title: Characterization of aqueous silver nitrate solutions for leakage tests.
abstract: OBJECTIVE
  To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated.
  
  
  METHODS
  A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silver nitrate salt (Merck, Synth or Cennabras) at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h) and concentrations (1, 5, 25, 50%) of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25% or 50% AgNO₃ solution and the primary teeth in 5% or 50% AgNO₃ solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (α=5%).
  
  
  RESULTS
  The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9). Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm). In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000).
  
  
  CONCLUSIONS
  Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO₃ solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5% concentration, the solutions were capable of indicating loss of marginal seal in the composite restorations; the 3-step conventional adhesive system had better performance regarding microleakage in enamel on primary and permanent teeth.
authors.affiliation: Department of Operative Dentistry, Dental School, Federal University of Maranhão, São Luiz, MA, Brazil.
authors.forename: José Ferreira
authors.initials: JF
authors.lastname: Costa
authors.forename: Walter Luiz
authors.initials: WL
authors.lastname: Siqueira
authors.forename: Alessandro Dourado
authors.initials: AD
authors.lastname: Loguercio
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
authors.forename: Elizabeth de
authors.initials: Ed
authors.lastname: Oliveira
authors.forename: Cláudia Maria Coelho
authors.initials: CM
authors.lastname: Alves
authors.forename: José Roberto de Oliveira
authors.initials: JR
authors.lastname: Bauer
authors.forename: Rosa Helena Miranda
authors.initials: RH
authors.lastname: Grande
mesh_terms: D000704:Analysis of Variance; D003763:Dental Leakage / Q000175:diagnosis*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007101:Immersion; D052578:Ionic Liquids / Q000737:chemistry*; D008422:Materials Testing; D012835:Silver Nitrate / Q000737:chemistry*; D013997:Time Factors
chemical_list: D017220:Dentin-Bonding Agents; D052578:Ionic Liquids; D012835:Silver Nitrate