Photodynamic therapy in combating the causative microorganisms from endodontic infections

Photodynamic therapy (PDT) is presented as a promising antimicrobial therapy that can eliminate microorganisms present in endodontic infections. This treatment is based on the use of a nontoxic photosensitizing agent followed by irradiation of a resonant light source being capable of generating highly reactive species that are harmful to microorganisms. The purpose of this paper is to review the dental literature about the main factors that encompass the use of PDT combined with endodontic treatment for decontamination of the root canal system. A literature search was performed using the following index databases: PubMed, ISI Web of Knowledge and MedLine, between 2000 and 2014, looking for studies regarding antimicrobial action of PDT and its application to endodontic therapy. It was observed that despite numerous promising results, it is still necessary to establish different parameters so that PDT can be used with maximum effectiveness in eliminating microorganisms that cause endodontic infections.

Antimicrobial photodynamic therapy for inactivation of biofilms formed by oral key pathogens

With increasing numbers of antibiotic-resistant pathogens all over the world there is a pressing need for strategies that are capable of inactivating biofilm-state pathogens with less potential of developing resistances in pathogens. Antimicrobial strategies of that kind are especially needed in dentistry in order to avoid the usage of antibiotics for treatment of periodontal, endodontic or mucosal topical infections caused by bacterial or yeast biofilms. One possible option could be the antimicrobial photodynamic therapy (aPDT), whereby the lethal effect of aPDT is based on the principle that visible light activates a photosensitizer (PS), leading to the formation of reactive oxygen species, e.g., singlet oxygen, which induce phototoxicity immediately during illumination. Many compounds have been described as potential PS for aPDT against bacterial and yeast biofilms so far, but conflicting results have been reported. Therefore, the aim of the present review is to outline the actual state of the art regarding the potential of aPDT for inactivation of biofilms formed in vitro with a main focus on those formed by oral key pathogens and structured regarding the distinct types of PS.

Ru(II) dyads derived from 2-(1-pyrenyl)-1H-imidazo[4,5-f][1,10]phenanthroline: versatile photosensitizers for photodynamic applications

Combining the best attributes of organic photosensitizers with those of coordination complexes is an elegant way to achieve prolonged excited state lifetimes in Ru(II) dyads. Not only do their reduced radiative and nonradiative rates provide ample time for photosensitization of reactive oxygen species at low oxygen tension but they also harness the unique properties of (3)IL states that can act as discrete units or in concert with (3)MLCT states. The imidazo[4,5-f][1,10]phenanthroline framework provides a convenient tether for linking π-expansive ligands such as pyrene to a Ru(II) scaffold, and the stabilizing coligands can fine-tune the chemical and biological properties of these bichromophoric systems. The resulting dyads described in this study exhibited nanomolar light cytotoxicities against cancer cells with photocytotoxicity indices exceeding 400 for some coligands employed. This potency extended to bacteria, where concentrations as low as 10 nM destroyed 75% of a bacterial population. Notably, these dyads remained extremely active against biofilm with light photocytotoxicities against these more resistant bacterial populations in the 10-100 nM regime. The results from this study demonstrate the versatility of these highly potent photosensitizers in destroying both cancer and bacterial cells and expand the scope of compounds that utilize low-lying (3)IL states for photobiological applications.

Comparative efficacy of photo-activated disinfection and calcium hydroxide for disinfection of remaining carious dentin in deep cavities: a clinical study

OBJECTIVES

To comparatively evaluate the efficacy of photo-activated disinfection (PAD), calcium hydroxide (CH) and their combination on the treatment outcome of indirect pulp treatment (IPT).

MATERIALS AND METHODS

Institutional ethical clearance and informed consent of the patients were taken. The study was also registered with clinical registry of India. Sixty permanent molars exhibiting deep occlusal carious lesion in patients with the age range of 18 - 22 yr were included. Clinical and radiographic evaluation and set inclusion and exclusion criteria's were followed. Gross caries excavation was accomplished. In group I (n = 20) PAD was applied for sixty seconds. In group II (n = 20), CH was applied to the remaining carious dentin, while in group III (n = 20), PAD application was followed by CH placement. The teeth were permanently restored. They were clinically and radiographically followed-up at 45 day, 6 mon and 12 mon. Relative density of the remaining affected dentin was measured by 'Radiovisiography (RVG) densitometric' analysis.

RESULTS

Successful outcome with an increase in radiographic grey values were observed in all three groups. However, on inter-group comparison, this change was not significant (p > 0.05).

CONCLUSIONS

PAD and CH both have equal disinfection efficacy in the treatment of deep carious dentin. PAD alone is as effective for treatment of deep carious lesion as calcium hydroxide and hence can be used as an alternative to CH. They can be used independently in IPT, since combining both does not offer any additional therapeutic benefits.

Infliximab attenuates inflammatory osteolysis in a model of periodontitis in Wistar rats

Periodontitis is a chronic inflammatory disease related to tooth loss in adults. Infliximab is a chimeric monoclonal antibody against TNF-α and is prescribed for the treatment of systemic inflammatory diseases. This study aimed to investigate the role of infliximab on experimental periodontal disease (EPD). EPD was induced by passing a 3.0 nylon thread around the upper left second molar in Wistar rats. Animals were either treated with intravenous infliximab (1, 5, 7, and 10 mg/kg) or saline solution 30 min before the periodontitis induction and were followed until they were sacrificed on the 11th day. A subset of rats was euthanized on the third day for analysis of gingival myeloperoxidase (MPO) and the blood MPO granulocyte index. In addition, we analyzed the bone loss index (BLI), the periodontal histopathological score, and the periodontal collagen network using confocal microscopy. We also analyzed metalloproteinase-1/-8, RANK, RANK-L, and osteoprotegerin in maxillary tissue by immunohistochemistry Gingival MPO, IL-1β, TNF-α were measured by ELISA. EPD caused leukocytosis, significant increases in BLI and gingival pro-inflammatory cytokines and cell infiltrates, with worse histopathological scores and periodontal collagen derangement. Infliximab (5 mg/kg) reduced granulocyte blood counts, gingival IL-1β, TNF-α, and MPO levels, diminished MMP-1/-8, RANK, and RANK-L bone immunolabeling with better periodontal histopathological scores and collagen network in comparison with the challenged saline group. We concluded that infliximab had significant anti-inflammatory and bone-protective effects in Wistar rats challenged by periodontitis.

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

INTRODUCTION

Photodynamic therapy was introduced as an adjuvant to conventional chemo-mechanical debridement during endodontic treatment to overcome the persistence of biofilms. The aim of this study was to evaluate the ability of photodynamic therapy (PDT) to disrupt an experimental microbial biofilm inside the root canal in a clinically applicable working time.

MATERIALS AND METHODS

Thirty extracted teeth were prepared and then divided in three groups. All samples were infected with an artificially formed biofilm made of Enterococcus faecalis, Streptococcus salivarius, Porphyromonas gingivalis and Prevotella intermedia bacteria. First group was treated with Aseptim Plus® photo-activated (LED) disinfection system, second group by a 650 nm Diode Laser and Toluidine blue as photosensitizer, and the third group, as control group, by ultrasonic irrigation (PUI) using EDTA 17% and NaOCl 2.6% solutions. The working time for all three groups was fixed at 3 min. Presence or absence of biofilm was assessed by aerobic and anaerobic cultures.

RESULTS

There was no statistically significant difference between results obtained from groups treated by Aseptim Plus® and Diode Laser (P<0.6267). In cultures of both groups there was a maximal bacterial growth. The group that was treated by ultrasonic irrigation and NaOCl and EDTA solutions had the best results (P<0.0001): there was a statistically significant reduction of bacterial load and destruction of microbial biofilm.

CONCLUSION

Under the condition of this study, Photodynamic therapy could not disrupt endodontic artificial microbial biofilm and could not inhibit bacterial growth in a clinically favorable working time.

Phototargeting human periodontal pathogens in vivo

The effects of blue light at 455 nm were investigated on the bacterial composition of human dental plaque in vivo. Eleven subjects who refrained from brushing for 3 days before and during phototherapy participated in the study. Light with a power density of 70 mW/cm(2) was applied to the buccal surfaces of premolar and molar teeth on one side of the mouth twice daily for 2 min over a period of 4 days. Dental plaque was harvested at baseline and again at the end of 4 days from eight posterior teeth on both the exposed side and unexposed sides of the mouth. Microbiological changes were monitored by checkerboard DNA probe analysis of 40 periodontal bacteria. The proportions of black-pigmented species Porphyromonas gingivalis and Prevotella intermedia were significantly reduced on the exposed side from their original proportions by 25 and 56 %, respectively, while no change was observed to the unexposed side. Five other species showed the greatest proportional reduction of the light-exposed side relative to the unexposed side. These species were Streptococcus intermedius, Fusobacterium nucleatum ss. vincentii, Fusobacterium nucleatum ss. polymorphum, Fusobacterium periodonticum, and Capnocytophaga sputigena. At the same time, the percentage of gingival areas scored as being red decreased on the side exposed to light from 48 to 42 %, whereas the percentage scored as red increased on the unexposed side from 53 to 56 %. No adverse effects were found or reported in this study. The present study proposes a new method to modify the ecosystem in dental plaque by phototherapy and introduces a new avenue of prophylactic treatment for periodontal diseases.

Minimally-invasive non-surgical periodontal therapy

Periodontitis is a complex disease that has both oral and systemic consequences. The treatment of periodontitis may be both surgical and non-surgical but, in recent years, there has been a shift towards managing disease non-surgically in preference to surgery. Fundamental to all types of therapy is the patient's role in disease control, in the form of self-performed plaque control, and it is important that the patient understands this. Non-surgical periodontal therapy has a long history and has traditionally been carried out using a variety of hand and powered instruments, the objective being root surface disinfection by the removal of plaque, calculus and contaminated root cementum. However, over the last 30 years or so, it has become apparent that calculus does not cause disease, cementum does not become significantly infected and bacteria and their toxins are only loosely adherent to the diseased root surface. This has led to the development of less invasive instrumentation principles which may be better for patients, more cost-effective and more easily applied in different clinical settings.

CLINICAL RELEVANCE

This paper aims to describe and justify a minimally-invasive approach to the management of the diseased root surface in periodontitis, to clarify the terminology used and to suggest how these principles may be applied in general practice.

Effect of hydrosoluble chlorine-mediated antimicrobial photodynamic therapy on clinical parameters and cytokine profile in ligature-induced periodontitis in dogs

BACKGROUND

Recently, a hydrosoluble chlorine composed of sodium salts chlorine e6, chlorine p6, and purpurine-5 has been shown to be a promising photosensitizer in antimicrobial photodynamic therapy (aPDT). The aim of this study is to evaluate the effects of adjunctive application of hydrosoluble chlorine-mediated aPDT compared with scaling and root planing (SRP) alone on clinical parameters and cytokine levels in gingival crevicular fluid of dogs with experimental periodontitis.

METHODS

Periodontal disease was induced by placing silk ligatures around both maxillary and mandibular teeth. After establishment of attachment loss, full-mouth SRP was performed in all dogs. One day after SRP, each quadrant randomly received one of the following treatment modalities: hydrosoluble chlorine plus diode laser (wavelength 662 nm, power 100 mW, continuous mode, time of irradiation 20 seconds), hydrosoluble chlorine alone, laser alone, or no adjunctive treatment. The same adjunctive procedure was repeated 1 week later. Clinical parameters including periodontal probing depth, clinical attachment level, and bleeding on probing, as well as crevicular levels of interleukin-1β and tumor necrosis factor-α, were evaluated at baseline, at 3 weeks, and at 3 months after treatment.

RESULTS

After both 3 weeks and 3 months, all treatment groups showed significant improvement in all clinical and immunologic parameters (P <0.001). No significant differences were found between the four groups with regard to the measured parameters (P >0.05).

CONCLUSION

Based on the results of this study, adjunctive use of hydrosoluble chlorine-mediated aPDT with the current setting has no additional effect on the clinical parameters or proinflammatory cytokine levels in ligature-induced periodontitis.

Low-cost periodontal therapy

Periodontitis is a complex infectious disease that affects low-income individuals disproportionately. Periodontitis is associated with specific bacterial species and herpesviruses, and successful prevention and treatment of the disease is contingent upon effective control of these pathogens. This article presents an efficacious, highly safe, minimally invasive, practical and low-cost periodontal therapy that involves professional and patient-administered mechanical therapy and antimicrobial agents. The major components are scaling for calculus removal, periodontal pocket irrigation with potent antiseptics, and treatment with systemic antibiotics for advanced disease. Povidone-iodine and sodium hypochlorite have all the characteristics for becoming the first-choice antiseptics in the management of periodontal diseases. Both agents show excellent antibacterial and antiviral properties, are readily available throughout the world, have been safely used in periodontal therapy for decades, offer significant benefits for individuals with very limited financial resources, and are well accepted by most dental professionals and patients. Four per cent chlorhexidine applied with a toothbrush to the most posterior part to the tongue dorsum can markedly reduce or eliminate halitosis in most individuals. Systemic antibiotics are used to treat periodontopathic bacteria that are not readily reached by topical therapy, such as pathogens within gingival tissue, within furcation defects, at the base of periodontal pockets, and on the tongue, tonsils and buccal mucosae. Valuable antibiotic therapies are amoxicillin-metronidazole (250 mg of amoxicillin and 250 mg of metronidazole, three times daily for 8 days) for young and middle-aged patients, and ciprofloxacin-metronidazole (500 mg of each, twice daily for 8 days) for elderly patients and for patients in developing countries who frequently harbor enteric rods subgingivally. Scaling to remove dental calculus and the prudent use of inexpensive antimicrobial agents can significantly retard or arrest progressive periodontitis in the great majority of patients.

Photodynamic inactivation of Candida albicans mediated by a low density of light energy

Shorter times and lower energies of application of light sources are desirable to use photodynamic antimicrobial chemotherapy (PACT) to the clinical control of candidiasis, especially among babies and children. Light energies ranging from 39.5 to 100 J/cm(2) were previously applied to kill Candida albicans by PACT. The present study evaluated the efficacy of a combination of 0.05 mg/mL toluidine blue O (TBO) and a short time of application (60 s) and a low density of light energy (18 J/cm(2)) of a red light-emitting diode (LED) in killing C. albicans planktonic cells. Standard suspensions of C. albicans were randomly assigned for four treatment groups: control (L-P-), LED alone (L+P-), TBO alone (L-P+), and PACT (L+P+). After treatments, serial dilutions of suspensions were prepared and streaked on Sabouraud dextrose agar to determine colony-forming units of C. albicans per milliliter (CFU/mL). The results were analyzed by ANOVA and Tukey's post-hoc test (P < 0.05). PACT significantly reduced CFUs of C. albicans in comparison to other three treatments. Our results demonstrated a fungicidal effect of PACT mediated by a shorter time of application of LED on C. albicans planktonic cells. Further in vivo studies are needed to elucidate the efficacy of PACT to treat human fungal infections.

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

Aim

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.

Materials and Methods

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/cm2), 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.

Results

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).

Conclusion

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.

The photodynamic therapy on Streptococcus mutans biofilms using erythrosine and dental halogen curing unit

The purpose of our study was to evaluate the effect of photodynamic therapy (PDT), using erythrosine as a photosensitizing agent and a dental halogen curing unit as a light source, on Streptococcus mutans in a biofilm phase. The S. mutans biofilms were formed in a 24-well cell culture cluster. Test groups consisted of biofilms divided into four groups: group 1: no photosensitizer or light irradiation treatment (control group); group 2: photosensitizer treatment alone; group 3: light irradiation alone; group 4: photosensitizer treatment and light irradiation. After treatments, the numbers of colony-forming unit (CFU) were counted and samples were examined by confocal laser scanning fluorescence microscopy (CLSM). Only group 4 (combined treatment) resulted in significant increases in cell death, with rates of 75% and 55% after 8 h of incubation, and 74% and 42% at 12 h, for biofilms formed in brain–heart infusion (BHI) broth supplemented with 0% or 0.1% sucrose, respectively. Therefore, PDT of S. mutans biofilms using a combination of erythrosine and a dental halogen curing unit, both widely used in dental clinics, resulted in a significant increase in cell death. The PDT effects are decreased in biofilms that form in the presence of sucrose.

Photodynamic effects of methylene blue-loaded polymeric nanoparticles on dental plaque bacteria

BACKGROUND AND OBJECTIVES

Photodynamic therapy (PDT) is increasingly being explored for treatment of oral infections. Here, we investigate the effect of PDT on human dental plaque bacteria in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles with a positive or negative charge and red light at 665 nm.

STUDY DESIGN/MATERIALS AND METHODS

Dental plaque samples were obtained from 14 patients with chronic periodontitis. Suspensions of plaque microorganisms from seven patients were sensitized with anionic, cationic PLGA nanoparticles (50 µg/ml equivalent to MB) or free MB (50 µg/ml) for 20 min followed by exposure to red light for 5 min with a power density of 100 mW/cm2 . Polymicrobial oral biofilms, which were developed on blood agar in 96-well plates from dental plaque inocula obtained from seven patients, were also exposed to PDT as above. Following the treatment, survival fractions were calculated by counting the number of colony-forming units.

RESULTS

The cationic MB-loaded nanoparticles exhibited greater bacterial phototoxicity in both planktonic and biofilm phase compared to anionic MB-loaded nanoparticles and free MB, but results were not significantly different (P > 0.05).

CONCLUSION

Cationic MB-loaded PLGA nanoparticles have the potential to be used as carriers of MB for PDT systems.

The effect of irradiation wavelengths and the crystal structures of titanium dioxide on the formation of singlet oxygen for bacterial killing

Safe and effective methods for oral bacterial disinfection have been desired, since bacteria cause many infectious diseases such as dental caries, periodontal disease, and endodontic infections. Singlet oxygen ((1)O(2)) is attractive, because it is toxic to prokaryotic cells, but not to eukaryotic cells. We selected irradiation of titanium dioxide (TiO(2)) as a source of (1)O(2), because it has been used in sunscreens and cosmetic products without complications. In order to establish the optimal oral photodynamic therapy conditions, we measured the rate of (1)O(2) formation from the irradiated anatase or rutile forms of TiO(2) using 365 or 405 nm lamps. The rate of (1)O(2) formation decreased in the following order: anatase, 365 nm > rutile, 405 nm > rutile, 365 nm > anatase, 405 nm. Therefore, we concluded that irradiation of the rutile form of TiO(2) by a 405 nm lamp is the most favorable photodynamic therapy condition, because visible light is more desirable than UV light from the viewpoint of patient safety. We also confirmed that there was no direct HO(•) formation from the irradiated TiO(2).

Study bioprospecting of medicinal plant extracts of the semiarid northeast: contribution to the control of oral microorganisms

Dental pathologies can be caused by plaque-forming bacteria and yeast, which reside in the oral cavity. The bacteria growing in dental plaque, a naturally occurring biofilm, display increased resistance to antimicrobial agents. The objective was the evaluation of a preclinical assay of medicinal plants of the semiarid region from the northeast against oral pathogenic microorganism, aiming at bioprospecting a new product. The selection of plant material for this study was based on the ethnobotanical data on the traditional use of plants from the semiarid region. The thirty extracts were subjected to the determination of antibiofilm activity against gram-positive, gram-negative bacteria and yeast. The hydroalcoholic extract which showed positive antibiofilm activity against most of the microorganisms tested in agar diffusion assay was further tested for the determination of minimum inhibitory concentration (MIC) and Bioassay with Artemia salina. Plant samples tested in this study exhibited good antibiofilm activity for the treatment of oral problems. The Schinopsis brasiliensis showed greater activity for Pseudomonas aeruginosa and Staphylococcus aureus, but toxicity against Artemia salina.

Bactericidal action of photogenerated singlet oxygen from photosensitizers used in plaque disclosing agents

Background

Photodynamic therapy (PDT) has been suggested as an efficient clinical approach for the treatment of dental plaque in the field of dental care. In PDT, once the photosensitizer is irradiated with light of a specific wavelength, it transfers the excitation energy to molecular oxygen, which gives rise to singlet oxygen.

Methodology/Principal Findings

Since plaque disclosing agents usually contain photosensitizers such as rose bengal, erythrosine, and phloxine, they could be used for PTD upon photoactivation. The aim of the present study is to compare the ability of these three photosensitizers to produce singlet oxygen in relation to their bactericidal activity. The generation rates of singlet oxygen determined by applying an electron spin resonance technique were in the order phloxine > erythrosine ≒ rose bengal. On the other hand, rose bengal showed the highest bactericidal activity against Streptococcus mutans, a major causative pathogen of caries, followed by erythrosine and phloxine, both of which showed activity similar to each other. One of the reasons for the discrepancy between the singlet oxygen generating ability and bactericidal activity was the incorporation efficiency of the photosensitizers into the bacterial cells. The incorporation rate of rose bengal was the highest among the three photosensitizers examined in the present study, likely leading to the highest bactericidal activity. Meanwhile, the addition of L-histidine, a singlet oxygen quencher, cancelled the bactericidal activity of any of the three photoactivated photosensitizers, proving that singlet oxygen was responsible for the bactericidal action.

Conclusions

It is strongly suggested that rose bengal is a suitable photosensitizer for the plaque disclosing agents as compared to the other two photosensitizers, phloxine and erythrosine, when used for PDT.

Effect of photodynamic therapy, diode laser, and deep scaling on cytokine and acute-phase protein levels in gingival crevicular fluid of residual periodontal pockets

BACKGROUND

There is an ongoing controversy on the benefits of treatment protocols, including dental lasers and photodynamic therapy (PDT). The purpose of this study is to compare the local biologic effects of PDT, diode soft laser (DSL) therapy, and conventional deep scaling and root planing (SRP) in residual pockets.

METHODS

Thirty-two individuals were included based on a history of previous treatment for periodontitis and the persistence of sites with probing depths >4 mm and bleeding on probing. Residual pockets were debrided with an ultrasonic device and then randomly assigned either to PDT, DSL, or SRP. Gingival crevicular fluid was collected before treatment, after 14 days, and at 2 and 6 months. Levels of 13 cytokines and nine acute-phase proteins were measured using a bead-based multiplexing analysis system.

RESULTS

Treatment with PDT, DSL, or SRP led to significant changes in several cytokines and acute-phase proteins: Compared with baseline, levels of interleukin-17, basic fibroblast growth factor, granulocyte colony-stimulating factor, granulocyte macrophage colony-stimulating factor, and macrophage inflammatory protein 1-α were lower 14 days and 2 months after treatment. Except for granulocyte colony-stimulating factor, these differences remained significant throughout the observation period. The levels of five acute-phase proteins (α-2 macroglobulin, haptoglobin, serum amyloid P, procalcitonin, and tissue plasminogen activator) were significantly higher at 6 months than at baseline. No significant differences were observed among the three treatment modalities at any time point for any biochemical parameter.

CONCLUSIONS

Levels of several cytokines and acute-phase proteins significantly changed after treatment regardless of treatment modality. There was no evidence for a specific DSL- or PDT-enhanced expression of inflammatory mediators.

Photodynamic therapy in the treatment of chronic periodontitis: a systematic review and meta-analysis

This meta-analysis was conducted to investigate the efficacy and safety of antimicrobial photodynamic therapy used alone or adjunctive to scaling root planing in patients with chronic periodontitis. The meta-analysis was conducted according to the QUOROM statement and recommendations of the Cochrane Collaboration. An extensive literature search was performed on seven databases, followed by a manual search. Weighted mean differences and 95% confidence intervals were calculated for clinical attachment level, probing depth and gingival recession. The I(2) test was used for inter-study heterogeneity; visual asymmetry inspection of the funnel plot, Egger's regression test and the trim-and-fill method were used to investigate publication bias. At 3 months, significant differences in clinical attachment level (p = 0.006) and probing depth reduction (p = 0.02) were observed for scaling root planing with antimicrobial photodynamic therapy, while no significant differences were retrieved for antimicrobial photodynamic therapy used alone; at 6 months no significant differences were observed for any investigated outcome. Neither heterogeneity nor publication bias was detected. The use of antimicrobial photodynamic therapy adjunctive to conventional treatment provides short-term benefits, but microbiological outcomes are contradictory. There is no evidence of effectiveness for the use of antimicrobial photodynamic therapy as alternative to scaling root planing. Long-term randomized controlled clinical trials reporting data on microbiological changes and costs are needed to support the long-term efficacy of adjunctive antimicrobial photodynamic therapy and the reliability of antimicrobial photodynamic therapy as alternative treatment to scaling root planing.

Butyrate enhancement of inteleukin-1β production via activation of oxidative stress pathways in lipopolysaccharide-stimulated THP-1 cells

Safe and effective methods for oral bacterial disinfection have been desired, since bacteria cause many infectious diseases such as dental caries, periodontal disease, and endodontic infections. Singlet oxygen (¹O₂) is attractive, because it is toxic to prokaryotic cells, but not to eukaryotic cells. We selected irradiation of titanium dioxide (TiO₂) as a source of ¹O₂, because it has been used in sunscreens and cosmetic products without complications. In order to establish the optimal oral photodynamic therapy conditions, we measured the rate of ¹O₂ formation from the irradiated anatase or rutile forms of TiO₂ using 365 or 405 nm lamps. The rate of ¹O₂ formation decreased in the following order: anatase, 365 nm > rutile, 405 nm > rutile, 365 nm > anatase, 405 nm. Therefore, we concluded that irradiation of the rutile form of TiO₂ by a 405 nm lamp is the most favorable photodynamic therapy condition, because visible light is more desirable than UV light from the viewpoint of patient safety. We also confirmed that there was no direct HO^• formation from the irradiated TiO₂.