title: Characterization of antibacterial and adhesion properties of chitosan-modified glass ionomer cement.
abstract: OBJECTIVE
  The aim is to investigate the effect of modifying the liquid phase of a conventional glass ionomer restorative material with different chitosan volume contents on the antibacterial properties and adhesion to dentin.
  
  
  METHODS
  The liquids of commercially available restorative glass ionomer cements (GIC) were modified with chitosan (CH) solutions at different volume contents (5%, 10%, 25%, and 50%). The GIC powders were mixed with the unmodified and the CH-modified liquids at the desired powder/liquid (P/L) ratio. For the characterization of the antibacterial properties, Streptococcus mutans biofilms were formed on GIC discs and characterized by scanning electron microscope (SEM), confocal microscopy, colony forming unit (CFU) count, and cell viability assay (MTS). The unmodified and CH-modified GICs were bonded to dentin surfaces and the micro-tensile bond strength (µTBs) was evaluated and the interface was investigated by SEM.
  
  
  RESULTS
  Modification with CH solutions enhanced the antibacterial properties against S. mutans in terms of resistance to biofilm formation, CFU count, and MTS assay. Generally, significant improvement in the antibacterial properties was found with the increase in the CH volume content. Modification with 25% and 50% CH adversely affected the µTBs with predominant cohesive failure in the GIC. However, no difference was found between the control and the 5% and 10% CH-modified specimens.
  
  
  CONCLUSIONS
  Incorporation of acidic solutions of chitosan in the polyacrylic acid liquid of GIC at v/v ratios of 5-10% improved the antibacterial properties of conventional glass ionomer cement against S. mutans without adversely affecting its bonding to dentin surface.
authors.affiliation: Dentistry Research Laboratories, Faculty of Dentistry, National University of Singapore, Singapore Discipline of Prosthodontics, Operative Dentistry and Endodontics, National University of Singapore, Singapore.
authors.forename: Marrwa A
authors.initials: MA
authors.lastname: Ibrahim
authors.affiliation: Discipline of Prosthodontics, Operative Dentistry and Endodontics, National University of Singapore, Singapore.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Neo
authors.affiliation: Discipline of Prosthodontics, Operative Dentistry and Endodontics, National University of Singapore, Singapore.
authors.forename: Roxanna J
authors.initials: RJ
authors.lastname: Esguerra
authors.affiliation: Discipline of Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore denasfmf@nus.edu.sg.
authors.forename: Amr S
authors.initials: AS
authors.lastname: Fawzy
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D048271:Chitosan / Q000031:analogs & derivatives* / Q000494:pharmacology*; D003804:Dentin / Q000378:metabolism; D005899:Glass Ionomer Cements / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D008422:Materials Testing; D013295:Streptococcus mutans / Q000187:drug effects; D013499:Surface Properties; D013718:Tensile Strength; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D005899:Glass Ionomer Cements; D048271:Chitosan
keywords: Glass ionomer; Streptococcus mutans; antibacterial properties; bonding to dentin; chitosan