Grinding a zirconia crown for “just 10 minutes” still triggers the OSHA silica standard — 29 CFR 1910.1053 — so I expect written exposure plans, HEPA capture at source, and documented P100 fit testing. Has your lab run a personal air sample in the last 12 months and logged corrective actions if you hit the action level, or are we still trusting a shop vac and luck?
On the “just 10 minutes” thing, the one tweak that finally stuck for us was adding a cheap magnehelic to the HEPA vac and posting a redline at 1.8 in. w.c.; when it creeps past that we swap the prefilter so capture at source stays consistent. After we did that, our personal air sample came back below the action level and we had something defensible in the plan. Your setpoint may differ with hose length and the shroud, but having a number beats guessing by sound.