title: Fluoride release from three glass ionomers after exposure to sodium fluoride and acidulated phosphate fluoride gels.
abstract: BACKGROUND
  Glass ionomer (GI) restorations exposed to fluoride have the ability to slowly release fluoride. Therefore, the aim of this study was to investigate fluoride release from three GIs before and after exposure to sodium fluoride (NaF) and acidulated phosphate fluoride (APF).
  
  
  METHODS
  Fifteen disc-shaped samples (6 mm in diameter and 2 mm in thickness) from three GIs (Fuji II, Fuji IX, Chem Flex) were made and suspended in a polypropylene recipient containing 10 mL distilled water and stored at 37°C. At the 13(th) day, the samples of each GI were randomly divided into 3 groups. Groups 1 and 2 were exposed to NaF and APF gels for 4 min and group 3 served as control in distilled water. The fluoride released was measured at day 1, 4, 10, 13, 14, 17, 20 and 23 by potentiometer. Data were analyzed by one-way ANOVA and Tukey test. P < 0.05 was considered as significant.
  
  
  RESULTS
  Fluoride release was highest after 24 h for the tested GIs, but Fuji II demonstrated the least amount. Fuji IX showed the highest fluoride release followed by Chem Flex. Exposure to fluoride gels significantly increased fluoride release for all materials (P < 0.05). The amount of fluoride release for the three GIs was significantly higher in APF groups during the test period.
  
  
  CONCLUSIONS
  Highly viscous conventional GIs (Fuji IX and Chem Flex) released higher quantity of fluoride.
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Masoud Fallahinejad
authors.initials: MF
authors.lastname: Ghajari
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Torabzadeh
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Nassim
authors.initials: N
authors.lastname: Safavi
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Azin
authors.initials: A
authors.lastname: Sohrabi
authors.affiliation: Department of Pediatric Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Faezeh Fotouhi
authors.initials: FF
authors.lastname: Ardakani
keywords: Acidulated phosphate fluoride; dental caries; fluoride release; glass ionomer; sodium fluoride