Kuniteru Nagahara

Three-dimensional computed tomography evaluation of postsurgical condylar displacement after mandibular osteotomy

OBJECTIVE The purpose of this study was to examine both condylar displacement of the temporomandibular joint after sagittal split ramus osteotomy with rigid osteosynthesis and intraoral vertical ramus osteotomy without osteosynthesis in patients with mandibular prognathism by means of three-dimensional computed tomography. STUDY DESIGN In this pilot study, five patients treated with sagittal split ramus osteotomy and 5 patients treated with intraoral vertical ramus osteotomy were evaluated. A technique to superimpose a postoperative three-dimensional computed tomography image on its corresponding preoperative image was designed. Postoperative condylar displacement, rotation, and tilting were measured in three-dimensional computed tomography images. RESULTS Within 3 to 6 months after surgery, changes in the inclination of the condylar axes were distinctly seen, although changes in the position of the condyles within the joints were minimal. In particular, outward rotation of the condylar long axes after intraoral vertical ramus osteotomy was a frequent finding. CONCLUSIONS The three-dimensional computed tomography superimposition technique was a practical method of evaluating postsurgical condylar displacement after mandibular osteotomy.

BONE FORMATION UNDER THE INFLUENCE OF BONE MORPHOGENETIC PROTEIN/SELF -SETTING APATITE CEMENT COMPOSITE AS A DELIVERY SYSTEM

Self-setting apatite cement (apatite cement) with a phase of hydroxyapatite (HAP) was employed as a delivery system for bone morphogenetic protein (BMP). A composite of BMP and apatite cement (BMP/HAP composite) was implanted both in thigh muscle and surgically created defect of a critical size of 5 mm, which is a size that does not heal spontaneously in the femur of mice, to evaluate its osteogenetic potential as an augmentation and reconstructive material for clinical usage. The histological and immunohistochemical assessment of proteoglycans reiterated osteogenesis in the muscle tissue. On day 14 postimplantation of BMP/HAP composite, chondroid tissue was formed in the muscle, and HAP particles were seen in newly formed chondroid tissue. On the 21st day, endo-chondral ossification had occurred, however, small HAP particles remained in the newly formed bone, i.e., HAP particles and newly formed osseous tissues coexisted in a central area. BMP/HAP composite was incorporated by newly formed osseous tissue in the experimented animals. HAP particle found in BMP/HAP composite implanted into the bone defect was resorbed and replaced by osseous tissue. The apatite cement was proved to have advantages for its shaping as well as collapsing properties, and thus, apatite cement containing BMP is suggested as a favorable augmentation material in clinical usage for delivery system of BMP.

Tenascin: Growth and adhesion modulation—Extracellular matrix degrading function: an in Vitro study

Tenascin (TN), a recently characterised extracellular matrix protein, largely confined to the process with the development of embryo in areas of epithelial-mesenchymal interactions and in areas where there are morphogenetic movements and tissue patterning, has a highly restricted expression in adult tissues. The expression of TN is enhanced in a variety of human neoplastic lesions. However, function(s) and molecular mechanisms of enhanced expression in neoplastic lesions remain unclear. We employed human tongue carcinoma cells (SCCKN), human salivary gland adenocarcinoma cells (SGT-1), normal mouse embryonic fibroblasts (NIH3T3-3) and K-ras-2 transformed fibroblasts (Cle-H3) in an in vitro study to elucidate the biological roles of TN. In in vitro studies, all the cell lines examined had enhanced secretion of TN in the presence of transforming growth factor-beta in a dose-dependent manner and TN itself was found to possess a growth-enhancing activity. Moreover, studies on adhesion of the cell lines on coated substrates of fibronectin (FN), laminin (LN), tenascin (TN), TN/FN and TN/LN showed that all the cells adhere and spread well on FN and LN. However, on TN they attach poorly and remain rounded. The relative concentrations of TN and FN affected the cellular adhesion and morphology. In SCCKN and SGT-1, but not in NIH3T3 and Cle-He3 fibroblasts, a higher concentration of TN inhibited cellular adhesion on fibronectin, suggesting that cells attach poorly on TN, it may interfere with the action of fibronectin, and the relative concentrations of TN, FN or LN may affect cellular adhesion and morphology which may differ in different cell types. When TN was added in the growth medium of exponentially growing cells, the cells lost their cell to cell contact and were seen to be separating. The presence of these extracellular matrix proteins were further tested to determine whether they could modulate the secretion of proteolytic enzymes responsible for extracellular matrix degradation by tumour cells, when the neoplastic cells but not the non-neoplastic cells grown on FN/TN substrate showed positive immunofluorescence for collagenase. FN, LN or TN alone did not induce collagenase in the tumour cells. If the same is true in vivo, although a number of factors and interactions may implicate the ultimate outcome, the enhanced expression of TN in neoplastic lesions may have potential implications for tumour growth, differentiation, cellular adhesion, invasion and metastasis.

Pathologic and enzyme histochemical studies on bone formation induced by bone morphogenetic protein in mouse muscle tissue.

Bone morphogenetic protein (BMP) irreversibly induced the differentiation of mesenchymal-type cells into osteoprogenitor cells for endochondral ossification. During the process of BMP-induced differentiation in mice, 4 cell type (chondroblasts, osteoblasts, chondroclasts, and osteoclasts) were examined for phosphatase and succinate dehydrogenase using a wide range of buffers (4.0 less than or equal to pH less than or equal to 9.2). During the chondroid tissue-forming stage (1 week), chondroblast-like or osteoblast-like cells expressed phosphatase activity at 6.8 less than or equal to pH less than or equal to 9.2; chondroclast-like or osteoclast-like cells expressed phosphatase activity at 4.0 less than or equal to pH less than or equal to 5.8. However, mature chondrocytes found in hyaline cartilage expressed phosphatase activity between 6.6 less than or equal to pH less than or equal to 7.6 (2 weeks). During the process of endochondral ossification, alkaline phosphatase activity decreased in osteoblast-like cells with traces of acid phosphatase activity still detectable. Chondroclastic and osteoclastic giant cells were characterized by intense succinate dehydrogenase activity.

Mechanisms of the immunosuppressive effects of mouse adipose tissue-derived mesenchymal stromal cells on mouse alloreactively stimulated spleen cells

The mechanisms of immunomodulation by mesenchymal stromal cells remain poorly understood. In this study, the effects of mouse adipose tissue-derived mesenchymal stromal cells (ASCs) on mouse spleen cells alloreactively stimulated by anti-CD3 and anti-CD28 antibody-coated (anti-CD3/CD28) beads were observed. Production of interferon-γ by the anti-CD3/CD28 bead-stimulated spleen cells was significantly suppressed in co-culture with ASCs. However, an augmented intensity of CD69 on the stimulated spleen cells was not suppressed in the presence of ASCs. The immunosuppressive effects of ASCs were partially mediated by one or more soluble factors (26% suppression). However, the ASCs require cell-cell contact in order to maximally exert suppression (88%). The suppressive effect of ASCs mediated by direct cell contact was partially reversed following knockdown of β2 microglobulin, a component of the major histocompatibility complex (MHC) class I molecule, with siRNA. The results of the study demonstrated that ASCs have significant immune modulatory effects on alloreactively stimulated spleen cells. The effects of ASCs on spleen cells are dependent on soluble factor(s) and cell contact, which is mediated by the MHC class I complex on ASCs.

Guided Bone Regeneration, Platelet Rich Plasma and Low-Intensity Ultrasound Irradiation for Dental Implants

Because a concept of an osteointegrated dental implant system was established, prognosis of a dental implant at treatment improved and the treatment of restoration for missing teeth was changed. However, a dental implant treatment into atrophic jaw bone requires bone augmentation, obviously. At this time, we studied for the purpose of establishing the evidence of each method for clinical application of these bone augmentation method, such as guided bone regeneration (GBR), and autogenous bone block graft (BBG). In addition, we pursued the basic study of the evidence about the bone formation with platelet rich plasma (PRP) which recognized the availability in clinic. Furthermore, we present the results of basic studies which we tested for the purpose of applying a low-intensity pulse ultrasound (LIPU) irradiation applied to a fracture treatment in orthopedics area to intra-oral area, specially the condition after implant placement. In the results of comparison with GBR site and BBG, the differences of labeling bands were observed with a fluorescence microscopy. There was much labeling bands on GBR sections in comparison with BBG. This meaning that the bone remodeling around implants at GBR site was more active than BBG site. And the new bone formation by PRP was identified on soft X-ray graphically at first week after PRP applied mandible bone defect (experimental side). At same region of first week specimen, we confirmed positive reactions of platelet derived growth factor