I know some dental schools prefer/require for applicants to take the labs that coincide with the lecture hour. See the requirements for the dental schools you're interested in. If you haven't yet assembled an idea of where you would like to attend, I would consider keeping it just to play it safe should one of your picks prefer/require you to take labs.
If it is taking up more of your time than the lecture + study time, it'd be economical to drop it. If dropping the lab will guarantee you receiving a higher grade in the lecture, should consider dropping. If you don't think it'd make that drastic of a punch to your lecture grade, should consider fighting through it.
In the long run, it is only worth 1 credit compared to your 3 credit hour lecture.