed with one milliliter of a S. mutans in BHI at 1.3 × 10⁸ CFU/mL suspension. After incubation, PDT or laser was performed. After MTT bacteria viability test, the data were submitted to the Kolgomorov-Smirnoff normality test, followed by one-way ANOVA and Tukey's posterior test, α < 0.05.ResultsGroup G6 showed significant inhibition (p < 0.001), followed by groups G4, G5, G7, and G8, which did not show significant differences among them (p > 0.05). Groups G2 and G3 also showed similar results (p > 0.05) and were the least active compared to the others.ConclusionsEB potentiated the antimicrobial action of GIC against S. mutans and laser irradiation over GIC/EB presented better antimicrobials results. The results indicate that EB could be a potential photosensitizer for aPDT.     

Antibacterial photodynamic therapy with curcumin and Curcuma xanthorrhiza extract against Streptococcus mutans

BackgroundBacteria are becoming increasingly resistant to conventional antibacterial chemotherapy. This has prompted the application of antibacterial photodynamic therapy (aPDT) in bacteria-related diseases due to its excellent biocide effects. However, few studies have attempted to develop a novel photosensitizer based on natural components. The aim of the present study was to compare the aPDT effects of curcumin and Curcuma xanthorrhiza extract (CXE) against Streptococcus mutans.MethodsA planktonic suspension containing an S. mutans strain was treated in three separate groups: aPDT with curcumin, CXE, and a mixture of curcumin and CXE (ratio= 1:1) at concentrations of 0, 10, 10², 10³, and 10⁴ ng/ml. Light irradiation with a center wavelength of 405 nm was applied using an LED (power density of 84.5 mW for 300 s at an energy density of 25.3 J/cm²). The phototoxicity of photosensitizers against S. mutans was investigated using a colony-forming-unit assay. Percentage logarithmic reductions [log₁₀(CFU/ml) values] were analyzed using one-way ANOVA followed by the Tukey test (p < 0.05) and Student’s independent t-test.ResultsThe viability of S. mutans in the presence of curcumin, CXE, and a mixture of these two components was substantially reduced during irradiation with 405 nm light. The phototoxicity of the photosensitizer varied with its solubility and concentration.ConclusionThese preliminary in vitro findings imply that combining curcumin and CXE with a 405 nm LED may be a novel method of applying aPDT. This could be advantageous in preventing and treating dental caries using devices that are readily available in clinics.     

Effect of methylene blue-induced photodynamic therapy on a Streptococcus mutans biofilm model

BackgroundSeveral studies have reported the use of antimicrobial photodynamic therapy (aPDT) to control biofilm but its efficacy depends on several factors, such as biofilm model used. This study aims to examine whether exposure to diode laser combined with methylene blue affects the bacterial viability and polysaccharide content in a Streptococcus mutans cariogenic biofilm model, which simulated ‘feast-famine’ episodes of exposure to sucrose that occur in the oral cavity.Materials and methodsS. mutans biofilms were formed on acrylic resin discs and exposed to a 10% sucrose solution for 1 min, eight times/day. After growing for 48 h, the biofilms were submitted to the following treatments, twice daily (n = 4): (i) 0.9% NaCl (NaCl) as the negative control; (ii) 0.12% chlorhexidine digluconate (CHX) as the positive antibacterial control; (iii) diode laser combined with methylene blue, using an energy density of 320 J/cm² (aPDT). After 120 h of growth, the biofilm formed on each disc was collected to determine the viable bacterial counts and concentration of insoluble exopolysaccharides (IEPS) and intracellular polysaccharides (IPS).ResultsBacterial counts in the biofilms formed differed among the treatments. Compared with NaCl, aPDT significantly destabilized biofilm (p < 0.0001). aPDT and CHX equally lowered the concentration of IEPS and IPS in biofilms.ConclusionUnder the experimental conditions assessed, our findings indicate that a twice-daily treatment with diode laser combined with methylene blue effectively decreased bacterial viability and the intra- and extracellular polysaccharide concentration in biofilms of S. mutans, a cariogenic bacterium.     

Peri-implant parameters and bone metabolic markers among water-pipe users treated with photodynamic therapy

AimThe study aimed to evaluate the efficacy of Mechanical debridement (MD) with and without adjunct antimicrobial photodynamic therapy (aPDT) in the treatment of peri‑implantitis among waterpipe smokers (WPS) and non-smokers with peri‑implantitisMaterial and methodsParticipants were stratified into two groups. Group 1: Subjects who smoked water pipes for the last 2 years with peri‑implant disease were treated with aPDT adjunct to MD and group 2: Participants who did not use water pipes in the last 2 years but have periimplantitis (controls) were treated with MD only. Participants were scrutinized with peri‑implantitis (PI) in one dental implant at least based on the inclusion and exclusion criteria. Using structured questionnaire information was gathered from participants. All participants underwent mechanical debridement (MD). Participants of WPS underwent antimicrobial photodynamic therapy (aPDT). Peri implant inflammatory parameters (PI, BI, PD, and CBL) were assessed in all participant at baseline, 3 months and 6 months follow-up. Periimplant sulcular fluid was collected for assessment of bone metabolic biomarkers RANK-L and OPG. For immunological and clinical peri‑implant parameters analysis of variance (ANOVA) and Kruskal-Wallis test were used. For multiple comparisons, Bonferroni post hoc test was deployed.ResultsClinical periodontal parameters at baseline were significantly different in the control group PI (49.8 ± 10.5), BI(46.8 ± 7.7), and PD (5.0 ± 1.8) compared to WPS PI (56.1 ± 12.0), BI (40.9 ± 8.3), and PD (5.6 ± 1.5) (p < 0.05). At 3 months follow-up after PDT, PI (19.1 ± 7.7) and PD (3.9 ± 1.4) were significantly lower in the control group compared to WPS group PI (23.5 ± 8.4) and PD (4.5 ± 1.2) (p < 0.05). Whereas, BI of control (16.3 ± 6.8) and WPS group (17.1 ± 5.3) at 3 months follow-up was comparable (p > 0.05). At six months follow up following PDT, PI (15.7 ± 5.5) and PD (3.4 ± 1.2) was significantly lower in the control group compared to participants with water piped users PI (18.6 ± 7.4) and PD (3.9 ± 1.3) (p < 0.05). No significant difference was noted in BI in both groups (p > 0.05). Participants treated with PDT adjunct to MD demonstrated significantly reduced mean RANK-L levels at both 3 and 6 months (p<0.05).ConclusionaPDT adjunctive to MD improved periodontal parameters i.e., plaque index, pocket depth, and crestal bone loss along with metabolic marker RANK-L in water pipe smokers compared to non piped smokers.     

Rutin-gallium complex mediated antimicrobial photodynamic therapy: An in vitro studies against Streptococcus mutans biofilms

BackgroundDiscoloration of teeth following antimicrobial photodynamic therapy (aPDT) is a serious concern. Common photosensitizers are colored, and access to a photosensitizer that does not leave color on the teeth or is the same color as the enamel and dentin is highly demanded. The physicochemical characterization, anti-virulence, and antimicrobial effects of a novel rutin-gallium (III) (Rt-Ga) complex as novel photosensitizer are presented herein.Materials and MethodsPhotophysical properties and cytotoxicity of the Rt-Ga complex were evaluated in comparison with the parental rutin. Intracellular reactive oxygen species (ROS) generation following Rt-Ga complex-mediated aPDT was measured using the fluorescent 2′,7′-dichlorofluorescein diacetate (H2DCF-DA) method. The anti-biofilm effects of Rt-Ga complex-mediated aPDT on Streptococcus mutans were assessed using a colorimetric assay. The virulence‑associated gtfB gene expression was assessed following Rt-Ga complex-mediated aPDT by quantitative real‑time PCR.ResultsThe photophysical properties of the Rt-Ga complex revealed a significant blue-shift in absorption (60 nm shift) and increased extinction coefficient (4100 M −1 cm −1; at λmax = 450 nm). Average (± SEM) DCF fluorescence intensities in an arbitrary unit (A.U.) were 7.1 ± 0.9, 4.1 ± 0.5, and 1.7 ± 0.3 for 10.0 μM of Rt-Ga complex-mediated aPDT, 7.5 μM of Rt-Ga complex-mediated aPDT, and 10.0 μM of Rt-Ga complex alone, respectively. The corresponding DCF fluorescence intensities were 710% (P = 0.001), 410% (P = 0.001), and 170% (P = 0.02) of the untreated S. mutans as the control group (1.0 ± 0.1 A.U.), respectively. The novel Rt-Ga complex-mediated aPDT exhibited no toxicity against primary human gingival fibroblast cells, a dose dependent decrease in S. mutans biofilm cell survival and virulence were observed (91.4% and 11.7-fold, respectively).ConclusionThe Rt-Ga complex-mediated anti-virulence and antimicrobial photodynamic effects were superior to the one caused by rutin alone making the Rt-Ga complex a more promising photosensitizer than the parent material.     

Hydrogen peroxide potentiates antimicrobial photodynamic therapy in eliminating Candida albicans and Streptococcus mutans dual-species biofilm from denture base

BackgroundCandida albicans (C.albicans) is the primary pathogen of denture biofilm. Moreover, it could establish a cross-kingdom relationship with bacteria to enhance its virulence and resistance to antifungal drugs. This study aimed to investigate the efficacy of antimicrobial photodynamic therapy (aPDT) in combination with hydrogen peroxide (H₂O₂) against C.albicans and Streptococcus mutans (S.mutans) dual-species biofilm formed on polymethyl methacrylate (PMMA) disk, and explore its involved mechanisms.MethodsC.albicans and S.mutans were grown on PMMA disk for 48 h to form biofilm and received different treatments. The treatments included:1) phosphate-buffered saline (PBS) group,2) 100 mM H₂O₂ group,3) aPDT group,4) aPDT+ H₂O₂ and 5) H₂O₂+aPDT group. Colony forming units (CFU), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and scanning electron microscope (SEM) were used to evaluate the antimicrobial effects. Extracellular polysaccharide substance (EPS) production and observation, cell permeability of biofilm, and uptake of toluidine blue O (TBO) by biofilm were assessed to investigate the involved mechanism.ResultsThere was no significant difference between PBS group and H₂O₂ group in viable microorganisms and metabolic activity of biofilm. The treatment protocols containing aPDT group reduced microorganism numbers and metabolic activity when compared to PBS group or H₂O₂ group (P<0.05). H₂O₂+aPDT treatment showed the highest antimicrobial efficacy in comparison with other treatments (P<0.05). Pretreatment with H₂O₂ could decrease EPS production and enhance cell permeability, leading to increased TBO uptake in biofilm.ConclusionPretreatment with H₂O₂ improved aPDT efficiency in eliminating dual-species biofilm from PMMA disk by reducing EPS amount, enhancing cell permeability, and increasing TBO uptake.     

In vitro antibacterial activity and durability of a nano-curcumin-containing pulp capping agent combined with antimicrobial photodynamic therapy

BackgroundConsidering the antibacterial properties of nano-curcumin (nCur) reinforced with antimicrobial photodynamic therapy (aPDT), this study aimed to assess the antibacterial activity and durability of Activa BioActive Base/Liner (ABBL) containing nCur (nCur-ABBL) as a pulp capping agent against Streptococcus mutans, the most common cause of secondary caries.Materials and methodsIn this in vitro experimental study, ABBL discs containing 0.5 %, 1%, 2%, and 5% (w/w) concentrations of nCur were fabricated. After aPDT using light emitting diode (LED) at 435 ± 20 nm wavelength for 5 min, the discs were undergone aging in artificial saliva for 90 days. The antibacterial activity of the discs against S. mutans was evaluated by the disc agar diffusion test, and the number of bacterial colonies present in the biofilm formed on the disc surfaces was counted after 0, 15, 30, and 60 days of aging.ResultsThe maximum growth inhibition zone was noted around the 5% nCur-ABBL discs. Increasing the concentration of nCur from 0.5 % to 5% combined with aPDT significantly decreased the number of S. mutans colonies in the biofilm over time (P < 0.05). nCur-ABBL discs containing 2% and 5% nCur had no difference in antibacterial activity at any time point up to 60 days (P > 0.05).ConclusionAccording to our data, 5% nCur-ABBL revealed the largest growth inhibition zone in S. mutans culture. Moreover, 5% nCur can serve as an excellent ABBL additive in aPDT producer against S. mutans biofilms up to 60 days of aging period.     

The effect of photodynamic therapy on postoperative pain in teeth with primary endodontic infection

Introduction: The objective of this study was to investigate the action of photodynamic therapy on pain control after endodontic treatment in asymptomatic teeth with a primary infection, within a single visit.Methods: Sixty (60) single-rooted teeth with pulp necrosis and periapical lesions were selected and randomly divided into two (2) groups (n = 30), according to the protocol; a control group (CG) and a group using photodynamic therapy (aPDT). The canals were instrumented with Reciproc files # 25 up to 40 along the entire length of the canal, using 2% chlorhexidine gel as the auxiliary chemical substance, followed by irrigation with sterile saline. aPDT consited of 0.005% methylene blue as photosensitizer, using AsGaAl diode laser, 660 nm wavelength, 100 mW of power and 9 J of energy, using optical fibers with 365 μm in diameter. The canals were filled with Endomethasone N cement.Results: Pain intensity was assessed at 8, 12, 24, 48, 72 h and 1 week after endodontic treatment using a visual analogue scale. The level of pain was classified as none (0), mild (1–3), moderate (4–7) or severe (8–10). The data were at a significance level of 5%. There was a statistically significant difference (p<0.05) in the periods of 8, 12, 24, 48 and 72 h between the control group and the aPDT group. After 1 week, there was no statistically significant difference.Conclusions: It is concluded that photodynamic therapy had a significant effect on decreasing post-endodontic treatment pain in teeth with necrotic pulp and asymptomatic periapical lesions.     

Rat tissue reaction and cytokine production induced by antimicrobial photodynamic therapy

BackgroundThe antimicrobial photodynamic therapy (aPDT) inactivates the target cell via reactions among the photosensitizer (PS), Laser or Led and O₂. The aim of this study was to evaluate the tissue reaction and cytokine production promoted by aPDT with curcumin photosensitizer.MethodsPolyethylene tubes containing saline solution (control), 5% sodium hypochlorite (NaOCl) and aPDT with curcumin PS 500 mg/L, were implanted into dorsal connective tissue of Wistar rats. After 7, 15, 30, 60 and 90 days of implantation, the animals were euthanized and the tubes with surrounding tissues were removed. The specimens were divided in two part, one half was processed, fixed and prepared for histological analysis by staining with hematoxylin and eosin. The other half was collected for IL-1β and IL-6 cytokine production using ELISA assay. The results were statistically analyzed by Kruskal-Wallis test followed by Dunn test (p < 0.05) for tissue reaction and ANOVA followed by Bonferroni’s correction (p < 0.05) for ELISA.ResultsAll groups showed severe tissue reactions at 7 days, whilst a significantly decrease by time was observed. Regarding to cytokine production, aPDT increases the IL-1β levels in all periods of time (p < 0.05). However, for IL-6 levels, the highest value was observed with aPDT on the 90th day (p < 0.05).ConclusionsaPDT with curcumin PS 500 mg/L demonstrated biocompatibility similar to saline solution and induced the IL-1β and IL-6 cytokines production.     

Effect of two hemostatic agents containing Aluminium chloride and ferric sulfate on bond integrity of resin-modified glass ionomer cement

ObjectiveTo evaluate the influence of hemostatic agents (Expasyl and Viscostat) on the bond values of RMGIC bonded to pretreated dentin surface with cavity conditioner (CC), self etch primer (SEP), and antimicrobial photodynamic therapy (aPDT)Materials and methodsOne hundred and eighty human third molars were embedded in a self-cure acrylic resin-filled polyvinyl cylinder. The dentinal surface was prepared and all the samples were arbitrarily distributed into three different groups liable to the hemostatic agent used (n = 60). Samples in group 1: no hemostatic agent used, Group 2: Samples exposed to Expasyl, and group 3: Viscostat. After applying the hemostatic agent, all the samples were surface treated with different surface conditioners. Subgroup A1, B1, C1 were conditioned with aPDT, Subgroup A2, B2, and C2 surface were treated with SEP, and Subgroup A3, B3, and C3 were smeared with CC. RMGIC was placed and SBS was assessed using a universal testing machine and failure mode analysis was performed using and stereomicroscope at 40x magnification. Analysis of variance (ANOVA) and Tukey's post hoc test compared the means and standard deviations (SD) following SBS testing (p = 0.05).ResultsHighest SBS was exhibited by group A2 (22.36 ± 1.66 MPa Control - SEP) whereas group A1 (14.14 ± 1.32 aPDT + Control) demonstrated the lowest SBS. Subgroups B1 (17.23 ± 0.33- Expasyl + aPDT) and C1 (18.36 ± 0.25 MPa -Viscostat + aPDT) were found to be comparable (p > 0.05). Similarly, A3 (19.69 ± 1.01- Control + CC) and B3 (18.23 ± 0.33 MPa- Expasyl + CC) and C3 (18.36 ± 0.37 Viscostat + CC) demonstrated no significant difference in bond scores (p > 0.05). Most of the failures in aPDT were adhesive. However, SEP and CC groups demonstrated admixed and cohesive failureConclusionDentin conditioned by aPDT after hemostatic agents improves bond values of RMGIC. Self etch Primer and Cavity conditioner using polyacrylic acid without hemostatic agent improves bond integrity of RMGIC.     

Aptamer decorated emodin nanoparticles-assisted delivery of dermcidin-derived peptide DCD-1L: Photoactive bio-theragnostic agent for Enterococcus faecalis biofilm destruction

BackgroundDespite the high success rate of root canal treatment, failures are observed in a broad range of cases. Therefore, the need for novel approaches with the development of new generations of antimicrobial agents and intracellular drug delivery systems as adjunctive therapy is undeniable. In this study, we investigated the antimicrobial effects of antimicrobial photodynamic therapy (aPDT) using dermcidin‑derived peptide DCD‑1L loaded onto aptamer-functionalized emodin nanoparticles (Apt@EmoNp-DCD-1L) against Enterococcus faecalis as one of the most common bacteria involved in recurrent root canal treatment failures.Materials and methodsFollowing preparation of EmoNp-DCD-1L, the binding of selected labeled Apt to EmoNp-DCD-1L was performed, followed by the specificity of Apt@EmoNp-DCD-1L to E. faecalis was determined. The antimicrobial potential of aPDT was then assessed after the determination of the minimum inhibitory concentration (MIC) of Apt@EmoNp-DCD-1L. The molecular docking analysis was conducted to evaluate the potential binding modes of EmoNp to the proteins involved in E. faecalis pathogenesis. Eventually, the anti-virulence capacity of Apt@EmoNp-DCD-1L-mediated aPDT was investigated via quantitative real-time PCR (qRT-PCR) assay following measurement of intracellular reactive oxygen species (ROS) generation.ResultsThe binding specificity of Apt@EmoNp-DCD-1L to E. faecalis was confirmed by flow cytometry. The results showed that the cell viability of E. faecalis exposed to aPDT groups employing the sub-MIC doses of Apt@EmoNp-DCD-1L (7.8 and 15.6 µM) was significantly reduced compared to the control group (P < 0.05). Also, Apt@EmoNp-DCD-1L in combination with a blue laser light was capable of enhancing the anti-biofilm activity of aPDT against E. faecalis biofilm. Data obtained from the qRT-PCR analysis showed significant downregulation in the expression level of genes involved in bacterial biofilm formation after exposure to aPDT (P < 0.05).Conclusions: This in vitro study highlights that aPDT with the minimum concentration of Apt@EmoNp-DCD-1L can be considered as a targeted bio-theragnostic agent for the detection and elimination of E. faecalis in the dispersed and biofilm states.     

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

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

Enhancement of photodynamic bactericidal activity of curcumin against Pseudomonas Aeruginosa using polymyxin B

BackgroundPseudomonas aeruginosa (P. aeruginosa) is an emerging opportunistic pathogen, which can cause bacterial skin diseases such as green nail syndrome, interdigital infections and folliculitis. Curcumin-mediated antimicrobial photodynamic therapy (aPDT) has been demonstrated as a promising therapeutic option for the treatment of skin infection though its inactivation of gram-negative bacteria such as P. aeruginosa.Materials and methodsIn the present study, we examined the adjuvant effect of polymyxin B on the antibacterial activity of curcumin-mediated aPDT against P. aeruginosa. P. aeruginosa was treated with curcumin in the presence of 0.1–0.5 mg/L polymyxin B and irradiated by blue LED light (10 J/cm²). Bacterial cultures treated with curcumin alone served as controls. Colony forming units (CFU) were counted and the viability of P. aeruginosa was calculated after aPDT treatment. The possible underlying mechanisms for the enhanced killing effects were also explored.ResultsThe killing effects of curcumin-mediated aPDT against P. aeruginosa was significantly enhanced by polymyxin B (over 2-log reductions). Moreover, it was also observed that addition of polymyxin B in the curcumin-mediated aPDT led to the apparent bacterial membrane damage with increased leakage of cytoplasmic contents and extensive DNA and protein degradation.DiscussionThe photodynamic action of curcumin against P. aeruginosa could be significantly enhanced by the FDA-approved drug polymyxin B. Our results highlight the potential of introducing polymyxin B to enhance the effects of aPDT treatment against gram-negative skin infections, in particular, P. aeruginosa.     

In vitro evaluation of adhesion/proliferation of human gingival fibroblasts on demineralized root surfaces by toluidine blue O in antimicrobial photodynamic therapy

BackgroundAntimicrobial photodynamic therapy (aPDT) in Dentistry has important effects as bacterial destruction in areas with periodontal disease. Some dyes applied in aPDT could present low pH and, consequently, result in tooth demineralization. This study evaluated demineralization produced by aPDT with toluidine blue O (TBO) at low pH and analyzed adhesion/proliferation of human gingival fibroblasts (HGF).MethodsIn the 1st phase, bovine enamel and root dentin fragments received 2 treatments: PDT4 group (TBO–100 μg/ml—pH 4–60 s) plus laser (660 nm, 45 J/cm², 1.08 J, 30 mW, 30 s, spot 0.024 cm², 1.25 W/cm², sweeping, non-contact) and CA group (citric acid plus tetracycline—pH 1–180 s). Surface hardness loss and tooth wear were statistically analyzed (Student’s t test, ANOVA/Tukey, p < 0.05). In the 2nd phase, human dentin fragments were divided in C (control group—scaling and root planing), PDT4 and CA. HGF (10⁴, 5th passage) were cultured on these fragments for 24, 48 and 72 h and counted in scanning electron microscopy photographs. Number of HGF was analyzed using repeated-measures ANOVA and Tukey (p < 0.05).ResultsPercentage of surface hardness loss was similar in dentin for PDT4 (71.5%) and CA (76.1%) (p > 0.05) and higher in enamel for CA (68.0%) compared to PDT4 (34.1%) (p < 0.05). In respect to wear, no difference was found between PDT4 (dentin: 12.58 μm, enamel: 12.19 μm respectively) and CA (dentin: 11.74 μm and enamel: 11.03 μm) (p > 0.05). Number of HGF was higher after 72 h in CA group (2.66, p < 0.05) compared to PDT4 (2.2) and C (1.33).ConclusionPDT4 is not as aggressive as CA for enamel. However, dentin demineralized promoted by PDT4 does not stimulate HGF adhesion and proliferation as CA.     

Antimicrobial photodynamic therapy combined to periodontal treatment: Experimental model

BackgroundAntimicrobial photodynamic therapy (aPDT) has been used as an adjuvant treatment for periodontitis. It combines a photosensitizer with a light source to induce reactive oxygen species and kill microbial cells. PpNetNI is a protoporphyrin derivative, and it has a chemical binding site at biofilm and great affinity to microbial cells. The aim of this study was to investigate the effects of aPDT as an adjuvant treatment for periodontitis.MethodsThirty healthy male rats Wistar (Rattus norvegicus) were used in this study (Approved by UNINOVE Ethical committee AN0029/2015). Periodontitis was induced by placing a cotton ligature around the first mandibular molar in a subgengival position. The contralateral mandibular first molar received neither a ligature nor any treatment, and was used as a control. After 7 days, the ligature was removed and all animals received scaling and root planing (SRP) and were divided according to the following treatments: SRP group (received SRP and irrigation with PpNetNI, 10 μM) and aPDT group (PpNetNI 10 μM followed by LED irradiation). aPDT was performed with a LED (630 nm) with an output power of 400 mW (fluence-rate 200 mW/cm²; fluence 18 J/cm²). Rats were euthanized at 24 h, 48 h and 7 days postoperatively. The area of bone loss in vestibular region of the first molar was evaluated by Optical Coherence Tomography (OCT, THORLABS LTD., Ely, UK). Data were analyzed statistically (ANOVA and Tukey tests, p < 0.05).ResultsThe animals treated by aPDT showed bone gain of approximately 30% compared to the SRP group following 7 days from the treatment.ConclusionaPDT promoted bone recovery 7 days after periodontal intervention.     

Antimicrobial photodynamic therapy using diode laser activated indocyanine green as an adjunct in the treatment of chronic periodontitis: A randomized clinical trial

IntroductionClinical studies have shown the usefulness of antimicrobial photodynamic therapy (aPDT) as an adjunctive in periodontal therapy. These studies did not utilize indocyanine green (ICG) as a recently introduced photosensitizer. The aim of this study was to perform a full-mouth double-blind randomized controlled clinical study to test the efficacy of adjunctive aPDT with ICG compared with scaling and root planing (SRP) alone in chronic periodontitis treatment.Materials and methodsFifty patients were selected for this study. All patients received SRP. Then, each patient was randomly assigned to either the test group (aPDT + SRP) or the control group (SRP). aPDT was performed with a diode laser (wavelength: 810 nm, power: 200 mW) and ICG as photosensitizer. The adjunctive procedure was repeated after 7, 17 and 27 days. The clinical parameters including bleeding on probing (BOP), clinical attachment loss (CAL), plaque index (PI), probing pocket depth (PPD), full mouth plaque score (FMPS) and full mouth bleeding score (FMBS) were measured at baseline and after 1 and 3 months.ResultsThere were no significant differences between two groups at baseline. BOP, PPD and FMBS showed significant improvements in the test group (P ≤ 0.001). In terms of PI, FMPS and CAL, no significant differences were observed between both groups (P ≥ 0.05).ConclusionaPDT as an adjunctive approach yielded complete resolution of inflammation and significant reduction in periodontal pocket depth. However, aPDT had no additional advantages in clinical attachment gain and plaque score.