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Synthetic octacalcium phosphate (OCP) has been shown to be a resorbable bone regenerative material. In this study, OCP combined with collagen (OCP/Col) or collagen was implanted into the critical-sized defects or into the subperiosteal region in rat crania and fixed at 4, 8 and 12 weeks after implantation. The percentage of newly formed bone and the tissue including the implant were determined by a histomorphometric analysis. Activities of tartrate resistant acid phosphatase (TRAP) were stained to examine phagocytotic multinucleated giant cells. The effect of implantation on crystalline phase of OCP in the implant was examined by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The present study suggests that the bone formation on OCP/Col and biodegradation of OCP/Col is distinct depending on the implantation sites.

The purpose of this study was to examine the effect of osteoblastic differentiation of mesenchymal stem cell (MSC) on new bone formation in β-TCP/MSC complex in vivo. Bone marrows were collected from beagle and cultured. Cultured cells were implanted into β-TCP. β-TCP/MSC complexes and control materials were surgically implanted into dorsal pouches of beagle. Eight weeks after the surgery, the implanted materials were harvested and evaluated. In all materials, new bone formation was observed. A significant increase in new bone formation was seen in non-differentiation complex and 1-day differentiation complex as compared with the control. However, new bone formation in 7-day differentiation complex was less than the other two complexes. The results suggest that the implantation of MSC intoβ-TCP enhances new bone formation, but the effect of osteoblastic differentiation of MSC is rather inhibitory.

The present study was designed to investigate whether the amount of octacalcium phosphate (OCP) facilitates osteoconductive characteristics of OCP/Collagen in vivo and in vitro. Radiographic and histological examination showed that the quantity of newly formed bone increased with increasing OCP concentration in collagen. The degree of differentiation of osteoblastic cells increased depending on OCP concentration up to day 14 of culture. The present study suggests that the osteoconductive characteristics of OCP/Collagen can be displayed by the intrinsic bone regenerative property of OCP, in concert with collagen matrix.

The present study was designed to investigate whether octacalcium phosphate (OCP) affects proliferation and differentiation of mouse bone marrow stromal ST-2 cells, an osteogenic cell line, in vitro. OCP facilitates the differentiation of ST-2 cells rather than hydroxyapatite (HA). It was also shown that OCP tends to convert into HA during the incubation. These results suggest that enhancement of osteoblastic cell differentiation by OCP may be associated with a process of irreversible conversion into HA.

The purpose of this study was to evaluate the marginal and internal fitness of zirconia all-ceramic crowns. Three brass dies were prepared with the following cervical margin forms: a shoulder and two types of rounded (curvature radius: 0.2 and 0.5 mm) shoulder preparations. Five crowns for each type of die were fabricated using the CAD/CAM system. The fitness was evaluated with a replica technique using silicon impression materials. The mean gap dimensions and standard deviations at the margins were 36 ± 32 µm for the shoulder, 27 ± 29 µm for the 0.2 mm rounded shoulder, and 41 ± 33 µm for the 0.5 mm rounded shoulder. There were no significant differences among the three groups regarding marginal fitness. The zirconia all-ceramic crowns made using the CAD/CAM system showed clinically acceptable marginal fitness.

The purpose of this study was to evaluate the periodic changes of marginal adaptation of cervical composite resin restorations. Class V saucer-type cavities or cervical cavities were prepared. A total of 159 restorations were placed in 40 patients by one operator. Four self-etching bonding systems were used in this study. Clinical findings of these fillings were periodically observed. In order to observe the marginal adaptation, precision replicas were made. These replicas were observed by SEM. In the Fluoro bond group (Shofu, Kyoto, Japan) and the Mega bond group (Kuraray, Okayama, Japan), maximum observation period is 3,121 days. In many cases of enamel and enamel dentin margin cavities, marginal steps were observed after 1 year. The width of steps was extended with time.

This study evaluated and compared the X-ray opacity of eight marketed fiber-reinforced composite (FRC) post brands by densitometric analysis of radiographs, taken of the separate posts and of posts seated in extracted human canine teeth, respectively. The fiber-reinforced resin posts studied had significantly different radiopacity. Two post brands were hardly detectable on the radiographs, whereas four brands were acceptably radiopaque; and two posts with >2 mm Al equivalent were very satisfactory for unequivocal detection on dental radiographs.

The present study was designed to investigate bone repair in a critical size defect compared to that in a smaller or a non-critical-size defect. Our original standardized rat calvarial bone defect model was used. The rate of bone formation was examined with X-ray morphometry, and the bone production was assessed by in situ hybridization for type I collagen and osteocalcin. Formation of repaired bone ceased within 24 weeks in both critical- and non-critical-size defects, whereas osteoblasts and osteocytes no longer expressed type I collagen or osteocalcin in week 24. The results suggest that osteoblasts and osteocytes cease bone formation within a limited period regardless of completion of the defect repair.

STRO-1 is a specific marker of mesenchymal stem cells, but the tissue localization of STRO-1 in developing teeth is not clear. The present study was designed to investigate the immunohistological localization of STRO-1 in developing and erupting rat molars. STRO-1 antigens were found in odontoblasts, dental pulp cells, periodontal ligament cells, cementblasts, periodontal osteoblasts, and blood vessels. The STRO-1 may be involved in hard tissue formation of dentin and alveolar bone.

A radio frequency identification (RFID) transponder covering the 13.56 MHz band was adapted to be placed in the pulp chamber of an endodontically treated molar human tooth. In an animal experiment, the transponder could be fixed in the cavity of a mandibular canine of a dog. An RFID reader positioned close to the dog’s face could communicate with the transponder in the dog’s tooth.