Since its first isolation in 1934, hyaluronic acid (HA) has been studied across a variety of research areas. This unbranched glycosaminoglycan consisting of repeating disaccharide units of N-acetyl-d-glucosamine and d-glucuronic acid is almost ubiquitous in humans and in other vertebrates. HA is involved in many key processes, including cell signaling, wound reparation, tissue regeneration, morphogenesis, matrix organization and pathobiology, and has unique physico-chemical properties, such as biocompatibility, biodegradability, mucoadhesivity, hygroscopicity and viscoelasticity. For these reasons, exogenous HA has been investigated as a drug delivery system and treatment in cancer, ophthalmology, arthrology, pneumology, rhinology, urology, aesthetic medicine and cosmetics. To improve and customize its properties and applications, HA can be subjected to chemical modifications: conjugation and crosslinking. The present review gives an overview regarding HA, describing its history, physico-chemical, structural and hydrodynamic properties and biology (occurrence, biosynthesis (by hyaluronan synthases), degradation (by hyaluronidases and oxidative stress), roles, mechanisms of action and receptors). Furthermore, both conventional and recently emerging methods developed for the industrial production of HA and its chemical derivatization are presented. Finally, the medical, pharmaceutical and cosmetic applications of HA and its derivatives are reviewed, reporting examples of HA-based products that currently are on the market or are undergoing further investigations.

Hyaluronic Acid in the Third Millennium.

Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) content varies widely in different joints and species. HA is a non-sulfated, naturally occurring non-protein glycosaminoglycan (GAG), with distinct physico-chemical properties, produced by synoviocytes, fibroblasts, and chondrocytes. HA has an important role in the biomechanics of normal SF, where it is partially responsible for lubrication and viscoelasticity of the SF. The concentration of HA and its molecular weight (MW) decline as osteoarthritis (OA) progresses with aging. For that reason, HA has been used for more than four decades in the treatment of OA in dogs, horses and humans. HA produces anti-arthritic effects via multiple mechanisms involving receptors, enzymes and other metabolic pathways. HA is also used in the treatment of ophthalmic, dermal, burns, wound repair, and other health conditions. The MW of HA appears to play a critical role in the formulation of the products used in the treatment of diseases. This review provides a mechanism-based rationale for the use of HA in some disease conditions with special reference to OA.

Hyaluronic Acid: Molecular Mechanisms and Therapeutic Trajectory.

A review of the designs and prominent biomedical advances of natural and synthetic hydrogel formulations

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics.

Background: Periodontitis and obesity are among the most common chronic disorders affecting the world’s populations, and recent reviews suggest a potential link between overweight/obesity and periodontitis. However, because of the scarcity of prospective evidence, previous reviews were primarily based on cross-sectional studies, with only a few longitudinal or intervention studies included. This study’s objective is to examine the time-dependent association between obesity and periodontitis and how weight changes may affect the development of periodontitis in the general population. Therefore, longitudinal and experimental studies that assessed the association among overweight, obesity, weight gain, waist circumference, and periodontitis are reviewed.Methods: Intervention and longitudinal studies with overweight or obesity as exposure and periodontitis as outcome were searched through the platforms PubMed/Medline and Web of Knowledge.Results: Eight longitudinal and five intervention studies were included....

Association Between Periodontal Disease and Overweight and Obesity: A Systematic Review

Pyogenic granuloma or granuloma pyogenicum is a well-known oral lesion. The name pyogenic granuloma is a misnomer since the condition is not associated with pus and does not represent a granuloma histologically. Pyogenic granuloma of the oral cavity is known to involve the gingiva commonly. Extragingivally, it can occur on the lips, tongue, buccal mucosa, palate, and the like. A history of trauma is common in such sites. The etiology of the lesion is not known, though it was originally believed to be a botryomycotic infection. It is theorized that pyogenic granuloma possibly originates as a response of tissues to minor trauma and/or chronic irritation, thus opening a pathway for invasion of nonspecific microorganisms, although microorganisms are seldom demonstrated within the lesion. Pathogenesis of pyogenic granuloma is still debatable. Medline and PubMed databases were searched under the following key terms: Pathogenesis of oral pyogenic granuloma, pyogenic granuloma, and oral pyogenic granuloma. This search was limited to articles on human/animal studies which were published in English language. After reviewing the searched articles, the relevant articles were selected for the present review. Through this article, we have tried to summarize and present all the concepts of pathogenesis related to this most common and most mysterious oral lesion.

Oral pyogenic granuloma: Various concepts of etiopathogenesis

Hyaluronic acid is a naturally occurring linear polysaccharide of the extracellular matrix of connective tissue, synovial fluid, and other tissues. Its use in the treatment of the inflammatory process is established in medical areas such as orthopedics, dermatology, and ophthalmology. The Pubmed/Medline database was searched for keywords "Hyaluronic acid and periodontal disease" and "Hyaluronic acid and gingivitis" which resulted in 89 and 22 articles respectively. Only highly relevant articles from electronic and manual search in English literature were selected for the present review article. In the field of dentistry, hyaluronic acid has shown anti-inflammatory and anti-bacterial effects in the treatment of periodontal diseases. Due to its tissue healing properties, it could be used as an adjunct to mechanical therapy in the treatment of periodontitis. Further studies are required to determine the clinical efficacy of hyaluronic acid in healing of periodontal lesion. The aim of the present review, article is to discuss the role of hyaluronic acid in periodontal therapy.

Hyaluronic acid: A boon in periodontal therapy

Recent epidemiological studies reveal that more than two-third of the world's population suffers from one of the chronic forms of periodontal disease. The primary etiological agent of this inflammatory disease is a polymicrobial complex, predominantly Gram negative anaerobic or facultative bacteria within the sub-gingival biofilm. These bacterial species initiate the production of various cytokines such as interleukin-8 and TNF-α, further causing an increase in number and activity of polymorphonucleocytes (PMN) along with these cytokines, PMNs also produce reactive oxygen species (ROS) superoxide via the respiratory burst mechanism as the part of the defence response to infection. ROS just like the interleukins have deleterious effects on tissue cells when produced in excess. To counter the harmful effects of ROS, human body has its own defence mechanisms to eliminate them as soon as they are formed. The aim of this review is to focus on the role of different free radicals, ROS, and antioxidants in the pathophysiology of periodontal tissue destruction.

Reactive oxygen species in periodontitis

Obesity is a multifaceted subject. It has increased at an alarming rate in recent years. Being overweight increases the likelihood of a patient having associated health and social problems which may affect dental services and dental management. A review of the literature on obesity and periodontal disease suggested that they both confound each other and obesity itself has been recognized as a major risk factor for periodontal disease. It has been found that adverse effects of obesity on the periodontium may be mediated through pro-inflammatory cytokines and various other bioactive substances. This article tries to focus on the possible role of obesity and obesity-related diseases like diabetes and coronary heart diseases (CHD), as a potential contributor to periodontal disease and vice versa. The meanings of these associations can be useful for various diagnostic and treatment planning purposes.

Obesity, periodontal and general health: Relationship and management.

Today, viral hepatitis has become a silent epidemic worldwide It is the major cause of liver cirrhosis and liver carcinoma In a dental office, infections can be expedited through several routes, including direct or indirect contact with blood, oral fluids, droplet splatter, aerosols, etc The aim of the present review is to increase the awareness among dental practitioners, so as to reduce the burden of hepatitis in their community Electronic databases like PubMed, Medline, ProQuest, etc were searched using the keywords hepatitis, dentist, liver disease, and infection control Manual search of various journals and books was also carried out Only highly relevant articles from English literature were considered for the present review The results revealed that the dentists were among the high-risk groups for hepatitis, and they have little information on the factors associated with adherence to hepatitis B vaccination A dentist can play a major role in the prevention of hepatitis by considering each and every patient as a potential carrier of hepatitis Proper infection control, sterilization, and prophylactic vaccination protocols should be followed in order to reduce the risk of hepatitis

Reet Kamal

Papers

Oral pyogenic granuloma: Various concepts of etiopathogenesis

Hyaluronic acid: A boon in periodontal therapy

Reactive oxygen species in periodontitis

Obesity, periodontal and general health: Relationship and management.

"Hepatitis" - Prevention and management in dental practice.