I'm think of every time visit the dentist is worried about getting cavities.
But I don't have cavities.
Here's your second corrected composition, Jimmy. Please take a look at the corrections below. Have a good rest there! 
What do you think of every time you visit the dentist?
I'm think of every time visit the dentist is worried about getting cavities.
>>> Every time I visit the dentist, I worry about getting cavities.
But I don't have cavities.
>>> OR: Luckily, I don't have any cavities!