Usefulness of the newly developed artificial denture plaque for practical denture care training.

Objectives: The aim of this study was to investigate whether the newly developed artificial dental plaque (A-DP) is useful as an educational tool for denture care of dental hygienist that compared it with conventional artificial dental plaque from the viewpoint of practical skills.

Material And Methods: The 125 dental hygienist school students and 26 dental hygienists who had clinical experience were subjected a practical training of denture plaque control using the conventional denture plaque (C-DP) and the A-DP. The questionnaires based on the semantic differential method were used to survey whether the A-DP is similar to the real denture plaque (R-DP).

Architecture of connective tissue regenerated by enamel matrix derivative around hydroxyapatite implanted into tooth extraction sockets in the rat maxilla.

We investigated the architecture of periodontal ligament regenerated by an enamel matrix derivative (EMD, Emdogain) coating on the surface of hydroxyapatite (EMD-HA). Immediately after extraction of the maxillary first molar in rats, HA alone or EMD-HA was implanted into the socket. At 5 days, and 2 and 4 weeks after implantation, the specimens were examined by light and transmission electron microscopy, and immunohistochemistry for periostin and matrix metalloproteinase (MMP)-13.

VAMP4 is required to maintain the ribbon structure of the Golgi apparatus.

The Golgi apparatus forms a twisted ribbon-like network in the juxtanuclear region of vertebrate cells. Vesicle-associated membrane protein 4 (VAMP4), a v-SNARE protein expressed exclusively in the vertebrate trans-Golgi network (TGN), plays a role in retrograde trafficking from the early endosome to the TGN, although its precise function within the Golgi apparatus remains unclear. To determine whether VAMP4 plays a functional role in maintaining the structure of the Golgi apparatus, we depleted VAMP4 gene expression using RNA interference technology.

Effect of the quantity and quality of cortical bone on the failure force of a miniscrew implant.

This study examined the influence of the quantity and quality of cortical bone on the failure force of miniscrew implants. Twenty-six titanium alloy miniscrew implants (AbsoAnchor) 1.4mm in diameter and 5 or 7 mm long were placed in cross-sectioned maxillae (n = 6) and mandibles (n = 20) of human cadavers.

Effects of local and whole body irradiation on the appearance of osteoblasts during wound healing in tooth extraction sockets in rats.

Irradiation before tooth extraction delays wound healing in the alveolar socket. This study examined the influences of local and whole body irradiation before tooth extraction on appearance of osteoblasts in the alveolar bone of rat maxillary first molars because bone formation is observed at the initial phase of wound healing. Several osteoblasts were generated 3 days after tooth extraction, and the number of cells increased day by day.

Metabolic mode peculiar to Meckel's cartilage: immunohistochemical comparisons of hypoxia-inducible factor-1alpha and glucose transporters in developing endochondral bones in mice.

The middle portion of Meckel's cartilage resembles endochondral bone formation accompanied by chondrocyte hypertrophy and death, cartilaginous matrix calcification, and chondroclastic resorption. We examined Meckel's cartilage specimens from mice mandibles taken on embryonic days 14-16 (E14-E16) using immunohistochemistry for hypoxia-inducible factor-1alpha (HIF-1alpha), glucose transporter 1 (GLUT1), glucose transporter 3 (GLUT3), and glucose transporter 5 (GLUT5), and using enzyme histochemistry for glucose-6-phosphate isomerase (GPI), lactate dehydrogenase (LDH), and cytochrome oxidase (COX), along with the periodic acid-Schiff (PAS) reaction, and compared the results with those of endochondral bones from E16 hind limbs. Periodic acid-Schiff-positive glycogen, HIF-1alpha, and GLUT immunoreactivity, and GPI, LDH, and COX activities were observed in Meckel's cartilage in E14 and E15 mandibles.

Matrix mineralization as a trigger for osteocyte maturation.

The morphology of the osteocyte changes during the cell's lifetime. Shortly after becoming buried in the matrix, an osteocyte is plump with a rich rough endoplasmic reticulum and a well-developed Golgi complex. This "immature" osteocyte reduces its number of organelles to become a "mature" osteocyte when it comes to reside deeper in the bone matrix.

An immunohistochemical and ultrastructural study of the pericellular matrix of uneroded hypertrophic chondrocytes in the mandibular condyle of aged c-src-deficient mice.

Objective: Previous studies indicate that hypertrophic chondrocytes can transdifferentiate or dedifferentiate and redifferentiate into bone cells during the endochondral bone formation. Mandibular condyle in aged c-src-deficient mice has incremental line-like striations consisting of cartilaginous and non-cartilaginous layers, and the former contains intact hypertrophic chondrocytes in uneroded lacunae. The purpose of this study is to determine the phenotype changes of uneroded hypertrophic chondrocytes.

In situ localization of gelatinolytic activity during development and resorption of Meckel's cartilage in mice.

Degradation of Meckel's cartilage in the middle portion is accompanied by hypertrophy and death of chondrocytes, calcification of the cartilaginous matrix, and chondroclastic resorption. We hypothesize that the gelatinolytic activity of matrix metalloproteinases (MMPs) largely contributes to the degradation of extracellular matrix (ECM) in the process. The activity in Meckel's cartilage of mouse mandibular arches at embryonic days 14-16 (E14-E16) was examined by a combination of in situ zymography (ISZ), using quenched fluorescent dye-labeled gelatin as a substrate, with CTT (a selective inhibitor of MMP-2 and -9) or with EDTA (a general MMP inhibitor).

Effects of local and whole body irradiation on appearance of osteoclasts during wound healing of tooth extraction sockets in rats.

We examined effects of local and whole body irradiation before tooth extraction on appearance and differentiation of osteoclasts in the alveolar bone of rat maxillary first molars. Wistar rats weighting 100 g were divided into three groups: non-irradiation group, local irradiation group, and whole body irradiation group. In the local irradiation group, a field made with lead blocks was placed over the maxillary left first molar tooth.

Contributions of matrix metalloproteinases toward Meckel's cartilage resorption in mice: immunohistochemical studies, including comparisons with developing endochondral bones.

The middle portion of Meckel's cartilage (one of four portions that disappear with unique fate) degrades via hypertrophy and the cell death of chondrocytes and via the resorption of cartilage by chondroclasts. We have examined the immunolocalization of matrix metalloproteinase-2 (MMP-2), MMP-9, MMP-13, and MMP-14 (members of the MMP activation cascade) and galectin-3 (an endogenous substrate for MMP-9 and an anti-apoptotic factor) during resorption of Meckel's cartilage in embryonic mice and have compared the results with those of developing endochondral bones in hind limbs. MMP immunoreactivity, except for MMP-2, is present in nearly all chondrocytes in the middle portion of Meckel's cartilage.

Radiation-induced apoptosis is independent of caspase-8 but dependent on cytochrome c and the caspase-9 cascade in human leukemia HL60 cells.

We investigated the role of the caspase activation cascade in apoptosis induced by ionizing radiation or hydrogen peroxide (H(2)O(2)) in human leukemia HL60 cells. Electron paramagnetic resonance (EPR) spectra revealed that hydroxyl and hydrogen radicals were generated in the culture medium after exposure to radiation or H(2)O(2). Initial accumulation of DNA fragments at 2 h after exposure was delayed in irradiated cells compared with H(2)O(2)-treated cells, although formation of abasic sites immediately after exposure was significantly higher in irradiated cells and similar quantities of hydroxyl radicals were produced under both conditions.

Immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in Meckel's cartilage compared with developing endochondral bones in mice.

We examined the immunolocalization of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in areas of resorption caused by osteoclasts/chondroclasts on embryonic days 14-16 (E14-16) in Meckel's cartilage, and compared the results with those in endochondral bones in mice. Intense RANKL and OPG immunoreactivity was detected in the chondrocytes in Meckel's cartilage. On E15, when the incisor teeth were closest to the middle portion of Meckel's cartilage, tartrate-resistant acid phosphatase (TRAP)-positive cells appeared on the lateral side of the cartilage.

Expression and localization of versican during postnatal development of rat temporomandibular joint disc.

To analyze the growth-related changes in extracellular matrix components in temporomandibular joint (TMJ) discs, the expression and localization of the core protein of a large chondroitin sulphate proteoglycan, versican, in rat TMJ discs during postnatal development (2-32 weeks) were examined using Western blot analysis, real-time quantitative PCR and immunohistochemistry. Western blot analysis showed that rat TMJ discs predominantly expressed one isoform (V1) and the core protein sharply increased after birth, reached a peak at 8 weeks, and then gradually decreased up to 32 weeks. Real-time quantitative PCR with TaqMan probes indicated that mRNA expression of versican was highest at 2 weeks and gradually decreased with growth.

Impaired alveolization in mice deficient in membrane-type matrix metalloproteinase 1 (MT1-MMP).

To clarify the involvement of membrane-type matrix metalloproteinase 1 (MT1-MMP) in lung organogenesis, we studied the lung morphology of 13-day-old MT1-MMP null mice. The lung architecture in MT1-MMP null mice was abnormal, and the airspace compartments were characterized by smooth walls and larger size. Most of the compartment wall consisted of one or two layers of cells and interstitial connective tissue that was thicker than that of normal alveoli.

Distinct expression pattern of insulin-like growth factor family in rodent taste buds.

The insulin-like growth factor (IGF) system is an important regulator of growth and differentiation in a variety of tissues. In the present study, the expression of IGF family members in the taste buds of mice and rats was examined. By reverse transcriptase polymerase chain reaction (RT-PCR) analysis, mRNA of IGF-I and -II, IGF-I receptor (IGF-IR), insulin receptor (insulin R), and IGF-binding protein (IGFBP)-2, -3, -4, -5, and -6 was detected in the taste bud-containing epithelium of the circumvallate papillae of mice.

Osteoclast differentiation in ectopic bone formation induced by recombinant human bone morphogenetic protein 2 (rhBMP-2).

Osteoclast differentiation in the process of ectopic bone formation induced by recombinant human bone morphogenetic protein 2 (rhBMP-2) was examined to clarify the relationship between osteoclast development and rhBMP-2-induced bone formation. A combination of rhBMP-2 with a porous microsphere (PMS) and blood clot was implanted subcutaneously on the bilateral chest muscles of rats. Tartrate-resistant acid phosphatase (TRAPase) activity, cathepsin K (cath K), and calcitonin receptor (CTR), as markers of osteoclasts and their precursors, were examined using enzyme and immunohistochemical analysis up to 7 days after implantation.

Apoptosis induced by generated OH radicals inside cells after irradiation.

OH radicals play a major role in radiation-induced DNA and cell membrane damage. These types of damage can also induce death by apoptosis through activation of a pro-apoptosis pathway. We attempted to detect OH radicals inside human promyelocytic leukemia (HL60) cells and estimate the relationship between radiation-induced apoptosis and OH radicals generated inside the cells.

Expression of fibrillins and tropoelastin by human gingival and periodontal ligament fibroblasts in vitro.

The elastic system fibers consist of three different types, oxytalan, elaunin and elastic fibers, which differ in the relative content of microfibrils and elastin. In periodontal tissues, oxytalan fibers are known to be distributed in the periodontal ligament and gingiva, while elaunin and elastic fibers are present only in the gingiva. We examined the in vitro synthesis of microfibrils and elastin by human gingival fibroblasts (HGF) and periodontal ligament fibroblasts (HPLF).