Question: What are the characteristics that are being altered in expired composite resins?

A question I wanted to ask is about expired composite resins. What are the characteristics that are being altered. Can these be altered before the expiring date when the composite is in the wrong environment? Thanks

Scott Aaron: Asking the question from another direction: if stored correctly are the expiry dates valid?

William Matthew Negreiros: That is actually a very good question. I am also curious! Salvatore SauroGabriel Abuna?

Salvatore Sauro: Not properly, most of the time they are still very “in shape” up to a couple of years beyond the expiring date……… But you need to take the risk

Loukas Giannis: Do not want to take the risk but this is a question of a colleague of mine

Gabriel Abuna: The most sensitive materials are self-etch adhesives and dual resins cements. For resin composites the self life could be prolonged if storaged correctly, but personally I would not take the risk!!!

Pantelis Kouros: To reverse the question, are the expiry dates valid if not properly stored?

Renato Cilli: This is a very interesting question. Once resin composites are acrylic and epoxi based resins, it is, in terms of degradation, long lasting materials although diluent monomers and vinyl-silane agent are incorporated. Expiry date could be related to the quantity of inhibitor present. Once it is totally consumed, resin composite monomers are prone to polymerise expontaneally, thus need properly storage to avoid inhibitor comsuption. Of course, during extended time of storage other problems may arise, such as color alteration. We need more research to ask all these points.

Renato Cilli: Also, there is another important question which is repeated warm ups of resin composite seringues to make those as luting agents. Although many other questions are related to this technique, compules, in my view, should be used.