Histological study on osseointegrated implants retrieved from irradiated bone in 2 clinical cases

There are a few papers that reported histological examination of clinically successful osseointegrated implants. In this paper, histological results of two cases involving two implants placed in human irradiated bone were reported. For treatment of malignant tumor, case 1 underwent 50 Gy irradiation, and case 2 underwent 60 Gy irradiation before implant placement. Implants were installed in the orbital region in case 1 and to the maxilla in case 2. In case 1, the implant was removed 24 months after installation because the patient died due to tumor recurrence. In case 2, the implant was removed 26 months after installation because it was situated at the margin of the tissue to be resected during tumor surgery. In each case, new bone formation surrounding the fixtures was observed. The rate of direct contact between bone and fixture surface was 61.3% in case 1 and 69.0% in case 2. The rate of inner space occupation of screw thread was 75.8% in case 1 and 81.2% in case 2. (author)