latex allergy and apicoectomy

I had a RCT on tooth 14 in Feb 2006 that was redone in May 2006 due to permanent pain.
After a couple of months without pain the pain came back and the doctor did an apicoectomy. There was no infection and the Dr. said it was an allergic reaction to the material in the root canals. I am allergic to latex and he said the material was a cousin to latex. They placed different material into the root canals. Is this really possible and can it cause so much pain? And how can you diagnose this?
Also my regular dentist told me that the survival rate of a tooth with an apicoectomy are not very high. What problems are there? The endodontist was not very happy with the 3/4 crown my dentist had put on this tooth. He said the tooth is more likely to fracture  now. Is this correct?

[Matthew Baron, D.M.D.]

Does the tooth feel better now that you don't have the latex cousin filling (called gutta percha) If it does feel better than maybe that was the problem.  the pain could have been caused by another problem, perhaps a fracture in the tooth.  Normally, I put a  porcelain fused to metal full coverage crown on a root canaled molar, but there are different schools of thought on that, depending on how much of the tooth structure remains after the root canal.