Tooth sensitivity / Novacaine

I am 31 and go to the dentist regularly and try to take very good care of my teeth.  My next dental appt. is not til the middle of June, so I would like to ask this question.  A couple of months ago I started having sudden sensitivity in an upper back tooth almost exclusively when brushing it!  Most foods do not bring this on - it seems to be when I brush the inner side of the tooth it is suddenly very sensitive.  Could there be a crack in the tooth or what could be causing this?  I have tried to look with my mirror and flashlight and all seems well, however there could be something that I can't see.  What do you think?

Also, I have recently been diagnosed with Sinus Node Re-entry tachycardia and have been placed on 50 mg. Lopressor twice daily.  I am worried that the next time I need dental work done that I won't have many anesthesia options.  I do not want anything with epinephrine in it because it makes my heart race and causes PVC's and the last time they gave me something that didn't have the epi in it BUT it didn't really numb me very well therefore, I still had some pain during the procedure.  Is there any other alternative for someone with tachycardia?

[Jerome Bogin, D.D.S.]

As far as the sensitivity is concerned, it is possible that the discomfort is emanting from root sensitivity. This occurs when the gum recedes from the tooth leaving a very sensitive area. At your next visit have your dentist take an X-ray of the area to check for any possilble cavities.
There are other anesthestics that may be more potent and longer lasting without the side effects of epinephrine, most notably mepivacaine with levonordefrin.