Accidental 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. A 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. In 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.

Octacalcium phosphate and its collagen composite have been recognized as bone substitute materials possessing osteoconductivity and biodegradation properties. We evaluated the effectiveness of octacalcium phosphate and its collagen composite used for bone augmentation in major oral and maxillofacial surgeries in a clinical trial. Octacalcium phosphate and its collagen composite were used in cases of sinus floor elevation in 1- and 2-stage, socket preservation, cyst, and alveolar cleft procedures. A total of 60 patients were evaluated for effectiveness after the implantation of octacalcium phosphate and its collagen composite. Although sinus floor elevation in 1-stage, cyst, and alveolar cleft cases met the criteria for the judgment of success, sinus floor elevation in 2-stage and socket preservation groups did not meet the criteria in the initial evaluation. However, an additional evaluation for reconfirmation revealed the effectiveness of octacalcium phosphate and its collagen composite in those groups, and all evaluation results ultimately indicated the success of this clinical trial. Therefore, this clinical trial suggested that application of octacalcium phosphate and its collagen composite for oral and maxillofacial surgery was safe and effective and that octacalcium phosphate and its collagen composite could be a bone substitute candidate instead of autologous bone.

Increased mineralisation rate and bone formation after surgery or fracture is the regional acceleratory phenomenon (RAP), and its systemic impact is the systemic acceleratory phenomenon (SAP). The proportion of circulating osteoblast lineage cells, including osteocalcin-positive (OCN⁺) cells, in the peripheral blood is markedly higher during pubertal growth and in patients with bone fractures. This study aimed to elucidate the dynamic changes in bone metabolic activity after orthognathic surgery by longitudinal prospective observation. Peripheral venous blood samples were collected from patients who had undergone orthognathic surgery, and serum bone metabolic markers and the proportion of OCN⁺ cells were measured. Orthognathic surgery induces systemic dynamic changes in bone metabolic activity by targeting steps in the bone healing process and related proteins, such as surgical stress/inflammation (C-reactive protein), bone resorption (type I collagen C-telopeptide), and bone formation (alkaline phosphatase and bone-specific alkaline phosphatase). During the early post-operative period, the population of OCN⁺ cells significantly increased. Confocal microscopy revealed that OCN proteins were localised in the cytoplasm in Triton X-100-treated OCN⁺ cells. Furthermore, OCN, ALP, and COL1A1 gene expression was detected in OCN⁺ cells, suggesting the contribution of the local maturation of bone marrow-derived OCN⁺ cells at the site of bone healing.

Nuclear factor‐κB (NF‐κB) is constitutively activated in many cancers, including oral squamous cell carcinoma (OSCC), and is involved in the invasive characteristics of OSCC, such as growth, antiapoptotic activity and protease production. However, the cellular mechanism underlying NF‐κB's promotion of bone invasion by OSCC is unclear. Therefore, we investigated the role of NF‐κB in bone invasion by OSCC in vivo. Immunohistochemical staining of OSCC invading bone in 10 patients indicated that the expression and nuclear translocation of p65, a main subunit of NF‐κB, was increased in OSCC compared with normal squamous epithelial cells. An active form of p65 phosphorylated at serine 536 was present mainly in the nucleus in not only differentiated tumor cells but also tumor‐associated stromal cells and bone‐resorbing osteoclasts. We next injected mouse OSCC SCCVII cells into the masseter region of C₃H/HeN mice. Mice were treated for 3 weeks with a selective NF‐κB inhibitor, NBD peptide, which disrupts the association of NF‐κB essential modulator (NEMO) with IκB kinases. NBD peptide treatment inhibited TNFα‐induced and constitutive NF‐κB activation in SCCVII cells in vitro and in vivo, respectively. Treatment with NBD peptide decreased zygoma and mandible destruction by SCCVII cells, reduced number of osteoclasts by inhibiting RANKL expression in osteoblastic cells and SCCVII cells, increased apoptosis and suppressed the proliferation of SCCVII cells. Taken together, our data clearly indicate that inhibition of NF‐κB is useful for inhibiting bone invasion by OSCC.