Dental school has the same type of service as medical school does. However, the applications differ a lot. So, you don't necessarily have to rush to submit you application,however, you don't want to wait until the last minute. Make sure you application is in by no later than July 15th. Since the first group of applications go out in mid-August, it is a good idea to in the first bunch.
Patience is a virtue, so be just that.
There is no need to rush. Since there are fewer applicants, dental schools generally take their time disseminating information. Some dental schools require this. So, it is better to have it and not use it, than to not have it when you need it. However, the recommendation should not just be something your family dentist wrote for you to meet this requirement.