Uncovering the Oral Dysbiotic Microbiota as Masters of Neutrophil Responses in the Pathobiology of Periodontitis

Numerous bacterial species participate in the shift of the oral microbiome from beneficial to dysbiotic. The biggest challenge lying ahead of microbiologists, immunologists and dentists is the fact that the bacterial species act differently, although usually synergistically, on the host immune cells, including neutrophils, and on the surrounding tissues, making the investigation of single factors challenging. As biofilm is a complex community, the members interact with each other, which can be a key issue in future studies designed to develop effective treatments. To understand how a patient gets to the stage of the late-onset (previously termed chronic) periodontitis or develops other, in some cases life-threatening, diseases, it is crucial to identify the microbial composition of the biofilm and the mechanisms behind its pathogenicity. The members of the red complex (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) have long been associated as the cause of periodontitis and stayed in the focus of research. However, novel techniques, such as 16S clonal analysis, demonstrated that the oral microbiome diversity is greater than ever expected and it opened a new era in periodontal research. This review aims to summarize the current knowledge concerning bacterial participation beyond P. gingivalis and the red complex in periodontal inflammation mediated by neutrophils and to spread awareness about the associated diseases and pathological conditions.

The Advent of COVID-19; Periodontal Research Has Identified Therapeutic Targets for Severe Respiratory Disease; an Example of Parallel Biomedical Research Agendas

The pathophysiology of SARS-CoV-2 infection is characterized by rapid virus replication and aggressive inflammatory responses that can lead to acute respiratory distress syndrome (ARDS) only a few days after the onset of symptoms. It is suspected that a dysfunctional immune response is the main cause of SARS-CoV-2 infection-induced lung destruction and mortality due to massive infiltration of hyperfunctional neutrophils in these organs. Similarly, neutrophils are recruited constantly to the oral cavity to combat microorganisms in the dental biofilm and hyperfunctional neutrophil phenotypes cause destruction of periodontal tissues when periodontitis develops. Both disease models arise because of elevated host defenses against invading organisms, while concurrently causing host damage/disease when the immune cells become hyperfunctional. This represents a clear nexus between periodontal and medical research. As researchers begin to understand the link between oral and systemic diseases and their potential synergistic impact on general health, we argue that translational research from studies in periodontology must be recognized as an important source of information that might lead to different therapeutic options which can be effective for the management of both oral and non-oral diseases. In this article we connect concepts from periodontal research on oral inflammation while exploring host modulation therapy used for periodontitis as a potential strategy for the prevention of ARDS a deadly outcome of COVID-19. We suggest that host modulation therapy, although developed initially for management of periodontitis, and which inhibits proteases, cytokines, and the oxidative stress that underlie ARDS, will provide an effective and safe treatment for COVID-19.

RESEARCH IN CLINICAL PERIODONTOLOGY: CURRENT APPROACHES AND FUTURE PERSPECTIVES

Research in the eld of periodontology has observed a huge upheaval in the last two decades unveiling newer alterations in techniques, methodologies, and material science. The recent centre of attention in periodontal research is an evidence-based approach which offers a bridge from science to clinical practice. Research inculcates scientic and inductive thinking and it promotes the development of logical habits of thinking and organization. In terms of research methodology, the article aim to inform the reader on topics relating to randomized controlled trials in periodontal research, evidence-based dentistry, calibration of clinical examiners and statistics relevant to periodontal research.

Potential for Hyaluronic Acid in Periodontal Research

Hyaluronic acid, known also as hyaluronan, is the most abundant glycosaminoglycan in the extracellular matrix. It is produced by most of the cells in the human body, possibly contributing to various fundamental biological processes. This prompts interest in its therapeutic value. Hyaluronic acid (HA) has been used for various treatments owing to its broad range of properties in medical and dental field specially in periodontology. The review gives an overview on the effects of HA on fibroblasts, bone, wound healing, periodontal regeneration, aphthous ulcer/stomatitis and stem cells. Outcomes of including Hyaluronic acid in non-surgical periodontal therapy, drug delivery system and surgical procedures such as root coverage, papilla regeneration, root conditioning, intrabony defects, guided tissue regeneration are rather optimistic. HA has shown astounding potential in treating periimplantitis. Newer frontiers have to be explored to comprehend the other promising properties of HA. Keyword – Hyaluronic Acid, Periodontology.

In vivo animal models in periodontal research - focus on rodents

Periodontal research has developed very fast in the last two decades. Although at this stage of science a lot of genetic and molecular-based trials are performed in order to elucidate the complex etiology, pathophysiology, biofilm-host interactions and responses on genetic and cellular level, in vivo animal models are still used. In many ways, in vivo experiments are superior to in vitro tests when the dynamics of the immune-inflammatory nature of the periodontal disease and peri-implantitis and the specific healing of soft and hard tissues is concerned. Screening the efficacy, mechanisms of action and application of different biomaterials requires in vivo experiments, be-fore the data translation to clinical settings. A number of small animals like rodents and large species like dogs and nonhuman primates are involved in periodontal research. As live creatures are used, the design of the studies must be well defined, with regard to the type of the animals, most suitable for the tested hypothesis, observation period, sample size, study power, critical size defects, and specific testing sites.

Periodontal Experimental Research

Periodontal research in the last few decades has shown discoveries and inventions related to techniques and material science. In the first part of the review, we have discussed the problems and difficulties faced in epidemiological research. In the second part, an overview of the difficulties encountered in experimental periodontal research has been discussed.