Yeah, you sure have a problem...there is no exact match. Well, I guess I would put it under Molecular Biology, because if I am not mistaken, isn't bioinformatics primarily used for genetic/molecular bio-data? The dental schools will have your transcripts, so they can always see what exact course it is. Or, I would just call one of the dental schools and ask someone there.
AADSAS should definitely add this course to their list for next year, since bioinformatics is becoming so popular now.