At my school, we are required to submit a minimum of three letters (Minimum 1 from Science professor, and 1 from a dentist) before we can even be considered for a committee letter. The committee then writes their own letter based on their knowledge of us (both personally, and through our grades, EC activities, as well as the letters we already submitted to them). The committee then "attaches" the letters we submitted to them along with the committee letter. In this sense, even though you officially only submitted the committee letter, the dental schools still have access to all of your other LOR's as well. I would assume most schools follow this protocol as well. If you are unsure, talk to your health professions adviser directly and don't just trust what other students have told you as they are often very, very misguided.