title: Biofilm formation affects surface properties of novel bioactive glass-containing composites.
abstract: OBJECTIVE
  This study investigated the effects of bacterial biofilm on the surface properties of novel bioactive glass (BAG)-containing composites of different initial surface roughness.
  
  
  METHODS
  BAG (65 mol% Si; 4% P; 31% Ca) and BAG-F (61% Si; 31% Ca; 4% P; 3% F; 1% B) were synthesized by the sol-gel method and micronized (size ∼0.1-10 μm). Composites with 72wt% total filler load were prepared by replacing 15% of the silanized Sr glass with BAG, BAG-F, or silanized silica. Specimens (n=10/group) were light-cured and divided into 4 subgroups of different surface roughness by wet polishing with 600 and then up to 1200, 2400, or 4000 grit SiC. Surface roughness (SR), gloss, and Knoop microhardness were measured before and after incubating in media with or without a Streptococcus mutans (UA 159) biofilm for 2 weeks. Results were analyzed with ANOVA/Tukey's test (α=0.05).
  
  
  RESULTS
  The SR of the BAG-containing composites with the smoothest surfaces (2400/4000 grit) increased in media or bacteria; the SR of the roughest composites (600 grit) decreased. The gloss of the smoothest BAG-containing composites decreased in bacteria and media-only, but more in media-alone. The microhardness of all of the composites decreased with exposure to media or bacteria, with BAG-containing composites affected more than the control.
  
  
  CONCLUSIONS
  Exposure to bacterial biofilm and its media produced enhanced roughness and reduced gloss and surface microhardness of highly polished dental composites containing a bioactive glass additive, which could affect further biofilm formation, as well as the esthetics, of restorations made from such a material.
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 110-768, 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: salehi@ohsu.edu.
authors.forename: Satin
authors.initials: S
authors.lastname: Salehi
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: D001422:Bacterial Adhesion; D018441:Biofilms; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D005898:Glass / Q000737:chemistry*; D006244:Hardness; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D013295:Streptococcus mutans; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials
keywords: Bioactive glass; Biofilms; Dental composites; Gloss; Microhardness; Streptococcus mutans; Surface roughness