Photodynamic therapy versus ultrasonic irrigation: interaction with endodontic microbial biofilm, an ex vivo study

Effects of self-etch adhesive agitation with diode laser on dentin bond strength

The present study assessed the effect of active application of self-etch adhesives with diode laser irradiation on the shear dentin bond strength. Sixty bovine incisors, each embedded individually in hard plaster blocks, were divided into two groups based on the adhesive system used: Group 1 Adper Easy One and Group 2 Clearfil SE Protect. Based on the application technique of self-etch adhesives, each main group was further divided into three subgroups: passive application, active application with a micro-brush, and active application with a 976-nm diode laser tip (phototherapy active application). Shear bond strength tests were conducted using a universal testing machine and the data were analyzed by two-way ANOVA. Post hoc multiple comparisons were performed with the Tukey HSD test. Additionally, the statistical analysis of failure mode distribution was carried out using the chi-squared test (p < 0.05). While the adhesive system exhibited significant differences in shear dentin bond strengths, there were no significant differences in application techniques. Regardless of the application technique, Clearfil SE Protect demonstrated significantly higher dentin bond strength than Adper Easy One. In the present study, the utilization of phototherapy through a 976-nm diode laser for the active application of the tested self-etch adhesives demonstrated similar initial dentin bond strengths to conventional application methods.

The effect of photodynamic therapy in controlling the oral biofilm: A comprehensive overview

Several resistance mechanisms are involved in dental caries, including oral biofilms. An accumulation of bacteria on the surface of teeth is called plaque. Periodontitis and gingivitis are caused by dental plaque. In this review article, we aimed to review the studies associated with the application of photodynamic therapy (PDT) to prevent and treat various microbial biofilm-caused oral diseases in recent decades. There are several studies published in PubMed that have described antimicrobial photodynamic therapy (APDT) effects on microorganisms. Several in vitro and in vivo studies have demonstrated the potential of APDT for treating endodontic, periodontal, and mucosal infections caused by bacteria as biofilms. Reactive oxygen species (ROS) are activated in the presence of oxygen by integrating a nontoxic photosensitizer (PS) with appropriate wavelength visible light. By causing irreversible damage to microorganisms, ROS induces some biological and photochemical events. Testing several wavelengths has been conducted to identify potential PS for APDT. A standard protocol is not yet available, and the current review summarizes findings from dental studies on APDT.

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.

Nanotechnology for Dentistry: Prospects and Applications

In the XXI century, application of nanostructures in oral medicine has become common. In oral medicine, using nanostructures for the treatment of dental caries constitutes a great challenge. There are extensive studies on the implementation of nanomaterials to dental composites in order to improve their properties, e.g., their adhesive strength. Moreover, nanostructures are helpful in dental implant applications as well as in maxillofacial surgery for accelerated healing, promoting osseointegration, and others. Dental personal care products are an important part of oral medicine where nanomaterials are increasingly used, e.g., toothpaste for hypersensitivity. Nowadays, nanoparticles such as macrocycles are used in different formulations for early cancer diagnosis in the oral area. Cancer of the oral cavity-human squamous carcinoma-is the sixth leading cause of death. Detection in the early stage offers the best chance at total cure. Along with diagnosis, macrocycles are used for photodynamic mechanism-based treatments, which possess many advantages, such as protecting healthy tissues and producing good cosmetic results. Application of nanostructures in medicine carries potential risks, like long-term influence of toxicity on body, which need to be studied further. The introduction and development of nanotechnologies and nanomaterials are no longer part of a hypothetical future, but an increasingly important element of today's medicine.

Can Type of Instrumentation and Activation of the Final Irrigant Improve the Obturation Quality in Oval Root Canals? A Push-Out Bond Strength Study

Simple Summary

The complete instrumentation of oval root canals remains practically unattainable. The majority of studies show that shaping oval, flat, and irregularly shaped canals is challenging, with more than half of the root canal area remaining unaltered. Furthermore, both rotary and reciprocating files compact hard tissue debris into the isthmus areas and buccal and/or lingual recesses of oval canals, impairing debridement and filling. In addition, one of the most essential variables in assessing the success of endodontic therapy is the adhesion of root canal filling material to dentin.

Abstract

To appraise the outcome of file systems and activation of the final irrigant on the push-out bond strength of root fillings in oval canals. Single-rooted mandibular premolars (n = 180) with oval canals were divided into three groups (n = 60) for instrumentation: ProTaper Next (PTN), WaveOne (WO), and Self-adjusting File (SAF). The specimens were further divided into subgroups (n = 20) and subjected to final irrigation with activation by EndoActivator or passive ultrasonic irrigation or without activation. Then, the specimens were again subdivided (n = 10) and obturated with gutta-percha and AH Plus (GP-AH) or C-Point with EndoSequence bioceramic sealer (C-EBC). One-millimeter-thick horizontal slices were cut from the apical third of the root, 5 mm from the apex, and subjected to push-out bond strength (BS) testing. Specimens for which SAF was used exhibited higher BS values than those for which PTN or WO was used (p < 0.05). Activation of the final irrigation did not affect the BS of the root fillings. Root fillings made of C-EBC presented a higher BS than those made of GP-AH (p < 0.05). Adhesive failure was more common with specimens instrumented using PTN and WO. Root canals instrumented with SAF, showed the highest bond strength values for both root filling materials. The C-EBC produced significantly higher bond strength values than those of the GP-AH.

Investigating the Antibacterial Effect of Passive Ultrasonic Irrigation, Photodynamic Therapy and Their Combination on Root Canal Disinfection

Introduction: Enterococcus faecalis is a gram-positive, facultative anaerobic bacterium associated with persistent endodontic infections. Conventional disinfection methods may not completely eradicate the bacteria within the root canal system. Therefore, novel modalities have been suggested to optimize root canal disinfection. The aim of this study was to evaluate and compare the antibacterial effect of photodynamic therapy (PDT), passive ultrasonic irrigation (PUI) and their combination in addition to conventional endodontic irrigation against E. faecalis biofilms in root canals. Methods: Root canals of 50 single-rooted extracted human teeth were prepared and incubated with E. faecalis for 21 days. They were then divided into 4 treatment groups and a control group as follows: (1) NaOCl-Syringe irrigation with 2.5% NaOCl, (2) PUI-Passive ultrasonic irrigation with NaOCl, (3) NaOCl+PDT-Photodynamic therapy following syringe irrigation with NaOCl, (4) PUI+PDT, (5) Control-Syringe irrigation with saline. Colony-forming units were counted and bacterial reduction was calculated for each treatment group. Results: All treatments led to significant reductions in the bacterial load compared to the control group. PUI and PUI+PDT led to the complete elimination of the bacteria from the root canals. NaOCl and NaOCl+PDT treatments reduced the bacteria by 99.9% and 99.5% respectively. NaOCl+PDT was significantly less effective in reducing the bacteria compared to other treatment groups. There were no significant differences between the NaOCl, PUI, and PUI+PDT groups. Conclusion: Passive ultrasonic irrigation with or without the combination of Photodynamic therapy completely eradicated the bacteria. The use of PDT as an adjunction to NaOCl syringe irrigation and PUI did not enhance their antibacterial effect.

Reduction of dual-species biofilm after sonic- or ultrasonic-activated irrigation protocols: A laboratory study

AIM

To evaluate the antibacterial effect of sonic- and ultrasonic-activated irrigation on bacterial reduction of a dual-species biofilm in root canals compared to nonactivated irrigation in a laboratory study.

METHODOLOGY

Two hundred and forty extracted human single-rooted maxillary anterior teeth were divided into two main groups (G, n = 120) according to the initial preparation size of the root canal (G1: size 25, 0.06 taper, G2: size 40, 0.06 taper). Root canals were inoculated with Enterococcus faecalis and Streptococcus oralis. After 5 days, G1 received combined instrumentation (up to size 40, 0.06 taper) and irrigation/activation, whereas G2 received solely irrigation/activation protocols. In both groups, irrigation was performed with sodium hypochlorite (NaOCl 1%) or physiological saline (NaCl 0.9%), using nonactivated syringe irrigation, sonic activation (2 x 30 s) or ultrasonic activation (2 x 30 s). Logarithmic reduction factors (LRFs) of colony-forming units were analysed separately for dentine-adherent and planktonic bacteria immediately after irrigation/activation protocols (time-point 1) or after 5 days of further incubation (time-point 2) by analysis of variance (anova) and post hoc tests (Tukey's HSD, t-test). The significance level was set at 0.05.

RESULTS

In G1 subgroups (combined instrumentation with irrigation/activation), LRFs were significantly affected by the applied irrigation solution (p < .0001), but not by the activation method (p > .05; anova). In G2 subgroups (solely irrigation/activation), both, irrigant solution and activation, significantly affected LRFs (p < .0001, anova). Sonic activation resulted in significantly higher LRFs than ultrasonic activation (p < .0001) which had significantly greater reductions than nonactivated irrigation (p < .05; Tukey's HSD). At T2, strong bacterial regrowth was observed in all groups; however, a significant bacterial reduction was detected for factors instrumentation, irrigant solution and activation (p < .0001; anova). Similar LRFs were found for dentine-adherent and planktonic bacterial cells in all groups (r = 0.91 at T1, r = 0.8 at T2).

CONCLUSIONS

In this laboratory study on extracted maxillary anterior teeth high-frequency sonic activation resulted in a greater bacterial reduction compared to ultrasonic activation in groups receiving solely irrigation/activation protocols; however, irrigation using NaOCl and ultrasonic activation also contributed significantly to bacterial reduction compared to the control groups.

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.

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.

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

AIM

This study aimed to compare the antibacterial effect of antimicrobial photodynamic therapy (aPDT) by use of light emitting diode (LED) and diode laser light sources with toluidine blue (TBO) photosensitizer on Enterococcus faecalis (E. faecalis) biofilm in root canals of extracted single-canal human teeth.

METHODS

Eighty-five sound human single-canal teeth were chosen for this study and standardized to have 15 mm of root length. The root canals were prepared with ProTaper rotary files and inoculated and incubated with E. faecalis for one week. Samples were divided into five experimental (n = 15) groups of PDT with TBO/LED, TBO/diode laser, LED, TBO and diode laser and one negative (NaOCl) and one positive (no treatment) control group. Dentin chip samples were collected from inside the canals using size 40 hedstrom file. The number of colony forming units (CFUs) in each group was calculated.

RESULTS

Irrespective of the light source used for activation of photosensitizer (diode or LED), PDT was significantly more effective than other experimental groups (P < 0.001). No significant difference was noted between aPDT with diode laser or LED (P > 0.05). No significant difference was noted in colony count among other groups (LED, TBO, diode; P > 0.05).

CONCLUSION

The results showed that aPDT significantly decreased residual bacteria in the canal. Thus, it may be used as an adjunct for root canal disinfection. Both diode and LED are suitable light sources for this purpose and can be used alternatively.

Evaluation of the outcome of various laser therapy applications in root canal disinfection: A systematic review

BACKGROUND

Any successful endodontic therapy requires elimination of the endodontic biofilms through meticulous root canal disinfection methods. Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are the most common effective irrigants, in removing smear-layer from the coronal and middle thirds of the dental canals but reduced considerably towards the apical one third. In recent years, newly alternative treatment modalities have been proposed, including high-power lasers and antimicrobial photodynamic therapy (aPDT). Our work was conducted to evalaute the outcome of root canal disinfection in relation to the efficacy of various treatment modalities. Furthermore, every effort was made to present an overview of the aPDT outcomes, as a model for this application, and to propose laser parameters protocol with positive results.

METHODS

The electronic databases PubMed was searched from January 2013- January 2019. Our inclusive criteria based on laser therapy applications, as a model for root canal disinfection. The search terms utilised various combinations as follows: photodynamic therapy or antimicrobial photodynamic therapy or photoactivated disinfection or light activated disinfection or laser activated disinfection or laser therapy, and endodontic.

RESULTS

The results of this systematic review concluded that the effectiveness of aPDT and various laser wavelengths protocols, in removing endodontic biofilms from infected root canals, remains unattainable.

CONCLUSIONS

Study concluded that the combination of aPDT with antimicrobial irrigants could provide a synergetic effect. However, due to the heterogeneity of the selected studies and their limitations, in terms of lack of standardised protocol or discrepancy in the methodology, authors suggest further validated approaches to achieve optimal outcomes.

Endodontic irrigants: Different methods to improve efficacy and related problems

Shaping and cleaning a root canal system along with the preservation of the surrounding periodontal tissues are the principal goals of an endodontic treatment. While most of the attention is paid to the mechanical aspects of a root canal treatment, an essential feature of it is the irrigation. All over the years, many materials have been used to clean the root canal of a tooth, and certainly, the sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid solutions are the most used and most reliable ones. Putting them inside of a canal is mostly done using a normal syringe, but many techniques have been involved in this process, including the use of sonic/ultrasonic instruments, the use of shaping files, and even laser, to increase the efficacy of irrigant solutions, especially of NaOCl one. Each one of this technique faces some disadvantages, just as the vapor lock effect and the apical extrusion, and has a different action on features such as the reaction rate and the shear stress of an endodontic irrigant solution. In this narrative review, we describe the different features of many irrigant solutions and the different ways of upgrading their efficacy in the cleaning of a root canal system, with the use of tables to summarize the entire description, and drawing the readers' attention to a photographic illustration for a better understanding of the topic.

Polymicrobial oral biofilm models: simplifying the complex

Over the past century, numerous studies have used oral biofilm models to investigate growth kinetics, biofilm formation, structure and composition, antimicrobial susceptibility and host-pathogen interactions. In vivo animal models provide useful models of some oral diseases; however, these are expensive and carry vast ethical implications. Oral biofilms grown or maintained in vitro offer a useful platform for certain studies and have the advantages of being inexpensive to establish and easy to reproduce and manipulate. In addition, a wide range of variables can be monitored and adjusted to mimic the dynamic environmental changes at different sites in the oral cavity, such as pH, temperature, salivary and gingival crevicular fluid flow rates, or microbial composition. This review provides a detailed insight for early-career oral science researchers into how the biofilm models used in oral research have progressed and improved over the years, their advantages and disadvantages, and how such systems have contributed to our current understanding of oral disease pathogenesis and aetiology.

The potential of commercially available phytotherapeutic compounds as new photosensitizers for dental antimicrobial PDT: A photochemical and photobiological in vitro study

The present study evaluated the effectiveness of extracts of commercially available Curcuma longa, Citrus lemon, Hamamelis virginiana and Hypericum perforatum as photosensitizers in Antimicrobial Photodynamic Therapy (aPDT). Each photosensitizer (PS) was analyzed in a spectrophotometer between 350 and 750 nm to determine the ideal light source. Once the absorption bands were determined, three light sources were selected. To determine the concentration of use, the compounds were tested at different concentrations on bovine dentin samples to evaluate the risk of staining. Once the concentration was determined, the PSs were evaluated for dark toxicity and phototoxicity on fibroblast and bacteria culture. Each compound was then irradiated with each light source and evaluated for the production of reactive oxygen species (ROS). The bacterial reduction was tested on E. faecalis culture in planktonic form and on biofilm using an energy of 10 J and an Energy Density of 26 J/cm². The tested compounds exhibited light absorption in three bands of the visible spectrum: violet (405 nm), blue (460 nm) and red (660 nm). At a 1:6 concentration, none of the compounds caused tooth staining as they did not exhibit significant toxicity in the cells or bacterial suspension. Additionally, significant ROS production was observed when the compounds were irradiated at each wavelength. When aPDT was performed on the plactonic and biofilm bacteria, significant microbial reduction was observed in both cases, reaching a reduction of up to 5Logs. In conclusion, extracts of Curcuma longa, Citrus lemon, Hamamelis virginiana and Hypericum perforatum exhibited potential for use as photosensitizing agents in aPDT.

Effect of EDTA and QMIX Ultrasonic Activation on the Reduction of Microorganisms and Endotoxins in Ex Vivo Human Root Canals

Abstract The present study aimed to compare the effectiveness of QMiX and 17% EDTA associated to passive ultrasonic irrigation (PUI) or manual agitation (MA) on the reduction of E. faecalis, E. coli and LPS from root canals. Forty single rooted human teeth were randomly divided into four groups (n=10), according to the final irrigation protocol: EDTA+MA, QMiX+MA, EDTA+PUI, QMiX+PUI. Sample collections were obtained from the root canal content immediately before preparation (baseline-S1), after instrumentation (S2), after final irrigation protocol (S3) and 7 days after instrumentation and final irrigation (S4). The antimicrobial effectivity and on endotoxin content were analyzed by culture procedure (CFU/mL) and LAL assay (EU/mL), respectively. The results were statistically analyzed by Kruskal-Wallis and Friedman test (α=5%). QMiX+MA and QMiX+PUI reduced 100% of E. coli and E. faecalis bacteria and also prevented E. faecalisregrowth at S4. EDTA significantly reduced E. coli, but it was not effective in reducing E. faecalis. All protocols reduced EU/mL when compared to S1, however at S4 there was a significant reduction of EU/mL only in the QMiX+MA and QMiX+PUI groups in relation to S3 and S2, respectively. Final irrigation with QMiX associated with MA or PUI had superior antibacterial efficacy compared to EDTA, eliminating 100% of E. coli and E. faecalis strains. In addition, QMiX+PUI reduced 97.61% of the initial content of LPS.

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.

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.

Antimicrobial Photodynamic Therapy to Control Clinically Relevant Biofilm Infections

Biofilm describes a microbially-derived sessile community in which microbial cells are firmly attached to the substratum and embedded in extracellular polymeric matrix. Microbial biofilms account for up to 80% of all bacterial and fungal infections in humans. Biofilm-associated pathogens are particularly resistant to antibiotic treatment, and thus novel antibiofilm approaches needed to be developed. Antimicrobial Photodynamic therapy (aPDT) had been recently proposed to combat clinically relevant biofilms such as dental biofilms, ventilator associated pneumonia, chronic wound infections, oral candidiasis, and chronic rhinosinusitis. aPDT uses non-toxic dyes called photosensitizers (PS), which can be excited by harmless visible light to produce reactive oxygen species (ROS). aPDT is a multi-stage process including topical PS administration, light irradiation, and interaction of the excited state with ambient oxygen. Numerous in vitro and in vivo aPDT studies have demonstrated biofilm-eradication or substantial reduction. ROS are produced upon photo-activation and attack adjacent targets, including proteins, lipids, and nucleic acids present within the biofilm matrix, on the cell surface and inside the microbial cells. Damage to non-specific targets leads to the destruction of both planktonic cells and biofilms. The review aims to summarize the progress of aPDT in destroying biofilms and the mechanisms mediated by ROS. Finally, a brief section provides suggestions for future research.

Bactericidal Effect of Various Laser Irradiation Systems on Enterococcus faecalis Biofilms in Dentinal Tubules: A Confocal Laser Scanning Microscopy Study

OBJECTIVE

The aim of this study was to compare the bactericidal effect of various laser irradiation systems on Enterococcus faecalis biofilms in dentinal tubules by using a novel dentin infection model and confocal laser scanning microscopy (CLSM).

BACKGROUND DATA

Laser-activated irrigations have been proposed as an adjuvant to conventional protocols of root canal treatment to enhance the smear layer removal, which is a promising protocol for root canal disinfection.

MATERIALS AND METHODS

E. faecalis were centrifuged into the dentinal tubules, cultured for 3 weeks, and then received 1- and 3-min treatments as follows: (A) 5.25% sodium hypochlorite (NaOCl) irrigation, (B) Nd:YAG laser irradiation, (C) diode laser irradiation, (D) Nd:YAP laser irradiation, (E) Er,Cr:YSGG laser-activated NaOCl irrigation, and (F) Er:YAG laser-activated NaOCl irrigation. Bacterial reductions were assessed by CLSM using a LIVE/DEAD^® bacterial viability stain method.

RESULTS

For each group, the bacterial reduction increased as the treatment time increased (p < 0.05). The Er,Cr:YSGG and Er:YAG laser significantly enhanced the bactericidal effect of NaOCl (p < 0.05). Under the conditions of the same treatment time, bacterial reductions were presented in the descending order of Er:YAG + NaOCl, Er,Cr:YSGG + NaOCl > Nd:YAP > Nd:YAG, diode > NaOCl.

CONCLUSIONS

Under the conditions of present study, treatments of Er:YAG + NaOCl and Er,Cr:YSGG + NaOCl presented the strongest bactericidal effect among the tested protocols and are potential protocols for root canal disinfection.

Methylene Blue and Hydrogen Peroxide for Photodynamic Inactivation in Root Canal - A New Protocol for Use in Endodontics

Objective

Antimicrobial photodynamic therapy (aPDT) is a controversial approach for endodontic disinfection. The objective of this study was to test the photosensitiser (PS) concentration and assess the optical shielding phenomenon, the use of hydrogen peroxide (H₂O₂) and minimal energy irradiation to optimise endodontic aPDT for suggesting a protocol for clinical use.

Methods

Different parameters for aPDT were tested. Aqueous solutions of methylene blue (MB) at 50, 100, 150 and 300 μM were tested in vitro for optical shield and reactive oxygen species (ROS) production by the reduction of N,N-dimethyl-4-notrosoaniline (RNO) at 440 nm absorbance when irradiated using a diode laser (660 nm). Ten single-rooted teeth were inoculated with bioluminescent bacteria Pseudomonas aeruginosa for 72 hours to form biofilms. Bioluminescence imaging was used to serially evaluate the minimum energy necessary during endodontic aPDT using MB and a diode laser coupled to an optical fibre for intracanal microbial reduction. In addition, teeth (n=21) infected with Enterococcus faecalis were treated with sequential combinations of endodontic aPDT and H₂O₂ and the colony-forming unit (CFU) was determined.

Results

ROS production was inversely proportional to the MB concentration in the solution due to quenching of MB. Optical shielding limited light penetration at high MB concentrations. The use of H₂O₂ before aPDT achieved higher disinfection compared to conventional aPDT or when MB was irradiated in an H₂O₂ solution. Energy irradiation of 9.6 J achieved a significant reduction and further light delivery did not produce further reduction.

Conclusion

PS concentration of about 50 μM, biofilm pre-treatment with H₂O₂ for 1 min and energy irradiation around 10 J appear to be an effective protocol for endodontic aPDT.

Effects of Diode Laser, Gaseous Ozone, and Medical Dressings on Enterococcus faecalis Biofilms in the Root Canal Ex Vivo

The objective was to compare the antibacterial effects of adjunctive disinfection using diode laser and gaseous ozone compared to the medical dressings calcium hydroxide (Ca(OH)₂) and chlorhexidine gel (CHX-Gel) on Enterococcus faecalis biofilms in human root canals ex vivo. Root canals of 180 human extracted teeth were infected by E. faecalis and divided into 3 main groups (G): G1, control; G2, instrumentation and irrigation using 0.9% NaCl; G3, instrumentation and irrigation using 1% NaOCl. In each main group, the following treatments were applied: gaseous ozone, diode laser, and medical dressings of Ca(OH)₂ or CHX-Gel for 7 days (n = 15). Reduction of colony forming units (CFUs) inside the root canal of planktons and frequencies of adherent bacteria after treatment were calculated. Bacterial reduction was significantly affected by the irrigation protocol (p < 0.0005) and the disinfection method (p < 0.0005), and a significant interaction between both factors could be observed (p < 0.0005; ANOVA). In G3 (instrumentation using 1% NaOCl), no significant effect of disinfection methods could be demonstrated on planktonic bacteria (p = 0.062; ANOVA) and frequencies of adherent bacteria (p > 0.05; chi-square test). Instrumentation and irrigation using NaOCl combined with ozone or laser application resulted in comparable bacterial reduction on E. faecalis to the application of medical dressings.

The potential of photodynamic therapy (PDT)-Experimental investigations and clinical use

Photodynamic therapy (PDT) is an intensively studied part of medicine based on free radicals. These reactive species, extremely harmful for whole human organism, are used for eradication numerous diseases. Specific structure of ill tissues causes accumulation free radicals inside them without attack remaining healthy tissues. A rapid development of medicine and scientific research has led to extension of PDT towards treatment many diseases such as cancer, herpes, acne and based on antimicrobials. The presented review article is focused on the aforementioned disorders with accurate analysis of the newest available scientific achievements. The discussed cases explicitly indicate on high efficacy of the therapy. In most cases, free radicals turned out to be solution of many afflictions. Photodynamic therapy can be considered as promising treatment with comparable effectiveness but without side effects characteristic for chemotherapy.

Can Antimicrobial Photodynamic Therapy (aPDT) Enhance the Endodontic Treatment?

In order to achieve a long-lasting effect, one of the main goals in root canal treatment is to eliminate the endodontic bacteria. Conventional chemomechanical debridement is considered as the basic treatment in root canal therapy, but adjunctive techniques such as antimicrobial photodynamic therapy (aPDT) can also be helpful. The aim of this study was to evaluate reports in the scientific literature that used different photosensitizers (PSs) for bacterial reduction. The literature search was conducted using databases including PubMed, Scopus, and Google Scholar with the keywords "photodynamic therapy," "antimicrobial photodynamic therapy," or "photoactivated disinfection" and "endodontic," "Enterococcus faecalis," or "root canal treatment," from 2000 to 2015. By evaluating different studies, it was concluded that aPDT should be applied in combination with conventional mechanical debridement and irrigants. However, it is also important to note that the success rate is critically dependent on the type of the PS, output power of the laser used, irradiation time, pre-irradiation time, and type of tips used.

Evolution of the role of phototherapy during endodontic decontamination

A microbe free root canal space before obturation leads to higher success rate and conventional chemo-mechanical debridement might not achieve this goal completely. First trials of laser in dentistry started from surgical intervention on caries and bones of oral cavity and extended to prepare cavities and even shaping root canals. Afterward lasers were implicated soon into direct debridement of root canal space. Anyhow failure of laser to remove debris totally from root canal space is demonstrated recently, additionally it might lead to damages to surrounding tissues or inorganic material of root canal if be used without precaution. Nowadays the theory of light assisted protocols became another start point for laser in endodontics. Laser has been introduced as an adjuvant to conventional debridement of root canals. We used Medline search engine to collect scientific publications to edit this review article in purpose of revealing the evolution of laser position from an ultimate cleaning methodology to an adjuvant to conventional root canal disinfection protocols.

Photodynamic Antimicrobial Chemotherapy for Root Canal System Asepsis: A Narrative Literature Review

Aim. The aim of this comprehensive literature review was to address the question: Does photodynamic therapy (PDT) improve root canal disinfection through significant bacterial reduction in the root canal system? Methodology. A comprehensive narrative literature review was performed to compare PDT effect with sodium hypochlorite as the comparative classical irrigant. Two reviewers independently conducted literature searches using a combination of medical subject heading terms and key words to identify relevant studies comparing information found in 7 electronic databases from January 2000 to May 2015. A manual search was performed on bibliography of articles collected on electronic databases. Authors were contacted to ask for references of more research not detected on the prior electronic and manual searches. Results. The literature search provided 62 titles and abstracts, from which 29 studies were related directly to the search theme. Considering all publications, 14 (48%) showed PDT to be more efficient in antimicrobial outcome than NaOCl (0.5-6% concentration) used alone and 2 (7%) revealed similar effects between them. Toluidine blue and methylene blue are the most used photosensitizers and most commonly laser has 660 nm of wavelength with a 400 nm diameter of intracanal fiber. Conclusions. PDT has been used without a well-defined protocol and still remains at an experimental stage waiting for further optimization. The level of evidence available in clinical studies to answer this question is low and at high risk of bias.

Antimicrobial efficacy of photodynamic therapy, Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm

BACKGROUND

Lasers have been recommended in final root canal disinfection protocol, however, there is no clear evidence about their efficacy against bacteria in biofilms. The aim of the study was to evaluate and compare the disinfection effect of antimicrobial photodynamic therapy (aPDT), Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm.

METHODS

The study sample consisted of 65 dentine slices, which were inoculated with E. faecalis and incubated anaerobically for three weeks. The dentine discs were randomly allocated to one of the following experimental groups: aPDT (100 mW, 10 mg/ml phenothiazinium chloride, 1 min), Nd:YAG laser (2 W, 15 Hz, 4×5 s), QMiX solution (1 min). Positive controls did not receive any treatment and negative controls were treated with 5.25% NaOCl. To harvest surviving adherent cells, each dentine sample was transffered to a test tube containing of TSB, serial ten-fold dilutions were made and aliquot of 1 ml was plated onto blood agar plates and incubated for 48 h. Colony forming units grown were counted and transformed into actual counts based on the dilution factor. The remaining viable cells after each protocol were analysed by FISH.

RESULTS

The aPDT and the QMiX solution were equally effective, with the reduction rate of E. faecalis CFUs of 98.8% and 99.3% respectively (p=1.107). The Nd:YAG laser caused 96% reduction of E. faecalis (P<0.001).

CONCLUSION

The aPDT and the QMiX solution showed similar antibacterial efficacy against old E. faecalis biofilm, followed by Nd:YAG irradiation.

Effects of photodynamic therapy on Enterococcus faecalis biofilms

Microbial biofilms are involved in almost all infectious pathologies of the oral cavity. This has led to the search for novel therapies specifically aimed at biofilm elimination. In this study, we used atomic force microscopy (AFM) to visualize injuries and to determine surface roughness, as well as confocal laser scanning microscopy (CLSM) to enumerate live and dead bacterial cells, to determine the effects of photodynamic therapy (PDT) on Enterococcus faecalis biofilms. The AFM images showed that PDT consisting of methylene blue and a 670-nm diode laser (output power 280 mW during 30 s) or toluidine blue and a 628-nm LED light (output power 1000 mW during 30 s) induced severe damage, including cell lysis, to E. faecalis biofilms, with the former also causing an important increase in surface roughness. These observations were confirmed by the increase in dead cells determined using CLSM. Our results highlight the potential of PDT as a promising method to achieve successful oral disinfection.

Manual and Rotary Instrumentation Ability to Reduce Enterococcus faecalis Associated with Photodynamic Therapy in Deciduous Molars

This aim of this study was to assess the ability of manual or rotary instrumentation associated with photodynamic therapy (PDT) to reduce Enterococcus faecalis using three combinations of light/photosensitizers: toluidine blue O/laser, fuchsin/halogen light and fuchsin/LED. Twenty deciduous molars were selected and contaminated with Enterococcus faecalis (McFarland 0.5 scale). Working length determination was performed by visual method. The teeth were randomly divided into two groups: G1 (n=10): manual instrumentation (Kerr-type files) and G2 (n=10): rotary instrumentation (ProTaper system). The bacteria were collected three times using sterile paper cones compatible with the anatomic diameter of the root canal for 30 s before and after instrumentation and after PDT. The samples were diluted in peptone water, seeded on blood agar plates and incubated in an oven at 37 °C for colony-forming units counting. The decrease of E. faecalis counts after instrumentation and after PDT was compared using the Wilcoxon test, t-test and Kruskal Wallis test. A significant reduction of E. faecalis occurred after manual and rotary instrumentation and after PDT using the three combinations of light/photosensitizer (p<0.05). It may be concluded that both rotary and manual instrumentation reduced E. faecalis. Fuchsin with halogen light or LED irradiation and toluidine blue O with laser irradiation can be used to reduce E. faecalis in root canals of primary molars. PDT can be used as an adjuvant to conventional endodontic treatment.

Assessment of Photodynamic Therapy (PDT) in Disinfection of Deeper Dentinal Tubules in a Root Canal System: An In Vitro Study

CONTEXT

The success of endodontic treatment therapy depends on how well we eliminate pathogenic microflora from the root canal system as micro organism as the major cause of root canal infection. Conventional root canal treatment can fail if microorganisms cannot be removed sufficiently by thorough cleaning, shaping of root canal. Newer modalities such as photodynamic therapy are being tried now a days for disinfection of root canals. Aim & Objectives: The basic aim of this study was assessment of the antimicrobial efficacy of Photodynamic Therapy in deeper dentinal tubules for effective disinfection of root canals using microbiological and scanning electron microscopic examination in vitro.

MATERIALS AND METHODS

The study was conducted at Teerthanker Mahaveer Dental College & Research Centre. The teeth required for study was collected from Department of Oral and Maxillofacial Surgery. Only freshly extracted 20 intact, non carious single rooted teeth which were indicated for orthodontic treatment were taken for this study. Statistical analysis was done using Student's Unpaired t-test were at (p<0.001) was found to be highly significant. Microbiological examination of samples were done and colony forming units were counted to assess the disinfection potential of photodynamic therapy. Scanning electron microscopic examination of samples was done to check penetration of bacteria's into deeper dentinal tubules.

RESULTS

On examination, there was a marked reduction in microbial growth after use of photodynamic therapy. On scanning electron microscopic examination, it was observed that there were less number of bacteria's in deeper dentinal tubules in case of PDT group as compared to control group.

CONCLUSION

The results of the present study indicate that PDT can be effectively used during antimicrobial procedures along with conventional disinfection procedure for sterilization of root canals.

Pulp revascularization of immature permanent teeth: a review of the literature and a proposal of a new clinical protocol

Tissue engineering is a growing field. In the near future, it will probably be possible to generate a complete vital tooth from a single stem cell. Pulp revascularization is dependent on the ability of residual pulp and apical and periodontal stem cells to differentiate. These cells have the ability to generate a highly vascularized and a conjunctive rich living tissue. This one is able to colonize the available pulp space. Revascularization is a new treatment method for immature necrotic permanent teeth. Up to now, apexification procedures were applied for these teeth, using calcium dihydroxide or MTA to produce an artificial apical barrier. However, the pulp revascularization allows the stimulation of the apical development and the root maturation of immature teeth. Two pulp revascularization techniques are used in the literature, one using calcium dihydroxide and the second using a triple antibiotic paste. Based on these two different pulp revascularization protocols, which obtain the desired therapeutic success, the literature will be reviewed and analyzed according to the relevance of their choice of materials. Based on the literature, we propose a new relevant protocol and a new mixture of antibiotics.

Comparative antibacterial efficacy of photodynamic therapy and ultrasonic irrigation against Enterococcus faecalis in vitro

Enterococcus faecalis poses a challenge to the efficacy of traditional root canal disinfection methods. This study was aimed to establish a synergistic root canal disinfection strategy combining ultrasonic irrigation with photodynamic therapy (PDT) together and to test its antibacterial efficacy against E. faecalis. Twenty-seven bovine root canals infected with E. faecalis were randomly divided into three groups and treated with different disinfection methods as follows: ultrasonic irrigation with 2.5% NaOCl, methylene blue (MB)-mediated PDT, or combined ultrasonic irrigation and PDT as described above. Quantification of E. faecalis was performed on the root canals before and immediately after the disinfection treatment. Residual bacteria were determined by counting colony-forming units. Samples were randomly selected from the three groups, and the morphology of residual bacteria inside the dentinal tubules was studied by scanning electron microscopy. The number of surviving E. faecalis in the group treated with the combination method was significantly lower (P < 0.05) than those in the ultrasonic irrigation-treated or PDT-treated groups. Similar results were found in the morphological studies of the three groups. The results of our study highlighted the importance of combination of ultrasonic irrigation and PDT to produce significant antibacterial efficacy against E. faecalis during root canal disinfection.