If you're talking about taking it cold turkey having majored in biochem, I wouldn't recommend it, although majoring in biochemistry will definitely have given yout the tools you need to succeed. Make sure that you study DAT-specific materials like crazy, like Kaplan's books, and take some practice tests.
With a good DAT score combined with your GPA, it should make you competitive for many dental schools. If you're going to take the DAT this summer and apply for 2005, though, I'd recommend applying ASAP.