Dr. Name
Office address
City, State ZIP
(or preferably print on letterhead)

Date

Mr. Patient
Address
CityStateZip

Dear Mr. ______:

I'm sorry there is confusion over your bill.  Hopefully I can help clarify the issue.  As we have explained, we proceeded with your treatment as you requested at the time:  we contacted your dental insurance company, they informed us of your current benefits, and we planned your treatment based on that information.  However, we were not informed, nor do we have any way to know, that part of your yearly benefits were used up by dental treatment at a different office.  

The financial responsibility for dental services lies solely with the patient.  Dental insurance is a contract between the patient and their insurance company.  Our involvement is only to submit a claim as a courtesy to help our patients.  We do our best to assist patients in determining their benefits, but as you can see, the insurance company does not always provide us with accurate or up-to-date information.  It is ultimately up to the patient to be fully aware and up-to-date on the status of their insurance at any particular time, and to pay for services rendered regardless of insurance coverage.

Please correct me if I am reading your letter wrong, but it looks like you are asking me to not bill you for $772.60.  Billing the insurance company for one amount and then billing the patient for a different amount is insurance fraud.  I know I do not want to be involved with insurance fraud, and I doubt this is your intention either.

Sincerely,

Dr. ________