Were you once a dental student, withdrawled and want to go again, is that your question?
I guess the answer depends on the circumstance of why you withdrawled, were you in good standing, can you make a VERY good explaination why the reason warranted withdrawling and proving the commitment of completing your degree this time around, will it be harder, most definitely, will it be impossible, UMMM no, I dont believe in that word, nothing you put your mind in is impossible, regardless of what others say.