title: Mineral loss on adjacent enamel glass ionomer cements restorations after cariogenic and erosive challenges.
abstract: OBJECTIVE
  the purpose of this study was to determine the mineral loss on surrounding enamel restored with glass ionomer cements (GIC) after erosive and cariogenic challenges.
  
  
  METHODS
  Bovine enamel specimens were randomly assigned into six groups according to the restorative material: G1 - composite resin; G2 - high viscous GIC; G3 - resin-modified glass ionomer with nanoparticles; G4 - encapsulated resin-modified GIC; G5 - encapsulated high viscous GIC; G6 - resin-modified GIC. After restorative procedures, half of specimens in each group were submitted to caries challenge using a pH cycling model for 5 days, and the other half were submitted to erosive challenge in citric acid for 10 min. Before and after the challenges, surface Knoop microhardness assessments were performed and mineral changes were calculated for adjacent enamel at different distances from restorative margin.
  
  
  RESULTS
  Data were compared for significant differences using two-way ANOVA and Student-Newman-Keuls tests (p<0.05). Erosive challenge significantly reduced enamel surface hardness, but no significant difference was observed irrespectively restorative materials (p>0.05). The cariogenic challenge promoted a higher surface hardness loss for the resin-modified GIC (G4) and only for the High viscous GIC (G2) an increase in surface hardness was observed. For enamel analyses, significant differences were observed with respect to the different materials (p<0.001) and distances (p=0.023). Specimens restored with the composite resin presented higher mineral loss and specimens restored with the conventional high viscous GIC and the encapsulated resin-modified GIC presented the lowest values for mineral loss.
  
  
  CONCLUSIONS
  The GICs exerts protective effect only for cariogenic challenge.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, University of São Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo, SP 005508-000, Brazil.
authors.forename: C F C
authors.initials: CF
authors.lastname: Salas
authors.forename: C A B
authors.initials: CA
authors.lastname: Guglielmi
authors.forename: D P
authors.initials: DP
authors.lastname: Raggio
authors.forename: F M
authors.initials: FM
authors.lastname: Mendes
mesh_terms: D000818:Animals; D002326:Cariogenic Agents / Q000009:adverse effects*; D002417:Cattle; D019343:Citric Acid / Q000009:adverse effects*; D003188:Composite Resins / Q000737:chemistry; D003743:Dental Enamel / Q000473:pathology*; D003764:Dental Materials / Q000737:chemistry; D003775:Dental Polishing / Q000379:methods; D003793:Dental Restoration, Permanent / Q000379:methods*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000032:analysis; D053758:Nanoparticles / Q000737:chemistry; D020011:Protective Agents / Q000737:chemistry; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D017001:Tooth Demineralization / Q000209:etiology*; D014077:Tooth Erosion / Q000150:complications*; D014089:Tooth Remineralization / Q000379:methods; D014783:Viscosity
chemical_list: D002326:Cariogenic Agents; D003188:Composite Resins; D003764:Dental Materials; D005899:Glass Ionomer Cements; D008903:Minerals; D020011:Protective Agents; D019279:Resin Cements; C084550:Vitremer; C533204:filtek Z350; C110713:fuji IX; D019343:Citric Acid