Search

Objective: The one-piece dental implant was originally designed to overcome the structural weaknesses of the two-piece implant. However, a fractured one-piece implant requires removal because the abutment cannot be repaired or replaced to support new prosthetic restorations. The aim of this study was to clarify the features and risk factors for fracture of the one-piece implant. Methods: This study was designed as a retrospective case series research. The subjects were patients who were treated for fractures of the one-piece implant at a clinic in Japan between 2012 and 2021. Fractures of the one-piece implant were diagnosed by cone-beam computed tomography, and the association between age and duration from implant placement to fracture was analyzed by one-way ANOVA followed by the Tukey test. Results: Eighteen patients and 20 one-piece implants (under 39 years: 5 patients and 6 implants; 40–59 years: 7 patients and 7 implants; over 60 years: 6 patients and 7 implants) had fractures in their one-piece implants. Of the fractured implants, 11 had a diameter of 3 mm, and 9 had a diameter of 4 mm. The mean durations up to implant fracture were 662 days in the younger group, 1467 days in the middle group, and 1239 days in older group, and the duration was significantly shorter in the younger group. In addition, 83.3% of fracture implants in the younger group were in the molar region. All fractures of the one-piece implants occurred under the bone margin. Two patients had torus mandibularis, and 1 patient was had bruxism. Conclusions: One-piece implants in younger patients that are located in the lower molar position are the most susceptible to implant fracture, and the fracture occurred under the bone margin in all cases. [ABSTRACT FROM AUTHOR]

Positron emission tomography/computed tomography (PET/CT) examinations are indispensable in determining the stage, evaluating the treatment response, and diagnosing recurrence and metastasis during oral cancer treatment. In this study, we examined the correlation between the maximum standardized uptake value (SUVmax) for 18F-FDG PET/CT and the progressive factors, biological characteristics, and prognosis of oral cancer. We included 52 cases of oral squamous cell carcinoma with surgery as the initial treatment. Inclusion criteria included tumor diameter of ≥ 1 cm excluding superficial cancer. We performed 18F-FDG PET/CT examinations before surgery and determined the correlation between SUVmax and clinicopathological factors, such as histological grade, Ki-67 expression, as well as progress factors. SUVmax was significantly correlated with clinical T stage, vascular invasion, lymphatic invasion, Ki-67 expression, and postoperative event (recurrence or metastasis) in Student's t test. Using a cut-off SUVmax of 8.0, clinical T stage, lymph node metastasis, vascular invasion, infiltrative pattern, and Ki-67 expression significantly correlated in chi-squared test. Although observed and expected 3-year overall survival rates were not significantly different, observed and expected 3-year disease-free survival rates were significantly different. Analyzing each clinicopathological factor using various data obtained from 18F-FDG PET/CT scans may be useful to determine prognosis during oral cancer treatment. [ABSTRACT FROM AUTHOR]

Osteocytes regulate bone remodeling, especially in response to mechanical loading and unloading of bone, with nitric oxide reported to play an important role in that process. In the present study, we found that 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP), a second messenger of nitric oxide in various types of cells, was produced by osteocytes in bone tissue as well as cultured osteocytic Ocy454 cells. The amount of 8-nitro-cGMP in Ocy454 cells increased during incubation with parathyroid hormone or prostaglandin E2, both of which are known to upregulate receptor activator of nuclear factor-κB ligand (RANKL) mRNA expression in osteocytes. On the other hand, exogenous 8-nitro-cGMP did not have effects on either the presence or absence of these bioactive substances. Furthermore, neither an inhibitor of nitric oxide synthase nor 8-bromo-cGMP, a cell-permeable analog of cGMP, showed remarkable effects on mRNA expression of sclerostin or RANKL. These results indicate that neither nitric oxide nor its downstream compounds, including 8-nitro-cGMP, alone are sufficient for induction of functional changes in osteocytes. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a degenerative joint disease caused by excessive death of chondrocytes and loss of the extracellular matrix (ECM) in articular cartilage. We previously reported that reactive oxygen species (ROS) generated by the NADPH oxidase (NOX) isoform NOX-2 are involved in chondrocyte death induced by interleukin-1β (IL-1β). In this study, we investigate the role of NOX-2 in the production and degradation of ECM by chondrocytes. Although IL-1β lowered the mRNA expression of type II collagen ( Col2a1) and aggrecan ( Acan) in mouse chondrocyte-like ATDC5 cells, RNA silencing of Nox2 did not change the mRNA expression of these major components of the ECM of cartilage. Hence, NOX-2 is not involved in the IL-1β-induced suppression of ECM production. On the other hand, the NOX inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), the ROS scavenger N-acetylcysteine and an antisense oligodeoxynucleotide for Nox2 prevented the loss of proteoglycan induced by IL-1β in highly differentiated ATDC5 cells. Furthermore, AEBSF did not affect the expression of hyaluronidase-1 and −2, whereas it suppressed hyaluronidase activity in culture medium. IL-1β-induced intra- and extracellular acidification was also suppressed by AEBSF, as was the antisense oligodeoxynucleotide for Nox2. Since hyaluronidase activity is known to be higher under acidic conditions, NOX-2 probably contributes to ECM loss by the activation of hyaluronidase through acidification. [ABSTRACT FROM AUTHOR]

Adenosquamous carcinoma (ASC) of the tongue is an uncommon malignant oral neoplasm with mixed glandular and squamous differentiation and a propensity for aggressive clinical behavior. Here, we report a rare case of ASC of the lateral border of the tongue in a 65-year-old Japanese man. The patient was treated by radical operation and remained well for 6 months before developing metastasis of the hilar and pretracheal lymph nodes. Subsequently, the patient was treated with combined chemotherapy (nedaplatin plus docetaxel and S-1 for two cycles, intravenously) and radiotherapy. Radiation therapy of metastatic lymph nodes was performed at a total dose of 60 Gy and was delivered in 2 Gy fractions 5 days/week. The patient is currently tumor free and is being followed up carefully. This article describes a rare case of ASC of the tongue and its conventional histologic, immunohistochemical, and electron microscopic findings, together with a review of the literature. The findings provide important information to better understand the possible clinical and therapeutic approaches for this uncommon tumor of the tongue. [ABSTRACT FROM AUTHOR]

It remains unclear whether dental implants are a risk factor for the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ). We retrospectively evaluated the status of dental implants in patients given intravenous bisphosphonates (BPs) in a breast cancer cohort to elucidate the risk for BRONJ at the implant site. We established a BRONJ oral monitoring program for 247 breast cancer patients given intravenous BP in our institution. The 3-year cumulative incidence rate was determined. The systemic and local risk factors of 44 patients who completed comprehensive oral examinations were evaluated by logistic regression analysis. The 3-year cumulative incidence rate of the 247 patients was 0.074 % (8/247, 95 % CI 0.0081-0.014). In the 44 orally examined patients, 6 (13.6 %: 6/44) had dental implants. Of these 6 patients, 1 developed BRONJ at the implant site. There were no significant differences in the age, total BP treatment period, number of residual teeth, time of regular oral monitoring, oral hygiene level, or dental implant insertion. Although a case of ONJ was identified, dental implants which were inserted before intravenous BP administration were not a risk factor for the development of ONJ in breast cancer patients. [ABSTRACT FROM AUTHOR]

Chondrosarcomas are rare tumors of which approximately 10 % are found in the maxillofacial region. They range from a well-differentiated growth resembling a benign cartilage tumor to a high-grade malignancy with aggressive local behaviour and the potential to metastasize. We report a case of high-grade chondrosarcoma of the maxilla extending to the pterygomandibular space which was treated with radical surgical excision without neck dissection and postoperative radiotherapy. The diagnosis was a conventional type of chondrosarcoma, Grade III. The postoperative course was uneventful, and the patient has had no recurrence in the 15-year follow-up period. [ABSTRACT FROM AUTHOR]

A solitary myofibroma (MF) is an unusual spindle cell neoplasm that usually arises in the soft tissue, skin, or bone of the head and neck region in infancy. We report an extremely rare case of MF of the mandible in an 18-year-old Japanese woman together with the conventional histologic, immunohistochemical, and electron microscopic findings. The tumor was well circumscribed and composed of fibroblast-like or myofibroblast-like spindle cells. On immunohistochemical evaluation the tumor cells were positive for vimentin, α-smooth muscle actin, HHF-35, and calponin, but negative for neurogenic antigens and markers for vascular endothelial cells. The Ki-67 labeling index was 10 % and the p53 labeling index was 10 %. Ultrastructural examination revealed smooth muscle cell differentiation. The patient was treated by surgical resection and underwent follow-up without any signs of recurrence. MF presents a wide range of differential diagnosis, including benign and malignant neoplasms. Therefore, accurate diagnosis may avoid an unnecessarily aggressive therapy. [ABSTRACT FROM AUTHOR]

Solitary fibrous tumor (SFT) is a rare mass-forming soft tissue tumor that occurs most commonly in the pleura, but has been described in various extrathoracic sites. Extrapleural manifestation of SFT, particularly in the head and neck region, is rare. The most common extrapleural site is the oral cavity; these tumors have also been described in the orbit, nasopharynx, paranasal sinuses, salivary glands, and larynx. We report an extremely rare case of a SFT in the subcutaneous region of the cheek. This tumor in the left cheek was a large firm mass, approximately 8.5 cm × 6 cm in size and was successfully treated by surgical resection. Immunohistochemistry revealed reactivity for vimentin, CD34, and bcl-2, but no staining for cytokeratin, epithelial membrane antigen, S-100, desmin, caldesmon, actin, α-smooth muscle actin, CD117, and CD99. Immunohistochemical study is the key to establish a definitive diagnosis of SFT, and ultrastructural study is also useful for making an accurate diagnosis. The patient recovered uneventfully without evidence of tumor recurrence 2 years after surgery. [ABSTRACT FROM AUTHOR]

Rapid and efficient animal models are needed for evaluating the effectiveness of many new candidate bone regenerative materials. We developed an in vivo model screening for calvarial bone regeneration in lipopolysaccharide (LPS)-treated mice, in which materials were overlaid on the periosteum of the calvaria in a 20 min surgery and results were detectable in 1 week. Intraperitoneal LPS injection reduced spontaneous bone formation, and local application of basic fibroblast growth factor (bFGF) increased the bone-forming activities of osteoblasts. A novel synthetic collagen gel, alkali-treated collagen (AlCol) cross-linked with trisuccinimidyl citrate (TSC), acted as a reservoir for basic substances such as bFGF. The AlCol-TSC gel in conjunction with bFGF activated osteoblast activity without the delay in osteoid maturation caused by bFGF administration alone. The AlCol-TSC gel may slow the release of bFGF to improve the imbalance between osteoid formation and bone mineralization. These findings suggest that our model is suitable for screening bone regenerative materials and that the AlCOl-TSC gel functions as a candidate reservoir for the slow release of bFGF. [ABSTRACT FROM AUTHOR]

Ideally, artificial bones should be dimensionally compatible with deformities, and be biodegradable and osteoconductive; however, there are no artificial bones developed to date that satisfy these requirements. We fabricated novel custom-made artificial bones from α-tricalcium phosphate powder using an inkjet printer and implanted them in ten patients with maxillofacial deformities. The artificial bones had dimensional compatibility in all the patients. The operation time was reduced due to minimal need for size adjustment and fixing manipulation. The postsurgical computed tomography analysis detected partial union between the artificial bones and host bone tissues. There were no serious adverse reactions. These findings provide support for further clinical studies of the inkjet-printed custom-made artificial bones. [ABSTRACT FROM AUTHOR]

Hard tissue reconstruction is very useful for bony defects of the maxillofacial region. Autogenous bone, allogeneic bone, and artificial bone have been used to reconstruct maxillofacial bone; however, the use of autogenous bone involves high surgical invasiveness because of the need to harvest the bone. The use of allogeneic bone is associated with infections, raises ethical concerns, and is not widely used in Japan. Artificial bone has several advantages, including no need for bone harvesting, excellent biocompatibility, and a relatively easy surgical procedure. Use of artificial bone avoids the much greater invasiveness of harvesting bone, and several types of artificial bone have been developed. Design requirements for artificial bone include surgical manipulability, structural compatibility with the defective area, support properties, and the ability to induce bone regeneration; however, no artificial bone meeting all these requirements has yet been developed. Artificial bone is used in many patients in our medical center, and we have been active in developing the next generation of artificial bone with better properties. In this article, we present a case history and discuss the future development of artificial bone for use in maxillofacial reconstruction. [ABSTRACT FROM AUTHOR]