To establish a simple and objective assessment of the residual ridge shape of edentulous patients, we investigated the utility of a newly developed "examination scale" based on our clinical research. The sites corresponding to the right and left first molars in study models of edentulous maxillae and mandibles were examined. Subjective assessment and assessment with the four-grade examination scale (U-shaped, middle, V-shape, flat) were performed by 16 dentists. Objective assessment (the breadth of the residual ridge) was performed with digital vernier calipers. Agreement among the subjective assessment, objective assessment, and assessment with the examination scale was analyzed with kappa values. Marked variations were noted in the relation between the subjective assessment and objective assessment regardless of the individual's clinical experience. Agreement between the subjective assessment and objective assessment was low (maxillae: less than 3 years of clinical experience: 0.28, more than 7 years of clinical experience: 0.30, mandibles: less than 3 years of clinical experience: 0.19, more than 7 years of clinical experience: 0.38). However, agreement between the assessment with the examination scale and objective assessment was high (maxillae: less than 3 years of clinical experience: 0.71, more than 7 years of clinical experience: 0.65, mandibles: less than 3 years of clinical experience: 0.57, more than 7 years of clinical experience: 0.63). The assessment by the newly developed examination scale for residual ridge shape of edentulous patients agreed well with the objective assessment, indicating the usefulness of this scale.

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Tulobuterol, which is a representative selective β₂-adrenoceptor agonist, is a drug primarily utilized as a therapeutic agent for bronchial asthma consequent to its bronchodilator effect. In recent years, the involvement of β₂-adrenoceptor agonist in the bone metabolism regulatory mechanism through the sympathetic nervous system has become clear. With respect to this mechanism, it is believed that bone resorption increases through the β₂-adrenoceptor leading to a reduction in bone mass. However, details of this mechanism remain sketchy. Therefore, this investigation sought to clarify the mechanism governing osteoclast formation through the β₂-adrenoceptor employing an osteoclastic cell formation system, in which tulobuterol was introduced to the co-culture system of the bone marrow stromal cell line (ST2-T cells) and bone marrow cells. RT-PCR experiment confirmed β₂-adrenoceptor expression in the bone marrow stromal cells and osteoblasts. Tulobuterol increased osteoclast number in co-culture system compared with control. In addition, formation of the osteoclast-like cells was inhibited by butoxamine, which is a β₂-adrenoceptor antagonist. On the other hand, osteoclasts were not formed despite the introduction of tulobuterol to the single culture system of bone marrow cells. Furthermore, it is believed that the cAMP signal transduction system is involved in the signal transduction of osteoclast-like cell formation given that cyclic adenosine 3′5′-monophosphate (cAMP) levels in ST2-T cells increased in a tulobuterol concentration-dependent manner. Based on these results, it is clear that differentiation from hematopoietic stem cells to osteoclasts occurs through the β₂-adrenoceptor, which is expressed in bone marrow stromal cells and osteoblasts.

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The purpose of this study was to quantify perceived hypernasality in children with cleft palate. One-third octave spectra of the isolated vowel [i] were obtained from 32 children with cleft palate and 5 children without cleft palate. Four experienced listeners rated the severity of hypernasality of the 37 speech samples using a 6-point equal-appearing interval scale. Based on the averaged normalized rating scores, the 37 samples were divided into three groups. Average 1/3 octave spectra were calculated for each of three groups and for the control group, except for the five speakers whose speech samples were used for the perceptual experiment. When the average 1/3 octave spectra from the hypernasal groups and the normal resonance group were compared, spectral characteristics of hypernasality were identified as increasing the amplitudes between F1 and F2 and decreasing the amplitudes in the region of F2 and F3.

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Gypsum-bonded investments have been widely used for dental casting. However, these investments could not be applied for titanium casting because of the decomposition experienced at high temperature. The purpose of this study was to investigate the application of experimental casting investment for titanium which was composed of gypsum as a binder and magnesium oxide (MgO) as a refractory material for titanium at a common casting process temperature of 700°C. Five kinds of investments (G-5, G-10, G-15, G20, G30) were experimentally prepared and used for this study according to the quantity of commercially available dental stone and MgO powder. Fundamental properties and titanium castings from them were also evaluated. All of the experimental investments took a long time to harden compared to commercial gypsum-bonded investments; however, the proper peaks were detected in each investment before and after firing. Fired strength was in the range of 3.4 to 6.2 MPa and G-5 had a significantly lower value than the others. All of the thermal expansion curves were similar, and the quantity depended on the amount of MgO. Although there were no remarkable differences for castability among investments tested, external defects were found in a few castings from G-5. On the other hand, the reaction between the mold and molten titanium seemed to be smaller than estimated. There were no significant differences in hardness during experimentation except for more than G-20. In conclusion, it was possible to apply experimental gypsum-bonded investments for the titanium casting technique, and G-10, with smaller compressive strength, showed good performance within the limitations of this study.

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Periodontal ligament (PL) contains fibroblastic cells, which may participate in formation and maintenance of PL fibers, and osteoblastic cells with a potential to generate alveolar bone and cementum, however, the specific markers for recognition and isolation of each cell type have not been clarified. The purpose of this study was to isolate alkaline phosphatase (ALP)-positive and -negative subpopulations from heterogeneous human PL (HPL) cells using flowcytometry and to identify functional difference between the 2 subsets in terms of mitogenic activity, osteogenic potential and expression of decorin as well as biglycan. We separately isolated ALP-positive and -negative cells from each of 5 populations of HPL cells. The mitogenic activity of ALP-negative cells was higher than that of ALP-positive cells, while ALP-positive cells showed remarkably stronger osteogenic potential, such as induction of ALP activity, bonespecific gene expression and mineralization by culturing with osteogenic differentiation medium (ODM), than ALPnegative cells. In ALP-positive cells, expression level of biglycan was higher, but decorin expression was weaker, as compared with ALP-negative cells. The ODM-induced osteoblastic differentiation was significantly enhanced by adding recombinant biglycan exogenously in ALP-positive cells. When the 2 subpopulations were cultured with ODM, gene expression of decorin was increased, whereas biglycan expression had no change. These results suggest that ALPpositive HPL cells have osteoblast-like phenotype, while ALP-negative HPL cells are fibroblastic cell population with weak osteogenic potential. Further, biglycan may positively regulate osteoblastic differentiation in ALP-positive HPL cells, while decorin, whose expression is increased by osteogenic induction, may negatively regulate mineralization in both subpopulations.

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Sphingosine-1-phosphate (S1P), which is mainly erythrocyte-derived, is a lipid mediator, which exists at high levels in plasma and acts on its receptors. S1P displays physiological functions, e.g., cell proliferation, cell migration and alteration of cellular morphology, through the S1P receptor. Among S1P receptors, stimulus via S1P_1/3 accelerates cell movement; in contrast, activation of S1P₂ inhibits cell movement. Osteoclasts are bone resorption cells that are fused and multinucleated through osteoclast precursor cells derived from hematopoietic stem cells. However, whether proliferation and fusion of osteoclast precursor cells are controlled and adjusted by the lipid mediator is unknown. This study examined the influence of S1P in terms of control of osteoclastic differentiation employing the osteoclastic cell formation process. Upon separation of erythrocytes from all bone marrow cells, the level of osteoclast formation decreased; subsequently, following the addition of S1P, the number of cells recovered. Furthermore, the number of osteoclasts decreased in the S1P_1/3 antagonist. RT-PCR revealed that S1P₁ mRNA expression is higher in bone marrow cells in comparison to osteoclasts; in contrast, S1P₂ mRNA expression is higher in osteoclastic cells. Therefore, red blood cells are involved in the process of osteoclast formation as the S1P source in plasma and proliferation of osteoclastic cells are controlled via inhibition of S1P_1/3. On the other hand, S1P₁ function was aided and cell differentiation was accelerated by inhibition of S1P₂. Based on the aforementioned findings, it is clear that S1P plays an important role in the regulation of osteoclast differentiation.

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Non-steroidal anti-inflammatory drugs (NSAIDs) are often prescribed for pain associated with tooth extraction or for inflammatory blockade. The efficacy of NSAIDs include not only analgesic and anti-inflammatory activity but also bone remodeling; for example, NSAIDs delay bone fracture healing in experimental models. NSAIDs inhibit two isozymes of cyclooxygenases (COX), COX-1 and COX-2. We discovered that a COX-1 inhibitor has more direct effectiveness on osteoclast activation than a COX-2 inhibitor. Osteoclasts were prepared from mouse hematopoietic stem cells to clarify the direct effect of NSAIDs on osteoclast differentiation and activation. Treated for 48-hours, COX-1 inhibitor (SC-560), non-selective NSAID (Diclofenac), and COX-2 inhibitor (SC-58125) significantly inhibits the number of tartrate-resistant acid phosphatase-positive cells. Levels of cathepsin K transcripts were almost down-regulated in osteoclasts treated with 10nM SC-560, Diclofenac, and SC-58125, respectively. Pit formation assay revealing the abolition of osteoclastic bone resorption showed a significant reduction with SC-560 and Diclofenac, while SC-58125 showed no inhibition. In this experiment, COX-1 inhibitor showed more efficacy on direct activation of osteoclasts than COX-2 inhibitor did.

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[in Japanese]

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[in Japanese]

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