AIM The aim was to explore patients' reactions on being diagnosed with peri-implantitis, their opinions on dental implant therapy and expectations on treatment of the disease. MATERIAL AND METHODS The study subjects were patients referred to a specialist clinic for treatment of peri-implantitis. The method of grounded theory was used in collecting and analyzing data. Audiotaped, thematized open-ended interviews were conducted. The interviews were transcribed verbatim and consecutively analyzed in hierarchical coding processes that continued until saturation was met (n = 15). RESULTS In the analysis, a conceptual model was generated that illuminated a process among patients. From having very high initial expectations on dental implant therapy as a permanent solution of oral/dental problems, patients realized that dental implants, such as teeth, require continuous care and that there is no guarantee for that dental implants provides a treatment alternative free from future problems. The core concept of the model "altered expectations on dental implant therapy" was composed of three main categories: "initial expectations on dental implant therapy and living with dental implants", "being referred to periodontist and become diagnosed with peri-implantitis" and "investing again in an expensive therapy with no guarantee for the future". CONCLUSION Patients may have unrealistically high expectations on dental implant therapy. The results illuminate the importance of patient-centered communication in dentistry and that treatment decisions should be based not only on professional expertise but also on expectations, abilities, wishes and life circumstances of the individual patient.