title: Influences of surface and solvent on retention of HEMA/mixture components after evaporation.
abstract: OBJECTIVE
  This study examined the retention of solvents within experimental HEMA/solvent primers after two conditions for solvent evaporation: from a free surface or from dentine surface.
  
  
  METHODS
  Experimental primers were prepared by mixing 35% HEMA with 65% water, methanol, ethanol or acetone (v/v). Aliquots of each primer (50 microl) were placed on glass wells or they were applied to the surface of acid-etched dentine cubes (2mm x 2mm x 2mm) (n=5). For both conditions (i.e. from free surface or dentine cubes), change in primers mass due to solvent evaporation was gravimetrically measured for 10min at 51% RH and 21 degrees C. The rate of solvent evaporation was calculated as a function of loss of primers mass (%) over time. Data were analysed by two-way ANOVA and Student-Newman-Keuls (p<0.05).
  
  
  RESULTS
  There were significant differences between solvent retention (%) and evaporation rate (%/min) depending on the solvent present in the primer and the condition for evaporation (from free surface or dentine cubes) (p<0.05). For both conditions, the greatest amount of retained solvent was observed for HEMA/water primer. The rate of solvent evaporation for HEMA/acetone primer was almost 2- to 10-times higher than for HEMA/water primer depending whether evaporation occurred, respectively, from a free surface or dentine cubes. The rate of solvent evaporation varied with time, being in general highest at the earliest periods.
  
  
  CONCLUSIONS
  The rate of solvent evaporation and its retention into HEMA/solvent primers was influenced by the type of the solvent and condition allowed for their evaporation.
authors.affiliation: Department of Restorative Dentistry, Dental Materials Area, University of Brasília-UnB, DF, Brazil. garciafcp@unb.br
authors.forename: Fernanda C P
authors.initials: FC
authors.lastname: Garcia
authors.forename: Linda
authors.initials: L
authors.lastname: Wang
authors.forename: Lúcia C G
authors.initials: LC
authors.lastname: Pereira
authors.forename: Safira M
authors.initials: SM
authors.lastname: de Andrade e Silva
authors.forename: Luiz M
authors.initials: LM
authors.lastname: Júnior
authors.forename: Marcela Rocha de Oliveira
authors.initials: MR
authors.lastname: Carrilho
mesh_terms: D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental; D002614:Chelating Agents / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D003804:Dentin / Q000648:ultrastructure; D004492:Edetic Acid / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D003764:Dental Materials; D008689:Methacrylates; D012997:Solvents; D014867:Water; D000096:Acetone; D000431:Ethanol; C005044:hydroxyethyl methacrylate; D004492:Edetic Acid; D000432:Methanol