From what I've noticed, most people do not generally retake it. Most people don't want to take it twice so spend a lot of time and resources studying in the hopes that they will get a high enough score on their first try that a retake won't be necessary. I would say the goal of dental applicants is to have to take it only once.
I was at a dental school open house and had the chance to talk to some dental students. One of them said that the first time he took the DAT he got a low score but still applied. He didn't get any acceptances. Before applying again he retook the DAT and after considerable time and effort he was able to get a higher score (I don't remember the exact scores, sorry :/). He got into pretty much all of the schools he had wanted to get into. He told us that dental schools liked seeing this drastic improvement as it showed how determined and dedicated he was to get into dental school. So yes, it can be an advantage. However I wouldn't recommend trying to purposely get a low score the first time and then getting a higher score on purpose the second time (and that's against the DAT rules anyways).
As others on this forum will tell you, take the DAT like you won't get the chance to take it again--give it your best shot the first time around. Best of luck.