The first thing is don't put yourself in a position of danger , always try to have someone else with you . Have alarms , handheld alarms and immediate alerts on computer systems and practice what will happen if one goes off. Try not to be alone with a patient in a room.
Have signs up to say zero tolerance of violence /abuse etc
No screens or anything separating reception from patients as tends to escalate violence.
Keep anything that can be used as a weapon locked away or out of sight. Easier said than done in a dental setting.
Watch body language so you can see when things are escalating .
Acknowledge patients frustrations and feelings , keep them informed about delays etc. Apologise early , if necessary .
Ask if they understand that shouting/threatening/swearing makes people feel intimated etc
Then , worst of all, what to do if physical violence occurs , which is basically give yourself time to run.
The majority is how to read the signs that people are losing control , not dismissing their complaint/concern , keep calm yourself and avoid getting into dangerous situation in the first place.