The woman's husband said they felt it was urgent because the dentist said that if she did not have the crowns in place, the lower third of her face would collapse, she would get wrinkles, and she would look odd.
Dr B denied telling Mrs A that her face would collapse if she did not have treatment immediately.
The husband also said they were told it had to be done that day, and that other patients had been cancelled in order to start his wife's treatment.
Dr C told the HDC that they gave Mrs A and her husband the options, but "we did not push them", and they gave them chance to think.
Dr B said the woman pushed ahead with the treatment because she was worried her husband would change his mind about paying for the procedure.
The dentist said she had not originally planned to put a crown on a sixth tooth with a root canal filling, but she discussed this further with Mrs A, who agreed that this tooth should be crowned also.
Mrs A said that it was possible that Dr B had talked about the sixth crown during the treatment, but at that point she was in no position to discuss it: she had her mouth open; she was "full of painkillers", and "a bit scared".
The patient went back for work the following day and had temporary crowns put in - one and a half of which had fallen out by the time she was due back for her third dental appointment, two weeks later on May 3.
The total cost came to $8935.
The woman and her husband were unhappy with the work and when they had returned to the dentist for the third appointment, they took the permanent crowns with them to have them fitted by another dentist.
Health and Disability Deputy Commissioner Theo Baker said she was not satisfied that Mrs A received adequate information either verbally or as a written treatment plan at the first consultation and therefore the woman did not give fully informed consent to the treatment.
She said Dr B also failed to make study models and diagnostic wax-ups, and the documentation was not in accordance with professional standards.
Ms Baker said Dr C also breached the Code of Rights because he should not have agreed to provide treatment without first ensuring the woman had sufficient time to consider any information provided and give fully informed consent.
She recommended both Dr B and Dr C review their practice in light of the findings.
The report will be sent to the Dental Council of New Zealand with a recommendation that it consider whether any further action is warranted.
