Positron emission tomography(PET)with ¹⁸F-choline was performed to examine squamous cell carcinomas in the oral cavity, and its usefulness in the diagnosis of oral cancers was investigated on the basis of comparison with[¹⁸F] -2-fluoro-2-deoxy-D-glucose(¹⁸F-FDG)PET. The subjects were 36 oral cancer patients, with 17 patients and 19 patients examined by ¹⁸F-choline and ¹⁸F-FDG PET, respectively. ¹⁸F-choline and ¹⁸F-FDG accumulation were analyzed in the primary lesions and in the brain, major salivary glands, liver, abdomen, and urinary bladder. ¹⁸F-choline accumulated less than ¹⁸F-FDG in the brain and bladder. For the remaining examined organs, ¹⁸F-choline accumulation was greater than that of ¹⁸F-FDG. The mean value of ¹⁸F-choline accumulation in the primary lesions was not significantly different from that of ¹⁸F-FDG. ¹⁸F-choline accumulation by the primary lesions peaked within 10 minutes after administration. ¹⁸F-FDG did not reach a maximum even after 50 minutes. In conclusion, ¹⁸F-choline accumulated in the primary lesions of oral cancers, similar to ¹⁸F-FDG. Furthermore, it is also useful for the diagnosis of cases that progress near the brain, which is difficult with ¹⁸F-FDG. ¹⁸F-choline shortens the PET examination time, markedly reducing the burden on patients more than ¹⁸F-FDG PET.

Hematopoietic stem cell transplantation （HSCT） is established as an effective treatment for patients with hematologic malignancies. However, chronic graft-versus-host disease （GVHD） after transplantation is a risk factor for the development of secondary solid cancer. We report a case of tongue cancer in a patient with chronic GVHD following allogeneic HSCT. The patient was a 57-yearold woman who underwent autologous peripheral blood stem cell transplantation （PBSCT） in 2009 after the diagnosis of acute myelocytic leukemia. A relapse occurred in 2011 and she underwent allogeneic PBSCT. She was diagnosed with chronic GVHD in 2013. Immunosuppressive agents and corticosteroids were administered for the treatment of chronic GVHD and the accompanying nephrotic syndrome. In 2016, right tongue cancer （cT1N0M0） developed and partial tongue resection was performed. However, 4 months later, a superior internal jugular node metastasis was detected. A conservative neck dissection was performed and one metastatic lymph node was histopathologically diagnosed. At a follow-up examination 1 year and 6 months later, there was no evidence of a recurrence or metastasis. In the present case, oral chronic GVHD and several years of immunosuppression may have been involved in the development of tongue cancer.

In recent years, dental implants have become indispensable treatment for missing teeth, and the development of the implant surface has been advanced. So far, comparative studies on maxillary sinus floor elevation by iliac crest have been reported and have often employed machined surface implants. On the other hand, there have been few reports, comparing different implant surfaces. In this case report, two different patients with highly atrophic maxilla had anodized surface implants or sandblasted with large grit and acid-etched （SLA） surface implants placed after reconstruction by maxillary sinus floor elevation with iliac bone graft. Case 1: A thirty-six-year-old male. In August 2010, bilateral maxillary sinus floor elevation was performed using iliac bone. In December of the same year, anodized surface implants were placed. Case 2: A forty-eight-year-old male. In December 2010, bilateral maxillary sinus elevation was performed using iliac transplantation.

In June 2011, the SLA surface implant was placed.

No abnormal bone resorption after surgery was observed in the cases. Abnormal findings such as inflammation and swelling have not been observed and the cases are now uneventful. Different implant surface properties were used in two cases, but there was no significant difference between the two cases.

When the volume of the grafting bone, which is harvested from the oral cavity, is insufficient and a large amount of bone grafting is necessary, iliac bone graft should be very effective.