Introduction: The term "leukaemia" is used to summarise malignant diseases of the blood-forming or lymphatic system. These are characterised by an abnormally increased production of functionless progenitor cells of leukocytes, which in the further course of haematopoiesis is disturbed. Depending on the course, acute and chronic forms of leukemia are distinguished, with the acute forms untreated leading to death in a few weeks to months if left untreated. Case report: A 25-year-old microsome patient was diagnosed with "chronic myelomonocytic leukaemia" at the age of one and successfully treated with chemotherapy and stem cell transplantation. The patient presented at the age of 22 years in the outpatient department of the University's Dental Clinic with a referral for prosthetic rehabilitation of the upper jaw. The clinical and radiological situation showed a reduced permanent carious dentition. Teeth 012 and 022 were not sustainable. The marginal gingiva was reddened in all four quadrants, and the Periodontal Screening Index (PSI) showed at least a value of 2. Oral hygiene could be improved by a 6-month hygiene phase. Conservative therapy and placement of the fillings were performed using Compomer (Henry Schein^®, New York, USA). Prosthetic restoration of teeth 017-025 with 012 and 022 as pontics was performed using a cemented, vestibular ceramic veneered non precious-based bridge restoration. However, the reddish colour of the marginal gingiva did not decline 3 years after the start of therapy, even though the inflammatory parameters (SBI, PBI, PSI) were constant in a physiological range. The recall interval is 3 months to keep oral hygiene at a high level. Discussion: The type of prosthetic restoration was chosen because the extent of the plastic restorations had exceeded the indication range in almost all lateral or abutment teeth. Thus, a minimally invasive prosthesis by means of adhesive bridges for the anterior tooth region was not indicated, although this represents a suitable alternative today. The treatment of the aesthetically insufficiently supplied anterior region could be carried out in this context. Summary: Patients with underlying diseases should be given intensive prophylactic care and be instructed on individual oral hygiene. Keywords: leukemia, marginal gingiva, periodontal findings, prosthetic rehabilitation