Caldwell-Luc surgery was established at the end of 19th century and then had been performed widely as main surgery for rhinosinusitis until very recently. Endonasal approaches were attempted separately, however, competent performance could not be obtained due to narrow operation field, bleeding and risk of surrounding vital organs. In 1990s, advancement in optical technology had endoscopic sinus surgery（ESS）established, and then the concept of sinus surgery has changed. At present, ESS is still developing and the indication of ESS has been extended into tumor and other diseases. As conservative treatments, low-dose, long-term administration of macrolides has been established as the first-line, standard treatment.

  These two main treatments, ESS and macrolides, have been established, but refractory types of rhinosinusitis have emerged. New treatments based on molecular pathophysiology of rhinosinusitis will be necessary in future.

  We used the P-m SHELL model-a medical accident analysis tool- to investigate the fundamental causes of medical accidents related to dental implants and thus prevent future accidents.

  Using online database and electronic book data, we gathered 10 cases of medical litigation related to dental implants that were processed between 1993 and November 2017. We then analyzed these cases, using the P-m SHELL model. Of the 10 cases, two were dismissed by the court. In the other eight, the complaints were as follows: four nerve injuries, two masticatory disorders, one of the mouth floor hematoma, and one maxillary sinus perforation（overlapping）. The oral hematoma caused airway obstruction that lead to the death of the patient. The most common reason for the lawsuits was nerve injury. All accidents were caused by persons other than the patients, and many factors lead to the human errors involved such as negligence of the medical workers, inadequate safety education and lack of comprehensive manuals.

  To prevent future accidents, medical staff must improve their knowledge and skills, foster an environment that allows easy communication among workers, confirm information efficiently, and maintain manuals.

  Patients undergone surgical operations of cleft lip and palate（CLP）have esthetic and functional problems, such as jaw deformities and malocclusion．For solution of such problems, the comprehensive treatment applied dental implants is useful. We encountered a case of CLP performed a comprehensive oral rehabilitation combined dental implants with orthognathic surgery.

  A 48-year-old woman who had multiple problems, including severe odontogenic sinusitis, maxillary retrognathia, and multiple pathologic teeth, visited our hospital wishing for total treatment of esthetic and functional improvement. She had been received several times of operation for CLP in her childhood. Postoperative maxillary retrognathia complicated with alveolar cleft was existed. Following extraction of the pathologic teeth with apical lesion from right second premolar to left second premolar, graft of autologous decalcified dentin particles and hydroxyapatites for alveolar cleft and socket preservation were undergone prior to implant therapy. Six months after grafting, dental implants were placed in the tooth defect of maxilla. Then an implant-supported provisional restoration was prepared before orthognathic surgery. Bilateral sagittal split ramus osteotomy and genioplasty was done for correction of retrognathia. After stabilization of occlusion, final implant-supported fixed prosthesis was installed. The satisfying result was obtained.

  We report a rare case of subdural abscess secondary to sinusitis by accidental insertion of implant. A 59-year-old man was referred to tachikawa hospital for removing implant inserted into left maxillary sinus accidentally. It was occurred after dental implantation at the left maxillary second molar area. We planned the surgery to remove it, but he was rushed to the hospital emergently due to lose his consciousness before surgery. CT and MRI examination revealed that subdural abscess was observed at the right cortex of frontal lobe. We diagnosed it as subdural abscess secondary to sinusitis by accidental displacement of dental implant. After administration antibiotics intravenously, we performed removing implant body and intraoral antrostomy. Then, antibiotics were administered intravenously. Furthermore, drainage by craniotomy was accurately carried out. The pathogens for subdural abscess were not elucidated. After all procedures, MRI examination showed no evidence of subdural abscess, and patient was relieved and left our hospital.