You know the sort of thing. The patient swears that you quoted $1,200 for the crown when you know that you quoted $1,600.
When giving written quotes there's trap to be wary of. It's underquoting.
Once you've issued a written quote you can't increase it without annoying the patient or even making them angry and belligerent.
So, when issuing a written quote always quote for the worst case scenario.
If, the tooth might need a root filling, put it in. If the tooth might need a core, put it in. If an extraction might turn into a surgical, put it in. And so on.
This allows you to say to the patient: “I've included the cost of a root filling in the quote but I'm 90% sure that you won't need it. If you don't need it then the cost will be less than I've quoted.”
Patients are never disappointed if the treatment costs less than you've quoted.
In fact they're delighted.