title: Water sorption and solubility of different calcium hydroxide cements.
abstract: OBJECTIVE
  Calcium hydroxide cements have been largely used in deep cavities due to their abilities to stimulate dentin formation. However, their resistance can be relatively low and their solubility relatively high, in many instances. This study evaluated water sorption and solubility of different calcium hydroxide cements, in order to show alterations that may reduce their effectiveness.
  
  
  METHODS
  Five discs (20 mm in diameter and 1.5 mm thick) of three different materials (Biocal, Dycal and Hidro C) were prepared with the aid of a ring-shaped metallic matrix. After being stored at 37 degrees C for 24 h, the discs were weighed on a precision weight scale, dehydrated and weighed again. Immediately after weighing, discs were stored for a week in 50 mL of distilled water at 37 degrees C and, then, weighed again, dehydrated and submitted to a new weighing. The loss of soluble material and its water sorption was obtained from the difference between the initial and the final dry mass of each disc, after 1 week of immersion in water. Data were analyzed for significant differences by two-way ANOVA and Tukey's test (p<0.05).
  
  
  RESULTS
  Mean water sorption values (g) +/- standard deviation and percentage (%), for each evaluated cement, were: Biocal (0.006 +/- 0.001 / 2.15); Dycal (0.016 +/- 0.004 / 5.49); and Hidro C (0.025 +/- 0.003 / 8.27). Mean solubility values (g) +/- standard deviation and percentage (%), for each evaluated cement, were: Biocal (0.002 +/- 0.001 / 0.72); Dycal (0.013 +/- 0.004 / 4.21); and Hidro C (0.023 +/- 0.004 / 7.65).
  
  
  CONCLUSIONS
  Biocal absorbed less water and was less soluble than the other evaluated cements; Hidro C exhibited the highest water sorption and solubility values; and there were significant differences among all evaluated experimental groups.
authors: Department of Operative Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil.
authors: Luciana Fávaro
authors: LF
authors: Francisconi
authors: Anderson Pinheiro
authors: AP
authors: de Freitas
authors: Polliana Mendes Candia
authors: PM
authors: Scaffa
authors: Rafael Francisco Lia
authors: RF
authors: Mondelli
authors: Paulo Afonso Silveira
authors: PA
authors: Francisconi
mesh_terms: D000042:Absorption; D000327:Adsorption; D002126:Calcium Hydroxide / Q000737:chemistry*; D003738:Dental Cements / Q000737:chemistry*; D003890:Desiccation; D006801:Humans; D007101:Immersion; D008422:Materials Testing; D008903:Minerals / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D003738:Dental Cements; D008903:Minerals; D014867:Water; C025702:Dycal; D002126:Calcium Hydroxide