Effect of various surface protections on the margin microleakage of resin-modified glass ionomer cements

Statement of problem. Because conventional glass ionomer cements are moistu re sensitive, a surface coating is recommended during the initial setting s tage. It is unknown whether resin-modified glass ionomer cements also need surface protection. Purpose. This study investigated the effect of various surface protections on microleakage with Class V resin-modified glass ionomer restorations. Material and methods. Forty extracted molars with buccal and lingual Class V cavity preparations were restored with a resin-modified glass ionomer (Fu ji II LC). The occlusal margin of each restoration was on enamel and the ce rvical margin on dentin. After immediate finishing and polishing, the teeth were divided into 4 groups according to the following surface protection t reatments: group I, unprotected; group II, Fuji varnish; group III, resin a dhesive; and group IV, acid etching and resin adhesive. After these procedu res, all teeth were stored in isotonic saline for 24 hours, thermocycled 15 00 times at 5 degreesC to 60 degreesC, and soaked in dye solution for 24 ho urs. The teeth then were longitudinally sectioned and observed under a ster eomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests (P < .05) Results. None of the 4 groups demonstrated complete margin sealing at eithe r the occlusal or cervical mar-ins. Groups II and III displayed the least m icroleakage at cervical margins; a significant difference existed between g roups I and III (P=.034). Compared with the other 3 groups, group IV showed significantly greater microleakage at the cervical margins. Conclusion. Although resin-modified glass ionomers can be finished immediat ely, they remain moisture sensitive. Within the limitations of this study, the results suggest that resin adhesive should be used as a surface protect ion to reduce margin microleakage of resin-modified glass ionomer restorati ons.