Yup, it's mainly lab work. I see patients from your normal hours in the day usually with classes sprinkled here and there (for example we may have current literature review from 7:45-9 AM then patients from 9-12, ortho-prosth seminar from 12-1, patients from 1-5). And because prosth is a restorative specialty, we have to engage with all specialists in terms of collab seminars. There isn't enough time in the day for us to do that so we have many seminars like perio-prosth, endo-prosth after hours like 5-7 PM. We also have to occasionally lecture to GPR residents after hours as well. This is not including lab work, studying or presentation making.
My usual day is 8-5 is normal class/patient hours (8-7 if we have specialty collab seminars). Then lab work until around 11-midnight, then literature reading and presentation making from 11ish-2ish AM (if I have less lab work, I usually am trying to catch up on literature since I'm always behind). Rinse and repeat. Again, not all programs are like this and some programs don't really have you doing too much lab work. There are programs I interviewed at that their residents leave at 5/6 PM everyday as well. I specifically chose an intensive program so I could learn as much as I could then when I go out, I'll be chilling (hopefully lol).
*I also did not include weekends. I am usually there both Saturday and Sundays catching up on lab work as well.