There is one big thing that you can do that will reduce your tiredness and stress levels at the end of the day – maintain your focus.
How it works is this.
Dentistry is a very precise, exacting job that requires focus and extremely fine motor movements. Once you are positioned and focussed on the “working surface” your best bet is to maintain that focus until the procedure is finished.
Every time you have to rotate your head or torso, extend your arm to grab something, or even just look away to something at a different focal distance you add to your tiredness.
But, don't take my word for it. Try it for yourself.
Work for a morning six-handed. Tell the nurses that unless the instruments and materials appear in the small circle around the “working surface” they will be invisible to you. Make everything come to you. Don't look away, reach or shift your focus.
See how you feel at the end of the morning.
Then tell the nurse to leave everything on the side bench for a morning. That way you have to turn, shift focus and reach out to pick things up.
I'm betting that, working the second way, you will be significantly more fatigued.