title: Insights into and relative effect of chitosan-H, chitosan-H-propolis, chitosan-H-propolis-nystatin and chitosan-H-nystatin on dentine bond strength.
abstract: OBJECTIVE
  The purpose of the study was to design and evaluate novel functional chitosan hydrogels (chitosan-H-propolis, chitosan-H-propolis-nystatin and chitosan-H-nystatin) by using the chitosan-H polymer as "dual function restorative materials".
  
  
  METHODS
  The nystatin/antioxidant carrier gel was prepared by dispersion of the corresponding component in glycerol and 3% acetic acid with 5% chitosan gelling agent was then added to the dispersion with continuous mixing. The natural bio-adhesive functionalized chitosan hydrogels were combined with built in drug delivery system and bio-actives such as propolis in order to increase the dentin bond strength capacity and maintain therapeutic properties of the alternative drug delivery system. The surface morphology, release behaviors (physiological pH and also in acidic conditions), stability of nystatin:antioxidant:chitosan and the effect of the hydrogels on the shear bond strength of dentin were also evaluated.
  
  
  METHODS
  Non-parametric ANOVA test was used to asses significance of higher shear bond values than dentine treated or not treated with phosphoric acid.
  
  
  RESULTS
  The release of both nystatin and propolis confer the added benefit of dual action of a functional therapeutic delivery when comparing the newly designed chitosan-based hydrogel restorative materials to commercially available nystatin alone. Neither the release of nystatin nor the antioxidant stability was affected by storage. Chitosan-H, chitosan-propolis, chitosan-nystatin and chitosan-nystatin-propolis treated dentine gives significantly (P < 0.05) higher shear bond values (P < 0.05) than dentine treated or not treated with phosphoric acid.
  
  
  CONCLUSIONS
  The added benefits of their unique functionality involve increased dentin adhesive bond strengths (after 24 h and after 6 months) and positive influence on the nystatin release. Nystatin was a model therapeutic agent, evaluating the concept of using functional materials as carriers for pro-drugs as well as displaying a certain degree of defence mechanism for free radical damage of the novel functional drug delivery. Overall, there was an insignificant relapse in the shear bond strength after 6 months.
authors.affiliation: Department of Research and Innovations, VTPCHEM Pty. Ltd., Glenhuntly, Melbourne, 3163, Australia.|School of Dentistry and Oral Health, Griffith University, Gold Coast, Southport, 4215, QLD, Australia.
authors.forename: Victoria Tamara
authors.initials: VT
authors.lastname: Perchyonok
authors.affiliation: School of Material Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
authors.forename: Shengmiao
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Oral and Dental Research Institute, Faculty of Dentistry, University of the Western Cape, Private Bag X1, Tygerberg 7505, Cape Town, South Africa.
authors.forename: Sias R
authors.initials: SR
authors.lastname: Grobler
authors.affiliation: School of Dentistry and Oral Health, Griffith University, Gold Coast, Southport, 4215, QLD, Australia.
authors.forename: Theunis G
authors.initials: TG
authors.lastname: Oberholzer
keywords: Antioxidant-chitosan hydrogels; bond strength; functional restorative materials; scanning electron microscopy