Hideaki Suda

Tokyo Medical and Dental University, Edo, Tōkyō, Japan

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Publications (201)312.25 Total impact

  • Jie Gu, Hideharu Ikeda, Hideaki Suda
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    ABSTRACT: Beta-2 adrenergic receptor has been found within the osteoblast membrane meditating bone remodeling. Propranolol is a sympatholytic beta antagonist commonly used as long-term medication for the management of many common diseases such as hypertension. This study was performed to verify the presence of this receptor on odontoblasts in rats and, if present, to investigate its possible association with tertiary dentinogenesis. Twenty male Sprague-Dawley rats (9 weeks old) were randomly assigned to 4 groups: CP0.8 group, cavity preparation + propranolol treatment (0.8 mg/day, n = 5); CP4 group, cavity preparation + propranolol treatment (4.0 mg/day, n = 7); CON group, cavity preparation + saline treatment (0.2 mL/day, n = 5); and NT group, no treatment (n = 3). Cavity preparation was performed on the mesial aspect of the maxillary first molars bilaterally. After 2 weeks, the tertiary dentinogenesis (CP0.8, CP4, and CON) was examined by hematoxylin-eosin staining, and the localization of beta-2 adrenergic receptor (NT) was examined by immunohistochemistry. The beta-2 adrenergic receptor immunoreactivity was observed in the odontoblastic layer in normal rat molar dental pulp. The tertiary dentinogenesis beneath the prepared cavity was significantly higher in the rats receiving 2-week systemic administration of propranolol than in those without the propranolol treatment. The higher-dose treatment of propranolol (P < .001) presented more effective up-regulation of tertiary dentinogenesis than the lower-dose treatment (P < .01). These results indicate that the sympathetic nervous system decreases tertiary dentin formation via beta-2 adrenergic receptors located on rat odontoblasts. It suggests that adrenergic beta antagonist is expected to use in the treatment of inducing tertiary dentin formation to protect dental pulp. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
    Journal of Endodontics 02/2015; DOI:10.1016/j.joen.2015.01.010 · 2.79 Impact Factor
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    ABSTRACT: AimTo determine the root surface strain (RSS) generated during root canal shaping and its effects on apical microcrack development.MethodologyTwenty-five extracted human mandibular premolars were selected and decoronated. The teeth were instrumented with either the ProTaper (PT) or WaveOne (WO) (Dentsply Maillefer) NiTi rotary systems (n=10 per group) or used as controls (n=5). Instrumented root canals were enlarged to ProTaper F4 (size 40, 0.06 taper) or using WaveOne LARGE (size 40, 0.08 taper) instruments according to the manufacturer's instructions.An electrical strain gage (KFG02-120-C1-16, Kyowa Dengyo, Tokyo, Japan) was fixed on the proximal root surface and connected to a strain amplifier via a bridge-box in order to measure RSS. During canal shaping, the strain output of the amplifier was recorded. The instantaneous RSS induced by each instrument and the maximum RSSs were determined. All teeth were then stained with contrast media and imaged with micro-computed tomography (micro-CT) at an isotropic resolution of 10 μm to detect microcracks. The mean maximum RSS values (microstrain) and mean number of microcracks recorded for both groups were tested for statistical significance using Mann–Whitney U test. Presence/absence of microcracks in both groups was compared by chi-square test.ResultsIncreased baseline RSS from strain accumulation during canal shaping was observed, with similar maximum RSS (mean ± S. D.) for PT (416.6 ± 185.1 μstrain) and WO (398.2 ± 163.8 μstrain) (P=0.94).. The inter-evaluator reliability for microcrack detection using micro-CT had a kappa value of 0.998. Compared to the PT group, there was a trend for fewer samples with microcracks in the WO group (P=0.051). On the micro-CT images, apical microcracks were detected in 20 PT and 11 WO samples (P=0.10). The microcracks were observed in the buccolingual direction in all WO and 81% of PT samples. No vertical root fractures were found. The maximum RSS obtained during canal shaping was poorly correlated with the number of microcracks found (R2=0.093).Conclusions Based on these preliminary data, canal shaping appears to cause apical microcracks regardless of the type of rotary instrument motion. Contrast-enhanced micro-CT was able to identify microcracks in roots.This article is protected by copyright. All rights reserved.
    International Endodontic Journal 11/2014; DOI:10.1111/iej.12406 · 2.27 Impact Factor
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    ABSTRACT: Introduction The purpose of this study was to investigate the ability of swept-source optical coherence tomographic (SS-OCT) imaging to detect a second mesiobuccal canal (MB2) in maxillary molars compared with visual inspection (VI) and dental operating microscopy (DOM). Methods Forty extracted human maxillary molars were examined. After the removal of half the crown and access cavity preparation, the existence of MB2 canals was confirmed based on cross-sectional images of each tooth obtained by micro–computed tomographic scanning as the reference standard. Then, the pulp chamber floor was scanned by SS-OCT imaging. Three dentists independently evaluated the SS-OCT images and the pulp chamber floor under VI and DOM for the presence of MB2 canals. The detection rate of MB2 canals for SS-OCT imaging, VI, and DOM was calculated, and statistical analysis was performed. Results MB2 canals existed in 19 of 40 teeth (47.5%) using micro-CT imaging. Sensitivity of DOM (0.947) was significantly higher than that of SS-OCT imaging (0.632). Specificity of SS-OCT imaging (0.714) was significantly higher than that of DOM (0.333). No statistically significant differences were found for accuracy among the 3 methods. Kappa values of SS-OCT, VI, and DOM were 0.526, 0.417, and 0.326, respectively. Conclusions SS-OCT imaging is noninvasive, involves no ionizing radiation, and is accurate for the detection of MB2 canals.
    Journal of Endodontics 09/2014; DOI:10.1016/j.joen.2014.07.012 · 2.79 Impact Factor
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    ABSTRACT: Objectives: The purpose of this study was to evaluate the accuracy of diagnosing vertical root fractures (VRFs) by comparing the volume of bone defects in VRFs with those in non-VRFs on reconstructed three-dimensional (3D) models (TDMs) using cone-beam CT (CBCT). Methods: Thirty-two maxillary premolars and anterior teeth with radiolucent areas were evaluated on pre-operative CBCT images. Of the 32 teeth, 16 had a fractured root (VRF group) and 16 had a non-fractured root (non-VRF group). The radiolucent area of each tooth was traced in each dimension [mesio-distal, bucco-lingual and horizontal (the apico-incisal aspect)] by two observers, and 3D images were reconstructed with Amira software. The volume, "V", of the TDM was divided into the coronal side and the periapical side at the horizontal slice through the apical foramen, and "v" was defined as the volume of the coronal side. Values of v/V were calculated for all cases. The Mann-Whitney U-test was used to compare values between the VRF group and the non-VRF group (P < 0.05). A receiver operating characteristic (ROC) curve was constructed to select the optimal cut-point. Results: There was a statistically significant difference in the value of v/V between the two groups (P < 0.05). With a cut-point derived from the ROC curve, the sensitivity, specificity and accuracy of predicting VRF were 1.00, 0.75 and 0.88, respectively. Conclusions: Lesions resulting from VRFs can be distinguished from those of non-VRFs on 3D CBCT images with a high degree of accuracy, based on their different 3D shapes.
    Dento-maxillo-facial radiology. Supplement 09/2014; 43(8):20140256. DOI:10.1259/dmfr.20140256
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    ABSTRACT: Introduction Matrix metalloproteinase (MMP)-3 is a member of the MMP family that degrades the extracellular matrix. Application of MMP-3 to injured pulp tissue induces angiogenesis and wound healing, but its anti-inflammatory effects are still unclear. Here, we evaluated the anti-inflammatory functions of MMP-3 in vitro and in vivo. Methods Nitric oxide and inflammatory mediator synthesis in macrophages activated by lipopolysaccharide (LPS) was measured in the presence or absence of MMP-3. The mouse Mmp3 (mMmp3) expression vector containing full length cDNA sequence of mMmp3 or cDNA sequence of mMmp3 missing the signal peptide and pro-peptide regions was transfected to RAW264, a mouse macrophage cell line, and NO synthesis and inflammatory mediator expression were evaluated. Pulpal inflammation was histologically and immunohistochemically evaluated in a rat model of incisor pulpitis induced by the application of LPS for 9 hours in the presence or absence of MMP-3. Results NO and pro-inflammatory mediator synthesis promoted by LPS was significantly down-regulated by MMP-3 in vitro. The full length of mMmp3 down-regulated the LPS-induced NO synthesis and chemical mediator mRNA expression, however the mMmp3 missing the signal peptide failed to block the NO synthesis induced by LPS. The numbers of major histocompatibility complex class II+ and CD68+ cells, which infiltrated into the rat incisor pulp tissues in response to the topical application of LPS, were significantly decreased by the application of MMP-3 in vivo. Conclusions These results indicate that MMP-3 possesses anti-inflammatory functions, suggesting its potential utility as an anti-inflammatory agent for pulpal inflammation.
    Journal of Endodontics 09/2014; DOI:10.1016/j.joen.2014.04.001 · 2.79 Impact Factor
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    ABSTRACT: The effects of cyclic fatigue on bending properties of NiTi endodontic instruments were investigated. Sixteen Profiles(®) were divided into two groups (A, and B). The sequence of cantilever bending test and cyclic fatigue test was alternated repeatedly until file separation occurred. In the cyclic fatigue test, the instrument curvature was 19° in group A and 38° in group B. Fractographic examination was performed to determine fracture patterns. In group A, there were significant differences between the bending load values measured before the cyclic fatigue test and the last cantilever bending test before instrument fracture at each deflection (p<0.05). Fractographic examination showed the specific patterns of cyclic fatigue fracture. The stress required to induce martensitic transformation might be reduced due to the softening behavior caused by the cyclic fatigue under the relaxation condition of the superelasticity range (group A). The SEM images were able to display specific patterns indicating cyclic fatigue fracture.
    Dental Materials Journal 08/2014; 33(4):539-44. DOI:10.4012/dmj.2013-318 · 0.81 Impact Factor
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    ABSTRACT: This study aimed to evaluate effects of torsional loading on the mechanical properties of endodontic instruments using the nanoindentation technique. ProFile (PF; size 30, taper 04; Dentsply Maillefer, Switzerland) and stainless steel (SS; size 30, taper 02; Mani, Japan) instruments were subjected to torsional test. Nanoindentation was then performed adjacent to the edge of fracture (edge) and at the cutting part beside the shank (shank). Hardness and elastic modulus were measured under 100-mN force on 100 locations at each region, and compared to those obtained from the same regions on new instruments. It showed that PF and SS instruments failed at 559 ± 67 and 596 ± 73 rotation degrees and mean maximum torque of 0.90 ± 0.07 and 0.99 ± 0.05 N-cm, respectively. Hardness and elastic modulus ranged 4.8-6.7 and 118-339 GPa in SS, and 2.7-3.2 and 52-81 GPa in PF. Significant differences between torsion-fractured and new instruments in hardness and elastic modulus were detected in the SS system used. While in PF system, the edge region after torsional fracture had significantly lower hardness and elastic modulus compared to new instruments. The local hardness and modulus of elasticity of endodontic instruments adjacent to the fracture edge are significantly reduced by torsional loading. SCANNING 9999:1-7, 2014. © 2014 Wiley Periodicals, Inc.
    Scanning 07/2014; 36(4). DOI:10.1002/sca.21139 · 1.29 Impact Factor
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    ABSTRACT: Objective: The purpose of this study was to measure strain generated during root canal shaping and its effect on apical microcrack development. Method: 25 mandibular premolars were selected and decoronated. Roots were distributed into 2 groups of 10 teeth according to the NiTi rotary systems used (ProTaper (PT) and WaveOne (WO), Dentsply Maillefer, Ballaigues, Switzerland) and control group of 5 teeth. During canal shaping, the root surface strain and the effective shaping time were recorded. After canal shaping, roots were stained and microCT imaged (InspeXio SMX-100CT, Shimadzu, Kyoto, Japan) to detect microcracks. Result: A rise in the strain baseline by strain accumulation during canal shaping was observed in PT and WO, with mean maximum strains of 416.6±185.1 and 398.2±163.8 µstrain, respectively (P =.94). The shaping time was significantly less for WO compared to PT, with 31.6 ± 5.5 and 63.7 ± 6.5 seconds, respectively (P = .00). The inter-evaluator reliability for microcrack evaluation was found to be Kappa = .998 (P < .001). Less but insignificant number of samples having microcracks in WO group (5 samples), compared to PT group (9 samples) (P =.051), and mean number of microcracks of 1.1 and 2, respectively (P = .10). Microcracks were observed in buccolingual direction in all samples of WO and 81% of PT. The maximum strain obtained during canal shaping showed poor correlation with the number of microcracks produced (R2=0.093). Conclusion : Regardless of the type of rotary instrument motion, the lateral forces produced by the instrument during canal shaping could cause apical microcracks. The unanimous agreement among the evaluators guarantees the usefulness of µCT with staining.
    IADR General Session and Exhibition 2014; 06/2014
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    ABSTRACT: Abstract Objective: The study aimed to evaluate the ability of optical coherence tomography (OCT) to guide and identify pulp exposure using an erbium: yttrium-aluminum-garnet (Er:YAG) laser. Background data: The Er:YAG laser has been proven to be effective in ablating dental hard tissue and offers advantages, as there is none of the vibration and noise you get with conventional methods, but it has limitations in relation to the tactile feedback that would aid in identification of entry into the pulp chamber. Based on depth-resolved optical reflectivity, OCT technology has been developed to provide high-resolution, cross-sectional images of the internal structure of biological tissues. Materials and methods: The pulp chambers of 20 human mandibular incisors were examined, and the average thickness of hard tissue covering the pulp chamber was assessed using micro-computed tomography (micro-CT) images. An Er:YAG laser was used to gradually penetrate the hard tissue over the pulp chamber under microscopic guidance. The preparation was constantly imaged using a swept-source OCT at 10 sec intervals until a pulp chamber exposure was identified using the technology. The pulp exposure was re-examined under the microscope and compared with micro-CT images for verification. Results: The pulp exposures of 20 incisors were all verified microscopically and with micro-CT images. The thickness of hard tissue penetrated by the laser ranged from 0.44 to 1.69 mm. Conclusions: Swept-source OCT is a useful tool for identifying pulp exposure during access opening with the Er: YAG laser.
    Photomedicine and Laser Surgery 06/2014; 32(6):356-359. DOI:10.1089/pho.2013.3688 · 1.58 Impact Factor
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    ABSTRACT: Objective: New instruments, such as WaveOne™ (Dentsply Maillefer, Switzerland) made of M-Wire, claim to be able to completely shape canals with only one instrument in a special reciprocal motion. However, little has been reported about the mechanical properties of this new instrument. The aim of this study was to evaluate the centering ability and bending property of WaveOne™Primary reciprocating files. Method: Plastic S-shaped canal models (Endo Training Bloc-S; Dentsply Maillefer) were shaped by the same operator using WaveOne™Primary files with reciprocal motion (Group 1) and ProTaper™ Universal (SX/S1/S2/F1/F2; Dentsply Maillefer) files according to the manufacturer’s instructions (Group 2), respectively (n=7 each). Cross-sectional canal model images before and after the shaping were taken by a digital microscope (VH-8000, Keyence, Japan) and superimposed to assess the centering ability of the files. The centering ratio, ranging from 0(best) to 1(worst), was determined at the first-curvature, the second-curvature, and the apical-portion. For the bending property, the bending loads of WaveOne™ Primary (Group 1) and ProTaper™ Universal F2 (Group 2) files, at 0.5 mm and 2.0 mm deflections during the loading process, were evaluated by our cantilever bending test. Result: Centering ratios (Mean±S.D.) were summarized in Table 1. The centering ratio of Group 1 was significantly better (lower value) than that of Group 2 at the apical portion (P<0.05). The bending load values (Mean(N)±S.D.) were summarized in Table 2. The bending load values of Group 1 were significantly lower than those of Group 2 (P<0.05). Table 1 First-curvature Second-curvature Apical-portion Group 1 0.32±0.13 0.34±0.10 0.38±0.07* Group 2 0.46±0.14 0.45±0.09 0.61±0.08 Table 2 0.5 mm-deflection 2.0 mm-deflection Group 1 1.54±0.24* 4.80±0.24* Group 2 2.87±0.16 6.20±0.46 Conclusion: WaveOne™Primary files had a good centering ability at the apical portion, possibly due to their better bending property than the ProTaper™ Universal F2 files.
    AADR Annual Meeting & Exhibition 2014; 03/2014
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    ABSTRACT: The dental pulp tissue is encased in hard tissue and surrounded by hard tissue-forming cells, but remains in a non-mineralized state itself, suggesting the presence of regulatory mechanisms precluding pulp mineralization. This study aimed to reveal the regulatory function of periostin (Postn), which is essential for osteoblast differentiation, for odontoblast differentiation/mineralization. We evaluated the effects of Postn overexpression and RNAi-mediated suppression in mouse dental papilla cells (MDPs) on the expression of odontoblastic markers and Notch signaling molecules, and on the formation of mineralized nodules. Localization of Postn in the dental pulp tissue of normal and cavity-prepared molars was observed immunohistologically. Enforced overexpression of Postn in MDPs induced down-regulation of odontoblastic markers and in vitro mineralization. Conversely, silencing of Postn mRNA in MDPs induced up-regulation of odontoblastic markers and ALP activity. Up- and down-regulation of Postn caused increased and decreased expression, respectively, of Notch signaling molecules. Postn expression was minimal in normal dental pulp, but was rapidly and globally increased in the whole pulp tissue of molar teeth at 1 day after cavity preparation, decreasing thereafter. These results indicate that Postn may be a negative regulator of odontoblast differentiation/mineralization, and that may exert its actions via Notch signals.
    Odontology 03/2014; DOI:10.1007/s10266-014-0152-7 · 1.35 Impact Factor
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    ABSTRACT: Three-dimensional (3D) spheroid culture is a method for creating 3D aggregations of cells and their extracellular matrix without a scaffold mimicking the actual tissues. The aim of this study was to evaluate the effects of 3D spheroid culture on the phenotype of immortalized mouse dental papilla cells (MDPs) that have the ability to differentiate into odontoblasts. We cultured MDPs for 1, 3, 7, and 14 days in 96-well low-attachment culture plates for 3D spheroid culture or flat-bottomed plates for two-dimensional (2D) monolayer culture. Cell proliferation and apoptosis were detected by immunohistochemical staining of Ki67 and cleaved caspase-3, respectively. Hypoxia was measured by the hypoxia probe LOX-1. Odonto/osteoblastic differentiation marker gene expression was evaluated by quantitative PCR. We also determined mineralized nodule formation, alkaline phosphatase (ALP) activity, and dentine matrix protein-1 (DMP1) expression. Vinculin and integrin signalling-related proteins were detected immunohistochemically. Odonto/osteoblastic marker gene expression and mineralized nodule formation were significantly up-regulated in 3D spheroid-cultured MDPs compared with those in 2D monolayer-cultured MDPs (p<0.05). Histologically, 3D spheroid colonies consisted of two compartments: a cell-dense peripheral zone and cell-sparse core zone. Proliferating cells with high ALP activity and DMP1 expression were found mainly in the peripheral zone that also showed strong expression of vinculin and integrin signalling-related proteins. In contrast, apoptotic and hypoxic cells were detected in the core zone. 3D spheroid culture promotes odonto/osteoblastic differentiation of MDPs, which may be mediated by integrin signalling.
    Archives of oral biology 03/2014; 59(3):310-7. DOI:10.1016/j.archoralbio.2013.12.006 · 1.65 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the influence of heat treatment on the mechanical properties of Ni-Ti file materials. Ni-Ti wire (1.00 mm ø) was processed into a conical shape with 0.30-mm diameter tip and 0.06 taper. Specimens were heated for 30 min at 300, 400, 450, 500 or 600°C. Non-heated specimens were used as controls. DSC, a cantilever-bending test and cyclic fatigue test were performed. Ms and Af for groups 400 and 450 were higher than those for others (p<0.05). The load/deflection ratios of groups 400, 450 and 500 were lower than that of group 600 (p<0.05). The bending load values at 2.0-mm deflection of groups 400, 450 and 500 were lower than those of group 300 and the control group (p<0.05). The NCFs of groups 400, 450 and 500 exceeded that of group 600(p<0.05). Changes in flexibility with heat treatment could improve the cyclic fatigue properties of Ni-Ti instruments.
    Dental Materials Journal 02/2014; 33(1):27-31. DOI:10.4012/dmj.2013-196 · 0.81 Impact Factor
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    ABSTRACT: Th17-related cytokines are essential factors in various pathological states, including inflammatory bone destruction. This study investigated the contribution of Th17-related cytokines to the progress of experimentally induced rat periapical lesions. Periapical pathoses were induced by unsealed exposure of the pulp chamber of the lower first molars. A variety of immunocompetent cells, including CD68(+) macrophages, Ia antigen(+) cells and TCRαβ(+) T cells, were observed in the lesions. The expression levels of Th17-related cytokines, IL-17 and IL-23, and of pro-inflammatory cytokines, IL-1β and IL-6, were significantly increased at 14 days (expansion stage) compared with normal periapical tissues. The expression levels of Foxp3, a regulatory T cell (Treg)-related gene, and of IL-10, an anti-inflammatory cytokine, were higher at 28 days (chronic stage) than at 14 days. These findings suggest that Th17-related cytokines may be primary contributors to the initiation of periapical bone destruction, and that lesion expansion may be regulated by anti-inflammatory mediators.
    Australian Endodontic Journal 12/2013; 39(3):164-70. DOI:10.1111/j.1747-4477.2012.00371.x · 0.74 Impact Factor
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    ABSTRACT: Nickel-titanium files often separate because of mechanical fatigue. The purpose of this study was to determine safe preparation techniques for separated file removal by using ultrasonics. Fifty nickel-titanium file fragments were divided into 5 groups. An ultrasonic tip was activated on a file fragment positioned between dentin blocks simulating several canal conditions: Group 1 consisted of the fragment protruding from a pair of straight dentin blocks. For group 2, the fragment was also positioned between 2 straight dentin blocks except one block was positioned 1 mm more apically than the other block, simulating a troughed area that is often created during file removal attempts. For groups 3-5, the fragment was positioned similarly as group 2 but between blocks with 30°, 45°, and 60° curvatures, respectively. The time it took for secondary fracture to occur was recorded, and the data were statistically analyzed. Fragments with dentin wall supporting on the opposite side of ultrasonic activation site resisted fracture significantly longer than those without it. Fragments in 30° and 45° curved blocks took significantly longer to fracture than the other groups (Fisher protected least significant difference, P < .05). Secondary fracture of separated files appeared to be reduced when the ultrasonic tip was applied to the inner curvature of the canal.
    Journal of endodontics 10/2013; 39(10):1300-5. DOI:10.1016/j.joen.2013.06.021 · 2.95 Impact Factor
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    ABSTRACT: Congenital anomalies of wingless-type mouse mammary tumor virus (MMTV) integration site family (Wnt) are frequently accompanied with tooth and dentin abnormality. The aim of this study was to investigate the effects of Wnt signaling on odontoblast differentiation of mouse dental papilla cells (MDPs). Mouse dental papilla cells were cultured in α-modified minimum essential medium containing 10% fetal bovine serum and antibiotics. Odontoblast differentiation was induced by bone morphogenic protein 2 (BMP2), and the expression of odontoblast-specific markers and Wnt-related signaling molecules was analyzed by real-time reverse transcription-polymerase chain reaction and immunohistochemistry. Odontoblast differentiation was evaluated by dentin sialophosphoprotein (Dspp) and dentin matrix protein (DMP) 1 expression. Localization of β-catenin in MDPs was detected by immunocytochemistry using an anti-β-catenin antibody. Dspp expression in MDPs was upregulated in the presence of BMP2. Wnt5a, Wnt11, Lef1 and Tcf4 expression was upregulated in BMP2-treated MDPs. Wnt11 expression was detected in rat dental pulp in vivo, and particularly strong expression of Wnt11 was detected in odontoblasts. Enhanced Dspp and DMP1 expression and alkaline phosphatase activity induced by BMP2 were completely negated by the Wnt antagonist: IWR-1-endo treatment. Nuclear translocation of β-catenin observed in BMP2-treated MDPs was also negated by IWR-1-endo treatment. These results indicate that Wnt signaling upregulates odontoblast marker expression in MDPs, suggesting a promoting effect of Wnt signaling on odontoblast differentiation.
    Congenital Anomalies 09/2013; 53(3):101-8. DOI:10.1111/cga.12011
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    ABSTRACT: Objective: We have reported that the signal of dental pulp inflammation induces the activation of both neuronal and glial cells, such as astrocytes in the rat central nervous system. To further understand the pulp injury-induced glial cell/neuronal interaction, we made pulp exposure injuries with or without local anesthetic pretreatment and examined thalamic expression of (1) glial fibrillary acidic protein (GFAP) and vimentin, which are intermediate filament proteins required for astrocyte activation; and (2) class II major histocompatibility complex (MHC) molecules, which are upregulated in activated glial cells under stressed condition. Method: A local anesthetic (lidocaine with epinephrine, AstraZeneca) or saline was injected into the tissue surrounding the mandibular left first molar of Wistar rats (n = 16). The tooth was then pulp-exposed, and the cavity was sealed with flowable composite (UniFill FlowAGC). After 0 h (normal pulp with local anesthetic or saline pretreatment) and 72 h, the contralateral thalamus (n = 4, in each experimental group) was retrieved and subjected to immunohistochemistry for GFAP, and real-time PCR analysis for GFAF, vimentin and class II MHC mRNAs. Result: The density of GFAP+ astrocytes showed a significant increase only in the saline-pretreated animals at 72 h. Expression levels of GFAF, vimentin and class II MHC mRNAs in the local anesthetic-pretreated animals were significantly lower than those in the saline-pretreated animals at 72 h. Conclusion: Inhibition of noticeptive signal from the injured pulp by the local anesthetic pretreatment suppressed the expression of glial cell activation markers in the thalamus.
    IADR Asia/Pacific Region (APR) Regional Meeting and Co-Annual Scientific Meeting of IADR Divisions 2013; 08/2013
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    ABSTRACT: Objective: To investigate pressure generated outside the apical foramen by laser-activated irrigation (LAI) with Er:YAG laser, passive ultrasonic irrigation (PUI), and conventional irrigation (CI). Method: Plastic root canal models shaped to a working length of 20 mm with apical size #40 and 0.06 taper were used. They were assigned into three groups: Group 1 (LAI): 6% NaClO solution was activated by Er:YAG laser (Erwin AdvErL, Morita, Japan, 70 mJ 10 pps) with a cone-shaped tip (R200T, Morita, φ= 200 μm) positioned 2 mm short of the working length for 20 seconds. Group 2 (PUI): PUI was performed for 20 seconds with an ultrasonic file (#20 U-file, SHOFU, Japan) driven by an ultrasonic device (Piezon Master 400, EMS, Switzerland, highest power setting).Group 3 (CI): hand irrigation with 3 ml of 6% NaClO solution was performed with a 27 gauge conventional flat needle (Nipro needle and syringe, Nipro, Japan) positioned 2 mm short of the working length. The mean maximum pressure caused by the irrigation was measured by a pressure sensor (AP-12S, Keyence, Japan) connected via a plastic tube to the model. Data were analyzed by using one-way ANOVA and Tukey-Kramer test at a significance level of p=0.05. Result: The mean maximum pressure caused by LAI and PUI was significantly lower than that by CI (p<0.05), and that by PUI was also significantly lower than that by LAI (p<0.05). In most of the measurements of PUI, negative values were recorded. Conclusion: Under the conditions of this preliminary study, pulsed Er:YAG laser did create irrigation pressure. Although it was smaller than that by the conventional irrigation method, the potential of fluid extrusion from the apical foramen should be considered in LAI.
    IADR Asia/Pacific Region (APR) Regional Meeting and Co-Annual Scientific Meeting of IADR Divisions 2013; 08/2013
  • Ying Li, Hideharu Ikeda, Hideaki Suda
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    ABSTRACT: OBJECTIVES: The size of the functional space available for hydrodynamic fluid movement between cellular components and the walls of dentinal tubules has not yet been investigated. We attempted to measure the space using small diameter fluorescent microspheres. METHODS: The coronal enamel of 144 rat molars was removed to expose the dentine, which was acid-etched. Fluorescent microspheres of different diameters (0.02-4.0μm) were applied to the exposed dentine for 60min before the rat jaws were cut into cryostat sections. The distribution and fluorescent intensities of the fluorescent microspheres were examined with confocal laser scanning microscope and analyzed using image analysis software. RESULTS: Microspheres with a diameter of 2.0-4.0μm were detected only on the surface of the cavities. A small number of microspheres with a diameter of 1.0μm accumulated primarily in the outer third of the dentine. Microspheres with a diameter of 0.2-0.5μm were found in the outer and middle thirds of the dentine. Microspheres with a diameter of 0.02-0.1μm accumulated in the middle and occasionally inner thirds of the dentine. Some of the microspheres measuring 0.02-0.04μm in diameter reached the dental pulp. CONCLUSIONS: The dentinal tubules in the inner third of the rat coronal dentine may have a space less than 0.1μm through which dentinal fluid can move, despite outward tapering of the dentinal tubules. Retrograde tapering may increase the pressure in the inner third of the dentine layer, and this elevated pressure may contribute to mechanical deformation of the content in the dentinal tubules.
    Archives of oral biology 07/2013; 58(7):780-787. DOI:10.1016/j.archoralbio.2013.01.007 · 1.65 Impact Factor
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    ABSTRACT: We have recently reported that the signal of pulp injury induces both neuronal and glial cell activation in the contralateral thalamus in rats, although the mechanisms of the glial cell/neuronal interaction remain unclear. This study was undertaken to test our hypothesis that p38 mitogen-activated protein kinase (MAPK) signaling pathways are involved in the pulp injury-induced glial cell/neuronal interaction in the thalamus. A local anesthetic (lidocaine with epinephrine) or saline (control) was injected into the tissue surrounding the left mandibular first molar of Wistar rats. The tooth was then pulp-exposed, and the cavity was sealed with flowable composite. After 0 (normal pulp with local anesthetic or saline pretreatment), 24, and 72 hours, the contralateral side of thalamus was retrieved and subjected to immunohistochemistry for phospho-p38 MAPK and glial fibrillary acidic protein and real-time polymerase chain reaction analysis of p38-MAPK family (MAPK 13 and MAPK 14) mRNAs. The area immunopositive to phospho-p38 MAPK increased until 72 hours after pulp exposure in both local anesthetic-pretreated and saline-pretreated animals, but the rate of increase was lower in the local anesthetic-pretreated animals. The density of glial fibrillary acidic protein-expressing astrocytes showed a significant increase only in the saline-pretreated animals. Expression levels of MAPK 13 and MAPK 14 mRNAs increased at 24 hours and still higher at 72 hours in the saline-pretreated animals. Notably, MAPK 13 and MAPK 14 mRNA levels at 24 and 72 hours in the local anesthetic-pretreated animals showed significantly lower levels than those in the saline-pretreated animals. It was concluded that pulp injury-induced up-regulation of MAPK 13, MAPK 14, and phospho-p38 MAPK in the thalamus was suppressed by the local anesthetic pretreatment, suggesting the involvement of p38 MAPK signaling pathways in the glial cell-neuronal interaction induced by pulpal nociception.
    Journal of endodontics 04/2013; 39(4):488-92. DOI:10.1016/j.joen.2012.11.018 · 2.95 Impact Factor

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2k Citations
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  • 1991–2015
    • Tokyo Medical and Dental University
      • • Division of Oral Health Sciences
      • • Graduate School of Medical and Dental Sciences
      • • Department of Restorative Sciences
      • • Faculty of Dentistry
      Edo, Tōkyō, Japan
  • 2011
    • Niigata University
      • Division of Cariology, Operative Dentistry and Endodontics
      Niahi-niigata, Niigata, Japan