Someone knows about a research about changes in properties of expired composites?
Sometimes in practice composites expired are wasted or trashed. i want to know if someone investigates changing in aesthetic properties, volumetric, adhesively....
Thank you in advance.
I don´t know if anyone has done some research on this topic (Idon´t think so...). However, what I know is that the chemically cured composites (or the dark hardening reaction of dual cure composite cements) are critical regarding their expiry date. In some cases, even some months before the expiry date the dark curing did not take place any more. The light curing reaction, however functions also many years after the expiry date (up to ten). The other properties should also not change too much.
Certainly Prof Ebert... here in Cuba many times we use it with great results, so I want to know if someone have some unpublished or published research to talk about it cause I couldn’t found one many month ago when I did a research.
Thank you for your answer and best regards.
I think the information of your question may be find in book :Physics of composites: thermodynamic and dissipative properties. Moscow. Russia. 1999. Publ. Science. Author Gladkov S.O.
I guess it would depend on wich component of the composite expired.
If the photoinitiator or the resin monomers expire, the composite would probably harden, but the degree of conversion would be lower (around 60% on a normal composite). That would seriously decrease the mechanical properties of the restoration and make it more prone to fracture in time.
In my experience there aren't composites that reveals in directions for use the date of the photoinitiator or the resin monomers expire. Would be great develope a clinical trials about it. Anyone interesting?
I dont have any experience with composite, but I have had an experience with expired glass ionomer cement (GIC). Normally GIC is not toxic to cells in vitro. But once, i unknowingly used expired GIC in vitro on cells. The results amazed me. Expired GIC killed nearly 95 % of the cells in the culture dish. In contrast, a normal GIC caused death of no more than 30 % cells. (PS. I didnt know the GIC was expired until i got the results. Only after observing death of such a high number of cells did I go and check, to realize that I had used an expired GIC)
So speaking of composite, I am not sure if physical properties may be affected or not. But there is a possibility that it may become more toxic after expiry.
Regards
Interesting your point Tahir about GIC but Why could be more toxic the composite after expired? There is any res4earch about it that you know ? Thank you in advance and best regards.
Well I am not sure about composite being more toxic after expiry, no reseach as far as i know, but i am just saying it is a possibility.
By the way regarding your research interest to check out the physical properties of composite after expiry, biological compatibility of expired composite also should be checked in my opinion
Regards
