Journal of Osaka Dental University
Online ISSN : 2189-6488
Print ISSN : 0475-2058
ISSN-L : 0475-2058
Volume 45, Issue 1
Displaying 1-17 of 17 articles from this issue
  • Muneyasu Shida, Masahiro Yoshida, Tadahiko Baba, Hirotaka Kon'i, ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 1-6
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We previously studied the effect of calcium hydroxide on the LPS-induced expression of hard tissue resorption-related genes in human osteoblastic cells (Saos-2), and reported that LPS-induced inflammatory cytokine expression and that the constant expression of RANKL was inhibited by calcium hydroxide. The objective of this study was to evaluate the effect of calcium hydroxide on the IL-1-induced expression of hard tissue resorption-related genes as a part of evaluation of the efficacy of calcium hydroxide for inflammatory hard tissue resorption. We used real-time reverse transcriptase-polymerase chain reaction to evaluate the effect of calcium hydroxide on the expression of genes of TNF-α, IL-6, OPG and RANKL synthesized by rhIL-1β-stimulated human osteoblast-like cells. The data were compared employing Student's t-test (n=6) with p<0.05 considered significant. Calcium hydroxide inhibited TNF-α and IL-6 gene expression in rhIL-1β-stimulated Saos-2, inhibited the enhancement of RANKL gene expression, and inhibited constant RANKL gene expression. Calcium hydroxide appeared to both resolve non-bacterial inflammation and inhibit hard tissue resorption.
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  • Yoshihito Tanaka, Osamu Takeuchi, Seiji Goda, Kazushi Yoshikawa, Kazuy ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 7-16
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We investigated the influence of the high-power GaAlAs semiconductor laser on dentin permeability and pulp cells. Sections of 1.0-3.0mm thicknesses were made from a human third molar. Each dentin disk was irradiated with the semiconductor laser and energy that penetrated through the dentin disk was measured by a laser power meter. The laser was applied in CW mode with 0.5-2.0W outputs. We found that the permeability was reduced as the thickness of the dentin increased. In another experiment, a healthy tooth extracted for orthodontic treatment was split to extract the pulp tissue. Irradiated cells were cultured at 37℃ under 5% CO_2, and increases in the number of cells after 24-72 hours were observed. These samples consisted of 25 experimental group samples that were irradiated for 15sec, 30sec, 1min, 3min, or 5min with an irradiation output of 0.5, 1, 2, 5 or 10W. A control group sample was not without irradiated. When the laser was applied to pulp cells, no influence on cell proliferation was noted at 1min, and a decrease in proliferation or death of cells was observed at 3min, with irradiation at 10W by the laser. These results suggest that maintaining appropriate irradiation energy and time based on tooth thickness is necessary when the high-energy semiconductor laser is used.
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  • Taro Kamono, Yueping Zhao, Koichiro Suzuki, Kazushi Yoshikawa, Kazuyo ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 17-23
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    Prior acid treatment of the coronal pulp chamber dentin to remove the smear layer and open dentinal tubules is a promising approach for enhancing the effect of walking bleaching. This in vitro study was conducted to estimate how acid treatment with 40% phosphoric acid and 3% EDTA on the pulpal dentin before walking bleaching effects the bond strength of the subsequent composite resin restorations. Specimens that had received phosphoric acid treatment showed marked demineralization at the fractured dentin surface compared to specimens that had received EDTA treatment or the control which had received no treatment. These results showed that when the pulp cavity is treated with 40% phosphoric acid prior to walking bleaching, there is a risk that the demineralized dentin compromises the bond to the subsequent composite resin restoration. We concluded that phosphoric acid of less than 40% can be recommended to open the dentinal tubules before walking bleaching and yet maintain a strong bond of the subsequent resin composite restoration.
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  • Hiroki Rensha, Seiko Miyao, Aki Nishiura, Emiko Nagaki, Yuki Nagata, N ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 25-30
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    The three-dimensional soft-tissue maxillofacial morphology of subjects with maxillary protrusion was compared with individuals having normal occlusion in order to evaluate the facial morphology of malocclusion subjects in three dimensions. The radius of curvature, with which characteristics of facial contours can be quantified in three dimensions, was used in this study. In order to create 3D facial data for each subject, a non-contact 3D laser scanner was used to expose 3D facial images of 12 subjects with maxillary protrusion and 26 subjects with individual normal occlusion. Four cross sections were extracted from the 3D facial data and the radius of curvature was calculated for five sections on each cross section. In order to compare facial soft-tissue morphology between maxillary protrusion and normal occlusion, the t-test was performed on 20 patterns of radius of curvature obtained by dividing the four cross sectional planes into five sections. We found that the central region of the anterior nasal spine and the lower lips of subjects with maxillary protrusion protruded more than in subjects with normal occlusion. This study revealed that maxillary protrusion created a very characteristic 3D soft-tissue morphology around the mouth. Hence it may be useful to consider this factor when making diagnoses or designing treatment plans in orthodontic treatment.
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  • Suguru Dateoka, Yuichi Ohnishi, Kenji Kakudo
    Article type: Article
    2011 Volume 45 Issue 1 Pages 31-36
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    CRM197, a mutated diphtheria toxin (DT), has been found in nontoxic proteins. Because it is non-toxic, this protein has been utilized for various purposes, including as an inhibitor of HB-EGF, which belongs to the EGF family, and has been implicated in the increased progression, proliferation, and metastasis of oral cancer. We analyzed the anti-tumor effects of CRM197 in oral cancer. Inhibitory agents against HB-EGF, such as CRM197, represent possible chemotherapeutic and chemosensitizing agents for oral cancer. In this experiment, we used the oral squamous cell carcinoma cell line HSC3, HSC4, and SAS. Cells treated with CRM197 were analyzed based on cell viability, MTT assay, Western blot, and zymography, following the manufacturers' instructions. Cell proliferation on treatment with CRM197 and/or CDDP was inhibited and apoptosis was observed. The invasiveness of CRM197-treated oral squamous cell carcinoma cells was relatively low. MMP-9 expression on reverse transcription polymerase chain reaction (RT-PCR) revealed that MMP-9 was suppressed in oral squamous cell carcinoma cells treated with CRM197. These results suggest that HB-EGF is a target for cancer therapy. We found that not only is CRM197 effective as a specific inhibitor of HB-EGF, but it also has a synergistic anti-tumor effect when combined with CDDP in oral cancer therapy.
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  • Daisuke Ehara, Akimichi Takemura, Fumihiko Suwa
    Article type: Article
    2011 Volume 45 Issue 1 Pages 37-53
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We analyzed histological changes during spontaneous healing in palatine mucosa lesions and examined whether there were any differences in healing between GK (diabetes group) and normal Wistar (control group) rats. Forty-three 8-week-old male rats (21 in each group) were used in this study. We created a cylindrical lesion 1.5mm in diameter in the palatine mucosa of the right maxillary first molar by removing all of the soft tissue. One Wistar rat was not given a lesion and was observed about normal histological structures. Immediately and one day after surgery, the experimental cavities of both groups were filled with blood clots. The mucosal epithelium converged on day 3 after surgery in the control group and on day 7 in the diabetes group. Granulation tissue was seen on day 5 in the control group and on day 7 in the diabetes group. Collagen fibers appeared on day 7 in the controls and on day 14 in the diabetes group. We observed the formation of sequestrum on days 14 and 28 in one of six rats in the control group and five of six in the diabetes group. Our results demonstrate that wound healing was delayed in the diabetes group compared with the controls. Furthermore, sequestrum formation occurred at a higher rate in the diabetes group.
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  • Tomomi Shibuya, Eiji Tanaka, Kazuya Takahashi, Yutaka Komasa
    Article type: Article
    2011 Volume 45 Issue 1 Pages 55-67
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    In clinical practice maxillary dentures are often designed to assume a form analogous to the patient's palatal morphology, with little attention paid as to how the design affects masticatory function. However, because many denture users are elderly, it is necessary to consider how age reduces masticatory function when designing the form of the palatal part of the denture. Denture morphology should be designed to facilitate the generation of the inner pressure needed for mastication. Therefore, we simultaneously measured the pressure in the oral cavity and the pharynx during mastication using three types of palatal bases. The palatal base was designed (1) with uniform base thickness, (2) with the base thick in the region anterior to the distal aspect of the bilateral maxillary canines, which emphasized contact with the lingual apex, or (3) with the base thick in the posterolateral region on both sides of the palate, which emphasized contact with the dorsal aspect of the tongue. The use of the latter base shortens the time needed for passage of the bolus through the oral cavity and pharynx. We also found that the pressure level and integrated pressure not only within the oral cavity but also in the middle pharynx can vary depending on the morphology of the base in the palatal region. These results suggest that when healthy individuals swallow water, the increase in contact pressure between the palate and the back of the tongue, which is dependant on base morphology, activates the muscles that coordinate with each other in swallowing. This in turn affects the pressure within the oral cavity and at the middle pharynx, as well as the time needed for passage through the oral cavity and pharynx.
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  • Yoshiaki Ono, Masataka Yoshioka, Eiji Tanaka, Takatsugu Asai, Naoto Ue ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 69-74
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    In order to investigate if it is possible to objectively assess gustatory sensation, which is one of the oral senses, we qualitatively analyzed pupillary responses using an infrared electronic pupillometer after stimulation with taste-testing preparations that elicit the taste sensations of sweet, sour, salty, and bitter. The Iriscorder^[○!R] C7364 (Hamamatsu Photonics, Shizuoka, Japan) was used to measure pupillary responses in 8 adult subjects. Taste discs^[○!R] (Sanwa Kagaku Kenkyusho, Nagoya, Japan) were used to stimulate the taste sensations of sweetness, sourness, saltiness, and bitterness. Water was used for no taste. Pupillary responses were measured before and after each taste stimulation, and the pupillary area and maximum pupillary contraction rate were analyzed. We found no significant difference in the maximum pupillary contraction rate, which is an index of parasympathetic activity, during any of the taste stimulations. However, the pupillary area, which is an index of sympathetic activity, showed significant increases on stimulations involving saltiness and bitterness. These results suggest the possibility of objectively assessing the sense of taste using an infrared electronic pupillometer.
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  • Masataka Yoshioka, Yoshiaki Ono, Eiji Tanaka, Kazufumi Iwayama, Yutaka ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 75-81
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We attempted to determine the optimal combination of stimulation and measurement method for the objective assessment of the sense of taste using pupillary responses. We examined the pupillary responses using an infrared electronic pupillometer when 7 adult subjects were exposed to the gustatory stimulation of bitterness. Comparisons were made between the measurement of pupillary light reflex and continuous measurement, between the filter paper disc method and whole mouth stimulation method, and between high-concentration stimulation and low-concentration stimulation. Differences in the amount of pupillary response were analyzed for each situation. We found that dispersion in the amount of pupillary response was less with whole mouth stimulation than with filter paper disc stimulation, and that it was significantly less with continuous measurement than with measurement by the pupillary light reflex. We consider a combination of continuous measurement and whole mouth stimulation optimal to assess the sense of taste using the pupillary response.
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  • Kohei Onda, Yoshinori Hatsuoka, Kazuyo Yamamoto
    Article type: Article
    2011 Volume 45 Issue 1 Pages 83-92
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    A vertically-fractured tooth may be restored by adhesion of the fractured fragments with resin cement. We did an in vitro investigation of the factors influencing the prognosis of restored vertically-fractured teeth. The two fragments of each tooth were bonded together with resin cement, and the micro-tensile bond strength was measured after trimming them to a dumbbell shape. A metal post was placed in the root canal of each tooth the force applied to the post that was necessary to fracture the tooth was measured. In another test, the two fragments of the fractured root were bonded together with resin cement, and either a metal or a resin post was placed in the canal. We then measured the force applied to the post that was necessary to break the bond of the adhered fragments. We found that when a fractured root is bonded with resin cement, the bond strength weakens as the cement layer becomes thicker. The methyl methacrylate (MMA) resins Super Bond C & B and Multi bond II acted as a buffer and prevented refracture when stress parallel with the tooth axis was exerted on the post. No difference was observed in the risk of refracture among post materials when they are not bonded to the tooth. The resistance of roots reconstructed by adhesion to stress parallel with the tooth axis less than 25% that of the intact root.
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  • Tadasuke Tanioka, Masahiro Tanaka, Takayoshi Kawazoe
    Article type: Article
    2011 Volume 45 Issue 1 Pages 93-101
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We investigated the relationship between temporomandibular disorders and the preferred chewing side (PCS) as evaluated by the deep temperature of the masseter muscle. The subjects were 12 adults with natural dentition, four males and eight females, with a mean age of 27±8 years. We used a deep body thermometer to measure the deep temperature of the masseter muscle after ten minutes of unilateral gum chewing. The subjects were then divided into two groups based on whether they had a preferred chewing side. The occlusal contacts and the presence or absence of temporomandibular disorders were compared for each group. We found that subjects with a PCS, as evaluated by the deep temperature of the masseter muscle, were at high risk of developing temporomandibular disorders.
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  • Takahisa Okawa, Masahiro Tanaka, Takayoshi Kawazoe
    Article type: Article
    2011 Volume 45 Issue 1 Pages 103-109
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We did an in vivo study of how the multifunctional vacuum tip and self-adhesive cement affected the bond strength between cement and core materials. A factorial design experiment was performed based on the design of experiments (DOE). As control factors, environmental conditions and types of cement were assigned to the inside cross table for full factorial design. As noise factors, insertion area 1, insertion area 2, subjects, clinical experience of the operators, and adherends were assigned to the outside cross table of the L9 orthogonal array. The bonding was done by two dentists on four teeth in two subjects under three operating environments using three different cements. The relative humidity in the mouth was measured at two locations under each operating environment. To compare humidity at different intraoral temperatures, the intraoral relative humidity was converted into the intraoral absolute humidity. Shear bond strength was analyzed using the signal-to-noise ratio. We found that the combination of a multifunctional vacuum tip and self-adhesive cement produced the best results. The multifunctional vacuum tip resulted in the lowest relative humidity. We concluded that the multifunctional vacuum tip and self-adhesive cement were useful in the bonding operation.
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  • Masataka Yoshioka, Yoshiaki Ono, Yutaka Komasa
    Article type: Article
    2011 Volume 45 Issue 1 Pages 111-119
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We attempted to obtain an index for evaluating oral senses by quantitatively analyzing pupil responses on taste stimulation. The subjects were 11 adults. For stimulation, the concentration of bitter-taste solution was adjusted, and the whole mouth stimulation method was employed. Pupil responses were serially measured and recorded before and after bitter-taste stimulation using an infrared electron pupillometer. The pupil response rate was employed as an analytical parameter. We examined the relationship between this parameter and the concentration. Variance analysis showed that the pupil response rate depended on the subject and concentration. Results of a multiple comparison test showed that concentrations without significant differences in the pupil response rate could be divided into 6 groups. A significant regression line was obtained on regression analysis. We concluded that the sense of taste could be quantitatively evaluated based on pupil responses. This suggests that measurement of pupil responses facilitates the assessment of oral senses.
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  • Yutetsu Akamine, Yuri Muroi, Ken Nakata, Kenji Kakudo
    Article type: Article
    2011 Volume 45 Issue 1 Pages 121-128
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    Excessive mechanical stress is thought to be a factor in the development of temporomandibular joint disorders (TMJD) through the expression of matrix metalloproteinases (MMPs) and related cytokines. Previously we examined the effects of cyclic compressive loading on matrix degradation of three-dimensional (3D) tissues containing human synovium-derived cells for one hour per day for 5 or 15 consecutive days. However, it is still unknown how the expressions of MMPs and inflammatory cytokine genes change after cyclic compression for only one hour. To investigate the biological response of synovial joints to mechanical loading, we quantitatively analyzed the expression of these genes after cyclic compressive load on human synovial cells in three-dimensional cultured tissue for one hour. Human synovial cells were seeded onto a collagen scaffold and then 20kPa or 40kPa of cyclic compressive load was applied for one hour. mRNA levels for catabolic genes were examined immediately after and 6 hours after compressive loading. The mRNA expression levels of IL-1β, IL-6, IL-8, MMP-1, MMP-3 and MMP-9 were significantly increased 6 hours after cyclic compression. These findings provide new insights into the pathomechanism of TMJD via increased expression of MMPs and related cytokines by mechanical loading.
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  • Muneyasu Shida, Tadahiko Baba, Yoichiro Taguchi, Tomoharu Okamura, Aki ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 129-133
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    An investigation of the interactions between neuropeptides and dental pulp cells is critical in elucidating the cellular mechanism of pulpitis. We investigated the effect of neuropeptide stimulation on the mRNA expressions of proinflammatory cytokines in human dental pulp cells. Human dental pulp cells (HDPC) were collected from first premolars extracted for orthodontic reasons. The HDPC were cultured in 10% FBS-containing Dulbecco's Modified Eagle's Medium (DMEM) to subconfluence. Third-passage cells were used for the experiment. Substance P (SP) and calcitonin gene-related peptide (CGRP) were used as neuropeptides. The mRNA expression of the proinflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α were quantified at 6 and 24 hours. In HDPC, the neuropeptides increased the mRNA expression of only IL-8 among the proinflammatory cytokines. At six hours after stimulation, the IL-8 mRNA expression of the SP 10^<-5>M, SP 10^<-4>M, and CGRP 10^<-6>M groups were significantly different from that of the negative control (p<0.05). The IL-8 mRNA expression of the SP 10^<-4>M+CGRP 10^<-6>M group was significantly increased (p<0.05). However, no synergistic effect was noted. Regarding the effect of neuropeptides on the dental pulp, the IL-8 mRNA expression induced localized neutrophil infiltration.
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  • Satoshi Sanda, Daigo Sakai, Rachel Waddington, Yutaka Komasa, Joji Oka ...
    Article type: Article
    2011 Volume 45 Issue 1 Pages 135-141
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    We investigated the potential of the osteoconductive material β-tricalcium phosphate to promote bone healing when coated on a titanium alloy screw implanted in the mandibular tooth socket of a healthy rat. Forty-eight 9-week-old male Wistar rats were divided into three groups: the Blast group, which received blast-treated screws; the βTCP group, which received β-tricalcium phosphate-coated screws; and the Control group, which received mechanically polished screws. Mandibles were removed at 3 or 9 weeks after screw implantation. Screw removal torques were measured using a handheld torque gauge and compared. At both 3 and 9 weeks after implantation, the screw removal torques were significantly greater in the βTCP group than in the Blast and Control groups (p<0.05). Removal torques did not differ significantly between the Blast and Control groups at either time point. These results suggest that a β-tricalcium phosphate coating on screws accelerates osseous healing around the screw and increases the retentive capacity of the screw. A β-tricalcium phosphate-coated implant fitted into the tooth socket immediately after extraction may therefore provide a favorable environment for early loading of implants.
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  • Masanori Nagame, Yutaka Komasa, Kazutoshi Kakimoto
    Article type: Article
    2011 Volume 45 Issue 1 Pages 143-150
    Published: 2011
    Released on J-STAGE: January 02, 2017
    JOURNAL FREE ACCESS
    The necessity of safe casting with the use of low-biotoxic materials has increased since the carcinogenicity of ceramic fibers was reported. We evaluated the use of noncarcinogenic biosoluble fibers as ring liners for dental casting. We previously used plate-like biosoluble fibers as ring liners, adjusted the amount of setting expansion to that of commercially available ring liners and performed a tension test, scanning electronic microscopic observation, element analysis employing energy dispersive X-ray spectroscopy (EDX), and crystal structure analysis using X-ray diffraction. In this study, we performed a compression test of the ring liner, measurement of the thermal expansion of investing materials, and a fitness tested the fit of the cast crowns for clinical application. The amount of displacement of the experimentally-produced ring liner was lower than that of a commercially available ring liner, showing that the buffering ability was slightly greater with the commercially available liner. However, the thermal expansion of the investing materials were similar. The fit of cast crowns produced using the biosoluble fibers was better than that of cast crowns produced using a commercially available ring liner. Therefore, we concluded that the ring liner of biosoluble fibers was acceptable for clinical application.
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