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

[Kitkat2109]

I just had a composite filling done on my furthest back lower tight 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? I don't feel pain in it. Is it because he didn't go deep enough to get out the decay (even though it seemed like he did from the pic on computer screen he showed me) where he carved it out? 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.

[scottma]

If a new cavity develops after a filling,the new cavity needs to be fixed. Otherwise, the cavity tends to get bigger over tome. It appears that you have tmj problem, seeing a tmj specialist is advised.