success of such motion would destroy all the "pay for the service" system as you do agree to pay for the service before it is rendered - otherwise the doctor willn't provide the service. To my understanding the ER is the only place where medical care muct be rendered without any pre-condition of entering into any contract.
(And even in the absence of a contract, there's a quasi-contract, so a finding of duress wouldn't obviate the requirement to pay for services rendered.)
This guy had a severe tooth ache and I can't really gather much more FTA for what he actually had. However, there's cracked teeth and abscesses that dentists see frequently that are expected to be much more painful.
I personally just don't feel dental pain, so what are the grounds for duress with me. I found out I'd had 5 cavities, potentially for over a year (it had been around 2 years since my last dental visit because of moving country and having no benefit plan) and I had no clue.