title: The effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base material.
abstract: BACKGROUND
  Polysiloxane has been used as a coupling material in restorative dental materials for several decades. However, few studies are available on the application of polysiloxane in other dental prosthesis functions.
  
  
  OBJECTIVE
  The purpose of this study was to investigate the effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base materials.
  
  
  METHODS
  Specimens were separated into 2 groups, uncoated and coated. They were coated with a film by using the dip-coating method. Specimens were incubated with Candida albicans 10(7) cells/mL for 1 hour, and the adherent cells were counted under an optical microscope. The following surface properties were measured: surface chemical composition with Fourier-transform infrared spectrometry, surface roughness with a surface profiler, surface energy with the sessile drop method, and surface hardness with a microhardness tester. The physical properties, including water sorption, water solubility, ultimate flexural strength, and flexural modulus, were evaluated according to International Organization for Standardization 20795-1 requirements. The adhesion of Candida albicans and the surface properties of the specimens were investigated after cleaning with effervescent tablets and brushing. An MTT assay was used to evaluate the coated specimens. The results were statistically analyzed with the Mann-Whitney U test (α=.05).
  
  
  RESULTS
  A significant reduction in Candida albicans adhesion (P=.002) was observed before cleaning. In addition, the surface energy was comparable (P=.100), the surface hardness increased significantly (P=.008), and the surface roughness remained unchanged (P=.310). After cleaning with effervescent tablets, a significant decrease in Candida albicans adhesion (P=.002) and in surface roughness (P=.008) was observed; however, similar surface energies were measured (P=.100). After cleaning with a toothbrush, the adhesion of Candida albicans was significantly higher on the coated specimen than on the uncoated specimen (P=.004). The surface roughness values were significantly different (P=.008), and the surface energies could not be determined. The coated specimen had a silicon-oxygen-silicon peak instead of an ester bond in the polymethyl methacrylate structure. The coating film reduced the water sorption (P=.008) and water solubility (P=.032), and increased the ultimate flexural strength (P=.008) and flexural modulus (P=.032) of the specimen. The coated specimen also had satisfactory toxicity results.
  
  
  CONCLUSIONS
  Reduced Candida albicans adhesion was observed on the coated specimens. The polymeric film did not change the surface roughness of the acrylic resin specimen; however, it did slightly reduce the surface energy. The physical properties of the acrylic resin did not decrease after it was coated with the film.
authors.affiliation: Doctoral candidate, Materials Science and Engineering Program, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Sirasa
authors.initials: S
authors.lastname: Yodmongkol
authors.affiliation: Doctoral candidate, Materials Science and Engineering Program, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Rojcharin
authors.initials: R
authors.lastname: Chantarachindawong
authors.affiliation: Associate Professor, Department of Microbiology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Sroisiri
authors.initials: S
authors.lastname: Thaweboon
authors.affiliation: Associate Professor, Department of Microbiology, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Boonyanit
authors.initials: B
authors.lastname: Thaweboon
authors.affiliation: Associate Professor, Department of Chemistry, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Taweechai
authors.initials: T
authors.lastname: Amornsakchai
authors.affiliation: Assistant Professor, Department of Physics, Faculty of Science, Mahidol University, Bangkok, Thailand. Electronic address: toemsak.sri@mahidol.ac.th.
authors.forename: Toemsak
authors.initials: T
authors.lastname: Srikhirin
mesh_terms: D065966:Absorption, Physicochemical; D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption; D018441:Biofilms; D002176:Candida albicans / Q000502:physiology*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003819:Denture Bases / Q000382:microbiology*; D003820:Denture Cleansers / Q000737:chemistry; D055119:Elastic Modulus; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry*; D018583:Pliability; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012821:Silanes / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D013500:Surface Tension; D014099:Toothbrushing / Q000295:instrumentation; D014867:Water / Q000737:chemistry; D017155:Wettability
chemical_list: D000180:Acrylic Resins; D020099:Coated Materials, Biocompatible; D003764:Dental Materials; D003820:Denture Cleansers; D012821:Silanes; D014867:Water; D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate