The effects on chronic periodontitis of a subgingivally-placed redox agent in a slow release device

Reactive Oxygen Species Enlightened Therapeutic Strategy for Oral and Maxillofacial Diseases-Art of Destruction and Reconstruction

Reactive oxygen species (ROS) are byproducts of cell metabolism produced by living cells and signal mediators in biological processes. As unstable and highly reactive oxygen-derived molecules, excessive ROS production and defective oxidant clearance, or both, are associated with the pathogenesis of several conditions. Among them, ROS are widely involved in oral and maxillofacial diseases, such as periodontitis, as well as other infectious diseases or chronic inflammation, temporomandibular joint disorders, oral mucosal lesions, trigeminal neuralgia, muscle fatigue, and oral cancer. The purpose of this paper is to outline how ROS contribute to the pathophysiology of oral and maxillofacial regions, with an emphasis on oral infectious diseases represented by periodontitis and mucosal diseases represented by oral ulcers and how to effectively utilize and eliminate ROS in these pathological processes, as well as to review recent research on the potential targets and interventions of cutting-edge antioxidant materials. The PubMed, Web of Science, and Embase databases were searched using the MesH terms "oral and maxillofacial diseases", "reactive oxygen species", and "antioxidant materials". Irrelevant, obsolete, imprecise, and repetitive articles were excluded through screening of titles, abstracts, and eventually full content. The full-text data of the selected articles are, therefore, summarized using selection criteria. While there are various emerging biomaterials used as drugs themselves or delivery systems, more attention was paid to antioxidant drugs with broad application prospects and rigorous prophase animal experimental results.

Antimicrobial activity of copaiba oil (Copaifera ssp.) on oral pathogens: Systematic review

Copaifera ssp. produces an oil-resin that presents antiinflammatory, antitumor, antiseptic, germicidal, antifungal, and antibacterial activity. This systematic review aimed to analyze the antimicrobial action of Copaiba oil against oral pathogens, when compared to that of control substances. A search on Medline/PubMed, LILACS, SciELO, EMBASE, and SCOPUS databases were performed up to March 2017. To be included, the studies needed to perform any antimicrobial activity essay, using copaiba oil and a control substance. The antimicrobial effect of each substance, in each study, was extracted. Eleven studies were included, and several copaiba species were used. All studies showed that copaiba oil, regardless of its species, presented a bactericidal and/or bacteriostatic effect in in vitro analyzes. Only one study showed that the antimicrobial effect of the Copaifera officinalis was similar to the one found in chlorhexidine. A higher risk of bias was detected in most of the included studies. The studies demonstrated that the antimicrobial activity of copaiba oil, in most cases, is lower than chlorhexidine, which is considered the gold standard. However, there is great potential against oral bacteria. Further high quality studies are warranted in order to assess the efficacy of copaiba oil on oral pathogens.

Pyrostegia venusta (Ker Gawl.) Miers Crude Extract and Fractions: Prevention of Dental Biofilm Formation and Immunomodulatory Capacity

Background:

Caries and periodontal diseases remain as important diseases in the Brazilian population. One important pathogen associated with this situation is Streptococcus mutans and other important factor is this pathogen's ability to adhere firmly to the tooth surface leading to dental biofilm formation and caries development.

Objectives:

Determine the antibacterial and other biological activities of P. venusta related to its potential to be used in the treatment of caries and periodontal disease.

Methods:

The growth inhibition by P. venusta of Streptococcus mutans, S. mitis, S. oralis and Candida albicans was determined using the broth microdilution method. In addition, the effect of the samples in adherence and reducing production of acids by S. mutans, and germ-tube formation of C. albicans was analysed. The Nitric Oxide (NO) production and cytotoxicity of P. venusta to peripheral blood mononuclear cells (PBMC) and RAW 264.7 Cell Line Murine Macrophage from Blood were assessed.

Results:

The crude extract (CE) and ethyl-acetate (AF) and n-butanol (BF) fractions showed antibacterial activity. The ethyl-acetate (AF) fraction showed the highest inhibition percentage against the adherence of S. mutans and C. albicans cells without budding, beyond NO production inhibition. There was not any cytotoxicity in the murine macrophages RAW 264.7 cells.

Conclusion:

Our results suggest that P. venusta presents potential to be used as a preliminary source of compounds that can provide helpful activity when used in prophylaxis or treatment of caries or periodontal disease.

SUMMARY

Biological activities of Pyrostegia venusta and its potential for use in formulations for the prevention of oral diseases.

Abbreviations used: NO: Nitric oxide, PBMC: Peripheral blood mononuclear cells, CE: Crude extract, AF: Ethyl-acetate fraction, BF: n-butanol fraction, HF: Hexane fraction, WF: Water fraction, MIC: Minimum inhibitory concentration, MBC: Minimum bactericidal concentration, ATCC: American Type Culture Collection, CFU: Colony-forming units, BHI: Brain heart infusion, RPMI: Roswell Park Memorial Institute, MOPS: 3-(N-morpholino)propanesulfonic acid, DMEM: Dulbecco's modified Eagle's médium, LPS: Lipopolysacharide, MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide, OD: Optical density, AC: Acteoside,

Photodynamic therapy for periodontal diseases: State of the art

BACKGROUND

Photodynamic killing of periodontopathogenic bacteria may be an alternative to the systemic application of antibacterial drugs used in the treatment of periodontal diseases. Even though the method is still in the experimental stage, increasing bacterial resistance problems may promote the introduction of photodynamic therapy (PDT) into periodontal practice.

AIM

In this review a literature survey is given of PDT as seen from a periodontal perspective.

METHODS

In this review, the present knowledge and experience of PDT is summarized. Literature data are presented on drawbacks of conventional antibiotics, the mechanism of PDT, bactericidal effects of PDT as well as results of clinical efforts. The future prospects of the method are discussed.

RESULTS

The application of photosensitizing dyes and their excitation by visible light enables effective killing of periodontopathogens. Encouraging studies using PDT in periodontitis and in peri-implantitis are known.

CONCLUSION

Even though PDT is still in experimental stages of development and testing, the method may be an adjunct to conventional antibacterial measures in periodontology. Clinical follow-up studies are needed to confirm the efficacy of the procedure.

Are dental diseases examples of ecological catastrophes?

Dental diseases are among the most prevalent and costly diseases affecting industrialized societies, and yet are highly preventable. The microflora of dental plaque biofilms from diseased sites is distinct from that found in health, although the putative pathogens can often be detected in low numbers at normal sites. In dental caries, there is a shift towards community dominance by acidogenic and acid-tolerant Gram-positive bacteria (e.g. mutans streptococci and lactobacilli) at the expense of the acid-sensitive species associated with sound enamel. In contrast, the numbers and proportions of obligately anaerobic bacteria, including Gram-negative proteolytic species, increase in periodontal diseases. Modelling studies using defined consortia of oral bacteria grown in planktonic and biofilm systems have been undertaken to identify environmental factors responsible for driving these deleterious shifts in the plaque microflora. Repeated conditions of low pH (rather than sugar availability per se) selected for mutans streptococci and lactobacilli, while the introduction of novel host proteins and glycoproteins (as occurs during the inflammatory response to plaque), and the concomitant rise in local pH, enriched for Gram-negative anaerobic and asaccharolytic species. These studies emphasized (a). significant properties of dental plaque as both a biofilm and a microbial community, and (b). the dynamic relationship existing between the environment and the composition of the oral microflora. This research resulted in a novel hypothesis (the 'ecological plaque hypothesis') to better describe the relationship between plaque bacteria and the host in health and disease. Implicit in this hypothesis is the concept that disease can be prevented not only by directly inhibiting the putative pathogens, but also by interfering with the environmental factors driving the selection and enrichment of these bacteria. Thus, a more holistic approach can be taken in disease control and management strategies.

The buccale puzzle: The symbiotic nature of endogenous infections of the oral cavity

The indigenous, 'normal', microflora causes the majority of localized infectious diseases of the oral cavity (eg, dental caries, alveolar abscesses, periodontal diseases and candidiasis). The same microflora also protects the host from exogenous pathogens by stimulating a vigorous immune response and provides colonization resistance. How can a microflora that supports health also cause endogenous oral disease? This paradoxical host-symbiont relationship will be discussed within the dynamic of symbiosis.Symbiosis means 'life together' - it is capable of continuous change as determined by selective pressures of the oral milieu. Mutualistic symbiosis, where both the host and the indigenous microflora benefit from the association, may shift to a parasitic symbiosis, where the host is damaged and the indigenous microflora benefit. Importantly, these are reversible relationships. This microbial dynamism, called amphibiosis, is the essential adaptive process that determines the causation of endogenous oral disease by a parasitic microflora or the maintenance of oral health by a mutualistic microflora.Complex microbial consortiums, existing as a biofilm, usually provide the interfaces that initiate and perpetuate the infectious assault on host tissue. The ecology of the various oral microhabitats is critical for the development of the appropriate selecting milieux for pathogens. The microbiota associated with dental caries progression is primarily influenced by the prevailing pH, whereas periodontal diseases and pulpal infection appear to be more dependent on redox potential. Candidiasis results from host factors that favour yeast overgrowth or bacterial suppression caused by antibiotics. Oral health or disease is an adventitious event that results from microbial adaptation to prevailing conditions; prevention of endogenous oral disease can occur only when we realize that ecology is the heart of these host-symbiont relationships.

Effects of hydrogen peroxide on growth and selected properties of Porphyromonas gingivalis

In this study we first evaluated the effects of hydrogen peroxide (H2O2) on growth and selected properties of Porphyromonas gingivalis, and compared them with those obtained by a reducing agent (cysteine). The growth of P. gingivalis was only moderately affected when H2O2 was added at concentrations up to 30 mM in a complex culture medium. However, when a defined basal medium was used, H2O2 at a concentration of 3 mM completely inhibited growth of P. gingivalis. Incorporation of cysteine at concentrations up to 30 mM in both media had no effect on growth. The effects of H2O2 and cysteine on cell-associated hemagglutinating and Arg-gingipain activities were evaluated using bacteria grown in the complex culture medium. Both activities were strongly decreased when H2O2 was added in the assay mixtures. This inhibitory effect of H2O2 was reversible. On the other hand, including cysteine in the assay mixtures increased both activities. H2O2 and cysteine had no effect on the expression of heat shock protein (HSP)-68 and HSP-75 by P. gingivalis, as determined by SDS-PAGE and Western immunoblotting analysis. In the second part of the study, we tested whether growth of selected oral bacterial species may modify the oxidation-reduction potential (Eh) of the environment. It was found that certain species were able to either decrease (P. gingivalis, Fusobacterium nucleatum, Peptostreptococcus micros, Streptococcus mutans) or increase (Streptococcus sanguis) the Eh of the medium. Our study provides evidence that an oxidizing agent such as H2O2 may affect the biology of P. gingivalis. Moreover, growth of some members of the oral microflora can generate oxidizing and reducing conditions, and thus potentially influence the ecology of subgingival sites by affecting strictly anaerobic bacteria such as P. gingivalis.

Contemporary interpretation of probing depth assessments: diagnostic and therapeutic implications. A literature review

This paper addresses the diagnostic and therapeutic implications of increased probing depths. In general, in untreated and treated patients, when deep and shallow probing depths are compared, the data indicate that deep sites are associated with increased bleeding upon probing, elevated subgingival temperatures, higher levels of pathogens, more probing errors, a greater amount of infiltrated connective tissue, reduced ability to remove subgingival deposits with root planing, and diminished effectiveness of oral hygiene to alter the subgingival microbiota. Clinical trials demonstrate that probing depth is not a good predictor of future disease progression. However, deep sites are at greater risk of disease progression than shallow sites in untreated and treated patients. Furthermore, the deeper the probing depth, the greater the risk of future disease progression. Overall, the preponderance of evidence indicates that it is advantageous, but not always necessary, for patients to have shallow probing depths. With regards to surgical reduction of probing depths beyond that attained with non-surgical therapy, clinicians need to consider the advantages (e.g., ease of maintenance, reduced risk of disease progression) and disadvantages (e.g., root sensitivity, cosmetic defects) of treatment procedures. Since numerous variables require consideration (e.g., response to root planing, goals of therapy, acceptable level of risk for future disease progression), treatment decisions will vary depending on the patient and the desired clinical outcome at specific sites.

Environmental effects on the growth and proteolysis of Treponema denticola ATCC 33520

The effect of pH, redox potential, O2 and H2 on the growth and proteolytic activity of Treponema denticola ATCC 33520 was studied in a chemostat at different growth rates. The peptidase and protease activities were estimated using different amido-methyl coumarin derivatives and azocasein. The maximum growth rate of T. denticola ATCC 33520 was 0.14 h-1. Reduction of the growth rate of T. denticola by 50-60% gave: an increase in cell mass of 150-200%, a higher acetogenesis and a shift of the pH optimum. The protease and phenylalanine peptidase activities seemed to be of greater importance for the growth of T. denticola ATCC 33520 than the rather low arginine and proline peptidase activities. The redox potential (Eh) played a secondary role. At microaerophilic conditions with 1-5% O2, the cultures maintained a redox potential below -311 mV and an optimal acetogenesis. The presence of H2 induced a marked growth stimulation of T. denticola ATCC 33520. It is concluded that the cell mass and proteolytic activity of T. denticola ATCC 33520 are modulated by the growth rate and the pH and to a lesser extend by the redox potential and presence of O2. Stagnation of the exudate-flow influences these factors and will lead to an increase of the spirochetal population and proteolysis in the periodontal pocket.