Black dot (cavity?) on 1 wk. old filling?

[Kitkat2109]

I just had a composite filling done on my furthest back lower right molar a week ago, one of three: 2 on the bottom and 1 on the top. I thought the dentist did a really good job because I have issues with a tight mouth/jaw and he really worked around that, even shaking the jaw and having me bite down on a rubber thing on the left side to try and relax my jaw. My tongue tends to touch the teeth a lot, and he said there is a lot of noise when I move my jaw because of the tightness. So what could be going on that the cavity reappeared a week after the filling? There isn't a bunch of pain. Is it because he didn't go deep enough to get out the decay (even though it seemed like he did a good job from the pic on computer screen he showed me)? Could the fact that my jaw is always tight (and therefore causing a lot of force in the mouth) be affecting the teeth? I don't grind my teeth during the day, I've only been known to grind on 2 occasions at night. There are 5 cavities on the left side that he was going to do next wk too because most of them developed under the sealants I got at young age, am now 24.

[Jerome Tsang, DDS]

Go ask your dentist to make sure its a cavity first.  It may either be a stain (especially if you had a metal filling in the tooth prior as metal fillings tend to stain the teeth over time) or it may be that your grinding may have chipped the tooth where the filling is at and causing a shadow/dark spot.