title: Chitosan/Riboflavin-modified demineralized dentin as a potential substrate for bonding.
abstract: Previous studies have suggested different approaches to modify dentin collagen for potential improvement in bonding to dentin. Here, we are proposing a new approach to reinforce dentin collagen fibrils network by chitosan as a reinforcement phase and UVA-activated riboflavin as crosslinking agent within clinically acceptable time-frame as potential substrate for bonding. The effect of modifying demineralized dentin substrates with chitosan/riboflavin, with a gradual increase in chitosan content, was investigated by SEM, nano-indentation, conventional-mechanical testing and hydroxyproline (HYP) release at collagenolytic and/or hydrolytic challenges. The resin/dentin interface morphology, immediate bond strength and short-term bond durability were also investigated using etch-and-rinse dentin adhesive. Modification with chitosan/riboflavin increased the mechanical properties, enhanced the mechanical stability of demineralized dentin substrates against hydrolytic and/or collagenolytic degradation challenges and decreased HYP release with collagenase exposure. When chitosan was added to riboflavin at 20%v/v ratio, significant improvement in bond strength at 24 h and 6 months in distilled water was found indicating the positive dual effect on bonding to dentin. With the gradual increase in chitosan content, obliteration of interfibrillar-spaces that might adversely affect bonding to dentin was found. Although it has a synergetic effect, chitosan content is crucial for any subsequent application in adhesive dentistry.
authors.affiliation: Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119083, Singapore. denasfmf@nus.edu.sg
authors.forename: Amr S
authors.initials: AS
authors.lastname: Fawzy
authors.forename: Lorraine I
authors.initials: LI
authors.lastname: Nitisusanta
authors.forename: Kulsum
authors.initials: K
authors.lastname: Iqbal
authors.forename: Umer
authors.initials: U
authors.lastname: Daood
authors.forename: Lu Thong
authors.initials: LT
authors.lastname: Beng
authors.forename: Jennifer
authors.initials: J
authors.lastname: Neo
mesh_terms: D000269:Adhesives / Q000737:chemistry; D000293:Adolescent; D000328:Adult; D001419:Bacteria / Q000201:enzymology; D002113:Calcification, Physiologic; D048271:Chitosan / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism; D017364:Collagenases / Q000378:metabolism; D001840:Dental Bonding / Q000379:methods*; D003804:Dentin / Q000378:metabolism*; D006801:Humans; D006909:Hydroxyproline / Q000378:metabolism; D055595:Mechanical Phenomena; D012117:Resins, Synthetic / Q000737:chemistry; D012256:Riboflavin / Q000378:metabolism*; D013997:Time Factors; D055815:Young Adult
chemical_list: D000269:Adhesives; D012117:Resins, Synthetic; D003094:Collagen; D048271:Chitosan; D017364:Collagenases; D006909:Hydroxyproline; D012256:Riboflavin