The effect of a single episode of antimicrobial photodynamic therapy in the treatment of experimental periodontitis. Microbiological profile and cytokine pattern in the dog mandible

Guidance on the assessment of the functionality of biomaterials for periodontal tissue regeneration: Methodologies and testing procedures

Innovative biomaterials and tissue engineering strategies show great promise in regenerating periodontal tissues. This guidance provides an overview and detailed recommendations for evaluating the biological functionality of these new biomaterials in vitro, focusing on mineralization, immunomodulatory effects, cellular differentiation, and angiogenesis. Additionally, it discusses the use of in vivo experimental models that mimic periodontitis and scrutinizes methods such as osteogenic differentiation, immunomodulation, and anti-inflammatory responses to assess the effectiveness of these biomaterials in promoting periodontal tissue reconstruction. The guidance also addresses translating these findings to clinical applications, including using large animal models. This article aims to provide general recommendations for assessing the biological performance of novel materials and scaffold-based strategies using in vitro and in vivo (animal models), examining their advantages, disadvantages, and methodologies to guide effective research and clinical translation of regenerative treatments in periodontology.

Brain-derived neurotrophic factor promotes bone regeneration in a canine model of peri-implantitis

PURPOSE

The present study aims to determine whether the brain-derived neurotrophic factor (BDNF)/high-molecular-weight hyaluronic acid (HMW-HA) complex could regenerate bone around implants lost due to peri-implantitis.

METHODS

Dogs had their three premolars extracted, and three implants were placed on each side. After osseointegration, 3-0 silk threads were ligated around the healing abutment for 12 weeks. Implants were classified into four groups-no treatment (control group), non-surgical debridement (debridement group), non-surgical debridement with application of HMW-HA (HMW-HA group), and non-surgical debridement with application of BDNF/HMW-HA complex (BDNF/HMW-HA group). Probing pocket depth (PPD), attachment level (AL), and bleeding on probing (BOP) were recorded before and 12 weeks after each treatment. Standardized intraoral radiographs were obtained, and histological analysis was conducted.

RESULTS

The bone level on radiographs significantly improved (median -0.15 mm, IQR -0.31 to 0.10) only in the BDNF/HMW-HA group, while changes in PPD and AL were similar to those in other groups. The BOP positivity rate decreased in the debridement and BDNF/HMW-HA groups. Unlike images of the other groups, histological images of the BDNF/HMW-HA group showed no epithelial migration toward the tip of the implant. Inflammatory cell infiltration was reduced compared with that in the other groups. New bone was observed around the implants only in the BDNF/HMW-HA group.

CONCLUSIONS

The BDNF/HMW-HA complex appears to promote bone regeneration when combined with non-surgical debridement for peri-implantitis.

Diode laser as an adjunctive treatment for periodontitis: Arandomized controlled trial

OBJECTIVE

The aim of this randomized controlled trial was to assess clinical and patient reported outcomes of subgingival instrumentation (SI) with adjunctive use of diode laser (DL) versus SI alone in the treatment of periodontitis.

METHODS

Participants requiring non-surgical periodontal treatment were randomly allocated into two treatment groups: SI with DL or SI alone. Clinical parameters [full mouth bleeding and plaque scores (FMBS and FMPS), probing pocket depth and clinical attachment level] were recorded at baseline, three and 6 months post-treatment. Visual analogue scale was used to evaluate postoperative participants' perception of pain, swelling, bleeding, bruising and root sensitivity. The impact of periodontal treatment on quality of life was assessed using the General Oral Health Assessment Index (GOHAI) at 6 months.

RESULTS

A total of 22 participants with stage III/IV periodontitis completed the 6-month follow-up. SI with or without DL resulted in statistically significant reduction in FMBS, FMPS, PPDs, and percentage of PPDs of ≥5 mm at 3- and 6-month follow-up visits (p = 0.001 to <0.001). The participants in SI/DL group had a greater reduction in the percentage of deep PPDs (≥5 mm) compared to those receiving SI alone, but statistically significant differences between the two groups were not observed (16.40 ± 9.57 vs. 32.50 ± 38.76 at 3 months and 7.20 ± 6.86 vs. 19.50 ± 35.06 at 6 months). The difference in the mean total GOHAI scores was not statistically significant at 6 months with total GOHAI scores of 7.25 ± 2.45 and 5.40 ± 3.06 for SI and SI/DL groups, respectively.

CONCLUSION

Within the limitations of this study, the use of DL as an adjunct to SI in the treatment of stage III/IV periodontitis did not produce significant additional improvement in clinical parameters or patient reported outcomes in the 6-month observation period.

Antimicrobial photodynamic therapy in treatment of aggressive periodontitis (stage III, grade C periodontitis): A comparison between photodynamic therapy and antibiotic therapy as an adjunct to non-surgical periodontal treatment

BACKGROUND

Treatment of aggressive periodontitis (stage III, grade C periodontitis) represents a challenge. The aim of the study was to compare the long-term results of antimicrobial photodynamic therapy (aPDT) and antibiotic therapy as an adjunct to conventional non-surgical therapy in patients with aggressive periodontitis.

MATERIALS AND METHODS

Twenty subjects with untreated aggressive periodontitis (stage III, grade C periodontitis) were divided into two groups: the test group (TG) received non-surgical therapy and two sessions of aPDT using a laser (HELBO TheraLite laser) with a wavelength of 670 nm associated with HELBO Blue photosensitizer, and the control group (CG) received non-surgical therapy and antibiotics (amoxicillin 500 mg and metronidazole 400 mg, 7 days). Clinical parameters of probing depth, clinical attachment level and bleeding on probing (BOP) were assessed at baseline, 3, 6, 9 and 12 months after treatment.

RESULTS

The mean probing pocket depths at baseline were 3.68 mm in TG and 3.51 mm in CG. These values decreased to 2.77 mm (p < 0.05) and 2.54 mm (p < 0.05) 3 months after treatment and stayed decreased after 12 months. Clinical attachment levels at baseline were 3.88 mm in TG and 3.70 mm in CG. These values decreased to 3.06 mm (p < 0.05) and 2.80 mm (p < 0.05) after 3 months and stayed decreased after 12 months. We also found a decrease in BOP after 3, 6, 9 and 12 months in TG and in CG.

CONCLUSIONS

aPDT and antibiotics as an adjunct to non-surgical periodontal treatment lead to a comparable improvement in long term periodontal parameters.

Influence of photodynamic therapy, different final irrigants, and ultrasonic activation on the bond strength of glass fiber posts to root dentin

OBJECTIVE

To evaluate the influence of photodynamic therapy (PDT), different final irrigants, and ultrasonic activation (US) on the bond strength of glass fiber posts (GFP) to root dentin.

METHODS

One hundred twenty bovine roots were divided into 12 groups according to PDT application, the type of final endodontic irrigant, and US. The samples were divided into 12 groups (n = 10): G1-DW(distilled water); G2-DW+US; G3-17% EDTA; G4-17% EDTA+US; G5-17% GA (glycolic acid); G6-17% GA+US; G7-PDT+DW; G8-PDT+DW+US; G9-PDT+17% EDTA; G10-PDT+17% EDTA+US; G11-PDT+17% GA; G12-PDT+17% GA+US. After cementing the glass fiber posts with resin cement, roots were sectioned into 2-mm-thick slices. One slice from the cervical third and another from the middle third were used for the push out test (PO), and the other two for the diametral compression test (DC). Thus, 10 samples were obtained per third for each mechanical test (n = 10). Kruskal-Wallis and Student-Newman-Keuls tests were used to analyze PO and DC data, and Pearson's correlation test was used to verify the relationship between the variables. Failure patterns were analyzed with chi-square test.

RESULTS

Significant differences were found in the PO test among the experimental groups (p < 0.001; power=1.00). PDT improved bond strength when using EDTA. PDT and US increased bond strength when using GA. Favorable failure patterns occurred more frequently in Group GA+US. There was no correlation between data obtained with PO and DC tests (r = 0.112; p = 0.729).

CONCLUSION

PDT provided the highest bond strength values of GFP to root dentin when associated with GA and US or when associated only with EDTA.

Morphological Assessment of the Effect of Nanosecond Diode Laser Radiation With a Wavelength of 1265 nm on Periodontal Tissue in the Treatment of Apical Periodontitis: An Experimental Study

Introduction: There is a morphological assessment of the damaged area and the inflammatory response of periodontal tissues after therapy. It seems relevant to evaluate the reaction of the periapical tissues of the teeth of experimental animals after the treatment of simulated apical periodontitis using laser photodynamic therapy (PDT) and non-pigment laser transcanal microablation using morphological research. Methods: The lower incisors of 15 rabbits were used to simulate acute apical periodontitis of pulpal origin. Subsequently, the traditional treatment of teeth canals using mechanical cleaning and irrigation with antiseptic solution started. Then, three groups underwent different therapies - using PDT (n = 5; photosensitizer chlorin e6, [l = 660 nm, 60 mW/cm² ] for 2 minutes), using a new technology of transcanal laser ablation (n = 5; diode laser [l = 1265 nm, 180 mW/cm² ] for 3 minutes), and without additional treatment (n = 5). Laser therapy in two groups was carried out for 10 days once in 2 days. The animals were euthanized 10 days after the treatment started, decapitation was performed, and morphological specimens were studied under a microscope. Descriptive analysis (study of inflammatory apical infiltrate, bone regeneration of the alveoli and periodontal ligament) and quantitative analysis were performed. The data were statistically processed using the Kruskal-Wallis test. Results: The group treated with the new laser technology showed the best results with moderate lymph-macrophage infiltration and congested vessels, moderate neoangiogenesis and fibrogenesis. The size of the lesion was 506.4 mm², compared with the PDT group - 872.0 mm² (P ≤ 0.05). Conclusion: A decrease in the focus of inflammation, moderate neoangiogenesis and fibrogenesis in the periapical region when using transcanal laser microablation indicate the prospects of using the new technology in clinical practice in the complex therapy of apical periodontitis.

Clinical and biochemical effect of laser as an adjunct to non-surgical treatment of chronic periodontitis

Objectives

To evaluate the clinical and biochemical efficacy of laser therapy as an adjunct to non‐surgical treatment in chronic periodontitis.

Methods

A systematic search was performed through the PubMed, EMBASE, and Cochrane Library for eligible articles published as of May 2, 2020, supplemented by information search in the System for Information on Programme Literature in Europe and a manual literature search. Only randomized controlled trials (RCTs) used to compare the adjunctive use of laser and non‐surgical treatment alone with an observation period of at least 6 months were included.

Results

Sixteen RCTs with a total of 525 subjects were included. Meta‐analysis suggested that the additional use of laser to scaling and root planing (SRP) showed significant superiority over SRP alone among most of clinical parameters involved. Regarding the GCF, although volume in the laser group was lower at week 4 and 12, no significant difference was found regarding the cytokines level. Subgroup analysis revealed that the combined therapy produced no significant difference in PD, CAL and PI at most time points for studies in respect to smokers. No treatment‐related adverse events had been reported in the included studies.

Conclusions

Pooled analysis suggested that laser‐assisted non‐surgical treatment improved clinical outcome to SRP alone in the management of non‐smoking chronic periodontitis patients.

Influence of a glycolic acid-based final irrigant for photosensitizer removal of photodynamic therapy on the microhardness and colour change of the dentin structure

INTRODUCTION

This study aimed to evaluate the influence of glycolic acid-based final irrigant for photosensitizer removal of photodynamic therapy on the microhardness and colour change of the dentin structure.

METHODS

Eighty extracted single-rooted human incisors were used. Sample preparation and root split resulted in 160 samples, 80 samples being used for microhardness and 80 samples for colour change evaluation. In the first, PDT protocol was performed and 80 samples were randomly divided into 4 groups (n = 20), according to the final irrigation protocol: distilled water (DW); 17 % ethylenediaminetetraacetic acid (EDTA); QMix; 17 % glycolic acid (GA). Microhardness was evaluated using the Vicker tester, before and after, PDT and final irrigation protocols, calculating the percentage of microhardness reduction. In the second evaluation, PDT and final irrigation protocols were performed in the same way. Colour change was evaluated using digital spectrophotometer before and after these protocols, calculating the ΔE colour change using the CIELAB system (L*a*b* values). Specific statistical analysis was performed for both evaluations (α = 5%).

RESULTS

The highest percentage of microhardness reduction was observed in 17 % EDTA, QMix and 17 % GA groups, with no significant difference among them (p > 0.05). Furthermore, none of these protocols was effective in photosensitizer removal, and all final irrigation protocols were statically similar to control group (p > 0.05).

CONCLUSIONS

GA promotes microhardness reduction and also contributes to the colourization of dentin structure during the photosensitizer removal process, followingPDT .

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

BACKGROUND AND OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Evaluation of Systemic Inflammation Parameters in Dogs with Periodontitis

Periodontal diseases are the most common diseases in veterinary medicine. The first clinical finding is chewing difficulty, saliva flow and bad oral odor. It further develops into plaque and tartar formation, gingival inflammation and hemorrhagic appearance of the gingiva, periodontal pockets formation, alveolar bone resorption and tooth loss.

In this study an evaluation has been made to determine which degree reflects on the parameters of systemic inflammatory reaction with special attention to IL-6 (Interleukine-6), CRP (C-reactive protein), osteopontin, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GPx) and Ig (Immunglobulins = Total protein – Albumin) and hematological parameters in dogs with periodontitis.

Two groups have been defined in this study. The first group included 10 healthy and owned dogs as a control group. The second group consisted of 10 owned dogs with moderate-severe periodontitis.

The difference between monocyte (p <0.001) and neutrophil (p <0.05) counts was found to be significant. In addition, the difference between SOD, MDA, glutathione peroxidase, CRP, IL-6 measurements in group 1 and group 2 was significant. (p <0.001). The level of osteopontin in moderate-severe periodontitis cases was found significantly higher than the level measured in the healthy group.

Measured values in the moderate-severe periodontitis cases are higher than the healthy group in terms of CRP, IL-6, and osteopontin levels. Increasing severity of periodontitis was associated with changes in oxidative stress parameters: increased MDA, decreased SOD and glutathione peroxidase levels. These differences provide important information about the evaluation of the cellular responses. There is a need for continued research into the systemic impact of periodontal disease.

Photodynamic antimicrobial chemotherapy has an overt killing effect on periodontal pathogens? A systematic review of experimental studies

The periodontal disease (PD) etiology is mainly associated with some bacterial strains, such as Porphyromonas gingivalis (P. gingivalis). Nonsurgical root scaling (e.g., antibiotics) may achieve a temporary decrease in the P. gingivalis level, yet it cannot eradicate the microorganism. Moreover, antibiotics can lead to bacterial resistance and undesirable side effects. This systematic review was performed to identify animal data defining antimicrobial photodynamic therapy (PACT) role on experimental PD models in the treatment of P. gingivalis. Embase, MEDLINE, and PubMed were examined for studies published from January 1980 to August 2018. MeSH terms and Scopus data were used to find more related keywords. Four studies were selected and reviewed by two independent researches with a structured tool for rating the research quality. The beneficial effect of PACT included reductions in P. gingivalis counts, bleeding on probing, redness, and inflammation on multiple sites (i.e., first molar, dental implants; subgingival; and mandibular premolars). Although our results suggest that PACT displays antimicrobial action on P. gingivalis, thus improving the PD, a nonuniformity in the PACT protocol and the limited number of studies included lead to consider that the bactericidal efficacy of PACT against periodontal pathogens in PD remains unclear.

Chlamydia pneumoniae is present in the dental plaque of periodontitis patients and stimulates an inflammatory response in gingival epithelial cells

Chlamydia pneumoniae is an airborne, Gram-negative, obligate intracellular bacterium which causes human respiratory infections and has been associated with atherosclerosis. Because individuals with periodontitis are at greater risk for atherosclerosis as well as respiratory infections, we in-vestigated the role of C. pneumoniae in inflammation and periodontal dis-ease. We found that C. pneumoniae was more frequently found in subgingival dental plaque obtained from periodontally diseased sites of the mouth versus healthy sites. The known periodontal pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, were also found in the plaque. In addition, C. pneumoniae could efficiently invade human gingival epithelial cells (GECs) in vitro, causing translocation of NF-κB to the nucleus along with increased secretion of mature IL-1β cytokine. Supernatants collected from C. pneumoniae-infected GECs showed increased activation of caspase-1 protein, which was significantly reduced when nlrp3 gene expression was silenced using shRNA lentiviral vectors. Our results demonstrate that C. pneumoniae was found in higher levels in periodontitis patients compared to control pa-tients. Additionally, C. pneumoniae could infect GECs, leading to inflammation caused by activation of NF-κB and the NLRP3 inflammasome. We propose that the presence of C. pneumoniae in subgingival dental plaque may contribute to periodontal disease and could be used as a potential risk indicator of perio-dontal disease.

Impact of photodynamic therapy versus ultrasonic scaler on gingival health during treatment with orthodontic fixed appliances

OBJECTIVES

Poor oral hygiene during treatment with fixed appliances results in plaque accumulation. The presence of bacteria in the gingival crevice triggers an inflammatory reaction in the gingival tissues. The aim of this study was to compare the impact of two preventive treatments, photodynamic therapy (PDT), and ultrasonic scaler (US), on gingival health in patients under fixed orthodontic treatment.

METHODS

Twenty orthodontic patients were randomly allocated to two groups: PDT or US. Each group received seven sessions [days 0, 15, 30, 45, 90 (3-months follow-up), 180 (6-months follow-up), 270 (9-months follow-up)] of experimental interventions, and clinical parameters [Plaque index(PI); gingival index(GI); probing depth(PD)], periodontopathogens [Agreggatibacter actinomycetemcomitans; Porphyromonas gingivalis; Prevotella intermedia; Micromonas micros; Fusobacterium nucleatum; Tannerella forsythia; Campylobacter rectus; Eikenella corrodens; Capnocytopaga sp.] and protein markers [IL-1β;IL-1ra;IL-6;IL-10;TNF-α;FGF-2/FGF basic] were monitored at baseline and at 3, 6, and 9 months. ANOVA, Student's t-test with Bonferroni correction and ANOVA with multiple rank test were used to identify differences between groups (P < 0.05).

RESULTS

Clinical assessments [PI, GI, and PD] yielded no differences (P > 0.05) between groups, which showed a major decrease at the start of the trial. Reductions in total colony forming units (log CFU reduction) were observed with both treatments, although to a greater extent in the PDT group, but with no differences between groups (P > 0.05). Similar reductions in log CFU counts of P. gingivalis, P. intermedia, and F. nucleatum were observed in both groups (P > 0.05). The two groups also showed similar trends for inflammatory mediators with decreased levels of IL-1β, IL-10, and TNF-α, whereas IL-6 and IL-1ra levels remained stable and those of FGF-2 were increased after both interventions, with no differences (P > 0.05) between groups.

CONCLUSION

Both PDT and US methods proved similar effectiveness for the treatment of gingival inflammation induced by fixed orthodontic appliances. Lasers Surg. Med. 51:256-267, 2019. © 2018 Wiley Periodicals, Inc.

BDNF/HMW-HA complex as an adjunct to nonsurgical periodontal treatment of ligature-induced periodontitis in dogs

BACKGROUND

Recently, brain-derived neurotrophic factor (BDNF)/high molecular weight hyaluronic acid (HMW-HA) complex with flap surgery has been shown to promote periodontal tissue regeneration. The objective of this study was to evaluate the effects of local subgingival application of BDNF/HMW-HA complex adjunctive to scaling and root planning (SRP) on ligature-induced periodontitis in dogs.

METHODS

The dogs were divided into four treatment groups: no treatment (control), SRP alone, SRP followed by local application of HMW-HA (SRP+HMW-HA), and SRP followed by local application of BDNF (500 μg/ml)/ HMW-HA complex (SRP+BDNF/HMW-HA). HMW-HA or BDNF/HMW-HA complex was topically applied to periodontal pockets using a syringe without surgery. Two weeks after treatment, clinical parameters (gingival index, clinical attachment level, periodontal pocket depth and bleeding on probing) were recorded and specimens were collected from anesthetized animals for histological analysis.

RESULTS

The SRP+BDNF/HMW-HA group showed significant improvement in all clinical parameters compared to other treatment groups. Histologic analysis showed greater suppression of apical migration of epithelial tissue and milder inflammatory cell infiltration in the SRP+BDNF/HMW-HA group than in the other treatment groups. Furthermore, new cementum and alveolar bone were regenerated, and collagen fibers were inserted into them in the SRP+BDNF/HMW-HA group.

CONCLUSION

BDNF/HMW-HA complex as an adjunct to nonsurgical periodontal treatment has the potential to reduce excess inflammation. Further investigation will be needed to clarify periodontal tissue regenerative effects of BDNF/HMW-HA complex in a nonsurgical setting.

Antimicrobial Photodynamic Therapy Mediated by Curcumin-Loaded Polymeric Nanoparticles in a Murine Model of Oral Candidiasis

Antimicrobial photodynamic therapy (aPDT) has been proposed as an alternative method for oral candidiasis (OC), while nanocarriers have been used to improve the water solubility of curcumin (CUR). The aim of this study is to encapsulate CUR in polymeric nanoparticles (NPs) and to evaluate its photodynamic effects on a murine model of OC. Anionic and cationic CUR-NP is synthesized using poly-lactic acid and dextran sulfate and then characterized. Female mice are immunosuppressed and inoculated with Candida albicans (Ca) to induce OC. aPDT is performed by applying CUR-NP or free CUR on the dorsum of the tongue, followed by blue light irradiation for five consecutive days. Nystatin is used as positive control. Afterward, Ca are recovered and cultivated. Animals are euthanized for histological, immunohistochemical, and DNA damage evaluation. Encapsulation in NP improves the water solubility of CUR. Nystatin shows the highest reduction of Ca, followed by aPDT mediated by free CUR, which results in immunolabelling of cytokeratins closer to those observed for healthy animals. Anionic CUR-NP does not show antifungal effect, and cationic CUR-NP reduces Ca even in the absence of light. DNA damage is associated with Ca infection. Consecutive aPDT application is a safe treatment for OC.

Antimicrobial photodynamic therapy - what we know and what we don't

Considering increasing number of pathogens resistant towards commonly used antibiotics as well as antiseptics, there is a pressing need for antimicrobial approaches that are capable of inactivating pathogens efficiently without the risk of inducing resistances. In this regard, an alternative approach is the antimicrobial photodynamic therapy (aPDT). The antimicrobial effect of aPDT is based on the principle that visible light activates a per se non-toxic molecule, the so-called photosensitizer (PS), resulting in generation of reactive oxygen species that kill bacteria unselectively via an oxidative burst. During the last 10-20 years, there has been extensive in vitro research on novel PS as well as light sources, which is now to be translated into clinics. In this review, we aim to provide an overview about the history of aPDT, its fundamental photochemical and photophysical mechanisms as well as photosensitizers and light sources that are currently applied for aPDT in vitro. Furthermore, the potential of resistances towards aPDT is extensively discussed and implications for proper comparison of in vitro studies regarding aPDT as well as for potential application fields in clinical practice are given. Overall, this review shall provide an outlook on future research directions needed for successful translation of promising in vitro results in aPDT towards clinical practice.

An experimental study for rapid detection and quantification of endodontic microbiota following photo-activated disinfection via new multiplex real-time PCR assay

BACKGROUND

The infected root canal system harbors one of the highest accumulations of polymicrobial infections. Since the eradication of endopathogenic microbiota is a major goal in endodontic infection therapy, photo-activated disinfection (PAD) can be used as an alternative therapeutic method in endodontic treatment. Compared to cultivation-based approaches, molecular techniques are more reliable for identifying microbial agents associated with endodontic infections. The purpose of this study was to evaluate the ability of designed multiplex real-time PCR protocol for the rapid detection and quantification of six common microorganisms involved in endodontic infection before and after the PAD.

MATERIALS AND METHODS

Samples were taken from the root canals of 50 patients with primary and secondary/persistent endodontic infections using sterile paper points. PAD with toluidine blue O (TBO) plus diode laser was performed on root canals. Resampling was then performed, and the samples were transferred to transport medium. Then, six target microorganisms were detected using multiplex real-time PCR before and after the PAD.

RESULTS

Veillonella parvula was found using multiplex real-time PCR to have the highest frequency among samples collected before the PAD (29.4%), followed by Porphyromonas gingivalis (23.1%), Aggregatibacter actinomycetemcomitans (13.6%), Actinomyces naeslundii (13.0%), Enterococcus faecalis (11.5%), and Lactobacillus rhamnosus (9.4%). After TBO-mediated PAD, P. gingivalis strains, the most resistance microorganisms, were recovered in 41.7% of the samples using molecular approach (P > 0.05).

CONCLUSION

As the results shown, multiplex real-time PCR as an accurate detection approach with high-throughput and TBO-mediated PAD as an efficient antimicrobial strategy due to the significant reduction of the endopathogenic count can be used for detection and treatment of microbiota involved in infected root canals, respectively.

Advances in antimicrobial photodynamic inactivation at the nanoscale

The alarming worldwide increase in antibiotic resistance amongst microbial pathogens necessitates a search for new antimicrobial techniques, which will not be affected by, or indeed cause resistance themselves. Light-mediated photoinactivation is one such technique that takes advantage of the whole spectrum of light to destroy a broad spectrum of pathogens. Many of these photoinactivation techniques rely on the participation of a diverse range of nanoparticles and nanostructures that have dimensions very similar to the wavelength of light. Photodynamic inactivation relies on the photochemical production of singlet oxygen from photosensitizing dyes (type II pathway) that can benefit remarkably from formulation in nanoparticle-based drug delivery vehicles. Fullerenes are a closed-cage carbon allotrope nanoparticle with a high absorption coefficient and triplet yield. Their photochemistry is highly dependent on microenvironment, and can be type II in organic solvents and type I (hydroxyl radicals) in a biological milieu. Titanium dioxide nanoparticles act as a large band-gap semiconductor that can carry out photo-induced electron transfer under ultraviolet A light and can also produce reactive oxygen species that kill microbial cells. We discuss some recent studies in which quite remarkable potentiation of microbial killing (up to six logs) can be obtained by the addition of simple inorganic salts such as the non-toxic sodium/potassium iodide, bromide, nitrite, and even the toxic sodium azide. Interesting mechanistic insights were obtained to explain this increased killing.

Evaluation of antimicrobial activity of association of chlorhexidine to photosensitizer used in photodynamic therapy in root canals infected by Enterococcus faecalis

INTRODUCTION

The aim of the present study was to evaluate, in vitro, the influence of the addition of chlorhexidine to photosensitiser in the antimicrobial activity of photodynamic therapy in root canals infected by Enterococcus faecalis.

METHODS

The root canals of 50 single-rooted human extracted teeth were enlarged up to a file F3 of Pro-Taper system, autoclaved, inoculated with Enterococcus faecalis and incubated for 14days. The samples were divided into five groups (n=10) according to the protocol of decontamination: G1 (control group) - no procedure was performed; G2-photosensitiser (0.01% methylene blue); G3-2% chlorhexidine gel; G4-photodynamic therapy; and G5-photodynamic therapy with photosensitiser modified by chlorhexidine. Microbiological test (CFU counting) was performed to evaluate the effectiveness of proposed treatments. Data were subjected to one-way ANOVA followed by post-hoc Tukey test (α=0.05).

RESULTS

Group 3 (CHX) showed the lowest mean contamination (2.03 log₁₀ CFU/mL), being statistically different from all other all groups (p<0.05). There was no statistically significant difference between groups 4 (PDT) and 5 (PDT+CHX) (p<0.05), being more effectives against E. faecalis when compared to groups 1 (NT) and 2 (MB), and less effective when compared to group 2 (CHX).

CONCLUSIONS

The addition of chlorhexidine to photosensitiser did not result in a better decontamination potential of photodynamic therapy alone over root canals infected by E. faecalis.

Photodvnamic Therapy in Endodontics

Commonly used irrigants do not always eradicate the entire microbial flora in infected root canals. Therefore, several other strategies, such as photodynamic therapy (PDT) have been developed. Photoactivated disinfection is based on the interaction of a photosensitive antibacterial agent and a light source. It uses a nontoxic dye named photosensitizer (PS) and low-intensity visible light. In oxygen presentation, these combine to produce some cytotoxic species. The PS molecules attach to bacteria membrane. Irradiation with a specific wavelength of the light may lead to the production of singlet oxygen, resulting in rupture of the microbial cell wall. There are several applications for PDT in dentistry. A successful periodontal treatment is based on elimination of bacteria from the infected area. Phenothiazinium PSs have been shown to be highly effective and safe for this purpose. However, scaling/root planing should be performed before the PDT. While performing the PDT, PS should be first injected in the periodontal pocket and allowed to pigment. Then, the special fiber should be inserted 1 mm short of the pocket base and lased. Photodynamic therapy has also been used to disinfect caries dentin before restoration, disinfecting oral tissues before or during surgical procedures, treating denture stomatitis, and treating oral candidiasis in immunocompromised patients. Photodynamic therapy can be used in combination with mechanical instrumentation and chemical antimicrobial agents, such as sodium hypochlo-rite, too. The purpose of this study was to review historical perspective, mechanism of action, and applications of PDT in dentistry and especially in endodontics was reviewed. Furthermore, the effects of PDT on dentin bonding and endo-toxin are discussed.

CLINICAL SIGNIFICANCE

Photodynamic therapy has been advocated to increase the disinfection level of the root canal system.

Clinical efficacy of photodynamic therapy adjunctive to scaling and root planing in the treatment of chronic periodontitis: A systematic review and meta-analysis

PURPOSE

To evaluate the clinical efficacy of photodynamic therapy (PDT) adjunctive to scaling and root planing (SRP) in patients with untreated chronic periodontitis based on up-to-date evidence.

METHODS

MEDLINE and the Cochrane Library were systematically searched to identify eligible randomized controlled trials (RCTs), supplemented by a manual literature search. Mean differences (MD) and the corresponding 95% confidence intervals (CI) of probing depth (PD) reduction and clinical attachment level (CAL) gain were synthesized. The I² test and Q statistics were used to determine the inter-study heterogeneity. Subgroup analysis based on smoking status was performed.

RESULTS

Eleven RCTs with a total of 243 subjects were included. Significant improvement in PD reduction (MD=0.13, CI:0.02-0.24, p=0.02) and marginal significant improvement in CAL gain (MD=0.18, CI:-0.005-0.363, p=0.056) were observed in favor of SRP+PDT at 3months. When evaluated at 6months after baseline, the association of PDT with SRP resulted in a significant benefit in PD reduction (MD=0.40, CI:0.05-0.74, p=0.03), but not in CAL gain (MD=0.37, CI:-0.18-0.93, p=0.18). Subgroup analysis revealed that the combined therapy produced no significant improvements in PD and CAL at neither 3months nor 6months for studies with smokers. No treatment-related adverse events or side effects had been reported by the included studies.

CONCLUSIONS

Pooled analysis suggests a short-term benefit of PDT as an adjunct to SRP in clinical outcome variables. However, evidence regarding its long-term efficacy is still insufficient and no significant effect has been confirmed in terms of CAL gain at 6months. Future clinical trials of high methodological quality are needed to establish the optimal combination of photosensitizer and laser configuration.

Photodynamic therapy using chloro-aluminum phthalocyanine decreases inflammatory response in an experimental rat periodontal disease model

BACKGROUND AND OBJECTIVE

Emerging evidence suggests that photodynamic therapy (PDT) can exhibit immunomodulatory activity. The purpose of the present study was to analyse cytokine profiles after application of PDT in gingival tissues of rats with ligature-induced periodontal disease (PD).

STUDY DESIGN/MATERIAL AND METHODS

Periodontal disease was induced through the introduction of a cotton thread around the first left mandibular molar, while the right side molars did not receive ligatures. After 7days of PD evolution, ligatures were removed from the left side, and the animals were randomically divided into the following treatment groups: I, rats without treatment; II, rats received chloro-aluminum phthalocyanine (AlClPc); III, rats received low-level laser alone; and IV, rats received AlClPc associated with low-level laser (PDT). The animals were killed 7days after the treatments, and the mandibles were histologically processed to assess morphological and immunohistochemical profile, while gingival tissues were removed for quantification of tumor necrosis factor (TNF)-α, interleukin (IL-)1β and IL-10 expression (by ELISA).

RESULTS

Histomorphological analysis of periodontal tissues demonstrated that PDT-treated animals show tissue necrosis, as well as lower TNF- α expression, compared to ligatured animals treated with AlClPc alone.

CONCLUSIONS

It was concluded that PDT using AlClPc entrapped in a lipid nanoemulsion may be useful in therapies, because of immunomodulatory effects that decreased the inflammatory response and cause tissue destruction.

Adjunctive Application of Antimicrobial Photodynamic Therapy in Nonsurgical Periodontal Treatment: A Review of Literature

Periodontal disease is caused by dental plaque biofilms, and the removal of these biofilms from the root surface of teeth plays a central part in its treatment. The conventional treatment for periodontal disease fails to remove periodontal infection in a subset of cases, such as those with complicated root morphology. Adjunctive antimicrobial photodynamic therapy (aPDT) has been proposed as an additional treatment for this infectious disease. Many periodontal pathogenic bacteria are susceptible to low-power lasers in the presence of dyes, such as methylene blue, toluidine blue O, malachite green, and indocyanine green. aPDT uses these light-activated photosensitizer that is incorporated selectively by bacteria and absorbs a low-power laser/light with an appropriate wavelength to induce singlet oxygen and free radicals, which are toxic to bacteria. While this technique has been evaluated by many clinical studies, some systematic reviews and meta-analyses have reported controversial results about the benefits of aPDT for periodontal treatment. In the light of these previous reports, the aim of this review is to provide comprehensive information about aPDT and help extend knowledge of advanced laser therapy.

NF-κB signaling and bone resorption

The transcription factor NF-κB is a family of proteins involved in signaling pathways essential for normal cellular functions and development. Deletion of various components of this pathway resulted with abnormal skeletal development. Research in the last decade has established that NF-κB signaling mediates RANK ligand-induced osteoclastogenesis. Consistently, it was shown that inhibition of NF-κB was an effective approach to inhibit osteoclast formation and bone resorptive activity. Identification of the molecular machinery underlying NF-κB activation permitted osteoclast-specific deletion of the major components of this pathway. As a result, it was clear that deletion of members of the proximal IKK kinase complex and the distal NF-κB subunits and downstream regulators affected skeletal development. These studies provided several targets of therapeutic intervention in osteolytic diseases. NF-κB activity has been also described as the centerpiece of inflammatory responses and is considered a potent mediator of inflammatory osteolysis. Indeed, inflammatory insults exacerbate physiologic RANKL-induced NF-κB signals leading to exaggerated responses and to inflammatory osteolysis. These superimposed NF-κB activities appear to underlie several bone pathologies. This review will describe the individual roles of NF-κB molecules in bone resorption and inflammatory osteolysis.

A modified method for inducing periodontitis in dogs using a silk-wire twisted ligature

This study was designed to assess the effectiveness of a modified silk ligature twisted with wire for inducing advanced periodontitis. Periodontitis was induced in five premolars and one molar of 20 healthy dogs over a 60-day period. The dogs were divided into four groups according to the ligature-inducing materials used: soft moistened food only, wire ligature (WL), silk ligature (SL) and twisted ligature with silk and wire (SWL). Periodontal indices were recorded, and dental radiographs were taken before and after 60 days of ligation. The ligatures were checked daily and the day the ligature fell out was noted. The period during which the ligatures were maintained was significantly shorter for the SL group compared to the SWL group (p < 0.05). Results of the clinical examination showed that almost all periodontal status parameters including the plaque index, gingival index, clinical attachment level, and bleeding on probing were significantly exacerbated in the SWL group compared to the other groups (p < 0.05). Radiographic evaluation demonstrated that alveolar bone levels were significantly lower in the SWL group than the other groups on day 60 (p < 0.05). These results suggested that experimental periodontitis induced by SWL could be an effective method for investigating periodontitis in canine models.

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.

Histomorphometric and microbiological assessment of photodynamic therapy as an adjuvant treatment for periodontitis: a short-term evaluation of inflammatory periodontal conditions and bacterial reduction in a rat model

OBJECTIVE

The aim of this study was to investigate the short-term effects of photodynamic therapy (PDT) in periodontal tissue when it is used as an adjuvant treatment for periodontitis.

BACKGROUND DATA

PDT has been used as an adjuvant in the combat of local infections, such as periodontitis, and combines a photosensitizer (PS) with a light source to induce reactive oxygen species (ROS) and kill microbial cells.

METHODS

Fifty healthy male rats were used in this study. Periodontitis was induced by placing a cotton ligature around the upper left second molar in a subgingival position. Posterior maxillas were removed and histologically prepared with hematoxylin & eosin (H&E) staining techniques. PDT was performed with a diode laser (λ=660 nm) with an output power of 100 mW. Methylene blue aqueous solution (100 μM) was used as the PS while control group used phosphate buffered saline (PBS). Collagen organization, inflammatory infiltrate, and bone loss were evaluated. Bacterial samples were collected before and immediately after treatment to determine bacterial reduction.

RESULTS

The experimental group that was treated with PDT presented better periodontal healing, as measured by collagen organization, inflammatory infiltrate, and bone loss. Significant bacterial reduction was achieved following treatment with or without PDT compared to control, with a higher microbial reduction observed in the PDT group.

CONCLUSIONS

PDT used as an adjuvant treatment showed effective short-term control of periodontitis infection.