Evaluation of Two Experimental GICs with New Apatite Formulations

Objectives: To examine the effect of heat, coating, storage agents and ageing on the mechanical behavior of two experimental glass-ionomer cements (GICs).
Methods: One commercially available GIC (Fuji9) and two experimental GICs (F9ap-sphere, F9ap-CFap) were used. The specimens were prepared with three different conditions; (1)Without coating, (2)20s heat application with LED(Translux Power Blue/Heraeus Kulzer) with coating, (3)20s heat application with LED without coating and stored in distilled water or artificial saliva at 37°C for one week and one month. Flexural Strength (FS) was evaluated using a three-point bending test on bar-shaped specimens (16×2×2mm) (n=10). Fragments of the three-point bending test were used to determine Vickers Hardness (VH) with a microhardness tester. Water sorption (Ws) was calculated as the difference between the dry mass of the GIC specimens before water sorption and after each immersion time using the three-point bending test specimens. Results were compared with one-way ANOVA and Tukey’s HDS post-hoc test (α=0.005). A multivariate analysis (general linear model) assessed the effect’s strength of the parameters GIC, coating, storage agent and storage duration on the considered properties.
Results: Post-hoc multiple comparisons revealed significant differences among the VH of all tested materials, Fuji9>F9ap-sphere>F9ap-CFap (p<0.001). The materials prepared according to manufacturer’s recommendation had higher VH (p<0.001). Application of heat, neither by means of coating nor without coating improved the VH (p>0.05). Storing in artificial saliva (η²=0.100) and increasing storage duration (η²=0.317) decreased the VH. Fuji9 showed lower FS than either F9ap-sphere or F9ap-CFap under all conditions(p=0.007). Preparation methods or ageing did not affect the FS (p>0.05). All materials showed similar water sorption levels for all testing conditions (p>0.05).
Conclusions: The experimental GICs might represent a promising approach due to their flexural strength, microhardness and water sorption characteristics but Fuji9 showed better mechanical properties than the tested two experimental GICs.