Photodynamic treatment of endodontic polymicrobial infection in vitro

Water-soluble vitamin-E for enhancing fluorescence diagnosis in infected human dentine treated with NaOCl

INTRODUCTION

Bacterial fluorescence methods are of interest in endodontics for informing endpoints for debridement. This study explored potential fluorescence quenching reversal effects of a water-soluble vitamin E conjugate (d-α-Tocopherol polyethylene glycol 1000 succinate, TPGS) when applied to polymicrobial biofilms grown on dentine that had been exposed to sodium hypochlorite (NaOCl) to cause quenching.

METHOD

Extracted human teeth were debrided, embedded in transparent acrylic resin and sectioned. After smear layer removal, tooth dentine sections were inoculated with a polymicrobial inoculum, and cultured for 7 days to create biofilms. Samples (n = 8 per group) were exposed to 1 % or 4 % NaOCl for 2 or 4 min, and then treated with TPGS. Bacterial fluorescence readings under laser excitation at 655 nm were assessed over 10 min using a calibrated DIAGNOdent device. All data were assessed for normality (Kolmogorov-Smirnov test) and analysed with ANOVA followed by Bonferroni post-hoc tests.

RESULTS

NaOCl at both concentrations quenched fluorescence readings of biofilms grown on dentine samples, with a maximal reduction of 40.4 % at 5 min after 4 % NaOCl. Treatment with TPGS gave faster recovery of fluorescence readings compared to the control at 5 and 10 min.

CONCLUSION

The water-soluble antioxidant TPGS partially reversed fluorescence quenching caused by NaOCl. This agent may have value clinically for reducing the time needed for fluorescence readings to recover when NaOCl is used as an irrigant. This will facilitate more accurate assessment of endpoints for canal debridement.

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.

In vitro antibiofilm effect of different irradiation doses in infected root canal model

BACKGROUND

Eradication of endodontic biofilms from the infected root canal system is still the main concern in endodontics. In this study, the role of the power density parameter in the efficacy of antimicrobial photodynamic therapy (PDT) with toluidine blue O (TBO) and phycocyanin (PC) activated by a 635 nm diode laser (DL) against Enterococcus faecalis biofilm in the root canal model was investigated.

MATERIALS AND METHODS

The E. faecalis biofilm in the root canal was treated with TBO and PC with different power densities (636, 954, 1273, and 1592 W/cm2). The untreated biofilm represented the control group. After the treatments, the biofilms were analyzed based on the number of colonies per milliliter.

RESULTS

TBO and PC activated with 635 nm DL with a power density of 1592 W/cm2 were more efficient in removing E. faecalis biofilms within the root canals than those with a power density of 636 W/cm2 (p = 0.00).

CONCLUSION

The light power density optimized the bacterial reduction of E. faecalis biofilms in the root canal spaces. These results provide information on the decisive parameters for performing PDT on intracanal biofilms.

Evaluation of cytotoxicity impacts of combined methylene blue-mediated photodynamic therapy and intracanal antibiotic medicaments on dental stem cells

Root canal therapy is a predominant method for treatment of dental pulp and periapical diseases. Conventional methods such as mechanical instrumentations, chemical irrigation and intracanal medicaments pose a huge limitation to root canal disinfection as they kill bacteria and dental stem cells simultaneously. Therefore, much attention has been focused on finding more efficacious antibacterial methods that has no or negligible cytotoxicity for dental stem cells. Herein, we hypothesized that combining antibacterial medicaments with Antimicrobial photodynamic therapy (aPDT) and methylene blue (MB) as a photosensitizer would be effective in reducing death of dental pulp stem cells (DPSCs). To examine this, DPSCs were isolated from third molar teeth through enzymatic digestion. Isolated cells were cultured in αMEM and when reached adequate confluency, were used for further analysis. Cytotoxicity effect of different groups of MB, DAP, MB, LED and their combination on DPSCs was analyzed using MTT assay. DPSCs membrane integrity as a marker of live cells was assessed through measuring lipid peroxidation and lactate dehydrogenase (LDH) release into extracellular space. Results showed that the combination of LED, MB and TAP or aPDT, MB and DAP was more effective in reducing DPSCs death rate compared to TAP and DAP administration alone. Moreover, Malondialdehyde (MDA) and LDH levels were found to be decreased in cells exposed to combination treatment in comparison with single TAP or DAP therapy. Our study shows the promising perspectives of employing combined aPDT, MB and antibiotic medicaments for reduction of dental stem cell death.

Does aPDT reduce bacterial load in endodontic infected teeth? A systematic review and meta-analysis

This systematic review investigated whether antimicrobial photodynamic therapy (aPDT) after chemomechanical root canal disinfection (CD) yields a greater microbial load reduction than only CD. An electronic literature search was conducted on four databases up to November 2022, with no language or publication date restrictions. Randomized and non-randomized clinical trials were included if participants had a primary endodontic infection in permanent teeth, and if microbial loads before and after using aPDT were compared. Two researchers independently screened titles and abstracts to determine study eligibility. Assessments included risk of bias and methodological quality. This review was registered in PROSPERO (CRD42020181783). Eight studies were included in the qualitative analysis, and six were eligible for meta-analysis. In the random effects model, aPDT significantly improved the results of root canal disinfection when compared with standard protocols for cleaning and shaping (p = 0.04, 95% CI -1.72, -0.05). Subgroup analysis suggested that aPDT has a better effect on reducing the load of anaerobic microorganisms (p = 0.003, 95% CI -3.36, -0.69). The use of aPDT as an adjunct to chemomechanical disinfection promotes additional reduction of the microbial load and, therefore, seems to improve the results of root canal treatments in permanent teeth with a primary endodontic infection. However, certainty of evidence should be improved.

Effectiveness of photodynamic therapy adjunct to oral debridement in improving clinical, microbiological, and pain in necrotizing ulcerative gingivitis

To evaluate the efficacy of photodynamic therapy (PDT) as adjunctive to oral debridement (OD) in the improvement of clinical, microbiological, and pain in patients with necrotizing ulcerative gingivitis (NUG). Patients with NUG were split into two groups: Group-OD + PDT received PDT with OD, while Group-OD underwent OD alone. Clinical inflammatory parameters including full mouth plaque scores (FMPS), full mouth bleeding scores (FMBS), and probing depth (PD) were assessed. Fusobacterium nucleatum and Prevotella intermedia were analyzed using the polymerase chain reaction technique. Pain examination was done using various pain scales. Group PDT + OD showed more reduction in FMPS, FMBS, and greater reduction in F. nucleatum and P. intermedia count compared to group OD at 12 weeks follow up (p < 0.01). Group PDT + OD showed significantly lower pain scores at 12 weeks (p < 0.05). PDT was more effective in improving clinical parameters, and reducing bacterial counts and pain in NUG patients than dental scaling alone.

Bioburden assessment of necrotic teeth disinfected with sodium hypochlorite, diode laser, and photodynamic therapy using flow cytometry-a randomized double-blinded clinical trial

This study aimed to comparatively evaluate the disinfecting potential of sodium hypochlorite, diode laser, and photodynamic therapy in non-vital teeth with or without periapical rarefaction. Forty-five patients with the diagnosis of pulp necrosis with apical rarefaction were randomly assigned to three groups (n = 15) based on the disinfection protocol. Access cavities were prepared and pre-instrumentation microbial samples were taken using a paper point. Working length determination followed by cleaning and shaping with rotary files was performed. The canals were lubricated with ethylenediaminetetraacetic acid (EDTA) during instrumentation and finally rinsed with copious amounts of saline. Canals in group 1 were irrigated with 5 mL of 5.25% NaOCl, those in group 2 received irradiation with 808-nm diode laser (30 s, 7W), and those in group 3 were soaked with methylene blue photosensitizer (5 min) before irradiation with 660-nm diode laser (3 min). Post-disinfection microbial samples were collected using a paper point. Pre- and post-disinfection live bacterial counts were analyzed using a flow cytometer. The data were statistically analyzed using one-way ANOVA and Student's t-test. Comparison of pre-instrumentation mean live bacterial count showed no significant difference between the groups (p > 0.05). The mean live bacterial count post-disinfection was 41.07%, 46.99%, and 34.45% in groups 1-3 respectively. A significant reduction in the bacterial count was seen following disinfection in all the groups (p < 0.05). It can be concluded that both diode laser and photodynamic therapy were equally effective as 5.25% NaOCl in reducing the bioburden in root canals. TRIAL REGISTRATION: CTRI/2018/03/012667.

Application of Photodynamic Therapy in Pediatric Dentistry: Literature Review

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

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.

Photobiomodulation Therapy and Pulp-Regenerative Endodontics: A Narrative Review

Regenerative endodontic procedures (REPs) were used to recover the dental pulp’s vitality in order to avoid the undesirable outcomes of conventional endodontic treatment and to promote dentinal formation, especially for immature permanent teeth. Photobiomodulation therapy (PBMT) exhibits photobiological and photochemical effects for improving the root canal’s environmental conditions by compensating for oxidative stress and increasing the blood supply to implanted stem cells and improving their survival. Basic research has revealed that PBMT can modulate human dental pulp stem cells’ (hDPSCs) differentiation, proliferation, and activity, and subsequent tissue activation. However, many unclear points still remain regarding the mechanisms of action induced by PBMT in REPs. Therefore, in this review, we present the applications of laser and PBMT irradiation to the procedures of REPs and in endodontics. In addition, the effects of PBMT on the regenerative processes of hDPSCs are reviewed from biochemical and cytological perspectives on the basis of the available literature. Furthermore, we consider the feasibility of treatment in which PBMT irradiation is applied to stem cells, including dental pulp stem cells, and we discuss research that has reported on its effect.

The role of the light source in antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to fight the growing problem of antimicrobial resistance that threatens health care, food security and agriculture. APDT uses light to excite a light-activated chemical (photosensitiser), leading to the generation of reactive oxygen species (ROS). Many APDT studies confirm its efficacy in vitro and in vivo against bacteria, fungi, viruses and parasites. However, the development of the field is focused on exploring potential targets and developing new photosensitisers. The role of light, a crucial element for ROS production, has been neglected. What are the main parameters essential for effective photosensitiser activation? Does an optimal light radiant exposure exist? And finally, which light source is best? Many reports have described the promising antibacterial effects of APDT in vitro, however, its application in vivo, especially in clinical settings remains very limited. The restricted availability may partially be due to a lack of standard conditions or protocols, arising from the diversity of selected photosensitising agents (PS), variable testing conditions including light sources used for PS activation and methods of measuring anti-bacterial activity and their effectiveness in treating bacterial infections. We thus sought to systematically review and examine the evidence from existing studies on APDT associated with the light source used. We show how the reduction of pathogens depends on the light source applied, radiant exposure and irradiance of light used, and type of pathogen, and so critically appraise the current state of development of APDT and areas to be addressed in future studies. We anticipate that further standardisation of the experimental conditions will help the field advance, and suggest key optical and biological parameters that should be reported in all APDT studies. More in vivo and clinical studies are needed and are expected to be facilitated by advances in light sources, leading to APDT becoming a sustainable, alternative therapeutic option for bacterial and other microbial infections in the future.

Synchronized Microbubble Photodynamic Activation to Disinfect Minimally Prepared Root Canals

INTRODUCTION

The purpose of this study was to evaluate the antimicrobial efficacy of a novel irrigation strategy using synchronized microbubble photodynamic activation (SYMPA) in a minimally prepared single canal.

METHODS

Single-canal mandibular incisors were inoculated with Enterococcus faecalis for 3 weeks and randomly allocated to 4 groups based on the irrigation protocols: (1) control (saline), (2) conventional needle irrigation (CI), (3) ultrasonic-assisted irrigation (UI), and (4) irrigation with SYMPA. The first 3 groups were instrumented to size 25.07v (WaveOne Gold Primary; Dentsply Sirona, Johnson City, TN), and the SYMPA group was minimally prepared to size 20.07v (WaveOne Gold Small, Dentsply Sirona). The apical 5 mm was resected for microbiological assessment using the culture technique (colony-forming unit), adenosine-5'-triphosphate-based viability assay (relative luminescence units), and the percentage of live bacteria using confocal laser scanning microscopy.

RESULTS

Log colony-forming units from the UI (2.37 ± 0.66) and SYMPA (2.21 ± 0.86) groups showed a reduction compared with the control (5.16 ± 0.75) and CI (4.08 ± 1.19) groups. Relative luminescence unit reduction was significant for UI (619.08 ± 352.78) and SYMPA (415.25 ± 329.51) compared with the control (1213.2 ± 880.03) (P < .05). The percentage of live bacteria was significantly lower in the UI and SYMPA groups compared with the control and CI groups. Although higher microbial reduction was observed in SYMPA compared with UI, there was no statistical significance (P > .05).

CONCLUSION

SYMPA in minimally prepared canals showed significant antimicrobial efficacy. The novel irrigation strategy using SYMPA could be an effective disinfection strategy for minimally prepared root canals.

Polymicrobial Infections and Biofilms: Clinical Significance and Eradication Strategies

Biofilms are population of cells growing in a coordinated manner and exhibiting resistance towards hostile environments. The infections associated with biofilms are difficult to control owing to the chronicity of infections and the emergence of antibiotic resistance. Most microbial infections are contributed by polymicrobial or mixed species interactions, such as those observed in chronic wound infections, otitis media, dental caries, and cystic fibrosis. This review focuses on the polymicrobial interactions among bacterial-bacterial, bacterial-fungal, and fungal-fungal aggregations based on in vitro and in vivo models and different therapeutic interventions available for polymicrobial biofilms. Deciphering the mechanisms of polymicrobial interactions and microbial diversity in chronic infections is very helpful in anti-microbial research. Together, we have discussed the role of metagenomic approaches in studying polymicrobial biofilms. The outstanding progress made in polymicrobial research, especially the model systems and application of metagenomics for detecting, preventing, and controlling infections, are reviewed.

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

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

Application of Reactive Oxygen Species in Dental Treatment

Reactive oxygen species (ROS) and free radicals, which have been implicated in inflammation, pain, carcinogenesis, and aging, are actually used in dental treatments such as tooth bleaching and composite resin polymerization. Recently, numerous studies have investigated the application of ROS in the medical and dental fields. In previous studies, ROS were generated intentionally through pathways such as photolysis, photocatalytic methods, and photodynamic therapy, which are used in the medical field to target cancer. In the field of dentistry, generated ROS are applied mainly for periodontal treatment and sterilization of the root canal, and its effectiveness as an antibacterial photodynamic therapy has been widely reported.. Given this background, the present article aimed to review the basic effects of ROS in dental medicine, especially endodontic therapy, and to discuss future applications of ROS.

Evaluation of photosensitizer-containing superhydrophobic surfaces for the antibacterial treatment of periodontal biofilms

Antimicrobial photodynamic therapy (aPDT) is a promising approach to control biofilms involved in periodontal diseases. However, certain challenges, such as staining of teeth, preferential interaction of photosensitizer (PS) with Gram-positive versus Gram-negative bacteria, and insufficient oxygen in hypoxic periodontal pockets have presented barriers to its use in the clinic. To overcome these challenges, a novel superhydrophobic (SH) film that generates airborne singlet oxygen has been developed. The SH-aPDT approach isolates the PS onto a topologically rough solid SH film on which channels allow air to diffuse to the PS surface, thus ensuring sufficient oxygen supply. Upon illumination, gas phase singlet oxygen (¹O₂) is produced and diffuses from the SH surface to the underlying biofilm. The killing efficacy was assessed as a function of transmitted fluence (17.9-89.5 J/cm²) and chorin e6 loading (96-1110 nmol/cm²) by counting of colony forming units, biofilm metabolism by XTT and confocal microscopy. The decrease in viability of both Gram-positive and Gram-negative bacteria in a multi-species biofilm was found to be linearly dependent on the fluence as well as the loading of the PS up to 71.6 J/cm² when 1110 nmols/cm² of chlorin e6 was used. A > 4.6 log bacterial reduction was observed under these conditions (p < 0.05). This novel SH-aPDT approach shows promise as an effective method to disinfect multi-species bacterial biofilms associated with periodontal disease and will be evaluated in animal models in future studies.

Photodynamic therapy for root canal disinfection in endodontics: an umbrella review

To evaluate and synthesize the evidence from the individual reviews that evaluated the efficacy of PDT therapy in root canal disinfection by undertaking an umbrella review. The protocol of the review was registered in the PROSPERO database under number CRD42021214056. The literature search was conducted using the following electronic databases: PubMed, Scopus, Web of Science, BVS, Cochrane Database of Systematic Reviews, Embase, and Epistemonikos, from inception to July 2021. Systematic reviews that evaluated the efficacy of PDT for root canal disinfection were included. Two authors independently performed a literature search, data extraction, and quality assessment of the included studies. Any disagreements were resolved by a third reviewer. The quality of the reviews was assessed using the AMSTAR 2 tool and the final categorization of each systematic reviews was classified as of "high," "moderate," "low," or "critically low" quality. Six systematic reviews were included in the current umbrella review and all of them were graded as critically low quality. From the critically low-quality evidence available, this umbrella review showed that the efficacy of PDT in root canal disinfection remains yet undetermined.

A critical analysis of research methods and experimental models to study intracanal medicaments

In order to ensure predictable decontamination of the root canal system, chemo-mechanical preparation of the root canal space is sometimes supplemented with the use of intracanal medication. As microbial control of the root canal space is fundamental to the resolution of apical periodontitis, root canal disinfection strategies haven been researched intensively. The use of intracanal medication as a supplementary step to the chemo-mechanical preparation of the root canal space is one of them. Because of the costs and limitations of clinical research it is relevant and common practice to first evaluate alternative or new root canal disinfection modalities in laboratory studies. This involves the simulation of a root canal infection in a laboratory model, on which different disinfection strategies can be tested. When modelling the infected root canal, different levels of infection can be discriminated: suspended bacteria, microbial biofilms and infected dentine. This review describes the experimental models associated with these infection levels and critically appraises their value and methodological details. Suggestions for relevant research methods and experimental models are given, as well as some good practices for laboratory-based microbiological studies.

Microbiological Aspects of Root Canal Infections and Disinfection Strategies: An Update Review on the Current Knowledge and Challenges

The oral cavity is the habitat of several hundreds of microbial taxa that have evolved to coexist in multispecies communities in this unique ecosystem. By contrast, the internal tissue of the tooth, i.e., the dental pulp, is a physiologically sterile connective tissue in which any microbial invasion is a pathological sign. It results in inflammation of the pulp tissue and eventually to pulp death and spread of inflammation/infection to the periradicular tissues. Over the past few decades, substantial emphasis has been placed on understanding the pathobiology of root canal infections, including the microbial composition, biofilm biology and host responses to infections. To develop clinically effective treatment regimens as well as preventive therapies, such extensive understanding is necessary. Rather surprisingly, despite the definitive realization that root canal infections are biofilm mediated, clinical strategies have been focused more on preparing canals to radiographically impeccable levels, while much is left desired on the debridement of these complex root canal systems. Hence, solely focusing on "canal shaping" largely misses the point of endodontic treatment as the current understanding of the microbial aetiopathogenesis of apical periodontitis calls for the emphasis to be placed on "canal cleaning" and chemo-mechanical disinfection. In this review, we dissect in great detail, the current knowledge on the root canal microbiome, both in terms of its composition and functional characteristics. We also describe the challenges in root canal disinfection and the novel strategies that attempt to address this challenge. Finally, we provide some critical pointers for areas of future research, which will serve as an important area for consideration in Frontiers in Oral Health.

Antimicrobial and cytotoxic activity of electrosprayed chitosan nanoparticles against endodontic pathogens and Balb/c 3T3 fibroblast cells

The aims of this study were to synthesize highly positively charged chitosan nanoparticles (Ch-Np) using the electrospraying technique, and to test their antimicrobial activity against endodontic pathogens, and cytotoxicity against fibroblast cells. Ch-Np were synthesized from low molecular weight chitosan (LMW-Ch) using the electrospraying technique, and characterized. The antimicrobial activity was evaluated against Streptococcus mutans, Enterococcus faecalis, and Candida albicans in their planktonic state using a Time-Kill Test performed by using broth micro-dilution technique, and against biofilm biomass using a microtiter plate biofilm assay. The cytotoxicity was evaluated using Balb/c 3T3 fibroblast cells with the standard MTT assay. Electrospraying of LMW-Ch produced Ch-Np with an average size of 200 nm, and a surface charge of 51.7 mV. Ch-Np completely eradicated S. mutans and E. faecalis in the planktonic state and showed fungistatic activity against C. albicans. Furthermore, it significantly reduced the biofilm biomass for all the tested microbial species [S. mutans (p = 0.006), E. faecalis (p < 0.0001), and C. albicans (p = 0.004)]. When tested for cytotoxicity using 3T3 cells, Ch-Np showed no cytotoxicity. In conclusion, the highly positively charged, colloidal dispersion of Ch-Np are effective as a biocompatible endodontic antimicrobial agent.

Efficacy of antimicrobial photodynamic therapy and Er,Cr:YSGG laser-activated irrigation on dentinal tubule penetration of MTA-based root canal sealer: a confocal microscopy study

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) and laser-activated irrigation (LAI) are adjunctive therapies developed to enhance the effectiveness of root canal disinfection. Sealer penetration into dentinal tubules is significant for preventing re-infection, and the sealer's penetration ability is affected by the chemo-mechanical preparation of the root canal. This study aimed to evaluate the efficacy of aPDT and LAI on dentinal tubule penetration of MTA-based root canal sealer.

METHODS

Forty single-rooted mandibular premolars were divided into four groups (n = 10): control, methylene blue 50 mg/L (MB50), curcumin 500 mg/L (C500), and Er,Cr:YSGG and sodium hypochlorite (LAI). The smear removal efficiency of the groups on intraradicular dentin was evaluated with a scanning electron microscope (SEM). Confocal laser scanning microscopy (CLSM) was performed to determine the depth of penetration of MTA Fillapex into dentinal tubules. Data were analyzed statistically.

RESULTS

The maximum penetration depth of the C500 group was significantly higher than that of the other groups in all three levels of root sections (p<0.05). Regarding mean penetration depth, the highest values were obtained from the C500 group. However, there was no statistically significant difference between the C500 and MB50 groups in the middle and coronal thirds of the root (p>0.05). The LAI group showed the lowest penetrated area percentage in the middle and coronal third of the root (p<0.05). The C500 and LAI groups were more effective in removing the smear layer than the control and MB50 groups.

CONCLUSION

aPDT could enhance the penetration of MTA-based root canal sealer into dentin tubules.

The Effect of Photodynamic Therapy on the Smear Layer Removal: a Scanning Electron Microscopic Study

Statement of the Problem

The efficacy of photodynamic therapy (PDT) in smear layer removal compared to the currently accepted protocol is not well established.

Purpose

This study aims to evaluate the effect of PDT on smear layer removal from human root canal compared to combined use of irrigation solutions including sodium hypochlorite (NaOCl) and ethylene diamine tetra acetic acid (EDTA) by scanning electron microscopy (SEM).

Materials and Method

In this in vitro study, straight roots from 48 extracted human maxillary incisors and canines were selected and decoronated. Instrumentation was completed with RaCe rotary system and normal saline irrigation between files. Then roots were randomly divided into 3 groups (n=16). Group 1 was the control group to confirm smear layer formation. In the group 2, the canals were irrigated with 2ml of 2.5% NaOCl solution for 10 minutes and 2ml of 17% EDTA solution for 1 minute. In the group 3, PDT with methylene blue and diode laser (625nm, 150mW, for 5minutes) was the final procedure for smear layer removal. All the specimens were sectioned into two halves, gold coated, and analyzed under SEM. The smear layer in the coronal, middle, and apical thirds, were evaluated and scored by two examiners independently. Statistical analysis was done using Chi-square test.

Results

It was observed that the NaOCl+EDTA removed the smear layer significantly better than PDT in the coronal and apical thirds (p< 0.05) whereas PDT was unable to remove the smear layer in none of the root areas. At the apical thirds, there was no significant difference between NaOCl+EDTA and PDT (p< 0.05). Both procedures were unable to remove smear layer from radicular dentine of this area.

Conclusion

According to the results of this in vitro study, the use of PDT alone is not recommended to remove smear layer. The combined application of NaOCl and EDTA is ineffective in removing smear layer of apical third, despite its efficacy on the coronal and middle regions.

Radiographic and antimicrobial evaluation of enterococcus Faecalis and Actinomyces Israelii micro-organisms after photodynamic therapy (aPDT)

This study evaluated the action of Antimicrobial Photodynamic Therapy (aPDT) on Enterococcus faecalis and Actinomyces israelii. Samples were taken from the root canal system, at different stages of treatment and bacteria were identified through qPCR. Fifty teeth (incisors, canines, and premolars) with pulp necrosis and periapical lesion diagnosis were randomly selected and divided into 2 groups: Group 1 (G1) - Endodontic Therapy with Mechanical Chemical Preparation (MPQ) and intracanal medication; Group 2 (G2) - Endodontic therapy with MPQ, intracanal medication, and 2 applications of aPDT. APDT was performed with application of 0.005% methylene blue, wavelength of 660 nm, and 90 seconds. Follow-up was performed with an initial x-ray and an x-ray 60 days after the end of treatment. The radiographs were scored evaluated by two examiners to classify periapical repair: total repair, partial repair, doubtful repair, or no repair. Enterococcus faecalis was found more frequently in G1 than G2. Actinomyces israelii was found equally in G1 and G2. Evaluation of the two bacteria between collections 1, 2 and 3, showed that there was no difference, both in G1 and in G2. There was association between the variables group and repair classification in radiographs evaluation. APDT did not promote better results in endodontic treatment, being similar to conventional treatment. However, this study pointed out that molecular methods may not be efficient in detecting bacteria after treatment, and colony-forming units may complement, being an effective quantifying method. Therefore, new studies must be carried out to show the possible effectiveness of aPDT.

Effect of photobiomodulation on post-operative symptoms in teeth with asymptomatic apical periodontitis treated with foraminal enlargement: A randomized clinical trial

AIM

To assess the efficacy of photobiomodulation in reducing post-operative symptoms and use of analgesics in teeth with asymptomatic apical periodontitis treated with foraminal enlargement in a single visit.

METHODOLOGY

This prospective double-blind, controlled, superiority, randomized clinical trial enrolled 70 patients requiring root canal treatment of one single-rooted tooth with asymptomatic apical periodontitis. The participants were randomized into one of the following two groups: 35 patients in the control group (C.G) - root canal treatment with foraminal enlargement, without any additional treatment and 35 patients in the photobiomodulation group (PBM.G) - root canal treatment with foraminal enlargement associated with photobiomodulation (antimicrobial photodynamic therapy and low-level laser therapy). The outcome variables were post-operative pain, tenderness, oedema and the use of analgesics. Pain intensity was measured using a visual analogue scale (recorded every day for 7 days, then the 14th and 30th days after root canal treatment). Facial oedema was assessed subjectively by two independent evaluators using photographs taken by one of the researchers at 48 h, 72 h and 7 days after the procedures. Data were tabulated and analysed using the Mann-Whitney U, Chi-Square, Fisher`s Exact, Student T and Ordinal Logistic Regression by Generalized Estimating Equations tests in SPSS software.

RESULTS

There were no significant differences in post-operative pain and tenderness between the groups at any observation period (p > .05). Photobiomodulation (beta = -0.77 / p = .01), time (beta = -0.23 / p < .01), and male gender (beta = -1.20 / p < .01) were associated with decreased post-operative pain. Only time (beta: -0.10; p < .01) and male gender (beta: -1.04; p < .01) were associated with decreased tenderness. For oedema and use of analgesics, there was no difference between the groups (p > .05).

CONCLUSIONS

Photobiomodulation had no significant effect on post-operative pain, tenderness, oedema and the use of analgesics after root canal treatment with foraminal enlargement, in single-rooted teeth treated in a single visit. Register of Clinical Trials: NCT03704857. Research Ethics Committee: no 2.353.996 / CAAE 74185417.9.0000.5626.

Fluorescence characteristics of E. faecalis in dentine following treatment with oxidizing endodontic irrigants

INTRODUCTION

This study aimed to assess changes in the fluorescence characteristics of Enterococcus faecalis in human dentine over a period of 24 h following treatment with endodontic irrigants.

METHOD

Sterilised, non-functional extracted third molars were embedded in acrylic resin and uniformly sectioned into 2 mm thick dentine sections. After the removal of smear layer, the dentine sections were inoculated with E. faecalis and cultured for 7 days. The infected dentine sections were subsequently treated with different concentrations of sodium hypochlorite (NaOCl) and hydrogen peroxide (H₂O₂). Bacterial fluorescence readings were assessed at different time points using a calibrated laser device. All data were assessed for normality (Kolmogorov Smirnoff test) and analysed using ANOVA with Bonferroni post-hoc tests.

RESULTS

Fluorescence readings were quenched when E. faecalis infected human dentine sections were treated with oxidizing irrigants in vitro. Throughout a 24-hour period, fluorescence recovered in part but did not return to baseline level.

CONCLUSION

The fluorescence quenching effect of these oxidizing agents needs to be considered when using laser fluorescence in assessing the quality of root canal debridement or disinfection.

Bactericidal effect of Er,Cr:YSGG laser irradiation on endodontic biofilm: An ex vivo study

AIM

This ex vivo study aimed to evaluate the of Er,Cr:YSGG laser effectiveness in the decontamination of an endodontic biofilm.

MATERIALS AND METHODS

Seventy-three single rooted human teeth, freshly were chosen. Each tooth was exposed to four associated species in an endodontic biofilm (Enterococcus faecalis, Streptococcus salivarius, Porphyromonas gingivalis, and Prevotella intermedia) and randomly allocated to one of the seven experimental groups. The group 1 (7 teeth) was used to finalize the reliable biofilm-forming technique. The groups 2 and 3 (15 teeth each group) were irradiated with two different Er;Cr:YSGG laser settings (0,75 W - 40 Hz and 4 W - 40 Hz, respectively). The groups 4 and 5 (15 teeth each group) were irrigated with two different solutions and laser irradiated with the same settings (1,5 W - 15 Hz). The group 6 (6 teeth) was the control group treated only with 4 ml 2,5% NaOCl irrigation during 60 s.

RESULTS

The observations of group 2 and 3 specimens showed the ripeness of the biofilm with the presence of Enterococcus faecalis and Streptococcus salivarius in chains but in group 3 thermal edge effects produced by the optic fiber in the canal walls were present. The group 4 specimens observation showed an average cleaning of the root canal walls while on the canal walls of group 5 samples the apical third presented several debris and smear layer and in the centre cracks and melting dentin of the radicular wall were observed.

CONCLUSION

In those experimental conditions, this study, demonstrated that Er,Cr:YSGG laser has a canals decontamination ability when associated to NaOCl irrigation.

Retrospective clinical evaluation of root canal treatment with or without photodynamic therapy for necrotic teeth and teeth subjected to retreatment

PURPOSE

To compare the effect of photodynamic therapy (PDT) as a procedure to complement root canal treatment (RCT), for both primary treatment and retreatment.

METHODS

This was a retrospective study based on analysis of clinical records. A total of 214 teeth that had undergone RCT on either a primary or retreatment basis, with or without complementary PDT, were evaluated. For 118 teeth that met the previously established inclusion criteria, the time until healing was evaluated. Complementarily, the need for application of calcium hydroxide (CaHy) between visits and the number of visits necessary for completing the treatment were assessed. Data were analyzed using the Mann-Whitney and χ² tests with a significance level of P < 0.05.

RESULTS

Periapical radiolucency resolution was achieved at 15 ± 9.33 months in the RCT + PDT group and 20.35 ± 22.1 months in the RCT group (P = 0.07). For primary treatment, CaHy was necessary in 72.4% of the RCT cases and 16.4% of the RCT + PDT cases (P < 0.01). For retreatment cases, CaHy was used in 82.7% of the RCT cases and 17% of the RCT + PDT cases (P < 0.01). In the RCT group, more than two visits were necessary for primary treatment in 18.6% of the cases, compared with 13.10% in the RCT + PDT group (P = 0.31), whereas for retreatment, more than two visits were necessary for 64.9% and 49.1% of cases, respectively (P = 0.05).

CONCLUSION

In comparison with RCT alone, teeth receiving RCT + PDT showed less variation in the time needed for periapical lesion healing, fewer cases required CaHy, and fewer cases required more than two visits to complete the treatment.

Photodynamic therapy associated final irrigation in root canals of the primary teeth

The aim of this study was to analyze, in vitro, the reduction of Enterococcus faecalis in root canals of primary teeth after final irrigation and photodynamic therapy (PDT) use. Twenty primary molars were contaminated with Enterococcus faecalis. The teeth were randomly distributed into four groups according to the irrigation solutions and PDT use: G1 (Saline solution and no PDT use), G2 (17 % EDTA and no PDT use), G3 (Saline solution and PDT use) and G4 (17 % EDTA and PDT use). For PDT, 0.005 % toluidine blue was chosen as the photosensitizer, which was inserted in the canals with sterile paper cones. Bacterial counts were performed with a BHI test in blood agar plate, where bacteria were collected inside the canal for 30 s using sterile paper cones. The collection took place before and after the irrigation and PDT protocols. The samples were diluted, spread onto a blood agar plate and then incubated at 37 °C for 24 h. There was a reduction of the microbiota from the irrigation solutions before and after the final irrigation for all groups. It was observed a statistically significant reduction (p < 0,05) when PDT was used (97.6 % at the saline solution and 89.8 % at the 17 % EDTA) when compared to the groups with no PDT use. Our data demonstrated that PDT, according to the parameters used, increased the disinfection performance of the solutions tested in the root canals of primary teeth.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Improving the Efficiency of Photodynamic Chemotherapy in Root Canals against Enterococcus faecalis In Vitro

The aim of this study was to evaluate the effect of photoactivated chemotherapy (PACT) on Enterococcus faecalis (E. faecalis) biofilms in root canals using an 90% isopropanol (IPA)-based photosensitizer and removing excess photosensitizer before light incubation. Three hundred and seven extracted human teeth with one root canal were infected with E. faecalis for 72 h and treated in groups: IPA irrigation; PACT; PACT and final rinse with IPA; PACT with photosensitizer removal using either 0.9% NaCl solution or sterile paper points or both; PACT using IPA-based photosensitizer with and without a final rinse of IPA. Root canals were sampled using sterile paper points and dentin chips collected from the root canal walls. Additionally, SEM (Scanning Electron Microscopy) images of the specimens were taken to evaluate the root canal walls for residue bacterial contamination. In all antimicrobial treatment groups treatments E. faecalis counts were significantly reduced in the root canals. Using IPA-based photosensitizer the antimicrobial effect of PACT was significantly enhanced. Irrigation with IPA alone or after PACT significantly increased the antimicrobial effect compared to PACT alone. The collected dentin chips revealed the highest amount of culture negative root canals (10%) after PACT using IPA-based photosensitizer. In the other groups, the culture negative samples ranged from only 0–2 specimens of 30 specimens. REM images show remaining E. faecalis cells on the root canal wall and inside dentin tubules. Using IPA-based photosensitizer significantly enhanced the antimicrobial effect of PACT against E. faecalis in the root canals.

Comparison of Antibacterial Effects of Photodynamic Therapy and an Irrigation Activation System on Root Canals Infected With Enterococcus faecalis: An In Vitro Study

Introduction: Enterococcus faecalis is a resistant bacterium which is the most abundant species in infected root canals. Photodynamic therapy (PDT) is a method for killing the bacteria with active Oxygen radicals generated in a photosensitizer when exposed to centralized light. Furthermore, as a new method of canal disinfection, a variety of irrigation activation systems have been introduced, one of which is GentleFile (GF) with rotary movements and spiral effects for antibacterial action. This study aimed to compare the effectiveness of the two mentioned methods when used with and without Sodium Hypochlorite in eliminating E. faecalis from infected root canals. Methods: Fifty-eight uniradicular teeth were randomly divided into 4 experimental groups of 14. Two specimens were selected for later scanning electron microscopy in order to screen the procedure steps. In each experimental group, 10 samples were selected to be treated with GF or PDT; 3 of them were selected as positive controls and the other one sample was chosen as a negative control. Experimental groups were as follows: (1) Irrigation activation system, (2) Irrigation activation system + sodium hypochlorite, (3) PDT, and (4) PDT+ sodium hypochlorite. The specimens were then cultured for a bacterial colony count. Results: The decrease in the bacterial count after the treatment with the irrigation activation system was 99.8% (P =0.011) and when the system was used with sodium hypochlorite, it was 100% (P =0.001). The antibacterial effect of PDT was 90.08% (P =0.011) and it was 99.7% when PDT was combined with sodium hypochlorite (P =0.011). Conclusion: All four methods can be administered as complementary methods in root canal disinfection. According to the results of disinfection in the experimental groups of current study it is concluded that integration of new technologies such as activation irrigation system or PDT in Combination with NaOCl ameliorates disinfection of root canal and can provide several advantages in the endodontic outcome.

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

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

Utility of Photodynamic Therapy in Dentistry: Current Concepts

The significant growth in scientific and technological advancements within the field of dentistry has resulted in a wide range of novel treatment modalities for dentists to use. Photodynamic therapy (PDT) is an emerging, non-invasive treatment method, involving photosensitizers, light of a specific wavelength and the generation of singlet oxygen and reactive oxygen species (ROS) to eliminate unwanted eukaryotic cells (e.g., malignancies in the oral cavity) or pathogenic microorganisms. The aim of this review article is to summarize the history, general concepts, advantages and disadvantages of PDT and to provide examples for current indications of PDT in various subspecialties of dentistry (oral and maxillofacial surgery, oral medicine, endodontics, preventive dentistry, periodontology and implantology), in addition to presenting some images from our own experiences about the clinical success with PDT.

Photodynamic therapy for endodontic treatment of primary teeth: A randomized controlled clinical trial

OBJECTIVES

This study aimed to evaluate the reduction in bacterial load following conventional endodontic treatment with and without antimicrobial photodynamic therapy (a-PDT) in primary teeth.

METHODS

Thirty primary anterior teeth with a diagnosis of pulp necrosis were selected. Patients were randomly allocated to two groups as follows: Group I, patients undergoing conventional root canal therapy (n = 15) and Group II, patients undergoing conventional root canal therapy combined with antimicrobial PDT (n = 15). For PDT, methylene blue, at a concentration of 0.005 %, was used as the photosensitizing agent, which was applied to the interior of the canal with a sterile paper cone for 3 min, followed by the administration of laser light for 40 s (wavelength: 660 nm, energy density: 4 J/cm², power: 100 mW), delivered in direct contact at the entrance to the root canal. Two microbiological samples of the intra-canal content were taken (one before and one immediately after treatment in both groups) using paper cones. Clinical follow-up involved the investigation of fistulas and mobility and was performed 1- and 3 months after treatment. Data were statistically analyzed.

RESULTS

The reduction in bacterial load was 93 % in Group I and 99 % in Group II, with no statistically significant difference.

CONCLUSIONS

Conventional treatment combined with antimicrobial PDT with parameters used in this study proved effective but presented equal efficacious capability to conventional endodontic treatment alone.

CLINICAL SIGNIFICANCE

The use of PDT has been studied in endodontic treatment protocols in permanent teeth. However, clinical trials in deciduous teeth are necessary for establishing the effectiveness and parameters of this application. The present study analyzes the results of PDT in the endodontic treatment of deciduous teeth.

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

BACKGROUND AND OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Comparison study of root canal disinfection by cold plasma jet and photodynamic therapy

INTRODUCTION

This study evaluated and compared the antibacterial effect of plasma and photodynamic therapy (PDT) in root canals infected with Enterococcus faecalis.

METHODS

One hundred single-rooted extracted human teeth (no treatment) were selected and sterilized. Root canals of teeth were prepared with the crown-down technique and contaminated with Enterococcus faecalis after sterilization, and incubated for one week. To investigate the effect of disinfection, 60 specimens were randomly selected for three disinfection groups: He and He/O₂ plasma (n = 20) in 5-s groups (control, 2, 4, 6 and 8 min treatments) and PDT (n = 20) in 2-s groups (control and PDT treatment). Next, for comparison, 40 remaining teeth were divided into four groups: control, 8 min He plasma, 8 min He/O_2, and PDT. Results of antibacterial action were reported by CFU/mL analysis and the structural changes of biofilm were evaluated by SEM.

RESULTS

All groups showed a significant reduction of bacteria after treatment, and He/O₂ plasma was more effective against E. faecalis, followed by PDT and He plasma respectively, further confirmed by SEM.

CONCLUSION

He/O₂ plasma is a strong sterilization method against E. faecalis biofilm and can, therefore, be an effective therapy in endodontics.

In vivo evaluation of painful symptomatology after endodontic treatment with or without the use of photodynamic therapy

Context:

Postoperative pain control after endodontic treatment is important to maintain patient comfort.

Aim:

The aim of this prospective clinical study was to evaluate the postoperative symptomatology of endodontic treatments performed in a single session, with or without photodynamic therapy (PDT), using Reciproc #40 file in necrotic unirradicular anterior teeth.

Materials and Methods:

In a prospective clinical study, 40 teeth indicated for endodontic treatment were treated by a single endodontist according to a preestablished protocol. The teeth were randomly divided into two groups (n = 20): control group (CG) and laser group (LG). After 24 h, 72 h, and 1 week of endodontic treatment, patients' pain symptomatology was evaluated through a Visual Analog Scale (VAS) ranging from 0 to 10, in which 0 corresponds to no pain and 10 indicates extreme pain. In both workgroups, similar protocols were used for instrumentation with the Reciproc system (R40), irrigation with 2.5% sodium hypochlorite, and filling by the gutta-percha plastification technique, in which the CG did not use PDT, and the LG used PDT after the instrumentation sequence. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 h if they experienced pain.

Results:

The results of the study, analyzing the VAS, did not show any difference in pain symptoms between the groups at 24 h, 72 h, and 1 week (P > 0.05).

Conclusions:

It was concluded that there was no statistical difference between the groups.

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.

Effect of Chloroaluminium phthalocyanine in cationic nanoemulsion on photoinactivation of multispecies biofilm

BACKGROUND

Photosensitizers in nanocarriers have been investigated for antimicrobial Photodynamic Therapy (aPDT). However, most studies are focused against microorganisms in planktonic or monospecies biofilm. Thus, this in vitro study evaluated the effect of aPDT using Chloroaluminium phthalocyanine (ClAlPc) in cationic nanoemulsion (NE) against Candida albicans, Candida glabrata and Streptococcus mutans grown as multispecies biofilm.

METHODS

Standard suspensions of each microorganism were added into wells of a microtiter plate for biofilm growth for 48 h in a candle jar. The biofilms were incubated with ClAlPc in cationic NE at 31.8 μM for 30 min and illuminated with red light fluence of 39.3 J/cm² (P+L+ group). Additional samples were treated only with photosensitizer (P+L-) or red light (P-L+) or neither (P-L-, control group). aPDT efficacy was assessed by colony quantification, biofilm's metabolic activity, total biomass, and confocal microscopy. Data were analyzed by ANOVA/Welch and post-hoc Tukey/Games-Howell tests (α = 0.05).

RESULTS

aPDT (P+L+) reduced the colony count in 1.30 to 2.24 lg₁₀ and the metabolic activity in 53.7% compared with the control group (P-L-). The total biomass showed no statistical difference among the groups. The confocal microscopy analyzes showed uptake of the PS in the biofilm, and dead cells were observed in the biofilm treated with aPDT.

CONCLUSION

aPDT mediated by ClAlPc in cationic NE promoted photoinactivation of the multispecies biofilm, which was confirmed by colony quantification, metabolic activity, and confocal microscopy. However, the total biomass of the biofilm was not affected by the treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Light Activated Disinfection in Root Canal Treatment-A Focused Review

Light activated disinfection (LAD) is a strategy for optimizing root canal disinfection by using a highly-selective, targeted killing of bacteria using a combination of photosensitizers and light. Over the past decade, numerous in vitro and clinical studies have been performed to demonstrate the effectiveness of this mode of root canal disinfection. While most studies offer an important understanding of the effectiveness of LAD on monospecies biofilms, few have offered credence to the fact that infections of the root canal system are mediated by polymicrobial biofilms. Hence, it is imperative to understand the effect of LAD on polymicrobial biofilms both in terms of microbial killing and the changes in the biofilm architecture. The aim of this review was to systematically review the literature to evaluate the effect of LAD on dual and multispecies biofilms and demonstrate the antibiofilm effect of LAD. Two databases (PubMed and Scopus) were searched to identify eligible studies using a combination of key words. These studies were reviewed to draw conclusions on the effect of LAD on dual and multi species biofilm and the antibiofilm effect of LAD. It was found that LAD alone may be unable to eradicate dual and multispecies biofilms, but it may enhance the effect of conventional canal debridement strategies. Novel formulations of photosensitizers with nanoparticles showed the potential to inhibit biofilm formation and/or disrupt the biofilm architecture.

A review and outlook in the treatment of osteosarcoma and other deep tumors with photodynamic therapy: from basic to deep

Photodynamic therapy, one of the most promising minimally invasive treatments, has received increasing focus in tumor therapy research, which has been widely applied in treating superficial tumors. Three basic factors - photosensitizer, the light source, and oxidative stress - are responsible for tumor cell cytotoxicity. However, due to insufficient luminous flux and peripheral tissue damage, the utilization of photodynamic therapy is facing a huge limitation in deep tumor therapy. Osteosarcoma is the typical deep tumor, which is the most commonly occurring malignancy in children and adolescents. Despite developments in surgery, high risks of the amputation still threatens the health of osteosarcoma patients. In this review, we summarize recent developments in the field of photodynamic therapy and specifically PDT research in OS treatment modalities. In addition, we also provide some novel suggestions, which could potentially be a breakthrough in PDT-induced OS therapies. PDT has the potential to become an effective therapy while the its limitations still present when applied on the treatment of OS or other types of deep tumors. Thus, more researches and studies in the field are required.

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.