Here's my 2 cents worth.
I sincerely believe using RDH (reg. dent. hyg.) to "pad" your resume is a bad choice. RDH is a career. A position held in great respect in the dental community and they are greatly needed. If you have absolutely no intention on being a RDH, then it truly shows your hidden agenda! Now if you've been a RDH for a couple of years and you find yourself drawn to the priviledges of a dentist-----that is a whole 'nother story.
The reason for the silence you are getting from the dental schools is obvious. They are seeking someone who has a passion for dentistry. One might think becoming a RDH is showing your passion----that is true if you intend I being a RDH for a while. Unfortunately, it doesn't demonstrate this if you intend on becoming a dentist with no desire for being a RDH. That simply shows immaturity and possibly a lack of true direction. Several individuals will question your motives. The interview could be brutal. Some question could be: Why did you get a RDH degree? Did you ever plan on being a RDH? Why aren't you a practicing RDH? Do you not respect to field? ETC...
The schooling you receive isn't going to be more beneficial than your undergrad pre-reqs. Especially if you don't intend on practicing as a RDH. Many dental schools don't accept RDH courses (bio. chem., physio, micro.) as equivalent to 4-year college "intense" courses---therefore, I doubt they going to help you in your first 2 years of dental school. Now the manual dexterity and procedures learned in RDH curriculum would be beneficial----but once again we are back to my original opinion.
If you are looking for experience then try volunteering, or possibly becoming a dental assistant. There are several ways to gain insight and advantages in dentistry without jeapordizing your motives or character. If you are looking for help with manual dexterity----pick-up a hobby like modeling (cars or airplanes). If you truly want to set yourself apart from others----start preparing for the DAT and score 22+/22+. By doing that you're a shoe-in for an interview, if not enrollment. And if you do that well on your DAT----then you should be adequately, if not extremely, prepared for your first 2 years of dental school.
Best wishes,
R.R.B