Effect of Polymerization Programs on the Microhardness of Resin-modified GIC

Method: Microhardness measurements were performed using a Vickers test. 5g and 10g loads were applied for 10s in Leitz Miniload2 Microhardness Tester on Fuji II LC (FIILC) and Photac Fil Quick Aplicap (PFQ). For each tested material and polymerization program 10 specimens, each 2mm high and 4mm in diameter, were prepared. Bluephase LED curing unit was used. Hardness was evaluated in intervals, starting immediately after a recommended cure (RC) and repeated after 1 day (1d), 7 days (7d) and 14 days (14d). The specimens were stored in deionized water at 37±0.3°C. The results were analyzed by ANOVA and Tukey post hoc test (p<0.01). 

Result: All tested materials showed an increase of microhardness during the time and for all polymerization programs. To illustrate the results, selected values are shown in Table 1. Values of microhardness measurements for FIILC with high polymerization program were significantly higher comparing to values obtained using soft and low program, except for soft program after 14d. PFQ showed significantly higher microhardness values after 14d for samples polymerized with high polymerization program comparing to low program.

Table 1. Microhardness values (mean ± standard deviation)

Conclusion: The measured microhardness values showed significant dependence on the polymerization program (high, soft, low) and storage time for both tested materials.