Antimicrobial photodynamic therapy (light source; methylene blue; titanium dioxide): Bactericidal effects analysis on oral plaque bacteria: An in vitro study

Effect of photodynamic therapy with 5-aminolevulinic acid and EDTA-2Na against mixed infection of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa

BACKGROUND

The increasing abundance of drug-resistant bacteria is a global threat. Photodynamic therapy is an entirely new, non-invasive method for treating infections caused by antibiotic-resistant strains. We previously described the bactericidal effect of photodynamic therapy on infections caused by a single type of bacterium. We showed that gram-positive and gram-negative bacteria could be killed with 5-aminolevulic acid and 410 nm light, respectively. However, clinically, mixed infections are common and difficult to treat.

OBJECTIVE

We investigated the bactericidal effects of photodynamic therapy on mixed infections of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa.

METHODS

We compared bacterial growth with and without photodynamic therapy in vitro. Then, in vivo, we studied mixed infections in a mouse skin ulcer model. We evaluated the rates of ulcer area reduction and transitions to healing in treated and untreated mice. In addition, a comparison was made between PDT and existing topical drugs.

RESULTS

We found that photodynamic therapy markedly reduced the growth of both methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, in culture, and it reduced the skin ulcer areas in mice. PDT was also more effective than existing topical medicines.

CONCLUSION

This study showed that photodynamic therapy had antibacterial effects against a mixed infection of gram-positive and gram-negative bacteria, and it promoted skin ulcer healing. These results suggested that photodynamic therapy could be effective in both single- and mixed-bacterial infections.

Photodynamic therapy in periodontitis: A narrative review

BACKGROUND

Periodontitis, a chronic infectious disease, is primarily caused by a dysbiotic microbiome, leading to the destruction of tooth-supporting tissues and tooth loss. Photodynamic therapy (PDT), which combines excitation light with photosensitizers (PS) and oxygen to produce antibacterial reactive oxygen species, is emerging as a promising adjuvant treatment for periodontitis.

METHODS

This review focuses on studies examining the antibacterial effects of PDT against periodontal pathogens. It also explores the impact of PDT on various aspects of periodontal health, including periodontal immune cells, human gingival fibroblasts, gingival collagen, inflammatory mediators, cytokines in the periodontium, vascular oxidative stress, vascular behavior, and alveolar bone health. Clinical trials assessing the types of PSs and light sources used in PDT, as well as its effects on clinical and immune factors in gingival sulcus fluid and the bacterial composition of dental plaque, are discussed.

RESULTS

The findings indicate that PDT is effective in reducing periodontal pathogens and improving markers of periodontal health. It has shown positive impacts on periodontal immune response, tissue integrity, and alveolar bone preservation. Clinical trials have demonstrated improvements in periodontal health and alterations in the microbial composition of dental plaque when PDT is used alongside conventional treatments.

CONCLUSIONS

PDT offers a promising adjunctive treatment for periodontitis, with benefits in bacterial reduction, tissue healing, and immune modulation. This article highlights the potential of PDT in periodontal therapy and emphasizes the need for further research to refine its clinical application and efficacy.

Titanium dioxide nanoparticles: Recent progress in antimicrobial applications

For decades, the antimicrobial applications of nanoparticles (NPs) have attracted the attention of scientists as a strategy for controlling the ever-increasing threat of multidrug-resistant microorganisms. The photo-induced antimicrobial properties of titanium dioxide (TiO₂ ) NPs by ultraviolet (UV) light are well known. This review elaborates on the modern methods and antimicrobial mechanisms of TiO₂ NPs and their modifications to better understand and utilize their potential in various biomedical applications. Additional compounds can be grafted onto TiO₂ nanomaterial, leading to hybrid metallic or non-metallic materials. To improve the antimicrobial properties, many approaches involving TiO₂ have been tested. The results of selected studies from the past few years covering the most recent trends in this field are discussed in this review. There is extensive evidence to show that TiO₂ NPs can exhibit certain antimicrobial features with disputable roles of UV light. Hence, they are effective in treating bacterial infections, although the majority of these conclusions came from in vitro studies and in the presence of some additional nanomaterials. The methods of evaluation varied depending on the nature of the research while researchers incorporated different techniques, including determining the minimum inhibitory concentration, cell count, and using disk and well diffusion methods, with a noticeable indication that cell count was the most and dominant criterion used to evaluate the antimicrobial activity. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

The Oral Microbiota: Community Composition, Influencing Factors, Pathogenesis, and Interventions

The human oral cavity provides a habitat for oral microbial communities. The complexity of its anatomical structure, its connectivity to the outside, and its moist environment contribute to the complexity and ecological site specificity of the microbiome colonized therein. Complex endogenous and exogenous factors affect the occurrence and development of the oral microbiota, and maintain it in a dynamic balance. The dysbiotic state, in which the microbial composition is altered and the microecological balance between host and microorganisms is disturbed, can lead to oral and even systemic diseases. In this review, we discuss the current research on the composition of the oral microbiota, the factors influencing it, and its relationships with common oral diseases. We focus on the specificity of the microbiota at different niches in the oral cavity, the communities of the oral microbiome, the mycobiome, and the virome within oral biofilms, and interventions targeting oral pathogens associated with disease. With these data, we aim to extend our understanding of oral microorganisms and provide new ideas for the clinical management of infectious oral diseases.

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.