Can the dentist guarantee treatment results?

doctor, dentist; CANNOT GUARANTEE the results of the treatment to be administered against the patient. Because the science of dentistry does not allow this. The physician's promise of a certain result to the patient in the contract does not make the quality of the contract a contract of work. The contract remains as a proxy contract.
In a decision of the Swiss Federal Court on the subject;

“…It is claimed that the surgeon who took over the dental set was responsible for the wrong set of the prosthesis. However, the surgeon cannot guarantee the result of this treatment applied to the patient's body” (Der Werkvertrag, Zürich 1996, 13, PN. 43vd, BGE 105 II 284 et al).

The Supreme Court has similar decisions. As a matter of fact, the 15th Civil Chamber of the Supreme Court of Appeals dated 3.10.2007 and 2006/4800E. – In a decision numbered 2007/5945 K.,

“…The legal relationship between the patient and the doctor in dental treatment is a contract of attorney. In dental treatment, the obligation of the doctor is to treat the patient by applying the method accepted in the medical world. Therefore, in the contract of attorney, there is no commitment to the outcome. In other words, even if the patient does not recover despite all the treatment, the doctor fulfills his obligation and is entitled to a fee.” provision was established.

According to the rule titled 'Success Guarantee' of the Turkish Dental Association Professional Ethics Rules of Dentistry, which was accepted at the 14th Ordinary General Assembly of TDB dated 11 November 2012;

“The dentist cannot guarantee that his attempt will be successful.”

As can be understood from the aforementioned professional ethics rule,  The relationship between the physician is not a result-oriented work contract, but a mandate contract. Thus, the responsibility of the physician is limited to making the intervention carefully. The physician cannot, or should not, guarantee a cure. If the conditions are met, the guarantee of cure may require the responsibility of the physician even for the crime of fraud. For this reason, the physician cannot be held responsible for any negative consequences caused by the physician's best efforts. (Hakeri, H., Ankara Bar Association Journal of Health Law Digesta, P.1, p.22, 2009, Ankara)

source:

https://www.eralp.av.tr/soru-179/#:~:text=CEVAP%20179%20%3A,s%C3%B6zle%C5%9Fmenin%20niteli%C4%9Fini%20eser%20s% C3%B6zle%C5%9Fme%20k%C4%B1 does not.