The Effect of Expiration Date on Mechanical Properties of Resin Composites

OBJECTIVE: The aim of this in vitro study is to evaluate the effect of expiration date on some mechanical properties of resin composites after controlled storage of syringes and compules in a refrigerator at 4°C. MATERIALS AND METHODS: Specimens were tested at 7 days after storage in distilled water at room temperature. The investigated properties are the static modulus of elasticity, the flexural strength, and the Vickers microhardness. Same batches of restorative materials were examined at baseline (at least 1 year before their expiration date) and 1 year after they expired. RESULTS: Paired t-test is used to compare the results between the two groups using StatView software (version 5.0) SAS Campus Drive Cary, North Carolina, USA. Except for the flexural strength, no statistical differences were found between the mechanical properties of the expired and the unexpired group. CONCLUSION: The 1-year expiry date did not seem to affect the investigated mechanical properties.