No abstract

Dental implant treatment is a highly predictable therapy, but when potentially lethal symptoms or complications occur, dentists must remove the implant fixture. Recently, reports on antiresorptive agent-related osteonecrosis of the jaw have increased in the field of dental implants, although the relationship between dental implant treatment and antiresorptive agents remains unclear. Here, we report a case of antiresorptive agent-related osteonecrosis of the jaw that developed after dental implant removal. A 67-year-old Japanese woman with a medical history of osteoporosis and 7 years of oral bisphosphonate treatment was referred to our hospital with a chief complaint of painful right mandibular bone exposure. A family dentist removed the dental implants from the right mandible using a trephine drill without flap elevation in August 2016. However, the healing was impaired; she was referred to our hospital 3 months after the procedure. We performed a sequestrectomy of the mandible under general anesthesia. In conclusion, this patient's course has two important implications: First, the removal of dental implants from patients who are prescribed oral bisphosphonates for long durations can cause antiresorptive agent-related osteonecrosis of the jaw. Second, meticulous procedures are required to prevent and treat the development of antiresorptive agent-related osteonecrosis of the jaw after dental implant removal.

Maxillary sinus floor augmentation is considered to play a critical role in dental implant treatment. Although many complications, such as maxillary sinusitis and infection, are well known, few reports are available on the risk of surgical ciliated cyst following the procedure. Here, we report a case of surgical ciliated cyst following maxillary sinus floor augmentation. A 55-year-old Japanese woman was referred to our hospital because of alveolar bone atrophy in the bilateral maxilla. We performed bilateral maxillary sinus floor augmentation by the lateral window technique without covering the window. The Schneiderian membrane did not perforate during the operation. She returned to our hospital after 9 years due to swelling of the left buccal region. Computerized tomography revealed a well-defined radiolucent area with radiodense border intraosseously localized in the left maxilla. We performed enucleation of the cyst with the patient under general anesthesia. Histological examination of the specimen showed a surgical ciliated cyst. In conclusion, the course of this patient has 2 important implications. First, the sinus membrane entrapped in the grafted bone without visible perforation and or tearing can develop into a surgical ciliated cyst. Second, there is a possibility that covering the lateral window tightly might prevent the development of a surgical ciliated cyst.

No abstract

We aimed to elucidate stress distribution in miniscrews and the surrounding bone when miniscrews inserted at different depths were implanted vertically or obliquely. The distributions of the equivalent stress on the screw surface and the minimum principal stress in the surrounding bone were calculated using finite element models. When the miniscrews were inserted vertically and obliquely, screw head displacement, greatest equivalent stress on the miniscrew surface, and absolute value of minimum principal stresses in the surrounding bone decreased with increasing insertion depth. Stresses in the obliquely inserted miniscrew with upward traction were smaller than in other insertion conditions, irrespective of insertion depth. With the application of orthodontic force, stress distribution around the miniscrew and surrounding bone is closely related to the insertion depth and insertion angle, which mutually affect each other. In particular, the obliquely inserted miniscrew with upward traction might be the most secure against screw failure and fracture.