yeah, as above posters mentioned, you should definitely spend some time researching about dental school admissions.
although they say deadline is march 1st or 15th (it doesnt really matter), everyone (i mean pretty much everyone that knows about the process) apply between May - October of the year before that deadline. After October is considered pretty much late in the process (although still possible to gain admission) and after December 1st is definitely considered pretty much too late.
Schools give out interviews starting August throughout January / February
and March is pretty much done.
Every schools make decisions on who to accept for their class by December 1st (of the year before the deadline, so in this cycle's case it was decided in December 1st of 2008), and from there, some people get multiple acceptances and they decline some other offers and more seats open up and they will be filled throughout the winter time.
At this point of time, even the people who had interview are either rejected or waitlisted and they will not interview you, so please save your money and wait 2 months. I had 2 interviews (one in August and November) and one of the schools has already filled their class completely on December 1st of 2008 and the other school I am waitlisted, and I applied in May of 2008.
I recommend you research many threads on this forum and also purchase ADEA Guide to Dental School Admission and also go speak with your pre-dental advisors at your school.