Is it permissible to refrain from paying the remaining costs of a teeth straightening procedure agreed upon with the dentist, based on the opinion of other doctors that the case does not warrant the amount paid, and due to dissatisfaction with the final result of the procedure?

The fundamental principle is the obligation to pay the physician the full agreed-upon amount if the work is completed. However, if you ascertain—through specialized and trustworthy physicians—that the physician has excessively overcharged you by requesting a fee significantly above the customary rate (اجرة المثل), and you were unaware of the customary rate at the time of the agreement, then you are permitted to limit your payment to the customary rate.

It is a condition that whoever estimates the customary rate must be free from bias, and the customary rate is determined by considering the type of procedure, its circumstances, and the physician's level.

As for the condition of the teeth after the procedure being less than what you expected, this does not affect the fee if the physician did not fall short. However, if the physician was negligent or made an error, then it is permissible to deduct from the fee what experts deem appropriate.

In cases of excessive overcharging and your ignorance of the customary rate, you have the right not to pay more than the customary rate, which is determined by specialists. If an agreement cannot be reached between the two parties, the matter must be referred to the court.