The influence of one month water storage on fracture strength and cyclic fatigue of experimental and commercial glass ionomer cements

Objectives: The aim of the present in vitro study was to determine the fatigue behavior of different glass ionomer cements. This was studied under the focus of different water storage times(1d, 7d, 30d).

Methods: Rectangular specimens of GIC materials (G111/4 (exp. GIC, Univ. of Erlangen, EG), Fuji IX® GP Fast (GC Corp., Japan FU), Ketac Molar® and Ketac Molar® Quick (3M ESPE, Germany KM, KMQ)) were produced and stored in dist. water of 37°C. Fracture strengths (FS; n=10) were evaluated using a three-point bending device. Flexural fatigue limits (FFL; n=20) for 10,000 cycles were determined in dist. water of 37°C using the same three-point-bending test according to the “staircase” approach and calculated as percentage of the mean strength.

Results: The results are listed below(1d/ 7d/ 30d).

Conclusions: A statistically significant increase of FS and FFL was measured for all GIC’s within one month of storage. The major increase happened within the first seven days. The FFL in % of mean strength demonstrated a decrease in flexural strength after fatigue of 55-90%. Higher percentages of FFL were exhibited for lower fracture strengths.