Objective: To compare the fluoride release and caries inhibition ability of RMGI luting cements in vitro. 

Methods: Materials used were 3M ESPE RelyX Luting Plus Cement (RLP), RelyX Luting Cement (RLC), Z250 composite/SingleBond (ZSB). Fluoride release from cured cement discs (20x1mm; n=3) in distilled water was measured at 7, 14 and 28 day intervals using F-specific electrode and TISAB buffer. Rectangular slots (6x2x1mm) were prepared in 24 dentin blocks cut from 8 bovine roots, and filled with ZSB, RLC, and RLP. The specimens were immersed in 25ml acetic acid solution pH 5.0 (37C, 3wks) then sectioned into 400mm slices.  Microradiography was performed and quantified with image analysis software. DeltaZ was calculated from mineral profiles, converted from gray scale, scanned at distances 0.5 and 1.0mm from the material.  DeltaZs were statistically analyzed (ANOVA, Fisher's, p<0.05). 

Results: ZSB is not fluoridated and did not exhibit F release. The other values are shown in the Table. Both RMGIs showed pronounced inhibition zones adjacent to dentin interface. Both RLP and RLC showed significantly less mineral loss than ZSB at 0.5mm and 1.0mm from the material margin. The values for RLP and RLC were not significantly different at 1.0mm.

Conclusion: RelyX and RelyX Plus luting cements released comparable amounts of fluoride, and, in contrast to the composite, demonstrated inhibition zones at the adjacent cavity margin when subjected to in vitro demineralization.  Both cements showed lower mineral loss in dentin compared to the composite up to 1.0mm adjacent to the bonded interface. Keywords: glass-ionomer, luting, dentin, demineralization, inhibition zone, mineral loss