Research certainly can't hurt you and I would recommend it. I've found it to be a very rewarding experience. However, not all schools are interested in weather or not you've done research or been published. If you're applying to d-schools keen on research i.e. UCSF (#1 research dental school), then obviously you're doing yourself a favor. But don't go into research just for that reason alone. Do research because you want to contribute something valuable to the field.
Also, consider your time-line. Some labs will tag your name onto a paper just for being there. But most competitive labs want you to have contributed something significant to the project before adding you as a co-author. This often can mean you need to have done over a year's worth of research with the lab. Then you submit the paper for an initial review. Then the reviewers decide weather or not to accept your publication. Then you do revisions. And finally, weeks or months after submitting the revisions, then you get published. All things to consider.