title: Susceptibility of restorations and adjacent enamel/dentine to erosion under different salivary flow conditions.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of erosion on direct tooth-coloured restorations and adjacent enamel/dentine under low and normal simulated salivary flow rates.
  
  
  METHODS
  Bovine enamel and dentine specimens were prepared (n=16) and restored with the following materials: resin composite (FiltekZ250), resin-modified glass ionomer cement (Fuji II LC), high-viscosity glass ionomer cement (Fuji IX), and conventional glass ionomer cement (Fuji II). They were submitted to in vitro erosion-remineralisation cycling simulating normal (0.5 ml/min) and low (0.05 ml/min) salivary flow rates, for 5 days. The restorative material, enamel and dentine substrates were assessed with optical profilometry for surface loss. Mixed-model ANOVAs were used for statistical comparisons (alpha=0.05).
  
  
  RESULTS
  Low-salivary flow significantly increased surface loss for all tested substrates (p<0.05), except FiltekZ250. Surface loss (mean±SD, in micrometres) under low-salivary flow was significantly higher in enamel (19.75±4.27) and dentine (23.08±3.48) adjacent to FiltekZ250 compared to Fuji II LC (16.33±2.30 and 20.47±2.58, respectively) and Fuji IX (15.79±2.41 and 20.63±2.34, respectively). Restoration surface degradation was significantly lower for Fuji II LC (2.17±0.73) than for both Fuji II (13.03±6.79), and Fuji IX (16.74±7.72) under low-salivary flow condition; whereas FiltekZ250 exhibited no meaningful surface loss (-0.35±0.19).
  
  
  CONCLUSIONS
  Limited to these in vitro conditions, low-salivary flow promoted higher erosive conditions for teeth and restorations. Some fluoride-containing restorative materials may reduce erosive wear on adjacent enamel and dentine. FiltekZ250 resisted erosive surface loss. Fuji II LC showed both reduced acid degradation and protection of adjacent dental surfaces to erosion.
  
  
  CONCLUSIONS
  Patients at risk for erosion and in need of restorations may benefit from fluoride-containing restorative materials that resist erosive degradation. The data of this study suggest that resin-modified glass ionomer may be a suitable restoration for patients at higher risk of erosion with low exposure to fluoride.
authors.affiliation: Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, 415 Lansing Street, Indianapolis, IN 46202-2876, USA; Department of Restorative Dental Science, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.
authors.forename: Maryam A
authors.initials: MA
authors.lastname: Alghilan
authors.affiliation: Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, 415 Lansing Street, Indianapolis, IN 46202-2876, USA.
authors.forename: N Blaine
authors.initials: NB
authors.lastname: Cook
authors.affiliation: Department of Restorative Dentistry, Indiana University School of Dentistry, Indianapolis, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Platt
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, USA.
authors.forename: George J
authors.initials: GJ
authors.lastname: Eckert
authors.affiliation: Department of Cariology, Operative Dentistry and Dental Public Health, Indiana University School of Dentistry, 415 Lansing Street, Indianapolis, IN 46202-2876, USA. Electronic address: ahara@iu.edu.
authors.forename: Anderson T
authors.initials: AT
authors.lastname: Hara
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D002417:Cattle; D019343:Citric Acid / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003743:Dental Enamel / Q000378:metabolism* / Q000473:pathology; D003764:Dental Materials / Q000737:chemistry / Q000378:metabolism*; D003793:Dental Restoration, Permanent / Q000379:methods*; D003804:Dentin / Q000737:chemistry / Q000473:pathology; D005459:Fluorides / Q000627:therapeutic use; D005899:Glass Ionomer Cements / Q000737:chemistry; D007180:Incisor; D012822:Silicon Dioxide / Q000737:chemistry; D014077:Tooth Erosion / Q000378:metabolism*; D014987:Xerostomia / Q000473:pathology
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; C015897:glass ionomer; D019343:Citric Acid; D012822:Silicon Dioxide; D005459:Fluorides
keywords: Composite resin; Glass ionomer cements; Hyposalivation; Teeth erosion; Xerostomia