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Mechanical properties of glass ionomers under static and dynamic loading
H Nakajima1, J H Watkins, K Arita
1Department of Biomaterials Science, Baylor College of Dentistry, Dallas, Texas, USA.
Objectives:
This study evaluated the mechanical properties under static and cyclic loading conditions of various types of glass ionomers used for bases and core build-ups under restorations.
Methods:
Compressive strength and three-point flexural strength of two different glass ionomers and two metal-reinforced glass ionomers were determined 1 d after the start of mixing. The flexural fatigue resistance of these materials was measured in the load range of 650 g to 1050 g using a three-point bending machine, and fractured surfaces of the specimens were examined using SEM.
Results:
All the glass ionomers exhibited similar compressive and flexural strengths. The results analyzed by Cox' proportional hazard model demonstrated that the admixed-type metal-reinforced glass ionomer had the highest fatigue resistance, while the water-hardening glass ionomer had the lowest fatigue resistance among the materials examined (p<0.5).
Significance:
There was no significant improvement in the static mechanical properties from incorporating metal particles into the glass ionomers. However, the addition of metal particles as in the admixed-type metal-reinforced glass ionomer produced a material with increased fatigue resistance.