Basically not that I am aware of.
If you had a really large facility maybe you could call it a hospital and apply lighting demand factors.
You might be able to use demand factors on receptacle loads per 220.44. Doesn't look like would be a major impact on a typical dental clinic though.
If you have any space that isn't patient care related, office space, or general storage areas - maybe you have some possible things that can have demand factors applied. Super neat break room that practically can be called a dwelling maybe? Most are not going to be that way though.