I've had a random variety of jobs, including pharmaceutical research lab assistant, tax preparation clerk, and elementary school teaching assistant. And I'm pretty sure that none of these experiences have tremendously contributed to my understanding of the field of dentistry, nor has any of these significantly prepared me for such a career. I honestly do not think that my work experience matters at all for dental school admissions. I think that the only reason they ask is to get a sense for what the applicant has dedicated his/her time to, whether it be academics, sports, ECs, research, work, or any combo of these. It's your whole package that matters. Just excel in the activities you choose to dedicate yourself to. They don't expect you to be able to do everything.