The use of diffuse laser photonic energy and indocyanine green photosensitiser as an adjunct to periodontal therapy

Adjunctive antimicrobial photodynamic therapy for treating periodontal and peri-implant diseases

BACKGROUND

Periodontitis and peri-implant diseases are chronic inflammatory conditions occurring in the mouth. Left untreated, periodontitis progressively destroys the tooth-supporting apparatus. Peri-implant diseases occur in tissues around dental implants and are characterised by inflammation in the peri-implant mucosa and subsequent progressive loss of supporting bone. Treatment aims to clean the pockets around teeth or dental implants and prevent damage to surrounding soft tissue and bone, including improvement of oral hygiene, risk factor control (e.g. encouraging cessation of smoking) and surgical interventions. The key aspect of standard non-surgical treatment is the removal of the subgingival biofilm using subgingival instrumentation (SI) (also called scaling and root planing). Antimicrobial photodynamic therapy (aPDT) can be used an adjunctive treatment to SI. It uses light energy to kill micro-organisms that have been treated with a light-absorbing photosensitising agent immediately prior to aPDT.

OBJECTIVES

To assess the effects of SI with adjunctive aPDT versus SI alone or with placebo aPDT for periodontitis and peri-implant diseases in adults.

SEARCH METHODS

We searched the Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase, two other databases and two trials registers up to 14 February 2024.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) (both parallel-group and split-mouth design) in participants with a clinical diagnosis of periodontitis, peri-implantitis or peri-implant disease. We compared the adjunctive use of antimicrobial photodynamic therapy (aPDT), in which aPDT was given after subgingival or submucosal instrumentation (SI), versus SI alone or a combination of SI and a placebo aPDT given during the active or supportive phase of therapy.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures, and we used GRADE to assess the certainty of the evidence. We prioritised six outcomes and the measure of change from baseline to six months after treatment: probing pocket depth (PPD), bleeding on probing (BOP), clinical attachment level (CAL), gingival recession (REC), pocket closure and adverse effects related to aPDT. We were also interested in change in bone level (for participants with peri-implantitis), and participant satisfaction and quality of life.

MAIN RESULTS

We included 50 RCTs with 1407 participants. Most studies used a split-mouth study design; only 18 studies used a parallel-group design. Studies were small, ranging from 10 participants to 88. Adjunctive aPDT was given in a single session in 39 studies, in multiple sessions (between two and four sessions) in 11 studies, and one study included both single and multiple sessions. SI was given using hand or power-driven instrumentation (or both), and was carried out prior to adjunctive aPDT. Five studies used placebo aPDT in the control group and we combined these in meta-analyses with studies in which SI alone was used. All studies included high or unclear risks of bias, such as selection bias or performance bias of personnel (when SI was carried out by an operator aware of group allocation). We downgraded the certainty of all the evidence owing to these risks of bias, as well as for unexplained statistical inconsistency in the pooled effect estimates or for imprecision when evidence was derived from very few participants and confidence intervals (CI) indicated possible benefit to both intervention and control groups. Adjunctive aPDT versus SI alone during active treatment of periodontitis (44 studies) We are very uncertain whether adjunctive aPDT during active treatment of periodontitis leads to improvement in any clinical outcomes at six months when compared to SI alone: PPD (mean difference (MD) 0.52 mm, 95% CI 0.31 to 0.74; 15 studies, 452 participants), BOP (MD 5.72%, 95% CI 1.62 to 9.81; 5 studies, 171 studies), CAL (MD 0.44 mm, 95% CI 0.24 to 0.64; 13 studies, 414 participants) and REC (MD 0.00, 95% CI -0.16 to 0.16; 4 studies, 95 participants); very low-certainty evidence. Any apparent differences between adjunctive aPDT and SI alone were not judged to be clinically important. Twenty-four studies (639 participants) observed no adverse effects related to aPDT (moderate-certainty evidence). No studies reported pocket closure at six months, participant satisfaction or quality of life. Adjunctive aPDT versus SI alone during supportive treatment of periodontitis (six studies) We were very uncertain whether adjunctive aPDT during supportive treatment of periodontitis leads to improvement in any clinical outcomes at six months when compared to SI alone: PPD (MD -0.04 mm, 95% CI -0.19 to 0.10; 3 studies, 125 participants), BOP (MD 4.98%, 95% CI -2.51 to 12.46; 3 studies, 127 participants), CAL (MD 0.07 mm, 95% CI -0.26 to 0.40; 2 studies, 85 participants) and REC (MD -0.20 mm, 95% CI -0.48 to 0.08; 1 study, 24 participants); very low-certainty evidence. These findings were all imprecise and included no clinically important benefits for aPDT. Three studies (134 participants) reported adverse effects: a single participant developed an abscess, though it is not evident whether this was related to aPDT, and two studies observed no adverse effects related to aPDT (moderate-certainty evidence). No studies reported pocket closure at six months, participant satisfaction or quality of life.

AUTHORS' CONCLUSIONS

Because the certainty of the evidence is very low, we cannot be sure if adjunctive aPDT leads to improved clinical outcomes during the active or supportive treatment of periodontitis; moreover, results suggest that any improvements may be too small to be clinically important. The certainty of this evidence can only be increased by the inclusion of large, well-conducted RCTs that are appropriately analysed to account for change in outcome over time or within-participant split-mouth study designs (or both). We found no studies including people with peri-implantitis, and only one study including people with peri-implant mucositis, but this very small study reported no data at six months, warranting more evidence for adjunctive aPDT in this population group.

Research Progress of Natural Product Photosensitizers in Photodynamic Therapy

Photodynamic therapy is a noninvasive cancer treatment that utilizes photosensitizers to generate reactive oxygen species upon light exposure, leading to tumor cell apoptosis. Although photosensitizers have shown efficacy in clinical practice, they are associated with certain disadvantages, such as a certain degree of toxicity and limited availability. Recent studies have shown that natural product photosensitizers offer promising options due to their low toxicity and potential therapeutic effects. In this review, we provide a summary and evaluation of the current clinical photosensitizers that are commonly used and delve into the anticancer potential of natural product photosensitizers like psoralens, quinonoids, chlorophyll derivatives, curcumin, chrysophanol, doxorubicin, tetracyclines, Leguminosae extracts, and Lonicera japonica extract. The emphasis is on their phototoxicity, pharmacological benefits, and effectiveness against different types of diseases. Novel and more effective natural product photosensitizers for future clinical application are yet to be explored in further research. In conclusion, natural product photosensitizers have potential in photodynamic therapy and represent a promising area of research for cancer treatment.

Antimicrobial photodynamic therapy for managing the peri-implant mucositis and peri-implantitis: A systematic review of randomized clinical trials

BACKGROUND

The presence of peri‑implant inflammation including peri‑implant mucositis and peri‑implantitis, is a crucial factor that impacts the long-term stability and success of dental implants. This review aimed to evaluate the safety and effectiveness of antimicrobial photodynamic therapy (aPDT) as an adjuvant therapy option for managing peri‑implant mucositis and peri‑implantitis.

METHODS

We systematically searched the PubMed/MEDLINE, Cochrane Library, Scopus, and Google Scholar databases (no time limitation). The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the quality of the studies was assessed using the Cochrane Collaboration tool.

RESULTS

Of 322 eligible articles, 14 studies were included in this review. The heterogeneity and poor quality of the articles reviewed prevented a meta-analysis. The reviewed articles used a light source (60 s, 1 session) with a wavelength of 635 to 810 nm for optimal tissue penetration. These studies showed improved clinical parameters such as probing depth, bleeding on probing (BOP), and plaque index after aPDT treatment. However, in smokers, BOP increased after aPDT. Compared to conventional therapy, aPDT had a longer-term antimicrobial effect and reduced periopathogens like Porphyromonas gingivalis, as well as inflammatory factors such as Interleukin (IL)-1β, IL-6, and Tumor necrosis factor alpha (TNF-α). No undesired side effects were reported in the studies.

CONCLUSION

Although the reviewed articles had limitations, aPDT showed effectiveness in improving peri‑implant mucositis and peri‑implantitis. It is recommended as an adjunctive strategy for managing peri‑implant diseases, but further high-quality research is needed for efficacy and long-term outcomes.

Phenylboronic Acid Modification Augments the Lysosome Escape and Antitumor Efficacy of a Cylindrical Polymer Brush-Based Prodrug

Timely lysosome escape is of paramount importance for endocytosed nanomedicines to avoid premature degradation under the acidic and hydrolytic conditions in lysosomes. Herein, we report an exciting finding that phenylboronic acid (PBA) modification can greatly facilitate the lysosome escape of cylindrical polymer brushes (CPBs). On the basis of our experimental results, we speculate that the mechanism is associated with the specific interactions of the PBA groups with lysosomal membrane proteins and hot shock proteins. The featured advantage of the PBA modification over the known lysosome escape strategies is that it does not cause significant adverse effects on the properties of the CPBs; on the contrary, it enhances remarkably their tumor accumulation and penetration. Furthermore, doxorubicin was conjugated to the PBA-modified CPBs with a drug loading content larger than 20%. This CPBs-based prodrug could eradicate the tumors established in mice by multiple intravenous administrations. This work provides a novel strategy for facilitating the lysosome escape of nanomaterials and demonstrates that PBA modification is an effective way to improve the overall properties of nanomedicines including the tumor therapeutic efficacy.

Clinico-microbiological Efficacy of Indocyanine Green as a Novel Photosensitizer for Photodynamic Therapy among Patients with Chronic Periodontitis: A Split-mouth Randomized Controlled Clinical Trial

Objective:

Conventional nonsurgical periodontal therapy, i.e., scaling and root planing (SRP), is not sufficient to completely eradicate the microorganisms present in dental plaque biofilm due to the incapability of instruments to reach the inaccessible areas of a tooth with anatomical variations. Hence, to increase the effectiveness of SRP, many adjunctive treatment strategies are proposed, including photodynamic therapy (PDT). Therefore, the purpose of this study was to determine the clinical and microbiological efficacy of PDT using Indocyanine green (ICG) as a novel photosensitizer for the treatment of chronic periodontitis.

Materials and Methods:

Twenty individuals who fulfilled the eligibility criteria were enrolled for this randomized controlled clinical trial using split-mouth design. Treatment sites from each individual were randomly allocated into two groups: SRP was done for the sites of the control group and an additional session of PDT using ICG was performed for the sites of the test group. Subgingival plaque samples were collected from both the sites and sent for quantitative analysis of Treponema denticola, Porphyromonas gingivalis, and Tannerella forsythia using real-time polymerase chain reaction (RT-PCR) technique. Probing pocket depth (PD), clinical attachment loss (CAL), and count of all the three microorganisms were assessed at baseline and after 3 months.

Results:

After 3 months, PD and CAL showed statistically significant improvement in the test sites (P < 0.001) compared to the control sites. However, the differences in the microbiological parameters were statistically nonsignificant between the groups.

Conclusion:

ICG as a photosensitizer may enhance the outcomes of SRP and can be used for PDT for the nonsurgical management of periodontal diseases.

Chalcogenide nanoparticles and organic photosensitizers for synergetic antimicrobial photodynamic therapy

Synergistic antimicrobial effects were observed for copper sulfide (CuS) nanoparticles together with indocyanine green (ICG) in the elimination of wild type pathogenic bacteria (Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa ATCC 27853) and also opportunistic fungal infective yeast (Candida albicans ATCC 10231). Furthermore, large antibacterial effects were observed for clinical isolates of Methicillin-resistant S. aureus (MRSA) PFGE strain-type USA300. This efficient antimicrobial action was attributed to the combined extra- and intracellular generation of reactive oxygen species upon light irradiation. Instead of the use of visible-light for the activation of common photosensitizers, both ICG and CuS nanoparticles can be activated in the near infrared (NIR)-region of the electromagnetic spectrum and therefore, superior tissue penetration would be expected in a potential elimination of pathogenic microorganisms not only on the skin but also in the soft tissue. In the different bacteria studied a 3-log reduction in the bacterial counts was achieved after only 6 min of NIR irradiation and treatment with ICG or CuS alone at concentrations of 40 and 160 µg mL^-1, respectively. A maximum bactericidal effect against S. aureus and USA300 strains was obtained for the combination of both photosensitizers at the same concentration. Regarding P. aeruginosa, a 4-log reduction in the CFU was observed for the combination of CuS and ICG at various concentrations. In Candida albicans the combination of both ICG and CuS and light irradiation showed an antimicrobial dose-dependent effect with the reduction of at least 3-log in the cell counts for the combination of ICG + CuS at reduced concentrations. The observed antimicrobial effect was solely attributed to a photodynamic effect and any photothermal effect was avoided to discard any potential thermal injury in a potential clinical application. The generation of reactive oxygen species upon near infrared-light irradiation for those photosensitizers used was measured either alone or in combination. The cytocompatibility of the proposed materials at the doses used in photodynamic therapy was also demonstrated in human dermal fibroblasts and keratinocytes by cell culturing and flow cytometry studies.

Is antimicrobial photodynamic therapy an effective treatment modality for aggressive periodontitis? A systematic review of in vivo human randomized controlled clinical trials

BACKGROUND

Limitations of scaling and root planing (SRP) have directed research to utilize additional therapies to enhance conventional techniques. The present systematic review was conducted to evaluate and present a comprehensive overview on effectiveness of antimicrobial photodynamic therapy (aPDT) in the management of aggressive periodontitis (AgP).

METHODOLOGY

The PRISMA statement guidelines and Cochrane Collaboration recommendations were followed to conduct this systematic review. The review protocol is registered in PROSPERO (CRD 42019143316). A structured electronic and manual search strategy was implied to gather the relevant published data on in vivo human RCTs from their earliest records until 31st October 2019. Relevant data was extracted from the eligible studies, analysed and impartially appraised for its quality.

RESULTS

Eleven papers met the eligibility criteria and included in this review. The data on standardized study protocol, ideal photosensitizer (PS) dye-wavelength combination, optimal parameters was inconclusive and a high risk of bias in majority of the studies noted, which are fundamental in establishing a standardized and replicable protocol.

CONCLUSION

Ultimately researchers should conduct well-designed and robust RCTs performed by trained clinicians in order to determine the effectiveness of aPDT, if any, after acknowledging the drawbacks highlighted in this systematic review.

Antimicrobial nanomedicine for ocular bacterial and fungal infection

Ocular infection induced by bacteria and fungi is a major cause of visual impairment and blindness. Topical administration of antibiotics remains the first-line treatment, as effective eradication of pathogens is the core of the anti-infection strategy. Whereas, eye drops lack efficiency and have relatively low bioavailability. Intraocular injection may cause concurrent ocular damage and secondary infection. In addition, antibiotic-based management can be limited by the low sensitivity to multidrug-resistant bacteria. Nanomedicine is proposed as a prospective, effective, and noninvasive platform to mediate ocular delivery and combat pathogen or even resistant strains. Nanomedicine can not only carry antimicrobial agents to fight against pathogens but also directly active microbicidal capability, killing pathogens. More importantly, by modification, nanomedicine can achieve enhanced residence time and release time on the cornea, and easy penetration through corneal tissues into anterior and posterior segments of the eye, thus improving the therapeutic effect for ocular infection. In this review, several categories of antimicrobial nanomedicine are systematically discussed, where the efficiency and possibility of further embellishment and improvement to adapt to clinical use are also investigated. All in all, novel antimicrobial nanomedicine provides potent and prospective ways to manage severe and refractory ocular infections.

Optimization of treatment and prevention of generalized periodontal diseases with the use of transgingival photoactived disinfection

The aim of the study is to develop protocols for the treatment and prevention of generalized periodontal disease using a nozzle that designed for transgingival photosensitizer activation. Methods. Analysis of available variants of irradiation nozzles for photoactivated disinfection. Circuit design and construction of authors’ irradiation nozzle for transgingival photosensitizer activation. Results. Based on the analysis of data, there was developed a nozzle design that allows treating periodontium areas within 4-6 teeth, evenly distributes the required power of laser radiation, and can be used in hard-to-reach areas of the oral cavity. Based on the above calculations, a nozzle for transgingival photosensitizer activation was created (jointly with Fotonika Plus, PE). To optimize the PAD procedure, there was created a protocol of transgingival photoactivated disinfection to be applied at the stage of professional oral hygiene, using the created irradiation nozzle NOU-9 of authors’ design, and diode 2 W laser LIKA-surgeon with a wavelength of 660 nm. The result is the accelerated procedure of transgingival photoactivated disinfection. Conclusions. The development of photoactivated disinfection technology allows supplementing the traditional treatment of generalized periodontal diseases. Studies of non-invasive, transgingival method of photosensitizer activation have recently become popular. This, in turn, carries a lower probability of cross-infection and less traumatization of periodontal tissues during the manipulation. The use of PAD cannot lead to resistance of the microflora in contrast to pharmacological antibacterial preparations. Carrying out PAD does not require any complex manual skills, the purchase of expensive equipment, provides an opportunity for widespread introduction of technology. The use of the therapeutic complex and protocols of PAD that were developed can significantly reduce the duration of the procedure, resulting in improved comfort for both the doctor and the patient. The NOU-9 irradiation nozzle allows reaching hard-to-reach areas of the oral cavity, distributing laser radiation efficiently and evenly on periodontal tissues. The LIKA-surgeon 2 W laser with a wavelength of 660 nm provides the operating parameters required to activate the photosensitizer. Due to low-intensity radiation, it is possible to enhance regenerative processes in the periodontium after traumatic intervention. Clinical studies on the antibacterial efficacy of the technology are ongoing

Novel indocyanine green mediated antimicrobial photodynamic therapy in the management of chronic periodontitis - A randomized controlled clinico-microbiological pilot study

BACKGROUND

The use of scaling, root planing, antimicrobials, or antibiotics in the treatment of Chronic Periodontitis have proven beneficial in the past. The reduction in inflammatory markers and significant resolve in the clinical signs and symptoms and microbial loads evinced by a number of studies are a clear corroboration of the fact, but certain restraints utilizing these methods call for more effective ways of treating the disease. Later, lasers or photodynamic dyes used with the lasers like methylene blue or toluidine blue O have also not proven much efficacy and need further research. Hence the present pilot study is a step forward in this direction as it helps analyse the microbiological and clinical effects of indocyanine green antimicrobial photodynamic therapy an as adjunct to the non-surgical periodontal therapy in treating chronic periodontitis patients.

MATERIALS AND METHODS

30 patients diagnosed with generalized chronic periodontitis were treated with scaling and root planing alone - control sites; and indocyanine green antimicrobial photodynamic therapy in addition to scaling and root planing - experimental sites. 810 ​nm low level Gallium Aluminium Arsenide diode laser was used to activate the dye in the periodontal pockets of the experimental sites. Clinical parameters i.e. gingival index, plaque index, sulcus bleeding index, probing pocket depth and relative attachment level; and microbiological parameter i.e. the total viable anaerobic count were recorded at the inception and at 3- and 6-months post therapy.

RESULTS

Experimental sites showed significantly greater amelioration in all inquired clinical parameters and microbiological parameter at the end of 3- and 6-months of therapy.

CONCLUSION

While the gold standard scaling and root planing remains, clinicians may also contemplate using the indocyanine green mediated antimicrobial photodynamic therapy as an adjunct to it. Also, it is a safer, cost effective, less arduous, and patient friendly means of treating the disease.

Laser-Assisted aPDT Protocols in Randomized Controlled Clinical Trials in Dentistry: A Systematic Review

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) has been proposed as an effective alternative method for the adjunctive treatment of all classes of oral infections. The multifactorial nature of its mechanism of action correlates with various influencing factors, involving parameters concerning both the photosensitizer and the light delivery system. This study aims to critically evaluate the recorded parameters of aPDT applications that use lasers as the light source in randomized clinical trials in dentistry.

METHODS

PubMed and Cochrane search engines were used to identify human clinical trials of aPDT therapy in dentistry. After applying specific keywords, additional filters, inclusion and exclusion criteria, the initial number of 7744 articles was reduced to 38.

RESULTS

Almost one-half of the articles presented incomplete parameters, whilst the others had different protocols, even with the same photosensitizer and for the same field of application.

CONCLUSIONS

No safe recommendation for aPDT protocols can be extrapolated for clinical use. Further research investigations should be performed with clear protocols, so that standardization for their potential dental applications can be achieved.

Photodynamic inactivation of oral bacteria with silver nanoclusters/rose bengal nanocomposite

Antimicrobial photodynamic therapy (a-PDT) is a promising anti-infective technique for generation of singlet oxygen (¹O₂) to target dental disease. However, conventional organic photosensitizers have problems for clinical use in terms of cytotoxicity, quenching of a-PDT activity by self-dimerization, and the lack of long-term antibacterial effect. We herein propose silver nanoclusters/rose bengal nanocomposite (AgNCs/RB) as a novel photosensitizer with two primary antibacterial effects: (1) ¹O₂ generation by irradiated RB and (2) Ag⁺ ion release from AgNCs. AgNCs/RB irradiated with white light-emitting diode (LED) for a short irradiation time of 1 min significantly decreased the bacterial turbidity of Streptococcus mutans, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans (P < 0.05). In SEM, TEM and LIVE/DEAD staining images, photoexcited AgNCs/RB reduced S. mutans colonization, destroyed the cell membrane, and increased the number of dead cells. The antibacterial efficiency of photoexcited AgNCs/RB was greater than that of AgNCs or RB alone (P < 0.05), suggesting a synergistic effect of ¹O₂ and Ag⁺ ions from photoexcited AgNCs/RB. By contrast, photoexcited AgNCs/RB did not affect WST-8 and LDH activities and morphology of NIH3T3 mammalian cells, indicating low cytotoxicity. Interestingly, the antibacterial activity of AgNCs/RB on S. mutans was maintained even after the cessation of LED irradiation, indicating a long-term antibacterial effect due to released Ag⁺ ions. The present AgNCs/RB photosensitizers provide effective synergistic antibacterial effects for dental a-PDT via ¹O₂ and Ag⁺ ions coupled with low cytotoxicity.

Novel nanomaterial-based antibacterial photodynamic therapies to combat oral bacterial biofilms and infectious diseases

Oral diseases such as tooth caries, periodontal diseases, endodontic infections, etc., are prevalent worldwide. The heavy burden of oral infectious diseases and their consequences on the patients' quality of life indicates a strong need for developing effective therapies. Advanced understandings of such oral diseases, e.g., inflammatory periodontal lesions, have raised the demand for antibacterial therapeutic strategies, because these diseases are caused by viruses and bacteria. The application of antimicrobial photodynamic therapy (aPDT) on oral infectious diseases has attracted tremendous interest in the past decade. However, aPDT had a minimal effect on the viability of organized biofilms due to the hydrophobic nature of the majority of the photosensitizers (PSs). Therefore, novel nanotechnologies were rapidly developed to target the delivery of hydrophobic PSs into microorganisms for the antimicrobial performance improvement of aPDT. This review focuses on the state-of-the-art of nanomaterials applications in aPDT against oral infectious diseases. The first part of this article focuses on the cutting-edge research on the synthesis, toxicity, and therapeutic effects of various forms of nanomaterials serving as PS carriers for aPDT applications. The second part discusses nanomaterials applications for aPDT in treatments of oral diseases. These novel bioactive nanomaterials have demonstrated great potential to serve as carriers for PSs to substantially enhance the PDT therapeutic effects. Furthermore, the novel aPDT applications not only have exciting therapeutic potential to inhibit bacterial plaque-initiated oral diseases, but also have a wide applicability to other biomedical and tissue engineering applications.

Effect of methylene blue photodynamic therapy on human neutrophil functional responses

Photodynamic therapy (PDT) has become an emerging novel therapeutic approach for treating localized microbial infections, particularly those sustained by multidrug-resistant strains. Given the irreplaceable role played by professional phagocytes in limiting infections, such as polymorphonuclear neutrophils, any newly designed antimicrobial therapeutic approach must not interfere with their function. The present investigation presents a detailed analysis of the effect of PDT on the viability and several functional responses of human polymorphonuclear neutrophils loaded with methylene blue (MB), one of the more commonly used photosensitizers in antimicrobial PDT. Taking advantage of the use of a specifically-designed optical LED array for illuminating MB-loaded human polymorphonuclear neutrophils, a number of cell functions have been assayed under miniaturized, strictly controlled and reproducible experimental conditions. The major findings of this study are the following: (1) MB-PDT increases human neutrophils adhesion and does not modify myeloperoxidase release; (2) MB-PDT markedly enhances reactive oxygen species generation that is independent of superoxide-forming phagocytic oxidase and very likely ascribable to LED-dependent excitation of accumulated methylene blue; (3) MB-PDT almost abolishes human neutrophils candidacidal activity by hindering the engulfing machinery. This in vitro study may represent a valuable reference point for future research on PDT applications for treating localized microbial infections.

Dual-Functional Supernanoparticles with Microwave Dynamic Therapy and Microwave Thermal Therapy

The cytotoxic reactive oxygen species (ROS) generated by photoactivated sensitizers have been well explored in tumor therapy for nearly half a century, which is known as photodynamic therapy (PDT). The poor light penetration depth severely hinders PDT as a primary or adjuvant therapy for clinical indication. Whereas microwaves (MWs) are advantageous for deep penetration depth, the MW energy is considerably lower than that required for the activation of any species to induce ROS generation. Herein we find that liquid metal (LM) supernanoparticles activated by MW irradiation can generate ROS, such as ·OH and ·O₂. On this basis, we design dual-functional supernanoparticles by loading LMs and an MW heating sensitizer ionic liquid (IL) into mesoporous ZrO₂ nanoparticles, which can be activated by MW as the sole energy source for dynamic and thermal therapy concomitantly. The microwave sensitizer opens the door to an entirely novel dynamic treatment for tumors.

Utilisation of antimicrobial photodynamic therapy as an adjunctive tool for open flap debridement in the management of chronic periodontitis: A randomized controlled clinical trial

BACKGROUND

Antimicrobial photodynamic therapy (aPDT) has proved to be an effective adjunctive modality with potential benefits in the management of chronic periodontitis. The combination of photothermal and photodynamic effects of Indocyanine green (ICG) dye, when it is photoactivated with a diode laser of 810 nm wavelength, has been well documented in literature.

AIM

This study was conducted to evaluate whether a single session of antimicrobial photodynamic therapy using ICG dye-810 nm diode laser combination can provide a substantial benefit when it is utilised as an adjunct to open flap debridement (OFD) in the management of chronic periodontitis.

MATERIALS AND METHOD

Following thorough scaling and root planing, a comparative split mouth randomized controlled clinical trial was carried out on 20 recruited subjects who provided one test (OFD + aPDT) and one control site (OFD alone) each (total 40 treatment sites). The test group was subjected to a single episode of aPDT using ICG photosensitiser dye (1 mg/ml) activated with 810 nm diode laser. The laser was used in a continuous wave, non-contact mode at a power output of 100 mW applied for 30 s/spot (the total of 4 spots per tooth) and delivered by 400 μm fibre, to provide a fluence (energy density) value of 0.0125 J/cm² per spot and generate a total energy of 3 J. The following clinical parameters were assessed at baseline and 3 months: probing pocket depth (PPD), relative attachment level (RAL), relative gingival margin level (RGML), plaque index (PI), gingival index (GI), and gingival bleeding index (GBI). Intragroup and intergroup comparison was performed using paired t-test and independent samples t-test respectively.

RESULTS

Intragroup comparison revealed a statistically significant improvement from baseline visit (p < 0.05). Intergroup comparison showed a statistically significant improvement in RAL, RGML and GI in the test group (p < 0.05).

CONCLUSION

Utilisation of ICG dye activated with 810 nm diode laser, which mediated aPDT, has demonstrated surplus clinical improvement following OFD in the management of chronic periodontitis.

Photodynamic therapy in 3D cancer models and the utilisation of nanodelivery systems

Photodynamic therapy (PDT) is the subject of considerable research in experimental cancer models mainly for the treatment of solid cancerous tumours. Recent studies on the use of nanoparticles as photosensitiser carriers have demonstrated improved PDT efficacy in experimental cancer therapy. Experiments typically employ conventional monolayer cell culture but there is increasing interest in testing PDT using three dimensional (3D) cancer models. 3D cancer models can better mimic in vivo models than 2D cultures by for example enabling cancer cell interactions with a surrounding extracellular matrix which should enable the treatment to be optimised prior to in vivo studies. The aim of this review is to discuss recent research using PDT in different types of 3D cancer models, from spheroids to nano-fibrous scaffolds, using a range of photosensitisers on their own or incorporated in nanoparticles and nanodelivery systems.

The Effect of Photodynamic Therapy in the Treatment of Chronic Periodontitis: A Review of Literature

Introduction: Chronic periodontitis is the most common periodontal disease which is related to the chronic accumulation of bacterial plaque. Since mechanical methods are not sufficient in the treatment of this disease, administration of local/systemic antibiotic is recommended following mechanical debridement. However, side effects of antibiotics such as microbial resistance and patient allergy led to development of alternative methods. One of these suggested methods is the antimicrobial photodynamic therapy (aPDT). PDT is a local noninvasive treatment modality without the side effects caused by antibiotics. The aim of this study was to review the articles related to the application of PDT with laser in the treatment of chronic periodontitis. Review of literature: In the present review of literature, the authors used key words such as chronic periodontitis, laser and photodynamic therapy, and conducted a literature search via Google Scholar and PubMed for the period of 1990 to 2015. A total of 47 articles in English were found. The articles that were not associated with the topic of research and review articles were deleted and only clinical trials were evaluated. After reviewing 23 articles' abstracts, the full texts of 16 articles were analyzed. Conclusion: Considering the safety, the lack of side effects and general advantages like more patient compliance, the PDT treatment with scaling and root planing (SRP) is recommended as an efficient adjunctive modality for the treatment of localized chronic periodontitis especially during the maintenance phase in non-surgical treatment.

Antimicrobial photodynamic activity and cytocompatibility of Au25(Capt)18 clusters photoexcited by blue LED light irradiation

Antimicrobial photodynamic therapy (aPDT) has beneficial effects in dental treatment. We applied captopril-protected gold (Au₂₅(Capt)₁₈) clusters as a novel photosensitizer for aPDT. Photoexcited Au clusters under light irradiation generated singlet oxygen (¹O₂). Accordingly, the antimicrobial and cytotoxic effects of Au₂₅(Capt)₁₈ clusters under dental blue light-emitting diode (LED) irradiation were evaluated. ¹O₂ generation of Au₂₅(Capt)₁₈ clusters under blue LED irradiation (420–460 nm) was detected by a methotrexate (MTX) probe. The antimicrobial effects of photoexcited Au clusters (0, 5, 50, and 500 μg/mL) on oral bacterial cells, such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis, were assessed by morphological observations and bacterial growth experiments. Cytotoxicity testing of Au clusters and blue LED irradiation was then performed against NIH3T3 and MC3T3-E1 cells. In addition, the biological performance of Au clusters (500 μg/mL) was compared to an organic dye photosensitizer, methylene blue (MB; 10 and 100 μg/mL). We confirmed the ¹O₂ generation ability of Au₂₅(Capt)₁₈ clusters through the fluorescence spectra of oxidized MTX. Successful application of photoexcited Au clusters to aPDT was demonstrated by dose-dependent decreases in the turbidity of oral bacterial cells. Morphological observation revealed that application of Au clusters stimulated destruction of bacterial cell walls and inhibited biofilm formation. Aggregation of Au clusters around bacterial cells was fluorescently observed. However, photoexcited Au clusters did not negatively affect the adhesion, spreading, and proliferation of mammalian cells, particularly at lower doses. In addition, application of Au clusters demonstrated significantly better cytocompatibility compared to MB. We found that a combination of Au₂₅(Capt)₁₈ clusters and blue LED irradiation exhibited good antimicrobial effects through ¹O₂ generation and biosafe characteristics, which is desirable for aPDT in dentistry.

Effects of Two Diode Lasers With and Without Photosensitization on Contaminated Implant Surfaces: An Ex Vivo Study

OBJECTIVE

The aim of this ex vivo study is to assess decontamination potential of two different diode laser wavelengths, with or without the aid of photodynamic therapy, on dental implant surfaces and to evaluate the harmful potential of temperature increase during laser irradiation.

MATERIALS AND METHODS

One hundred thirty-two machined sterile implants were placed into sterile porcine bone blocks with standardized coronal angular bony defects and inoculated with Streptococcus sanguinis. Four different treatment protocols were used: 810 or 980 nm laser, with or without photosensitization. Two nontreated control groups were used, one with samples coated with indocyanine green dye. Samples were rinsed and plated on agar plates for subsequent colony count. Irradiation was repeated without contamination at room temperature and in a 37°C water bath monitoring the temperature variation.

RESULTS

There is a statistically significant decontamination effect when the laser is used. Both wavelengths minimize contamination. There was modest improvement given by the photosensitization being more marked in the 810 nm groups, but was not statistically significant compared to laser only. A critical temperature increase was never observed when the sample was in a 37°C water bath.

CONCLUSIONS

The use of both diode laser wavelengths in implant surface decontamination was efficacious regardless of the use of photosensitization and without dangerous increase of temperature.

Photoantimicrobials-are we afraid of the light?

Although conventional antimicrobial drugs have been viewed as miraculous cure-alls for the past 80 years, increasing antimicrobial drug resistance requires a major and rapid intervention. However, the development of novel but still conventional systemic antimicrobial agents, having only a single mode or site of action, will not alleviate the situation because it is probably only a matter of time until any such agents will also become ineffective. To continue to produce new agents based on this notion is unacceptable, and there is an increasing need for alternative approaches to the problem. By contrast, light-activated molecules called photoantimicrobials act locally via the in-situ production of highly reactive oxygen species, which simultaneously attack various biomolecular sites in the pathogenic target and therefore offer both multiple and variable sites of action. This non-specificity at the target circumvents conventional mechanisms of resistance and inhibits the development of resistance to the agents themselves. Photoantimicrobial therapy is safe and easy to implement and, unlike conventional agents, the activity spectrum of photoantimicrobials covers bacteria, fungi, viruses, and protozoa. However, clinical trials of these new, truly broad-spectrum, and minimally toxic agents have been few, and the funding for research and development is almost non-existent. Photoantimicrobials constitute one of the few ways forward through the morass of drug-resistant infectious disease and should be fully explored. In this Personal View, we raise awareness of the novel photoantimicrobial technologies that offer a viable alternative to conventional drugs in many relevant application fields, and could thus slow the pace of resistance development.

Antimicrobial photodynamic therapy using Indocyanine green and near-infrared diode laser in reducing Entrerococcus faecalis

BACKGROUND

The use of Antimicrobial Photodynamic Therapy (aPDT) has been suggested as an adjuvant method to eliminate facultative bacteria during root canal disinfection. The purpose of this preliminary in vitro study was to determine whether the light-activated antimicrobial agent, Indocyanine green (ICG), could be used as photosensitizer and kill Enterococcus faecalis strain under planktonic conditions when irradiated with near-infared (NIR) diode laser emitting in 810nm wavelength.

METHODS

Planktonic suspension containing Enterococcus faecalis strain was divided into nine experimental groups: (1) aPDT with ICG and laser (medium energy fluence), (2) aPDT with ICG and laser (high energy fluence), (3) only ICG without laser activation, (4) only laser emission without ICG (5) 2.5% Sodium hypochlorite (NaOCl) as irrigant, (6) 2.5% NaOCl and aPDT with ICG and laser, (7) 2.0% Chlorhexidine gluconate (CHX) as irrigant (8) No treatment (positive control), (9) No bacterial biofilm growth (negative control). The samples were incubated for 7days and colony-forming units (CFUs) were determined to evaluate bacterial viability.

RESULTS

The microbiological test revealed that aPDT groups, regardless the overall power, showed significant lower mean log₁₀ CFU levels, than groups 3, 4 and 7 (p<0.01). The irrigation with 2.5% NaOCl and the combination of PDT and NaOCl achieved total elimination of bacteria.

CONCLUSION

These preliminary in vitro findings imply that the combination of ICG and NIR diode laser may be a novel supplement in aPDT and provide better disinfection during endodontic treatment.

Clinical Approach of High Technology Techniques for Control and Elimination of Endodontic Microbiota

The main goal in endodontic treatment is to eradicate or at least reduce intraradicular microbial population to levels that are more compatible with periapical lesions healing process. Since endodontic infections are polymicrobial in nature, intraradicular survival of endodontic microbiota and their pathogenic properties are influenced by a combination of their virulence factors. The purpose of this article is to review the endodontic microbiota and their respective virulence attributes, as well as perform a literature review of the effects of disinfection procedures in the treatment of endodontic infections to gain best practices. Conventional technique for root canal preparation includes mechanical debridement and application of antimicrobial irrigants. Recently, laser irradiation has been used to enhance the results of root canal treatment through its thermal effect. To reduce thermal side effects, laser activated irrigation (LAI) and photon induced photoacoustic streaming (PIPS) were introduced. Antimicrobial photodynamic therapy (aPDT) by photochemical reaction uses light at a specific wavelength to activate a nontoxic photosensitizer (PS) in the presence of oxygen to produce cytotoxic products. Different PSs are used in dentistry including methylene blue (MB), toluidine blue O (TBO), indocyanine green (ICG) and curcumin. Among different options, ICG could be the best choice due to its peak absorption at wavelength of 808 nm, which coincides with the commercial diode laser devices. Also, this wavelength has more penetration depth compared to other wavelengths used in aPDT.