Flexural strength and flexural fatigue properties of resin-modified glass ionomers.

OBJECTIVE: To determine the physical properties of several resin-modified glass ionomers (RMGIs) by means of flexural strength and flexural fatigue testing, and to compare them to conventional glass ionomer cements (GICs) and flowable composite resins.

METHODS: RMGI samples were fabricated according to ISO 4049 standard. Rectangular specimens were produced using a polytetrafluoroethylene (PTFE) mold with dimensions of 2 x 2 x 25 mm. Flexural strength and flexural fatigue were measured by means of the 3-point bending tests using an Instron universal testing machine at 0.75 mm/min and 0.03 Hz for 100 cycles, respectively. Flexural stress, load, and displacement were recorded for all tests. Data were statistically compared (ANOVA, SNK, p < 0.05). Statistical data analysis for flexural fatigue was achieved through the least frequent events method (failures versus non-failures). The following RMGIs, flowable composites, and GICs were tested: 1) Activa Bioactive-Restorative; 2) Activa Bioactive-Base/Liner; 3) Tetric EvoFlow; 4) Beautifil Flow Plus; 5) Geristore; 6) Fuji Filling LC; 7) Fuji Lining LC; 8) Ketac Nano; 9) Fuji Triage; 10) Ketac Nano; and 11) Vitrebond Plus.

RESULTS: The flexural strength of Activa-enhanced RMGIs was statistically significantly greater than all other RMGIs and GICs (p < 0.001). The flexural fatigue of Activa-enhanced RMGIs and flowable composites was significantly greater than all other materials (p < 0.00 1). The flexural fatigue of the Activa-enhanced RMGIs was comparable to the two flowable composites tested.

CONCLUSION: The Activa-enhanced RMGIs demonstrated comparable flexural strength and flexural fatigue to flowable composites. Activa-enhanced RMGIs and flowable composites demonstrated flexural strength and flexural fatigue significantly greater than all other tested materials.