Adequate patient understanding of the potential complications of dental implants, such as peri-implantitis, is imperative to prevent poor decision-making and manage unrealistic expectations. This study included 135 patients (411 implants) undergoing peri-implant maintenance. 70.4% of patients agreed that ‘implants are a life-lasting treatment’. Although the frequency of peri-implantitis was 17.8% at the participant level, 74.1% did not have any knowledge about peri-implant pathology. Sixty-four percent of patients with peri-implantitis were worried or concerned and 32% reported that living with the disease was terrible. The authors concluded patients’ understanding and perception of peri-implantitis and its prognosis was generally poor, and the results reflected unrealistic expectations about implants and disappointment when informed about peri-implantitis. Peri-implantitis was found to affect quality of life and the need to develop standardised information guidelines to educate patients was emphasised.