title: Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation.
abstract: OBJECTIVE
  To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation.
  
  
  METHODS
  Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch-and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24h-incubation at 37°C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM).
  
  
  RESULTS
  R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results.
  
  
  CONCLUSIONS
  The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors.
authors: Department of Health Sciences, University of Milan, Milan, Italy.
authors: Eugenio
authors: E
authors: Brambilla
authors: Department of Health Sciences, University of Milan, Milan, Italy.
authors: Andrei
authors: A
authors: Ionescu
authors: Department of Medical Sciences, University of Trieste, Trieste, Italy.
authors: Annalisa
authors: A
authors: Mazzoni
authors: Department of Medical Sciences, University of Trieste, Trieste, Italy.
authors: Milena
authors: M
authors: Cadenaro
authors: Department of Health Sciences, University of Milan, Milan, Italy.
authors: Massimo
authors: M
authors: Gagliani
authors: Dipartimento di Medicina del Lavoro, University of Milan, Milan, Italy.
authors: Monica
authors: M
authors: Ferraroni
authors: Department of Oral Biology, College of Dental Medicine, Georgia Health Sciences University, Augusta, GA, USA.
authors: Franklin
authors: F
authors: Tay
authors: Department of Oral Biology, College of Dental Medicine, Georgia Health Sciences University, Augusta, GA, USA.
authors: David
authors: D
authors: Pashley
authors: Department of Biomedical and Neuromotor Sciences, DIBINEM, University of Bologna, Alma Mater Studiorum, Bologna, Italy. Electronic address: lorenzo.breschi@unibo.it.
authors: Lorenzo
authors: L
authors: Breschi
mesh_terms: D018441:Biofilms; D001840:Dental Bonding; D003804:Dentin / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008855:Microscopy, Electron, Scanning; D013295:Streptococcus mutans / Q000378:metabolism*
keywords: Biofilms; Dentin bonding systems; Hydrophilicity; Streptococcus mutans