The combination of dental injuries and oral-maxillofacial trauma is common in the field of maxillofacial emergencies. Traumatic injuries can cause anatomic deficiencies in both soft and hard tissues, often resulting in the loss of attached mucosa and severe boney alveolar processes, with a loss of teeth and supporting structures. These sequelae can complicate the potential prosthetic management of functional and esthetic dental implant rehabilitation, rendering use of a top-down, restorative dental implant in comprehensive maxillofacial trauma management and care difficult. These patients require various boney regenerative treatments, including pre-implant bone augmentation surgery (e.g., bone grafting, guided bone regeneration, and distraction), followed by further soft-tissue surgery (e.g., gingival grafting with vestibuloplasty) to achieve a positive long-term prognosis and stable management. Thus, it is important to adopt a prosthetic oral rehabilitation strategy that involves functional and esthetic dental implant treatment for these oral maxillofacial trauma patients to improve their prognosis. The appropriate treatment for such patients is intense, and we routinely promote and endorse the following for functional and esthetic oral rehabilitation using dental implants: 1) A multidisciplinary approach by a team consisting of professionals in various fields, such as dentistry and oral-maxillofacial surgery, as well as dental hygienists specializing in perio-oral implant maintenance care. 2) The use of three-dimensionally sufficient boney pre-implant augmentative regeneration based on various regenerative augmentation techniques. 3) Implant soft-tissue care, including keratinized gingival grafting with vestibuloplasty management and regular follow ups for maintenance. 4) Precise, safe, and minimally invasive computer-assisted oral-maxillofacial regenerative and implant surgery. This clinical report describes the comprehensive oral-maxillofacial trauma management and care approach we adopt for primary maxillofacial emergencies involving functional and esthetic oral rehabilitation using dental implants.

  Human mandibular bone forms at the position of future mental foramen, lateral to Meckel's cartilage, at 7 weeks of gestation. Ossification progresses toward both anterior and posterior position by forming “bone trabeculae” along with blood vessels during fetal period. After birth, mandibular bone formation progresses by adding lamellar bone on the bone surface. Simultaneously, bone modeling, coupled with bone formation and resorption, makes specific shape of mandibular bone. Adult mandibular bone consists “basal bone”, “alveolar part”, and “muscular part”. The shape of mandibular bone is established at the end of growth period. However, the shape of mandibular bone continues to change little by little during lifetime. After loosing teeth, the alveolar part is first resorbed, subsequently the muscular part starts to be resorbed, and consequently the basal bone remains. There is a regular resorption pattern in the process of resorption of alveolar part. The resorption of buccal side precedes that of lingual side, and consequently the arcuate alveolar ridge is formed on the line connecting the center of alveolus.

  Some differences between membrane bone (including mandibular bone) and endochondral bone (including limb bone) have been reported. Adding to the difference of embryonic origin, there are some differences in biochemical characteristics including organic components and tendency of taking resorption between both types of bone.

  Although radiation therapy (RT) is the indispensable treatment for head and neck malignancies, one of serious complications is osteoradionecrosis of the jaw (ORN). The most well-known causative factor is surgical trauma (e.g., tooth extraction). We here report a case of osteoradionecrosis of the jaw around dental implants. A 68-year-old female underwent surgery and postoperative chemoradiotherapy for adenoid cystic carcinoma of the left submandibular gland. Three years after RT, she suffered from the right mandibular peri-implant infection, and visited to our department. We diagnosed ORN around the dental implants which were inserted before RT. The long-term conservative treatments such as the oral administration of antibiotics and the local irrigation were performed. Five years after RT, the sequestration with dental implants was removed under the local anaesthesia.

  In general, ORN is difficult to be treated, and the treatment should be determined according to severity of accompanying symptoms and patient's general condition, etc. For prevention of ORN, the strict oral management to maintain good hygiene around dental implants is essential.

  There are many reports of tumor which occurred around dental implants, but there are few reports of the cyst. We report a case of nasopalatine duct cyst which occurred in the dental implant insertion area.

  A 54-year-old female underwent immediate implant placement in the maxillary right central incisor one year before visiting our hospital. In 2007, panoramic radiograph and CT showed an oval-shaped radiolucency around the apex of the implant. By the hope of the patient, we performed only enucleation of the cyst without implant removal. Histopathological diagnosis was nasopalatine duct cyst. In 2015, panoramic radiograph and CT image showed a recurrence of the cyst. We performed enucleation of the cyst again and implant removal because of the agreement of the patient. Histopathological diagnosis was nasopalatine duct cyst. The postoperative course was uneventful. The recurrence is not seen 20 months after operation.

  Background: Serious medical complications related to implant surgery is indicated to be a social problem. Here we report our experience of administering a questionnaire survey among members of Japanese Academy of Maxillofacial Implants comparing the results with those of a previous survey conducted from January 2009 to the end of December 2011.

  Methods: Questionnaires on severe medical trouble related to implant surgery during the 3-year period from January 1, 2012 to the end of December 2014 were sent to 118 facilities approved by the Society and the results were collected and analyzed.

  Results: The response rate was 89.0%, and the total number of occurrences in 3 years was 360 cases. The main occurrence was maxillary sinusitis (73 cases; 20.3%), followed by inferior alveolar nerve injury (68 cases; 18.9%), migration of the implant into the maxillary sinus (67 cases; 18.6%), psychosomatic disorder (45 cases; 12.5%), and mental nerve injury (33 cases; 9.2%).

  Conclusion: The number of cases of medical trouble decreased from 471 in the previous survey to 360 in the present survey. The top five items in the present survey were the same as those in the previous survey but in a different order.