Kenko Tanaka

Removal of dental implant displaced into maxillary sinus by combination of endoscopically assisted and bone repositioning techniques: a case report.

BackgroundAccidental displacement of a dental implant into the maxillary sinus is an infrequent although not uncommon complication encountered in dental clinical practice, with the main cause thought to be inadequate bone height in the posterior maxilla. We report a case of migration of a dental implant into the maxillary sinus, and discuss the benefits of its removal by a combination of endoscopically assisted and bone repositioning techniques.Case presentationA 35-year-old Japanese man with a partially edentulous maxilla underwent implant placement at a private clinic. Three months later, at the time of abutment connection, the implant at the site of his maxillary right first molar was accidentally pushed into the sinus. The hole on the alveolar ridge made for placement of the implant was small and far from the dislocated implant, thus access was achieved in a transoral manner via the frontal wall of his maxillary sinus with an endoscopic approach. Piezoelectric instruments were used to perform an osteotomy. The bone lid was removed, and the implant was identified using a rigid endoscope and removed with a surgical aspirator, followed by repositioning of the bony segment; the area was secured with an absorbable suture. Removal of migrated implants should be considered in order to prevent possible sinusal disease complications.ConclusionsIn the present case, removal of a dental implant displaced into the maxillary sinus by use of a combination of endoscopically assisted and bone repositioning techniques proved to be a safe and reliable procedure.

Self-activated mesh device using shape memory alloy for periosteal expansion osteogenesis

The present study evaluated the use of this self-activated shape memory alloy (SMA) device, with a focus on its effects in the region under the periosteum. Twelve Japanese white rabbits were used in this study. The device was inserted under the periosteum at the forehead. In the experimental group, the device was pushed, bent, and attached to the bone surface and fixed with a titanium screw. In control group, the device was only inserted under the periosteum. After 14 days, the screw was removed and the mesh was activated in the experimental group. Rabbits were sacrificed 5 and 8 weeks after the operation and newly formed bone was histologically and radiographically evaluated. The quantitative data by the area and the occupation of newly formed bone indicated that the experimental group had a higher volume of new bone than the control group at each consolidation period. Histologically, some newly formed bone was observed and most of the subperiosteal space underneath the device was filled with fibrous tissue, and a thin layer of immature bone was observed in the control group. In the experimental group, multiple dome-shaped bones, outlined by thin and scattered trabeculae, were clearly observed under the SMA mesh device. The use of self-activated devices for the periosteal expansion technique may make it possible to avoid donor site morbidity, trans-skin activation rods, any bone-cutting procedure, and the following intermittent activation procedure.

Apatite-coated Hyaluronan for Bone Regeneration

The materials for the repair of bone defects require bone-inductive and bioabsorbable properties. We developed an apatite-coated hyaluronan (ACH) as a bone-regeneration material. To examine the initial behavior of osteoblast-like cells on ACH and its bone-inductive activity, we evaluated the proliferation and differentiation of osteoblast-like cells grown on ACH in vitro, and examined the effect of ACH on bone regeneration in vivo, comparing these with the effects of an atelocollagen sponge (AS). Hyaluronic acid, cross-linked by divinylsulfone, was freeze-dried and formed apatite in simulated body fluid. MC3T3-E1 osteoblast-like cells were cultured on ACH and AS. Alkaline phosphatase activity and osteocalcin mRNA expression increased more in cells grown on ACH than in those grown on AS. In vivo, round defects were created in rat crania and either filled with ACH or AS or left unfilled (sham group). After surgery, the ACH-treated group showed higher levels of bone formation than the other groups. These findings demonstrate that ACH is more effective than AS in promoting in vitro osteoblast-like cell differentiation and bone formation during the repair of bone defects in vivo, indicating that it may be of use in the treatment of various bone defects.

Elderly patients with maxillofacial trauma: study of mandibular condyle fractures.

BACKGROUND/AIM The aim of this study was to investigate the trends and characteristic features of mandibular condyle fractures in elderly patients in terms of etiology, patterns, and treatment modalities. PATIENTS AND METHODS Records of 201 patients aged 65 years and older, who were treated for maxillofacial fractures at the Department of Oral and Maxillofacial Surgery, Kyushu Dental University, and Tohoku University from January 2002 to December 2013, were retrospectively analyzed. Patient records and radiographs were examined, with the following information: relevant medical history, cause of fracture, the presence and state of premolars and molars in the maxilla and mandible, number and location of mandible fracture, and method of treatment. As for the state of premolars and molars, premolars or molars in the mandible in contact with the maxilla were regarded as contacted. RESULTS A fall was responsible for the majority of the fractures (173/201). With condyle fractures, there was a significant difference between the contacted and non-contacted group in regard to incidence. Furthermore, there was a significantly greater number of cases with symphysis and condyle combination fractures in the non-contacted group (70.9%) than in the contacted group (51.9%). As for the method of treatment, arthrocentesis was the most commonly employed. CONCLUSIONS The present findings suggest that contacted molars in the maxilla and mandible have an influence on condyle fractures in elderly individuals.

Prosthetic Reconstruction for Oral Cancer Patients Using Dental Implants

Prosthetic reconstruction for patients who had ablative head and neck tumor surgery is still challenging because both soft and hard tissues are required. Use of dental implants in oral cancer reconstruction has become an important aspect of the reconstructive plan for these patients. For the mandibular defects, first, the continuity of the mandible should be restored according to tissue condition. In severe cases, free flap transfer should be performed. Relatively short segments or benign tumors with sufficient vascularity could possibly be treated with the bone-grafting procedure with particulate cancellous bone marrow (PCBM) combined with titanium mesh (PCBM-MESH). Second, facial contours and the final dental occlusion are simulated to determine the optimal base of the dental implant or conventional dentures. The final prosthetic treatment requires an intra-oral environment for the prosthesis, particularly enough alveolar ridge with good and healthy soft tissue around the prosthesis. For this purpose, PCBM-MESH is a useful technique to link between optimum facial contour and alveolar reconstruction. Local tissue management including thinning of the skin paddle and/or vestibuloplasty is often required. The choice of prosthesis depends on the condition of the reconstruction, the remaining dentition, the maxilla–mandibular relationship, and other factors.