Fluoride release, weight loss and erosive wear of modern aesthetic restoratives.
OBJECTIVE
In this investigation, the in vitro sustained fluoride release, weight loss and erosive wear of three conventional glass ionomer cements (Fuji IX, ChemFil Superior, Ketac-Silver), three resin-modified glass ionomer cements (Fuji II LC, Vitremer, Photac-Fil), a polyacid-modified resin composite (Dyract), and a resin composite control material (Z100) were compared.


METHODS
The amounts of fluoride released and weight changes were measured for 12 weeks using a fluoride electrode with TISAB III buffer. After 12 weeks, the specimens were recharged with fluoride using 2 mL of 1.23% APF gel. The recharged specimens were assessed for the amounts of fluoride released and weight changes over another 12 weeks. At the end of the experiment, the specimens were examined with SEM and surface profilometry.


RESULTS
All materials, with the exception of Z100, showed the highest initial fluoride release rates during the first 2 days, dropping quickly over 2 weeks and becoming largely stabilised after 5 weeks, in an exponential mode. The recharging of the specimens with APF gel caused a large increase in the amounts of fluoride released during the first 2 days only. Analyses for all cements showed strong correlations between mean weight loss and cumulative fluoride release over a 5-week period following the application of the APF gel. SEM and surface profilometry found that roughness increased from the polyacid-modified resin composite to the conventional glass ionomer cements.


CONCLUSIONS
APF gel caused erosive wear of the glass ionomer cements especially, and the wear correlated well with the weight losses. To minimise surface erosion, APF gel should not be used on these cements, especially as the recharging effects are transitory.
Yip
H K
HK
Faculty of Dentistry, University of Hong Kong, China.
Lam
W T
WT
Smales
R J
RJ
D000704:Analysis of Variance; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003738:Dental Cements / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data; D004955:Esthetics, Dental; D005459:Fluorides / Q000032:analysis / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D016014:Linear Models; D008422:Materials Testing / Q000379:methods / Q000706:statistics & numerical data; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties
D003738:Dental Cements; D005899:Glass Ionomer Cements; D005459:Fluorides