Photo-activated Disinfection Research Articles

Photodynamic Therapy- A Ray towards Periodontics

The increase of microbial resistance and development of lighting devices with safe and accurate delivery of energy, today professionals can count on therapies to manage pathogens in different fields of dentistry, especially periodontics. The possibility of development of resistance to antibiotics by the target organism has led to development of a new concept with fewer complications i.e. Photodynamic Therapy. The combination of laser light and photosensitizer known as photodynamic therapy (PDT) can be used in periodontal therapy. LASER produces a monochromatic, collimated and coherent light beam. This unique form of light can interact with living tissues leading to surgical and/ or therapeutic applications. A Photosensitizer is a dye substance that is absorbed by the microorganism, cell or tissue allowing it to interact with the light. This mode of treatment is referred to as photodynamic therapy (PDT) or photo-activated disinfection (PAD). Application of photodynamic therapy in periodontics such as pocket debridement, gingivitis, aggressive periodontitis continue to evolve into a mature clinical treatment modality, and is considered as a promising novel approach for eradicating pathogenic bacteria in periodontitis. This Article presents an overview of photodynamic therapy as it represents a novel therapeutic approach in the management of periodontal diseases.

Effect of photo-activated disinfection on bond strength of three different root canal sealers.

Introduction:The aim of this in vitro study was to evaluate the bond strength of Photo-Activated Disinfection (PAD) system to dentin with different root canal sealers by using a push-out test design.Materials and Methods:A total of 30 extracted mandibular premolar teeth with single and straight roots were used. The crowns were removed and the root canals were prepared by using ProTaper rotary files. The smear layer was removed and the roots were randomly divided into two groups (n = 15) according to the use of PAD system as the final disinfecting agent. Each group was then divided into 6 (n = 5) subgroups and obturated with gutta-percha and 3 different root canal sealers. The groups were Group 1: Sodium hypochlorite (NaOCl) + ethylenediaminetetraacetic acid (EDTA)-AH Plus sealer; Group 2: NaOCl + EDTA + PAD-AH Plus; Group 3: NaOCl + EDTA-Sealapex; Group 4: NaOCl + EDTA + PAD-Sealapex; Group 5: NaOCl + EDTA-mineral trioxide aggregate (MTA)-Fiallapex; and Group 6: NaOCl + EDTA + PAD-MTA-Fillapex. 1-mm thickness horizontal sections (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement.Results:Group 3 and 4 showed significantly lower bond strengths compared with all the other groups (P < 0.05). No statistically significant difference was found among Groups 1, 2 and 5, but there was statistically significant difference between Group 5 and 6 (P < 0.05).Conclusion:This in vitro study indicated that the PAD system adversely affected the bond strength of the MTA Fillapex root canal sealer.

A COMPARATIVE STUDY OF MICROLEAKAGE OF OBTURATED ROOT CANALS AFTER DISINFECTION WITH Nd:YAG LASER, PDT AND NAOCL AND EDTA.

SUMMARY Endodontic therapy consists of cleaning and shaping the root canal system, removing organic debris and sealing the intracanal space with permanent filling materials. The use of lasers and photo-activated disinfection in endodontic treatment may cause morphological changes in the dentin of the root canal. The purpose of this laboratory study was to compare the degree of hermetic obturation of root canals after endodontic treatment and disinfection with Nd: YAG laser, photo-activated disinfection with FotoSan, NaOCL 2,5% + EDTA 17% and obturated with AH 26 sealer and guttapercha. For the laboratory study we used 30 freshly extracted single rooted teeth. After that the teeth are divided into three groups, depending on the mode of additional root canal disinfection and obturated. The leakage was shown using dye penetration test with methylene blue for a period of 3 days at 37°C. Microleakage was observed in all studied groups.

EFFICENCY OF PHOTOACTIVATED DISINFECTION ON EXPERIMENTAL BIOFILM - SCANING ELECTRON MICROSCOPY RESULTS

Photoactivated disinfection is a new antimicrobial method for root canal disinfection, based on photodynamic therapy. Purpose: The goal of this study is to investigate the antimicrobial effect of photoactivated disinfection on experimental biofilm from Enterococcus faecalis and Candida albicans, through scanning electron microscopy. Material and Methods: Freshly extracted, one root teeth were prepared with a sequence of rotary nickel-titanium files (ProTaper ; Dentsply ; Mailefer ), irrigated, the external root canal surfaces isolated with nail polish and autoclaved. After the incubation with the experimental biofilm, the root canals were filled with photosensitizer – Toluidine Blue – 0,01% and irradiated with Foto San(CMS Dental), 630 nm, 2000mW/cm 2 for 30 seconds. SEM was performed on the coronal, middle and apical third of the root canal, for evaluation of the results. Results and discussion: In the range of 600 to 8000, SEM showed significant reduction of microorganisms from the canal system. A large increase in microorganisms was observed, showing a disturbance in the cell membrane, as effect from the activation of chromophore with the laser and the penetration of the photosensitizer in dental tubules. In the apical third single microorganisms were observed. This may due to decreased penetration of the photosensitizer, incomplete pervasion of MB in the biofilm or insufficient oxygenation. Conclusion: FAD has the potential to be a good alternative and addition to the conventional root canal disinfection methods. SEM is a precise method for endodontic treatment result evaluation.

Effect of Photoactivated Disinfection on Bond Strength of Root Canal Filling

IntroductionThe aim of this in vitro study was to assess and compare the effect of photoactivated disinfection (PAD) on the bond strength of root canal sealers to human root canal dentin using the push-out test. MethodsFifteen extracted human mandibular premolar teeth with single and straight roots were used. After the clinical crowns were removed from the cementoenamel junction, root canals were prepared with the ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) rotary system to the size of the F3 file. The smear layer of the roots was removed using 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl) and distillate water. The roots were then randomly divided into 3 groups (n = 5) according to the final irrigation regimen. In group 1, PAD (FotoSan; CMS Dental, Copenhagen, Denmark) was applied to the root canals and light cured for 20 seconds. Group 2 was finally irrigated with a 2% solution of chlorhexidine gluconate, and group 3 served as the control group (NaOCl + EDTA). All the canals were then obturated with the lateral condensation technique using gutta-percha and AH Plus sealer (Dentsply Maillefer) sealer. One-millimeter-thick horizontal sections from the coronal and midthirds of each root (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. The data were converted to megapascals and statistically analyzed using 1-way analysis of variance and the post hoc Tukey test. ResultsThere was no significant difference among the bond strength of PAD, chlorhexidine gluconate, and NaOCl (P > .05). ConclusionsWe conclude that PAD does not adversely affect the bond strength of the AH Plus sealer to root canal dentin and that it can be used for the final disinfection of root canals.

Use of new minimum intervention dentistry technologies in caries management

Preservation of natural tooth structure requires early detection of the carious lesion and is associated with comprehensive patient dental care. Processes aiming to detect carious lesions in the initial stage with optimum efficiency employ a variety of technologies such as magnifying loupes, transillumination, light and laser fluorescence (QLF® and DIAGNOdent® ) and autofluorescence (Soprolife® and VistaCam®), electric current/impedance (CarieScan(®) ), tomographic imaging and image processing. Most fluorescent caries detection tools can discriminate between healthy and carious dental tissue, demonstrating different levels of sensitivity and specificity. Based on the fluorescence principle, an LED camera (Soprolife® ) was developed (Sopro-Acteon, La Ciotat, France) which combined magnification, fluorescence, picture acquisition and an innovative therapeutic concept called light-induced fluorescence evaluator for diagnosis and treatment (LIFEDT). This article is rounded off by a Soprolife® illustration about minimally or even non-invasive dental techniques, distinguishing those that preserve or reinforce the enamel and enamel-dentine structures without any preparation (MIT1- minimally invasive therapy 1) from those that require minimum preparation of the dental tissues (MIT2 - minimally invasive therapy 2) using several clinical cases as examples. MIT1 encompasses all the dental techniques aimed at disinfection, remineralizing, reversing and sealing the caries process and MIT2 involves a series of specific tools, including microburs, air abrasion devices, sonic and ultrasonic inserts and photo-activated disinfection to achieve minimal preparation of the tooth. With respect to minimally invasive treatment and prevention, the use of lasers is discussed. Furthermore, while most practices operate under a surgical model, Caries Management by Risk Assessment (CaMBRA) encourages a medical model of disease prevention and management to control the manifestation of the disease, or keep the oral environment in a state of balance between pathological and preventive factors. Early detection and diagnosis and prediction of lesion activity are of great interest and may change traditional operative procedures substantially. Fluorescence tools with high levels of magnification and observational capacity should guide clinicians towards a more preventive and minimally invasive treatment strategy.

ENDODONTICS AND THERMOVISION-TEMPERATURE CHANGES DURING PHOTO-ACTIVATED DISINFECTION IN ROOT CANALS. THERMOVISION DIAGNOSIS IN ENDODONTIC TREATMENT.

Introduction: The application of thermovision in endodontics is an innovative method and has a great informative value, evidence proved, thanks to the use of last generation camera Flir A310 and a software ThermaCam Reporter 8.3 Pro. In the recent years a new method of root canal disinfection is introduced – photo-activated disinfection (PAD). Temperature increase have always been a concern during dental laser treatment. Aim: The purpose of our study is to evaluate the temperature elevation on the outer root surface at extracted teeth and in periapical tissues when photodynamic therapy with 630-nm diode laser is used for root canal disinfection. Materials and methods: For the laboratory study we used 72 single-rooted freshly extracted human teeth. They were divided into six groups depending on the power of the light source (220 mW, 360 mW and 500 mW ) and the type of photosensitizer agent - Fotosan and Zn-phtalocianine. In our clinical study participated 8 patients, who came in to our clinic with complaints of spontaneous pain or were with infected root canals and were referred for endodontic treatment. PAD was performed with a diode laser with wavelength of 630 nm using an endodontic handpiece with fiberoptic connector, allowing penetration to 4 mm from the apical stop, and movements of fibreoptic (200 µm) in apicalcoronal direction . Results: The highest temperature value was detected at 500mW and 360mW. The average temperature increase recorded in our study at the external surface of the root canal did not exceed 10°C only at power setting of 220 mW during PAD with Zn-phtalocianine. Conclusion: In conclusion, photo-activated disinfection of the root canal with Zn-phtalocianine and 630-nm diode laser using 200 µm fibreoptic tips at a power setting of 220 mW for 60 seconds induces a temperature increase which isn’t sufficient to damage the neighbouring tissues. Based on this results we don’t recommend root canal preparation over 02 or 04 taper when PAD will be performed.

Effect of photoactivated disinfection with a light-emitting diode on bacterial species and biofilms associated with periodontitis and peri-implantitis

To determine the effect of photoactivated disinfection (PAD) using toluidine blue and a light-emitting diode (LED) in the red spectrum (wave length at 625-635 nm) on species associated with periodontitis and peri-implantitis and bacteria within a periodontopathic biofilm. Sixteen single microbial species including 2 Porphyromonas gingivalis and 2 Aggregatibacter actinomycetemcomitans and a multispecies mixture consisting of 12 species suspended in saline without and with 25% human serum were exposed to PAD. Moreover, single-species biofilms consisting of 2 P. gingivalis and 2 A. actinomycetemcomitans strains and a multi-species biofilm on 24-well-plates, grown on titanium discs and in artificial periodontal pockets were exposed to PAD with and without pretreatment with 0.25% hydrogen peroxide. Changes in the viability were determined by counting the colony forming units (cfu). PAD reduced the cfu counts in saline by 1.42 log₁₀ after LED application for 30s and by 1.99 log₁₀ after LED application for 60s compared with negative controls (each p<0.001). Serum did not inhibit the efficacy of PAD. PAD reduced statistically significantly (p<0.05) the cfu counts of the P. gingivalis biofilms. The viability of the A. actinomycetemcomitans biofilms and the multi-species biofilms was statistically significantly decreased when PAD was applied after a pretreatment with 0.25% hydrogen peroxide. The biofilm formed in artificial pockets was more sensitive to PAD with and without pretreatment with hydrogen peroxide compared with those formed on titanium discs. PAD using a LED was effective against periodontopathic bacterial species and reduced viability in biofilms but was not able to completely destroy complex biofilms. The use of PAD following pretreatment with hydrogen peroxide resulted in an additional increase in the antimicrobial activity which may represent a new alternative to treat periodontal and peri-implant infections thus warranting further testing in clinical studies.

Ex vivo killing of Enterococcus faecalis and mixed plaque bacteria in planktonic and biofilm culture by modified photoactivated disinfection

To compare the efficacy of conventional and modified photoactivated disinfection (PAD) against Enterococcus faecalis and mixed plaque bacteria in suspension and biofilms. Enterococcus faecalis (four strains) and mixed plaque bacteria from three adult volunteers were suspended in water, added to methylene blue (MB, 15 μmol L⁻¹), MB mixed with 0.5% hydrogen peroxide and 0.05% chlorhexidine (CHX), MB mixed with 0.5% hydrogen peroxide and 0.05% EDTA or MB mixed with 0.05% EDTA and 0.05% CHX and exposed to laser irradiation from 10 s to 5 min. After exposure, samples were taken, serially diluted and grown aerobically and anaerobically on Tryptic Soy Agar plates or on blood agar plates for 24 and 72 h, respectively. For biofilm experiments, E. faecalis and mixed plaque biofilms were grown on sterile hydroxyapatite (HA) discs coated overnight with bovine dermal collagen type I for 3 weeks. After exposure to MB or MB and low concentration of EDTA with either hydrogen peroxide or CHX, the percentage of killed bacteria by PAD was evaluated using viability staining and confocal laser scanning microscope. For statistical analysis, one-way analysis of variance was performed. Conventional PAD killed from 90.76% to 100% E. faecalis for 3 min, but failed to kill all plaque bacteria even after 5 min of laser irradiation. In modified PAD, up to 100% of suspended E. faecalis and mixed plaque bacteria were killed after 1 min and 30 s of irradiation. Up to twenty times more biofilm bacteria were killed by modified PAD than by conventional PAD with 15 μmol L⁻¹ MB (P < 0.001) and up to eight times more than 2% CHX (P < 0.001) and 1% sodium hypochlorite (P < 0.001). Modified PAD was superior to conventional PAD against planktonic and biofilm bacteria.

Photoactivated disinfection using light‐emitting diode as an adjunct in the management of chronic periodontitis: a pilot double‐blind split‐mouth randomized clinical trial

This split-mouth double-masked randomized controlled clinical study evaluated the effectiveness of photoactivated disinfection (PAD) using light-emitting diode (LED) as an adjunct in the management of patients affected by moderate to severe chronic periodontitis. Sixteen patients affected by moderate to severe chronic periodontitis were enrolled. After scaling and root planing (SRP), each quadrant was assigned to one of the following groups: LED group (625-635 nm, maximum power density: 2000 mW/cm(2) ), photosensitizer group (tolouidine blue O, 0.1 mg/ml), PAD group (photosensitizer and LED) and control group (no adjunctive treatment). The adjunctive treatments were repeated after 7 and 14 days. The clinical parameters of bleeding on probing, probing pocket depth and clinical attachment level were measured at baseline and 1 and 3 months after SRP. At 1 and 3 months, all groups showed significant improvements with regard to all clinical parameters compared to baseline (all p: <0.001). There were no significant differences among groups in terms of changes of clinical parameters in any time interval (all p > 0.05). The application of PAD using LED with the current setting did not have additional effects on clinical parameters in patients diagnosed with moderate to severe chronic periodontitis compared with SRP alone.

Effectiveness of Photoactivated Disinfection (PAD) to KillEnterococcus faecalisin Planktonic Solution and in an Infected Tooth Model

The aim of this study was to investigate the effectiveness of photoactivated disinfection (PAD) in killing Enterococcus faecalis (EF) in planktonic solution and in an infected tooth model. One hundred and thirty-two glass tubes of EF samples with concentration of 10(14) colony forming units (CFU)/mL and photosensitizer were prepared. Sixteen groups were set up and subjected to diode laser, and then received a radiation energy dose ranging from 0.5 to 5.5 J. The bactericidal effect was measured by the mean CFU of viable EF after irradiation. Sixty single-rooted teeth were selected and contaminated with EF, and then given PAD therapy; 5.25% NaOCl irrigation and saline solution were used to disinfect the root canals. Microbial samples were taken before and after disinfection, and after 72 h recovery, and then the CFU were counted. The bactericidal effect increased linearly with the irradiation energy dose in planktonic solution. For the same irradiation energy dose, the bactericidal effect was greater in group receiving 100 mW than in that receiving 50 mW and exposed to doubled irradiation time (p<0.05). No bacterium was detected after irrigation in the NaOCl group in the root canal model, but the recovery of bacteria after 72 h was detected in 11 samples. Bacteria were detected in all the other groups, and PAD was significantly more effective than saline solution in reducing the number of bacterial cells within the root canals (p<0.05). PAD was shown to have bactericidal effect on EF, and the bactericidal effect increased linearly with the irradiation energy dose and was superior using higher output power. PAD could decrease EF in root canals effectively, but was no more effective than 5.25% NaOCl, and PAD is more effective in planktonic solution than in root canals.

Antimicrobial efficacy of a high‐power diode laser, photo‐activated disinfection, conventional and sonic activated irrigation during root canal treatment

To evaluate the antimicrobial effect of a diode laser irradiation, photo-activated disinfection (PAD), conventional and sonic activated irrigation with 2.5% sodium hypochlorite (NaOCl) on Enterococcus faecalis. Root canals of 120 human extracted teeth with single straight canals were prepared with ProTaper files, sterilized, contaminated with an E. faecalis suspension and incubated for 7 days. They were then randomly distributed into six groups: G1, diode laser irradiation (2 W, 3 × 20 s); G2, PAD (100 mW, 60 s); G3, PAD with 3D Endoprobe (100 mW, 60 s); G4, 30-gauge syringe irrigation with NaOCl (60 s); G5, sonic agitation of NaOCl with the EndoActivator system (60 s); G6, 30-gauge syringe irrigation with NaCl (60 s). The pattern of colonization was visualized by scanning electron microscopy. The root canals were sampled by flushing with saline solution at baseline and after the treatments. The number of bacteria in each canal was determined by plate count. The presence and the absence of E. faecalis in root canals were also demonstrated by polymerase chain reaction (PCR). There was a significant reduction in the bacterial population after all treatments (P < 0.001). The PAD, using both laser systems, and the sonic activated NaOCl irrigation were significantly more effective than diode irradiation and single NaOCl irrigation in reducing CFUs (P < 0.05). High-power diode laser and single NaOCl irrigation had an equal antibacterial effect (P > 0.05). The PAD and EndoActivator system were more successful in reducing the root canal infection than the diode laser and NaOCl syringe irrigation alone.

Antimicrobial efficacy of a high power diode laser, photoactivated disinfection, conventional and sonic activated irrigation during endodontic therapy

Antimicrobial efficacy of a high power diode laser, photoactivated disinfection, conventional and sonic activated irrigation during endodontic therapy

Using photoactivated disinfection and chemical agents in remineralization of initial caries

Using photoactivated disinfection and chemical agents in remineralization of initial caries

Using photoactivated disinfection and DIAGNOdent to increase Tunnel technique success

Using photoactivated disinfection and DIAGNOdent to increase Tunnel technique success

Temperature changes in periodontal tissues during photo-activated disinfection

Temperature changes in periodontal tissues during photo-activated disinfection

In vitro study of temperature changes of external root surface during photo-activated disinfection

In vitro study of temperature changes of external root surface during photo-activated disinfection

Photoactivated Disinfection (PAD) in Endodontics: an in vitro Microbiological Evaluation

The objective of the present study was the in vitro evaluation by MTT test of the antimicrobial effect of photoactivated disinfection (PAD) and, comparatively, of a conventional 5.25% NaOCl irrigating solution. Enterococcus faecalis, Streptococcus mutans and Streptococcus sanguis strains were selected for the test. Freshly extracted single-rooted human teeth were endodontically treated, inoculated with bacterial strains and then divided into different groups, each of them treated with PAD, with PAD plus 0.5% NaOCl solution, with TBO, with PAD for longer time and with 5% NaOCl solution (positive control). The results were significantly different among the various groups, and for Enterococcus faecalis, Streptococcus mutans and Streptococcus sanguis. PAD applied for a longer time (in respect to manufacturer's instructions) or PAD associated to 5% NaOCl showed the significantly higher antibacterial effects.

Evaluation of the effect of photoactivated disinfection with Radachlorin ® against Streptococcus mutans (an in vitro study)

The use of photoactivated disinfection has had a significant medical and technological effect in bacterial inactivation, as an alternative to conventional antimicrobial methods. The main goal of this study was to investigate the effect of photoactivated disinfection on Streptococcus mutans, when Radachlorin(®) was used as a photosensitizer. Streptococcus mutans samples of two different initial concentrations were treated with Radachlorin(®) gel (0.1%), irradiated by the light of a He-Ne laser (633nm), with energy density of 6J/cm(2), and cell viability was evaluated after culturing. It was observed that the combination of Radachlorin(®) and laser was more effective than Radachlorin(®) or laser alone (p<0.05), in reduction of S. mutans and Radachlorin(®) was cytotoxic, in the dark, only for the lower concentration of bacteria. Lower concentration of S. mutans resulted in higher amount of killing, in the case of using Radachlorin(®) with or without laser. The photoactivation of Radachlorin(®) using a He-Ne laser could inactivate S. mutans to a significant level. In addition Radachlorin(®) might be cytotoxic in the dark, for the lower concentration of bacteria.

Disinfection of clinical materials using photo-activated tolonium chloride solution

Photo-activated disinfection is beginning to be used in dental surgery to treat deep seated bacterial infection. It works by combining a photosensitiser and light of a specific frequency to generate singlet oxygen which is toxic to many types of bacteria. It is suggested that this technique could be used as a means to help treat infection more generally. To do so, it needs to work with materials and geometries exhibiting different physical and optical characteristics to teeth. In these trials, samples of stainless steel and polymethylmethacrylate were exposed to bacterial solutions of Staphylococcus aureus and Staphylococcus epidermis. These were treated with tolonium chloride-based photo-activated disinfection regimes showing positive results with typically 4 log10 reductions in colony forming units. Tests were also carried out using slotted samples to represent geometric features which might be found on implants. These tests, showed disinfectant effect however to a much lesser degree. © 2011 Inderscience Enterprises Ltd.