Well, you need recommendation letters from science professors or a committee letter if your college has a pre-dental department to write those. Also, many (I think most) schools require a letter from a dentist also.
Also, your dental experience is important too. Some schools don't require very much, others require at least 100 hours of dental experience (VCU for example requires 100 hours, but recommend at least 150 hours, too bad they don't tell you that on the website). Dental experience can be shadowing a general dentist (dental schools like general dentist better than specialists because general dentistry is what they teach you in dental schools, so don't go for the specialists), you can volunteer at a dental clinic, or even work as a dental assistant.
And yes, hospital work doesn't have much to do with dentistry, so dental schools don't really care so much for it I don't think.