title: Influence of biofilm formation on the optical properties of novel bioactive glass-containing composites.
abstract: Bioactive glass (BAG) has been suggested as a possible additive for dental restorative materials because of its antimicrobial effect and potential for promoting apatite formation in body fluids. The purpose of this study was to investigate the effects of bacterial biofilm on the change of colorimetric value and translucency of novel BAG-containing composites having different initial surface roughness.
  
  
  
  Composites with 72wt% total filler load were prepared by replacing 15% of the silanized Sr glass with BAG (65 mol % Si; 4% P; 31% Ca), BAG-F (61% Si; 31% Ca; 4% P; 3% F; 1% B), or silanized silica. Light-cured discs of 2-mm thickness (n=10/group) were divided into 4 different surface roughness subgroups produced by wet polishing with 600 and then up to 1200, 2400, or 4000 grit SiC. CIE L*a*b* were measured and the color difference and translucency parameter (TP) were calculated before and after incubating in media with or without a Streptococcus mutans (UA 159) biofilm for 2 wks (no agitation). Results were analyzed using ANOVA/Tukey's test (α=0.05).
  
  
  
  All the color differences for BAG and BAG-F composite showed significant decreases with bacterial biofilm compared to media-only. The mean TP (SD) of BAG and BAG-F composite before aging [10.0 (2.8) and 8.5 (1.4)] was higher than that of the control composite [4.9 (0.8)], while the change in TP with aging was greater compared to the control with or without bacteria. BAG-F composites with the smoothest surfaces showed a greater decrease in TP under bacterial biofilm compared to the BAG composite.
  
  
  
  Highly polished dental composites containing bioactive glass additives may become slightly rougher and show reduced translucency when exposed to bacterial biofilms, but do not discolor any more than control composites that do not contain the BAG.
authors.affiliation: Department of Pediatric Dentistry, Dental Research Institute, School of Dentistry, Seoul National University, Seoul National University Dental Hospital, 101 Daehakno, Jongno-gu, Seoul 03080, Republic of Korea. Electronic address: hege1@snu.ac.kr.
authors.forename: Hong-Keun
authors.initials: HK
authors.lastname: Hyun
authors.affiliation: Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University, 2730 S.W. Moody Avenue, Portland, OR 97201, USA. Electronic address: ferracan@ohsu.edu.
authors.forename: Jack L
authors.initials: JL
authors.lastname: Ferracane
mesh_terms: D018441:Biofilms; D003188:Composite Resins; D003764:Dental Materials; D005898:Glass; D008422:Materials Testing; D013295:Streptococcus mutans; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials
keywords: Bioactive glass; Biofilms; Color; Dental composites