A little over a month ago I went in for a 6 month check up/cleaning and it was discovered that my #30 had a crack ed cusp from clenching. Over the course of the week prior to my follow up visit for my crown prep, my #3 started developing a weird sensation that would come and go with or without physical stimulation from my tongue or food. My dentist examined and determined that the composite filling in the lingual groove was worn, but didn't appear to be leaking. He referred me to an Endodontist who didn't see anything wrong with the tooth but noted that it wouldn't respond to cold testing. His EPT wasn't working so it was inconclusive. No X-rays showed any signs of infection or anything abnormal. The tooth eventually started feeling a little more normal, but almost numb. My dentist insisted on repairing the worn filling by removing part of it and refilling as the only conservative means of eliminating a leaking filling as the cause of a problem. The next night I had a moderate throbbing toothache that went away after taking ibuprofen. It has since been feeling the same as it was before (numb, then weird, then normal). It doesn't respond to cold or heat abnormally and any discomfort may or may not be referred pain from sensitivity/recession on my #4. The tooth has about 3mm of recession on both lingual and buccal sides as well as a very small amalgam filling in lewis offset and another composite filling on the other side of the distolingual cusp. There is a craze line from the lingual filling to the gum line, a craze line on the cusp between the composite fillings, and craze lines on each side of the distal cusp. There is no pain from bite testing and the only discomfort ever felt from biting was on a waffle cone (not since repeated). This is a novel, but I'm hoping someone may have an idea because my dentist, an endodontist and my friend who is a dentist all are not sure. All suggest waiting and seeing. I'm praying that the tooth is still vital and that I won't need a root canal. I have since been fitted for a custom acrylic night guard (had been wearing an OTC one) and have done all I can do to address the trauma of nightly clenching/grinding. Please help.