My biggest concern regarding a dental visit is aerosols left in the room from other patients, not the dental staff or fomites on surfaces. The latter can be easily controlled via proper PPE and surface cleaning procedures.
However, aerosolized COVID can last in the air for several hours if there is not good air ventilation. Several dental procedures are known to cause aerosols.
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Also, I would ideally choose the first patient appointment of the day (preferably on a Monday morning) to reduce the risk of aerosols still being present in the air from a prior patient.
I have the exact same concern and for that reason will only go to the Dentist (which I've had to do twice during COVID due to thinking I had bad cavities developing) first thing in the AM. First time was on a Monday. Second time was just this Weds.
If you can manage to get the very first appointment in a particular room and ensure with 100% certainty that NO other patient has been in that room before you that day, that's a huge help.
My Dentist wore a N-95 AND face shield on the first appt. Now that she's been vaccinated (as has her assistant), they both had surgical masks and face shields on this time.
She also runs a HEPA air filtering machine in the room.
Wife and I have gone pretty much NO-WHERE (and I mean no-where!) since last March, and even as "extreme quarantine" as we've been, I actually felt reasonably 'safe' during my two visits - though I sure had a lot of concern and anxiety before going both times as well..because as someone else said up-thread.."we made it this far..ain't gonna blow in the final innings.." (or something like that).
The only other medical appts I've done is my knee Dr when I blew out my knee and my Urologist. Urology office was decent - Dr had a very solid looking surgical mask and wore it "right"..although another Dr who poked his head into the room to update me on status of MY Dr who was running late that day had a flimsier surgical mask with his NOSE EXPOSED (DOH! And this guy is a Doctor?). Knee Dr visit was worse..front desk girl had a cloth Star Wars mask (great). Doctor himself had a flimsy BANDANA (OMG) and nothing else. Worse, I asked every single time what precautions people were taking and was told that they were all wearing "proper" masks, etc. Uh, no.....
Both the Urology appt and my 2nd Dentist visit were this week, back to back days..so I'm in the wait and see if I managed to once again successfully avoid COVID..I think the risks are pretty low, but definitely not completely zero..