Influence of ZOE temporary restorations on microleakage in composite restorations

This study investigated the influence of zinc-oxide eugenol (ZOE) temporary restorations on microleakage in composite restorations. Class V cavities were prepared on the buccal surfaces of 32 freshly extracted, non-carious human premolars. The teeth were randomly divided into four groups of eight teeth. Specimens in Group 1 (control) received no temporary restoration. Group 2 and 3 specimens were covered with IRM (Type III ZOE cement) mixed at powder:liquid (P:L) ratio of 10g:1g and 10g:2g, respectively. Specimens in Group 4 were covered with poly-carboxylate cement (eugenol-free) mixed at a P:L ratio of 2.85g:1g. The temporary restorations were removed mechanically with an ultrasonic scaler after one week storage in distilled water at 37 degrees C. The preparations were washed and restored with Scotchbond Multi-Purpose Plus and Z100 according to manufacturers' instructions. The restorations were finished, thermally stressed for 400 cycles and subjected to dye penetration testing. Results were analyzed using Kruskal-Wallis and Mann-Whitney tests at a significance level of 0.05. At both enamel and dentin margins, the microleakage associated with Group 3 was significantly greater than for Groups 1, 2 and 4. For Groups 1 and 4, leakage at the dentin margins was significantly greater than in enamel margins. For the groups pretreated with IRM, no significant difference in dye penetration scores was observed between enamel and dentin. Pre-treatment with IRM mixed at a P:L ratio of 10g:2g significantly increased microleakage and is not recommended clinically.