Yoshiki Hamada

Tsurumi University, Yokohama, Kanagawa, Japan

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Publications (79)105.48 Total impact

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    ABSTRACT: Objective This study investigated the expression of CD44 and CD133, the two surface markers most commonly used to identify cancer stem cells (CSCs), as predictive markers for clinicopathological progression and lymph node metastasis in oral squamous cell carcinoma (OSCC). Methods OSCC primary tumor specimens obtained from 29 patients with OSCC who underwent resection as well as the normal oral mucosa samples of 14 healthy volunteers were enrolled in this study. We studied expression of CD133 and CD44 using real-time RT-PCR, immunohistochemistry and western blot analysis in primary OSCC, and investigated the correlation of clinicopathological factors. Results Although CD133 protein expression was not obviously detected, CD133 mRNA expression in primary OSCC tissues significantly correlated with lymph node metastasis, depth of invasion, extranodal invasion, and clinical stage. Conclusions CD133 mRNA over-expression in OSCC primary tumors could be a novel independent prognostic marker that correlates with tumor progression and lymph node metastasis.
    Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology. 04/2014;
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    ABSTRACT: Myofibroma is a benign tumor composed of myoid spindle cells. The prevalence of myofibroma in the oral cavity is very low, with the mandible being the most common site. This report describes an adult case of myofibroma that arose on the mandible and includes magnetic resonance imaging (MRI) and positron emission tomography (PET) findings. On the MRI T1-weighted images, the tumor appeared with signal iso-intensity and was highly and heterogeneously enhanced with contrast material. On the T2-weighted images, it appeared with increased signal intensity. 18 F-fluorodeoxyglucose (FDG)-PET imaging showed abnormal strong accumulation of FDG in the left mandibular region. The tumor was removed by marginal resection of the left mandible under general anesthesia. Histopathological findings revealed that the tumor stroma contained abundant thin-walled vessels. The postoperative course was uneventful, and we found no evidence of recurrence at the postoperative 34-month follow-up.
    World Journal of Surgical Oncology 03/2014; 12(1):69. · 1.09 Impact Factor
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    ABSTRACT: Chromium (Cr) causes delayed-type hypersensitivity reactions possibly mediated by accumulating T cells into allergic inflamed skin, which are called irritants or allergic contact dermatitis. However, accumulating T cells during development of metal allergy are poorly characterized because a suitable animal model is not available. This study aimed to elucidate the skewing of T-cell receptor (TCR) repertoire and cytokine profiles in accumulated T cells in inflamed skin during elucidation of Cr allergy. A novel model of Cr allergy was induced by two sensitizations of Cr plus lipopolysaccharide solution into mouse groin followed by single Cr challenge into the footpad. TCR repertoires and nucleotide sequences of complementary determining region 3 were assessed in accumulated T cells from inflamed skin. Cytokine expression profiles and T-cell phenotypes were determined by qPCR. CD3+CD4+ T cells accumulated in allergic footpads and produced increased T helper 1 (Th1) type cytokines, Fas, and Fas ligand in the footpads after challenge, suggesting CD4+ Th1 cells locally expanded in response to Cr. Accumulated T cells included natural killer (NK) T cells and Cr-specific T cells with VA11-1/VB14-1 usage, suggesting metal-specific T cells driven by invariant NKT cells might contribute to the pathogenesis of Cr allergy.
    PLoS ONE 01/2014; 9(1):e85983. · 3.53 Impact Factor
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    ABSTRACT: Intramuscular hemangioma (IMH) is relatively rare benign tumor of vascular origin. Phleboliths are calcified thrombi found in the presence of hemangioma. The main treatment of the hemangioma is a surgical extirpation based on location, accessibility, and cosmetic considerations. We herein report a rare case of IMH with phleboliths of the tongue with clinical, imaging, and histopathological findings.
    Indian Journal of Dentistry. 01/2014;
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    ABSTRACT: This is the first report to our knowledge of an intramuscular lipoma that arose in the masseter muscle. Excision biopsy under general anaesthesia showed that the mass could easily be separated from the surrounding soft tissues on the lateral side, but was firmly adherent to the muscle on the medial side, so complete excision required resection of part of the masseter. Histopathological examination showed that it was an intramuscular lipoma. Two years and 6 months postoperatively there was no evidence of recurrence.
    British Journal of Oral and Maxillofacial Surgery 01/2014; · 2.72 Impact Factor
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    ABSTRACT: Abstract The objective of this study is to evaluate usefulness of mandibular reconstructions using a custom-made titanium mesh (Ti-mesh) tray and particulate cancellous bone and marrow (PCBM). A consecutive nine patients who underwent mandibular reconstruction were enrolled in this study. They were five men and four women (mean age: 53.9 years). Virtual reality simulation was performed using computer software based on the pre-operative computed tomography data. A 3-dimensional (3-D) skull model was constructed using a 3-D printer. A tray was custom-made from a Ti-mesh sheet bent to adapt to the model. After PCBM harvesting from bilateral posterior ilia, the tray was fixed to the host bone. New bone formation and configuration of the reconstructed mandible were assessed radiologically. Complications were recorded in each patient during the follow-up period. Patients, satisfaction with post-operative facial contour was evaluated using a visual analogue scale (VAS score, range = 0-100). In six of nine patients, excellent new bone formation was recognised and expected results were radiologically achieved. Complications occurred in four patients. These complications included Ti-mesh fracture, Ti-mesh exposure in the oral cavity, and delayed infection. Mean VAS score on patient satisfaction was 77.6. Although the data are preliminary, the results suggest that this method is clinically useful.
    Journal of plastic surgery and hand surgery. 10/2013;
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    ABSTRACT: Nickel (Ni) can cause delayed-type hypersensitivity reactions, which are thought to be mediated by the accumulation of T cells into inflamed skin. Accumulated T cells at the developmental stages in metal allergy are poorly characterized because a suitable animal model has not been established. To investigate the accumulated T cells in allergic inflamed skin, we generated a novel murine model of Ni-induced allergy. The murine model of Ni allergy was induced by two sensitizations of Ni plus lipopolysaccharide solution into the groin followed by three challenges with Ni solution into the footpad. Here we show that a specific TCR repertoire bearing Vα14Jα18, called natural killer (NK) T cells, was expanded monoclonally in BALB/c or C57BL/6 mice. Accumulation of NKT cells was characterized as CD4(+) or CD4(-)CD8(-) T cells. These results suggested that NKT cells are major pathogenic T cells at the elicitation phase of Ni allergy.
    Cellular Immunology 08/2013; 284(1-2):163-171. · 1.74 Impact Factor
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    ABSTRACT: OBJECTIVE: This study aimed to establish a mouse model in which dental pulp cells (DPCs) could be used as a cell source for the treatment of salivary gland hypofunction. DESIGN: DPCs were isolated from green fluorescent protein (GFP)-expressing mice and were differentiated into dental pulp endothelial cells (DPECs). DPEC behaviour was studied in vitro and in vivo to investigate their capacity to participate in neovascularisation. For in vivo assessment, a combination of DPECs and Matrigel was subcutaneously injected into nude mice. Two weeks after injection, Matrigel plugs were analysed for CD31 and GFP. Furthermore, both submandibular glands of the irradiated mice were injected with DPECs. Eight weeks after irradiation, the effect of DPECs on saliva secretion was evaluated by measuring amounts of saliva secretion. RESULTS: DPECs showed typical endothelial morphology, including a cobblestone appearance. RT-PCR analysis of DPECs showed positive expression of CD31, foetal liver kinase-1, vascular-endothelial-cadherin, vascular endothelial growth factor-A and von Willebrand factor. DPECs reorganised into tube-like structures on Matrigel after 24h in vitro. Positive merged staining for both CD31 and GFP was observed in the tube-like structures, representative of the injected DPECs. The average saliva flow rate in mice treated with DPECs was significantly higher than that observed in mice treated with PBS (P=0.0452). CONCLUSIONS: Our results show that radiation-induced salivary hypofunction is partially reverted following transplantation of DPECs. We established a mouse model in which DPCs could be used as a cell source for the treatment of salivary gland hypofunction.
    Archives of Oral Biology 04/2013; · 1.55 Impact Factor
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    ABSTRACT: In the present study, we investigate the expression profile of the epidermal growth factor receptor family, which comprises EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4 in oral leukoplakia (LP). The expression of four epidermal growth factor receptor (EGFR) family genes and their ligands were measured in LP tissues from 14 patients and compared with levels in 10 patients with oral lichen planus (OLP) and normal oral mucosa (NOM) from 14 healthy donors by real-time polymerase chain reaction (PCR) and immunohistochemistry. Synchronous mRNA coexpression of ErbB1, ErbB2, ErbB3 and ErbB4 was detected in LP lesions. Out of the receptors, only ErbB4 mRNA and protein was more highly expressed in LP compared with NOM tissues. These were strongly expressed by epithelial keratinocytes in LP lesions, as shown by immunohistochemistry. Regarding the ligands, the mRNA of Neuregulin2 and 4 were more highly expressed in OLP compared with NOM tissues. Therefore, enhanced ErbB4 on the keratinocytes and synchronous modulation of EGFR family genes may contribute to the pathogenesis and carcinogenesis of LP.International Journal of Oral Science (2013) 5, doi:10.1038/ijos.2013.10; published online 15 March 2013.
    International Journal of Oral Science 03/2013; 5. · 2.72 Impact Factor
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    ABSTRACT: Nicotinic acetylcholine receptor (nAChR) clustering is a key event in the synaptogenesis of the neuromuscular junction (NMJ) for the efficient transmission of neural signals from motor neurons to skeletal muscle. The microphthalmic mouse (mi/mi) with a mutation in the mitf gene cannot perform occlusion, because its teeth do not erupt. The present study attempted to elucidate the contribution of occlusion to the clustering of nAChR in the NMJ of the masseter, with mi/mi as a model system. In mice at 1 week of age, no significant change in the fragmentation or volume of the nAChR cluster was observed in either the masseter or gastrocnemius between breast-fed +/+ and mi/mi. In mice at 4 and 12 weeks of age, after the occlusion emerged in the +/+, excessive fragmentation and volume decline in the nAChR cluster were observed in the masseter of mi/mi fed a powdered diet compared with +/+ fed a pellet or powdered diet, whereas, in the gastrocnemius, no such differences were observed between the 2 strains. These results indicate abnormal formation of the nAChR cluster in the NMJ of the masseter of mi/mi, suggesting that occlusion is essential for the normal progress of nAChR clustering in the NMJ of the masseter.
    Journal of dental research 01/2013; · 3.46 Impact Factor
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    ABSTRACT: Metal allergy is categorized as a delayed-type hypersensitivity reaction, and is characterized by the recruitment of lymphocytes into sites of allergic inflammation. Because of the unavailability of suitable animal models for metal allergy, the role of T cells in the pathogenesis of metal allergy has not been explored. Thus, we developed a novel mouse model for metal allergy associated with infiltration of T cells by multiple injections of palladium (Pd) plus lipopolysaccharide into the footpad. Using this model, we characterized footpad-infiltrating T cells in terms of phenotypic markers, T cell receptor (TCR) repertoires and cytokine expression. CD3+ CD4+ T cells accumulated in the allergic footpads 7 days after Pd challenge. The expression levels of CD25, interleukin-2, interferon-γ and tumor necrosis factor, but not interleukin-4 and interleukin-5, increased in the footpads after challenge, suggesting CD4+ T helper 1 (Th1) cells locally expanded in response to Pd. Infiltrated T cells in the footpads frequently expressed AV18-1 and BV8-2 T cell receptor (TCR) chains compared with T cells in the lymph nodes and exhibited oligoclonality. T-cell clones identified from Pd-allergic mouse footpads shared identical CDR3 sequences containing AV18-1 and BV8-2. These results suggest that TCR AV18-1 and BV8-2 play dominant and critical parts in the antigen specificity of Pd-specific Th1 cells.
    PLoS ONE 01/2013; 8(10):e76385. · 3.53 Impact Factor
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    ABSTRACT: The common marmoset () is considered a novel experimental animal model of non-human primates. However, due to antibody unavailability, immunological and pathological studies have not been adequately conducted in various disease models of common marmoset. Quantitative real-time PCR (qPCR) is a powerful tool to examine gene expression levels. Recent reports have shown that selection of internal reference housekeeping genes are required for accurate normalization of gene expression. To develop a reliable qPCR method in common marmoset, we used applets to evaluate the expression stability of eight candidate reference genes (, , , , , , and ) in various tissues from laboratory common marmosets. analysis showed that , , and were generally ranked high in stability followed by . In contrast, , and exhibited lower expression stability than other genes in most tissues analyzed. Furthermore, by using the improved qPCR with selected reference genes, we analyzed the expression levels of CD antigens (CD3ε, CD4, CD8α and CD20) and cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12β, IL-13, IFN-γ and TNF-α) in peripheral blood leukocytes and compared them between common marmosets and humans. The expression levels of CD4 and IL-4 were lower in common marmosets than in humans whereas those of IL-10, IL-12β and IFN-γ were higher in the common marmoset. The ratio of Th1-related gene expression level to that of Th2-related genes was inverted in common marmosets. We confirmed the inverted ratio of CD4 to CD8 in common marmosets by flow cytometric analysis. Therefore, the difference in Th1/Th2 balance between common marmosets and humans may affect host defense and/or disease susceptibility, which should be carefully considered when using common marmoset as an experimental model for biomedical research.
    PLoS ONE 01/2013; 8(2):e56296. · 3.53 Impact Factor
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    ABSTRACT: This case report presents an unusual case of a simple mandibular bone cyst with remarkable tooth resorption. A 52-year-old woman was referred to our clinic for examination of a radiolucent lesion located in the right third mandibular molar region. The lesion could not be identified on panoramic radiograph at 6 years ago. Imaging examinations demonstrated a relatively well demarcated radiolucent lesion in the right mandible with marked resorption of the third molar. Based on the tentative diagnosis of an intraosseous benign tumor, biopsy was performed. The lesion was a simple bone cavity containing sanguineous fluid with no evidences of a cystwall lining or tumoral tissue. Intraoperative diagnosis was a simple bone cyst, and the lesion including the remained third molar was carefully removed. Histopathologically, thin fibrous connective tissue without epithelial cover was observed on the surface of the bony wall. The histopathologic findings were consistent with those of a simple bone cyst. However, myxofibromatous connective tissue and woven bone were observed only on the surface of the resorbed dental hard tissue. This case may be associated with the fibro-osseous lesion to some degree. One year later, complete healing was observed.
    Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology. 01/2013; 25(1):93–96.
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    ABSTRACT: Solitary fibrous tumor (SFT) is an uncommon spindle-cell mesenchymal tumor of probable fibroblastic derivation that most often occurs in the pleura, where it is typically benign. This report describes a case of a large SFT that arose in the buccal space, and includes computerized tomography, magnetic resonance imaging, and positron emission tomography (PET) findings. (18)F-Fluorodeoxyglucose (FDG) PET axial imaging showed weak abnormal accumulation of FDG in the left buccal region. The tumor was located behind the posterior wall of the maxilla, adjacent to the medial aspect of the coronoid process and was compressed between the coronoid and maxillary alveolar processes. We resected it with the use of a transoral approach in combination with coronoidectomy. Coronoidectomy was chosen because it facilitated safe removal of the tumor by improving its visibility and providing enough working space to resect it through a transoral approach.
    Oral surgery, oral medicine, oral pathology and oral radiology. 07/2012; 114(1):e9-e14.
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    ABSTRACT: Clenbuterol, a β(2) -adrenergic agonist, increases the hypertrophy of skeletal muscle. Insulin-like growth factor (IGF) is reported to work as a potent positive regulator in the clenbuterol-induced hypertrophy of skeletal muscles. However, the precise regulatory mechanism for the hypertrophy of skeletal muscle induced by clenbuterol is unknown. Myostatin, a member of the TGFβ super family, is a negative regulator of muscle growth. The aim of the present study is to elucidate the function of myostatin and IGF in the hypertrophy of rat masseter muscle induced by clenbuterol. To investigate the function of myostatin and IGF in regulatory mechanism for the clenbuterol-induced hypertrophy of skeletal muscles, we analysed the expression of myostatin and phosphorylation levels of myostatin and IGF signaling components in the masseter muscle of rat to which clenbuterol was orally administered for 21 days. Hypertrophy of the rat masseter muscle was induced between 3 and 14 days of oral administration of clenbuterol and was terminated at 21 days. The expression of myostatin and the phosphorylation of smad2/3 were elevated at 21 days. The phosphorylation of IGF receptor 1 (IGFR1) and akt1 was elevated at 3 and 7 days. These results suggest that myostatin functions as a negative regulator in the later stages in the hypertrophy of rat masseter muscle induced by clenbuterol, whereas IGF works as a positive regulator in the earlier stages. Copyright © 2012 John Wiley & Sons, Ltd.
    Cell Biochemistry and Function 06/2012; · 1.85 Impact Factor
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    ABSTRACT: A 57-year-old man attempted to commit suicide by thrusting a chopstick into his throat during a meal, resulting in penetrating injury into the cranium. Computed tomography revealed that the chopstick had penetrated the soft palate and passed through the jugular foramen to the cerebellum, damaging the internal jugular vein. The chopstick fractured in the lateral pharyngeal space and was impossible to observe directly from the oral cavity, requiring surgical cooperation with neurosurgeons to remove the object under general anesthesia. After one end of the chopstick body was identified in the deep portion of the styloid prominence, an approach was made from the neck to prevent hemorrhage and gas embolism in the affected internal jugular vein. The other end of the chopstick was identified near the jugular foramen and it was removed through the neck via occipital craniotomy. Post-operative management included sedation and artificial ventilation to manage brain contusion and edema and intracranial inflammation. The patient was gradually recovered and transferred to a general ward 4 weeks after the surgery. After 4 years, the patient retains clear mentation, but remains hospitalized in a rehabilitation hospital because of persistent quadriplegia.
    Asian Journal of Oral and Maxillofacial Surgery 05/2012;
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    ABSTRACT: Our aim was to explore important inflammatory mediators for synovial chondromatosis in the temporomandibular joints (TMJs) by analysing synovial fluid. Samples were collected from 10 patients with unilateral synovial chondromatosis of the TMJ. Control samples were obtained from 11 subjects with no symptoms in the TMJ. Concentrations of aggrecan, interleukin (IL)-2, IL-4, IL-5, IL-6, IL-8 (CXCL8), IL-10, interferon (IFN)-γ, tumour necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF)-A were measured in the samples of synovial fluid, and the results in the two groups compared. The tissues from the affected TMJ were examined histologically and immunohistochemically. Of the proteins evaluated, the concentrations of aggrecan, IL-6, and VEGF-A were significantly higher in the group with synovial chondromatosis. The immunohistochemical analysis showed that the synovial cells around the osteocartilaginous nodules were vigorously expressing VEGF-A. IL-6 and VEGF-A are thought to have important roles in the pathology of synovial chondromatosis of the TMJ.
    British Journal of Oral and Maxillofacial Surgery 04/2012; · 2.72 Impact Factor
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    ABSTRACT: Interdisciplinary treatment was used for an adult patient born with complete bilateral cleft lip and palate. He had a severe maxillary deficiency with a wide cleft involving the alveolar and maxillary bone and palate. Reconstruction of the arches and occlusion in patients who missed the optimal treatment time is a difficult task for orthodontists. The clinical examination showed severe hypogenesis of the maxillary bone with a total crossbite. The maxillary dental arch was extremely narrow, and the maxillary incisors showed extensive caries caused by improper oral hygiene. Fixed and removable expansion appliances were used to improve the lateral crossbite. Alveolar bone grafting and unilateral LeFort I maxillary osteotomy were performed on the right side for alignment of the maxillary arch. Mandibular setback with bilateral sagittal split ramus osteotomy was also performed to correct the anteroposterior skeletal discrepancy. After postsurgical orthodontic treatment, prosthetic treatment was carried out for final reconstruction of esthetics and orthognathic function. Interdisciplinary treatment was necessary for this patient to achieve a proper occlusion and better esthetics.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 04/2012; 141(4 Suppl):S149-58. · 1.33 Impact Factor
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    ABSTRACT: The aims of this study were (1) to assess the validity of limited cone beam CT (CBCT) in detecting the distribution of bifid mandibular canals in the retromolar region by comparing its findings with those of panoramic radiography and spiral CT imaging, and (2) to confirm the contents of such canals depicted on limited CBCT images by using gross anatomical and histological methods. Bilateral bifid mandibular canals of a Japanese cadaver were investigated. The canals depicted on panoramic radiography, spiral CT and limited CBCT images were compared. Cross-sectional limited CBCT images of these canals were compared with gross anatomical sections of the mandible and their contents were confirmed histologically. The spiral CT and limited CBCT images showed the bilateral bifid mandibular canals in the retromolar region whereas the panoramic radiographs indicated the presence of only the left bifid mandibular canal. The canal distribution was more distinct in the limited CBCT images than in the spiral CT images and the cross-sectional limited CBCT images were consistent with the gross anatomical sections. Histologically, the canals contained several nerve bundles and arteries among which the largest nerve and artery were of a similar size. Limited CBCT is valuable for assessing the distribution of bifid mandibular canals. It is clinically significant to accurately localize a bifid mandibular canal of the retromolar region because it contains a nerve bundle and artery.
    Dentomaxillofacial Radiology 11/2011; 41(6):460-5. · 1.27 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the effect of stereotactic radiosurgery on local control and organ preservation in cases of primary head and neck cancer. In this retrospective study, 14 patients with a mean age of 73 years were treated between March 2006 and September 2007 with stereotactic radiosurgery for the management of primary head and neck cancer. The patients had biopsy confirmation of disease before treatment and all patients were confirmed with squamous cell carcinoma. The staging consisted of T2 (5 cases), T3 (3 cases), T4 (6 cases), N0 (13 cases), and N1 (1 case). Marginal doses were 3,500 to 4,200 cGy in 3 or 5 fractions. The outcome was assessed according to Response Evaluation Criteria in Solid Tumors criteria based on magnetic resonance imaging and positron emission tomography/computed tomography. Significant tumor reduction was noted at the third month of follow-up with 5 complete responses and 9 partial responses. At a mean follow-up of 36 months (range, 14-40 mo) the local control and overall survival rates were 71.4% (10/14) and 78.6% (11/14), respectively. These results show the feasibility of using stereotactic radiosurgery for primary head and neck cancer and its potential benefit in local control and organ preservation.
    Journal of oral and maxillofacial surgery: official journal of the American Association of Oral and Maxillofacial Surgeons 07/2011; 70(2):461-72. · 1.58 Impact Factor

Publication Stats

369 Citations
105.48 Total Impact Points

Institutions

  • 2000–2014
    • Tsurumi University
      • • Department of Oral and Maxillofacial Surgery
      • • School of Dental Medicine
      Yokohama, Kanagawa, Japan
  • 2013
    • National Institute of Infectious Diseases, Tokyo
      Edo, Tōkyō, Japan
  • 2007
    • Sagamihara National Hospital
      Йокосука, Kanagawa, Japan
  • 2005
    • Nihon University
      • Department of Oral Surgery
      Edo, Tōkyō, Japan
  • 2002–2005
    • Akita University
      • Department of Dentistry and Oral Surgery
      Akita-shi, Akita-ken, Japan