black spot on chhek after dental work

Hi,Last december i had some dental work done part of which was having a rear molar tooth that had broke be rebuilt. Dont know exactly what they did but it involved putting something over the chipped part and then putting some sort of blue light in the mouth. However since then i have had a little black mark on the piece of cheek that rests on that tooth when the cold gets into the cheek it sets my tooth off with a slight ache, what could this be  and will it go on its own?

[Jerome Bogin, D.D.S.]

Dear Cbonner, The filling you describe is probably a composite restoration. It is tooth colored. This type of filling can be sensitive to temperature changes. The black mark you are mentioning has nothing to do with that tooth. There are a couple of possiblies for that black spot-- one is what we call an amalgam tatoo, which is absolutely harmless, or could be a blood blister which is also benign. I do think it should be checked by an oral surgeon.