I received a root canal on the upper right first molar a couple of years ago. At the time, I was unable to get a crown. I was given a filling as a temporary measure. Recently, I went to the dentist and was informed I needed a crown, or the tooth would break off, and I would lose the tooth. Some of the tooth portions are already chipped, but at the time of my dental visit, there was enough tooth to put a crown. As of this evening, a little more of the tooth has chipped off, and there is exposed dark gutta-percha. I am trying to get a crown as soon as possible, but it is difficult for me to do it right now and may take several weeks. What can I do to protect my tooth and take care of it while waiting for a crown?