Method: A total of fifty disc-shaped specimens (6 mm diameter x 2.5 mm thick) were prepared and allocated into five groups (n=10); I-Fuji IX GP eXtra, II-Dyract eXtra, III-Fuji IX GP eXtra + Fuji Varnish, IV-Fuji IX GP eXtra + G-Coat Plus, V-Dyract eXtra + G-Coat Plus. The aging procedure was performed in artificial saliva at 37 °C for 3 different time periods (7, 30 and 90 days). Microhardness test (Vickers hardness test) was performed using a universal test machine (Shimadzu Micro Hardness Testers HMV-2) at 3 different time periods. Data was analyzed using Repeated Measures ANOVA, Tukey and Dunnett T3 tests (p=0.05).
Result: The microhardness values of glass ionomer cement groups significantly increased in the first week and first month (p<0.05). In contrast, the microhardness values of compomer groups decreased by time however the difference was not statistically significant (p>0.05). G-Coat Plus and Fuji Varnish had significant benefit on glass ionomer cement restorations at the end of 1-week and 1-month (p<0.05), however at the end of 3-month evaluation period surface-coating had no significant effect on the microhardness of the tested glass ionomer cement.
Conclusion:
The mechanical properties of the restorative materials were positively affected by surface coating in 1-month evaluation period.