re: Is there such thing as an emergency dentist?

It should. Root canals can still fail though. Essentially a root canal will take the nerve out of the tooth making it non vital. They can still get an infection if not cleaned properly or filled properly. Sometimes they just fail for no rhyme or reason. I send my patients to a specialist for back tooth root canals. Many of them can take a 3d x-ray showing all of the canals and anatomy. Those back teeth have more than one root and sometimes more than one canal in each root making treatment tricky. Having said that I would have the root canal done. The other option is taking it out and that should be a last resort. I see it daily in my office where people have had their back take teeth taken out because of pain and they elected to extract instead of save the tooth. What they end up with is front tooth problems (breaking/wear) because your back teeth protect your front teeth when you bite. I completely understand taking it out though, due to finances as it can be expensive to save a tooth. If possible I recommend saving it with a root canal.