Rationale for caries inhibition of debonded glass ionomer sealants: an in vitro study.

PURPOSE: This study's purpose was to test the hypothesis that, after glass ionomer (GI) sealant debonding, remaining GI in the deepest parts of fissures and/or the inhibition of enamel demineralization after artificial caries challenge imparts the residual cariostatic property observed in clinical studies. METHODS: Fuji IX GI sealant was placed on one tooth from 14 matched pairs of noncarious extracted human permanent molars and premolars; the other tooth was the control. Sealed teeth underwent thermocycling (4,000 cycles), and the sealant was manually debonded. The amount of remaining sealant in the fissures was determined using a stereomicroscope. All teeth were placed in lactic acid gel (pH 5.0) at 37 degrees Celsius for three weeks to simulate caries formation. The extent of demineralization was determined using the serial micro-hardness method on the cross-sectioned specimens at 0.5 mm from the depth of the central fissure. RESULTS: All teeth had GI retained in the fissures at a microscopic level. Enamel demineralization adjacent to the remaining GI was not significantly different from the control (t test; P=.88). CONCLUSIONS: The residual cariostatic property of glass ionomer sealant is most likely due to a physical barrier of remaining GI in the fissures rather than a chemical effect on demineralization inhibition.