hyaluronic acid ( ha ) is a linear polymer of glucuronic acid and n - acetylglucosamine disaccharide .
the main function of ha includes tissue healing including activation and moderation of the inflammatory responses , promotion of cell proliferation , migration , and angiogenesis .
ha is a hygroscopic macromolecule and its solutions are highly osmotic . in the oral mucosa , this property enables to control of tissue hydration during periods of inflammatory process or response to tissue injury resulting in ulcer formation .
high - molecular - weight ha [ figure 1 ] acts as an anti - inflammatory molecule and has been shown to be beneficial in supporting gingival health .
it is the most abundant high - molecular - weight glycosaminoglycan ( gag ) in the extracellular matrix of soft periodontal tissues .
studies indicate that ha exhibits beneficial anti - inflammatory and antibacterial activity in the treatment of gingivitis and periodontitis .
topically , ha has been used as a 0.2% solution for the treatment of recurrent aphthous ulcers in clinical trials .
ha is commercially available as sodium hyaluronatein combination with polyvinylpyrrolidone ( pvp ) and glycyrrhetinic acid .
the combination was launched as gelclair sachets ( sinclair pharma , uk ltd ) in 2002 and received us food and drug administration ( us fda ) approval for management of oral mucositis associated with chemotherapy .
pvp , an important constituent of this preparation , has remarkable properties such as good chemical and biological inertness , very low toxicity , high media compatibility , and crosslinkable flexibility , which gives stability to the formulation .
topical ha 0.2% or pvp - sh gel forms a protective coating around the oral cavity to shield exposed or sensitized nerve endings from overstimulation [ figure 2 ] .
each of the ingredients in pvp - sh performs a specific role , as listed here:- topical hyaluronic acid ( ha ) forms a barrier film on exposed nerve endings 
 polyvinylpyrrolidone  it is a hydrophilic polymer with muco - adherent and film - forming properties , which enhances tissue hydration.hyaluronic acid ( as sodium hyaluronate )  it coats the oral mucosa , enhances tissue hydration , and accelerates healing.glycyrrhetinic acid  it is a breakdown product of glycyrrhizin , the active component of licorice and has anti - inflammatory properties that aid in ulcer healing .
polyvinylpyrrolidone  it is a hydrophilic polymer with muco - adherent and film - forming properties , which enhances tissue hydration .
hyaluronic acid ( as sodium hyaluronate )  it coats the oral mucosa , enhances tissue hydration , and accelerates healing .
it is a breakdown product of glycyrrhizin , the active component of licorice and has anti - inflammatory properties that aid in ulcer healing .

 oral mucositisrecurrent and generalized aphthous oral ulcersulcers due to drug reactionsulcers following the use of dental amalgam as a restorative materialulcers due to orthodontic brackets and wiresulcers due to ill - fitting denturesulcers due to diseases as lichen planus , behcet 's diseasetraumatic ulcersulcers due to radiotherapy / chemotherapyxerostomia , sjogren 's syndromepost - vaporization of oral lesions with co2 laser 
  recurrent and generalized aphthous oral ulcers ulcers due to drug reactions ulcers following the use of dental amalgam as a restorative material ulcers due to orthodontic brackets and wires ulcers due to ill - fitting dentures ulcers due to diseases as lichen planus , behcet 's disease ulcers due to radiotherapy / chemotherapy xerostomia , sjogren 's syndrome post - vaporization of oral lesions with co2 laser
the entire contents of the single - dose pvp - sh sachet are dissolved in 40 ml or two tablespoons of water .
the mixture is stirred and used immediately as an oral rinse for at least a minute or as long as possible to coat the tongue , palate , throat , buccal mucosa and all oral tissue thoroughly , and then spit out . depending on the discomfort caused by oral ulcers ,
pvp - sh gel can be used at least three times per day or as needed .
it is advised not to eat or drink for at least one hour following use . in children under the age of 6 years who may be unable to rinse or gargle ,
nolan et al , evaluated the efficacy of a topical ha preparation ( 0.2% ) in the management of recurrent aphthous in 120 patients in a randomized , placebo - controlled , double - blind trial .
patients treated with topical ha recorded few ulcers on day 5 of the investigation than those treated with placebo ( p < 0.001 ) . also , the occurrence of new ulcers was lower in the ha - treated group on day 4 when compared with placebo - treated group ( p = 0.047 ) .
lee et al , tested the efficacy of topical 0.2% ha gel on recurrent oral ulcers in 33 patients with recurrent aphthous ulceration or behcet 's disease .
the patients were asked to use topical 0.2% ha gel twice daily for 2 weeks .
the subjective parameters investigated s included number of ulcers , healing period and visual analogue scale ( vas ) for pain .
the objective assessment included number of ulcers , maximal area of ulcer , and inflammatory signs , which were inspected by a physician .
after 2 weeks , a subjective reduction in the number of ulcers was observed in 72.7% of the patients .
a decrease in the ulcer healing period was observed in 72.7% of the patients , and 75.8% experienced improvement in vas for pain .
objective inspection of the ulcers revealed a reduction in the number of ulcers in 57.6% of the patients , and a decrease in the area of 78.8% of the ulcers was seen . among the inflammatory signs , swelling and local heat showed significant improvement after treatment .
ha 0.2% or pvp - sh gel offers advantages over topical steroids in that it is safe to be used in all patients including infants and pregnant women , in whom there may be reluctance to use steroids .
it can be used in all grades of oral ulceration [ table 1 ] . who grading of oral mucositis
the only contraindication is known history of allergy or hypersensitivity to ha or any of the ingredients in the pvp - sh gel .
 hyaluronic acid is a hygroscopic macromolecule formed by the polymerisation of glucuronic acid and n - acetylglucosamine disaccharide . 
 it is a primary component of the extracellular matrix in various body tissues . 
 ihe use of topical hyaluronic acid in the treatment of oral ulcers has been recently reported . 
 this article reviews the mechanism of action , indications and efficacy of topical hyaluronic acid gel in the management of oral ulcers . 
Introduction
Molecular Structure and Availability
Mechanism of Action (
Indications
Directions for Use
Efficacy of Topical HA
Advantages of Topical HA in Oral Ulcers
Contraindications