Background: A complaint from a patient can have a serious impact on the well-being of dentists. Little is known, however, about the nature and the extent of this impact. Methods: Therefore in 2013 an anonymous survey was conducted among 955 dentists and dental specialists who were involved in a complaints procedure dealt with by the Complaints Committee of the Royal Dutch Dental Association (KNMT) in the period of mid-2008 to mid-2013. Results: In total 413 (43 %) of these dentists participated in the study. As a result of a formal complaint 71 % of the respondents experienced a considerable impact in their professional practising, while 52 % stated that it had (also) seriously influenced their attitude towards colleagues and patients. Furthermore, 60 % (also) mentioned effects of a complaints procedure regarding their mental and/or physical well-being. Conclusions: Being confronted with a formal complaint from a patient leads to a considerable impact on dentists' professional practice and personal well-being. It is remarkable this did not only pertain to a 'negative' impact, but also to a 'positive' impact. Despite unpleasant feelings, several dentists regarded the complaint as a 'wake-up call'. Furthermore, given the relatively high number of successful mediation attempts it can be concluded that this form of complaint handling appears to be a successful way of solving problems that have arisen between patients and dentists.