S Miyawaki

Kagoshima University, Kagosima, Kagoshima, Japan

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Publications (129)327.19 Total impact

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    ABSTRACT: Objective: In this study, the authors investigated the modulation of the masticatory path at the mandibular first molar during natural chewing of a hard gummy jelly in adults with normal occlusion. Methods: The unilateral mastication sequence was divided into three stages, and the masticatory path of the mandibular first molar on the working side was analyzed at 2·0, 3·0, 4·0, and 5·0 mm vertical slice levels below the intercuspation in the frontal and sagittal views. Results: In the frontal view, the closing and opening angles and cycle width of the final stage at 3·0, 4·0, and 5·0 mm slice levels were smaller and narrower than those of the initial stage, although those at the 2·0 mm slice level were little changed. Discussion: Masticatory paths of the mandibular first molar at slice levels greater than 3.0 mm were evidently modulated to adapt to the changing properties of the food, and those at the 2·0 mm slice level remained stable throughout the masticatory sequence.
    Cranio: the journal of craniomandibular practice 09/2014; · 1.11 Impact Factor
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    ABSTRACT: A posterior cross-bite is defined as an abnormal bucco-lingual relationship between opposing molars, pre-molars or both in centric occlusion. Although it has been reported that patients with unilateral posterior cross-bite often show unique chewing patterns, the relationship between the form of cross-bite and masticatory jaw movement remains unclear in adult patients. The objective of this study was to investigate masticatory jaw movement among different forms of cross-bite. One hundred and one adults were recruited in this study: 27 had unilateral first molar cross-bite (MC group); 28, unilateral pre-molar cross-bite (PC group); 23, anterior cross-bite (AC group); and 23, normal occlusion (control group). Masticatory jaw movement of the lower incisor point was recorded with six degrees of freedom jaw-tracking system during unilateral mastication. Our results showed that the reverse chewing ratio during deliberate unilateral mastication was significantly larger in the MC group than in the PA (P < 0·001), AC (P < 0·001) and control (P < 0·001) groups. These findings suggest that compared to the anterior or pre-molar cross-bite, the first molar cross-bite is more closely associated with a higher prevalence of a reverse chewing cycle.
    Journal of Oral Rehabilitation 08/2014; · 2.34 Impact Factor
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    ABSTRACT: Abstract This case report describes the successful extraction treatment of a Class II division 2 malocclusion with mandibular posterior discrepancy and a congenitally missing maxillary lateral incisor on the left side. The posterior space in the mandibular arch was small, and the mandibular second molars were impacted, with distal tipping. The discrepancies in the maxillary and mandibular arches were resolved by extraction of the maxillary lateral incisor on the right side and the mandibular second premolars on both sides. The mesial movement of the mandibular first molars occurred appropriately, with the second molars moving into an upright position. A lip bumper was used with a preadjusted edgewise appliance in the maxillary dentition to reinforce molar anchorage and labial movement of the retroclined incisors. Despite the extraction treatment, a deep bite could be corrected without aggravation as a result of the lip bumper and utility arch in the mandibular dentition. Thus, an Angle Class I molar relationship and an ideal overbite were achieved. The occlusal contact area and masticatory muscle activities during maximum clenching increased after treatment. The maximum closing velocity and the maximum gape during chewing increased, and the chewing pattern changed from the chopping to grinding type. The findings in the present case suggest that the correction of a deep bite might be effective for improving stomatognathic function.
    The Angle Orthodontist 07/2014; · 1.18 Impact Factor
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    ABSTRACT: Scissors-bite is a malocclusion characterised by buccal inclination or buccoversion of the maxillary posterior tooth and/or linguoclination or linguoversion of the mandibular posterior tooth. This type of malocclusion causes reduced contact of the occlusal surfaces and can cause excessive vertical overlapping of the posterior teeth. This case–control study is the first to evaluate both masticatory jaw movement and masseter and temporalis muscle activity in patients with unilateral posterior scissors-bite. Jaw movement variables and surface electromyography data were recorded in 30 adult patients with unilateral posterior scissors-bite malocclusion and 18 subjects with normal occlusion in a case–control study. The chewing pattern on the scissors-bite side significantly differed from that of the non-scissors-bite side in the patients and of the right side in the normal subjects. These differences included a narrower chewing pattern (closing angle, P < 0·01; cycle width, P < 0·01), a longer closing duration (P < 0·05), a slower closing velocity (P < 0·01) and lower activities of both the temporalis (P < 0·05) and the masseter (P < 0·05) muscles on the working side. In 96% of the patients with unilateral posterior scissors-bite, the preferred chewing side was the non-scissors-bite side (P = 0·005). These findings suggest that scissors-bite malocclusion is associated with the masticatory chewing pattern and muscle activity, involving the choice of the preferred chewing side in patients with unilateral posterior scissors-bite.
    Journal of Oral Rehabilitation 04/2014; 41(4). · 2.34 Impact Factor
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    ABSTRACT: Recent studies have been revealing the relationship between the stomatognathic system and the gastrointestinal tract. However, the effect of oesophageal acid stimulation on masticatory muscle activity during wakefulness has not been fully elucidated. To examine whether intra-oesophageal acidification induces masticatory muscle activity, a randomised trial was conducted investigating the effect of oesophageal acid infusion on masseter muscle activity, autonomic nervous system (ANS) activity and subjective symptoms. Polygraphic monitoring consisting of electromyography of the masseter muscle, electrocardiography and audio–video recording was performed in 15 healthy adult men, using three different 30-min interventions: (i) no infusion, (ii) intra-oesophageal saline infusion and (iii) intra-oesophageal infusion of acidic solution (0·1 N HCl; pH 1·2). This study was registered with the UMIN Clinical Trials Registry, UMIN000005350. Oesophageal acid stimulation significantly increased masseter muscle activity during wakefulness, especially when no behaviour was performed in the oro-facial region. Chest discomfort, including heartburn, also increased significantly after oesophageal acid stimulation; however, no significant correlation was observed between increased subjective symptoms and masseter muscle activity. Oesophageal acid infusion also altered ANS activity; a significant correlation was observed between masticatory muscle changes and parasympathetic nervous system activity. These findings suggest that oesophageal-derived ANS modulation induces masseter muscle activity, irrespective of the presence or absence of subjective gastrointestinal symptoms.
    Journal of Oral Rehabilitation 03/2014; · 2.34 Impact Factor
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    ABSTRACT: It is known that maximum bite force has various influences on chewing function; however, there have not been studies in which the relationships between maximum bite force and masticatory jaw movement have been clarified. The aim of this study was to investigate the effect of maximum bite force on masticatory jaw movement in subjects with normal occlusion. Thirty young adults (22 men and 8 women; mean age, 22·6 years) with good occlusion were divided into two groups based on whether they had a relatively high or low maximum bite force according to the median. The maximum bite force was determined according to the Dental Prescale System using pressure-sensitive sheets. Jaw movement during mastication of hard gummy jelly (each 5·5 g) on the preferred chewing side was recorded using a six degrees of freedom jaw movement recording system. The motion of the lower incisal point of the mandible was computed, and the mean values of 10 cycles (cycles 2-11) were calculated. A masticatory performance test was conducted using gummy jelly. Subjects with a lower maximum bite force showed increased maximum lateral amplitude, closing distance, width and closing angle; wider masticatory jaw movement; and significantly lower masticatory performance. However, no differences in the maximum vertical or maximum anteroposterior amplitudes were observed between the groups. Although other factors, such as individual morphology, may influence masticatory jaw movement, our results suggest that subjects with a lower maximum bite force show increased lateral jaw motion during mastication.
    Journal of Oral Rehabilitation 02/2014; · 2.34 Impact Factor
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    ABSTRACT: Objective : To examine the changes in autogenous bone from 6 to 12 months after alveolar bone grafting (ABG) (T1) through completion of edgewise treatment (T2). Design : Retrospective longitudinal study. Setting : Multidisciplinary long-term follow-up at Kagoshima University Hospital. Patients : Forty-three patients with unilateral cleft lip and palate or alveolus. Main Outcome Measures : At T1 and T2, the bone bridge and quantity of grafted bone were evaluated using the Chelsea scale and the ABG scale. The cleft-adjacent tooth angles before ABG and at T2, as well as the number of orthodontic space closures, were examined. Patients were classified as having either adequate (type A or C; adequate group) or poor bone bridges (type B, D, E, or F; poor group) by the assessment at T1. Results : At T1, the ABG scores for the cleft-adjacent central incisor side of patients in the adequate group were higher than those of patients in the poor group (P < .001). At T2, the adequate group had higher ABG scores for the cleft-adjacent central incisor side (P = .022) and the canine sides (P = .034). No significant differences in tooth angles or the number of orthodontic space closures were noted between the groups. Conclusions : These results suggest that the quantity of grafted bone in the cleft-adjacent central incisor at 6 to 12 months post-ABG may be an indicator of the quantity of grafted bone that will be present after edgewise treatment.
    The Cleft Palate-Craniofacial Journal 09/2013; · 1.24 Impact Factor
  • Aya Maeda, Yoko Sakoguchi, Shouichi Miyawaki
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    ABSTRACT: This report describes the treatment of a 20-year-old woman with a dental midline deviation and 7 congenitally missing premolars. She had retained a maxillary right deciduous canine and 4 deciduous second molars, and she had an impacted maxillary right third molar. The maxillary right deciduous second molar was extracted, and the space was nearly closed by mesial movement of the maxillary right molars using an edgewise appliance and a miniscrew for absolute anchorage. The miniscrew was removed, and the extraction space of the maxillary right deciduous canine was closed, correcting the dental midline deviation. After the mesial movement of the maxillary right molars, the impacted right third molar was aligned. To prevent root resorption, the retained left deciduous second molars were not aligned by the edgewise appliance. The occlusal contact area and the maximum occlusal force increased over the 2 years of retention. The miniscrew was useful for absolute anchorage for unilateral mesial movement of the maxillary molars and for the creation of eruption space and alignment of the impacted third molar in a patient with oligodontia.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 09/2013; 144(3):430-40. · 1.33 Impact Factor
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    ABSTRACT: Obesity has a prevalence of 15-30% among European and American populations. It is an incurable chronic disease associated with considerable mortality and co-morbidity. The co-morbidity risk can be reduced substantially by a moderate weight loss of 5-15%. Notably, additional weight gain exacerbates the morbidity of any concurrent disease. Obesity is also recognized as the basis for metabolic syndrome. Recent research has shown that adipocytes secrete various hormones and cytokines that contribute to obesity. Leptin is an adipostatic hormone that acts on receptors in the hypothalamus to suppress food intake and increase energy consumption. Reduced sensitivity to this molecule can trigger the onset of obesity. Neuropeptides such as leptin also affect salivary secretion. Various neuropeptides have been identified in saliva; the associated receptors are located in the salivary glands or in the nerves innervating the salivary glands. Obesity is associated with hyposalivation and thereby related to several aspects of oral health, such as caries and periodontitis. Hyposalivation is a severe morbidity that can lead to a precipitous decline in oral hygiene, which further leads to multifocal dental caries and periodontitis, or even cardiac disorders. In this article, we review the relationship between salivary secretion and neuropeptides known to play a role in obesity.
    Obesity Research & Clinical Practice 09/2013; 7(5):e321-9. · 0.51 Impact Factor
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    ABSTRACT: There are few large-scale epidemiologic studies examining the associations between sleep problems, gastroesophageal reflux disease (GERD) symptoms, lifestyle and food habits and problem behaviors in adolescents. The objective of this study was to evaluate the associations among these factors in Japanese adolescents. We performed a cross-sectional survey of 1,840 junior high school students using questionnaires. The subjects were classified into problem behavior (PB) or normal behavior (NB) groups by using the Pediatric Symptom Checklist. The scores of the sleep-related factors, sleep bruxism, lifestyle and food habits, and GERD symptoms were compared. Logistic regression analysis was performed to determine the factors related to problem behaviors. The mean age was 13.3 ± 1.8 years. The PB group had significantly longer sleep latency and higher scores of GERD symptoms (P < 0.001). Furthermore, the PB group was significantly more likely to experience absences of the mother at dinner time, skip breakfast, and have less than 30 min of conversation among family at dinner time. The PB group had significantly higher frequencies of sleep bruxism, difficulty falling asleep within 30 min, nightmares, feeling of low sleep quality, daytime somnolence, and daytime lack of motivation. Feelings of low sleep quality had the strongest association with problem behaviors, with an adjusted OR (95% CI) of 12.88 (8.99-18.46). Our large-scale cross-sectional study found that problem behaviors in adolescents were associated with sleep problems, including sleep bruxism, as well as lifestyle and food habits and GERD symptoms.
    Pediatrics International 08/2013; · 0.88 Impact Factor
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    ABSTRACT: Functional dyspepsia (FD) is a functional gastrointestinal disorder (FGID). According to the Rome III consensus, FD is divided into 2 subgroups: epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). Although multiple mechanisms of FD pathogenesis have been suggested, its underlying etiology and pharmacological therapy remain unclear. Ghrelin is a gut-derived peptide found in the stomach. It plays a role in the regulation of gastric motility and appetite. The ghrelin gene encodes 3 molecular forms, acyl ghrelin, des-acyl ghrelin and obestatin. Acyl ghrelin acts as an endogenous ligand for growth hormone secretagogue receptor; furthermore, it is orexigenic, with effects on food intake, energy homeostasis and gastrointestinal motility. Des-acyl ghrelin exerts an opposite effect to acyl ghrelin. Obestatin exerts an inhibitory effect on the motor activity of the antrum and duodenum in fed animals. These peptides exert differential effects on gut motility and food intake. The therapeutic potential of ghrelin has attracted attention due to its varied bioactivities. Certain studies have shown that total ghrelin levels are significantly lower in patients with FD compared with healthy volunteers and that the acyl ghrelin levels of patients with FD are higher compared with healthy volunteers. However, a recent study demonstrated that acyl ghrelin levels in patients with PDS were lower compared with healthy volunteers; the association between FD and other ghrelin family gene products also remains unclear. Although certain studies have demonstrated the beneficial effects of acyl ghrelin administration and its agonist in patients with FD, only a few clinical reports exist. Further studies are required in order to examine the effects of ghrelin on FD.
    International Journal of Molecular Medicine 06/2013; · 1.96 Impact Factor
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    ABSTRACT: BACKGROUND: Difficult laryngoscopy and tracheal intubation are occasionally encountered in children with congenital anomalies or micrognathia. However, no study has elucidated anatomical etiology in relation to craniofacial development. METHODS: Two hundred ten patients aged 8 months-18 years were analyzed. We analyzed the lateral cephalograms of: (i) eight patients in whom laryngoscopy was anticipated as difficult before anesthesia and who were unable to be intubated by direct laryngoscopy and needed fiberoptic bronchoscopy (group A); (ii) 11 patients in whom laryngoscopy was anticipated as difficult before anesthesia but who were able to be intubated by direct laryngoscopy (group B); and (iii) 191 patients in whom laryngoscopy was anticipated as easy before anesthesia and was actually found to be easy (group C). Eight cephalometric parameters were measured and age-parameter relationships were plotted. Logistic regression analysis was performed to characterize group A children for each of the cephalometric variables. RESULTS: Apparently insufficient growth of the mandible was observed in the group A children. Furthermore, the group A children of aged <4 years had undeveloped maxilla, longer mandibular plane-hyoid distances (≥1.3 cm), and deeper depth of the oropharynx; those of aged ≥4 years showed increased inclination of the mandible (sella-nasion plane to mandibular plane angle of ≥46.5°). CONCLUSIONS: Difficult laryngoscopy and tracheal intubation are expected in children aged <4 years with lower-positioned hyoid bone caused by caudal larynx as well as undeveloped maxilla and mandible, and in those aged ≥4 years with increased inclination of the mandible as well as undeveloped mandible.
    Pediatric Anesthesia 04/2013; · 2.44 Impact Factor
  • Orthodontic Waves 03/2013; 72(1):36.
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    ABSTRACT: Although in 1990s the number of patients with taste disorders in USA and Japan was over 1 million people each year, it is annually increasing. Taste disorders are caused by several factors such as genetic disease, head trauma, structural changes, glossodynia, cancer, lifestyle, and others. The role of zinc in the treatment of taste disorders has been studied since the oral administration of zinc by patients was reported to improve their taste disorders. Carbonic anhydrase (CA), a zinc metalloenzyme, has also been studied in association with taste disorders, since the regulation of serum CA levels was shown to influence the effect of orally administrated zinc in the treatment of taste disorders. Zinc is an essential trace element that contributes to the active center of approximately 300 enzymes. Studies have revealed that zinc is involved in various physiological functions. Moreover, some medications have been shown to induce a zinc deficiency, which has been associated with a variety of clinical conditions. Hence, since the relationship between taste disorder and serum zinc concentration have been discussed for long time, taste disorder may be useful in diagnosing zinc deficiency. Moreover, the appearance of the medicine of the zinc-containing supplement type contributes to the treatment of taste disorders due to zinc deficiency. Orally administered zinc has been shown to directly stimulate food intake via neuropeptide in the hypothalamus. Therefore, zinc administration may be potentially used to treat taste disorders as well as several other diseases by stimulating feeding.
    Recent patents on food, nutrition & agriculture. 01/2013;
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    ABSTRACT: Although they are widely used as diagnostic signs of temporomandibular disorders, mandibular border movements reflect not only condylar movement, but also other factors. In the present study, the authors investigated the effect of craniofacial morphology on three different mandibular border movements: maximum jaw opening, maximum jaw protrusion, and maximum jaw laterotrusion. One hundred female subjects were selected from outpatients visiting the orthodontic clinic of Okayama University Hospital. The mandibular border movements were measured using an optical recording system in three dimensions as six degrees of freedom. The craniofacial morphology was evaluated using lateral cephalograms. The results suggest that craniofacial morphology had different influences on each mandibular border movement. In particular, during maximum jaw laterotrusion, lower incisor movement strongly reflected condylar movement, and the influence of craniofacial morphology on mandibular border movement was minimal. Therefore, lower incisor movement during maximum jaw laterotrusion appears suitable to evaluate condylar movement.
    Cranio: the journal of craniomandibular practice 01/2013; 31(1):14-22. · 1.11 Impact Factor
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    ABSTRACT: Objective :  To determine whether the long axis and eruption of the cleft-adjacent canine affect postoperative outcomes in secondary autogenous bone grafting (SABG). Design :  Retrospective longitudinal study. Setting :  Multidisciplinary long-term follow-up at Kagoshima University Hospital. Subjects and Methods :  Twenty-five patients with complete unilateral cleft lip and palate (11 male, 14 female) were compared between unerupted and erupted groups for canine developmental stage, canine angle, and vertical height at bone grafting at 1 year and more than 4 years after SABG. The interalveolar septal heights at 1 and more than 4 years were evaluated by orthopantomograms. Results :  All patients in both groups accomplished dental rehabilitation with orthodontic treatment alone without prosthetic appliances. Although the rate of an acceptable bone bridge tended to be lower in the unerupted group (62.5%) than in the erupted group (88.8%), the difference was not significant (P = .158). The canine angle at bone grafting was significantly different between acceptable (69.2° ± 12.2°) and poor cases (77.3° ± 6.2°) at more than 4 years in the unerupted group (P = .049). The acceptable bone bridge rate might reflect mechanical stress added by natural eruption and orthodontic force. Conclusions :  We suggest that SABG should be planned in accordance with the canine angle, crown and root development, the eruption position of the cleft-adjacent canine, and the timing of added mechanical stress in the alveolar cleft, considering the bone formation in the alveolar cleft.
    The Cleft Palate-Craniofacial Journal 11/2012; · 1.24 Impact Factor
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    ABSTRACT: PurposeIt is clinically believed that humans with a broad and rounded dental arch accompanied by a shallow curve of Spee have good masticatory function. However, the relationship between them has not been elucidated fully. The purpose of this study was to quantitatively examine the relationship between occlusal curvatures and bite force.Materials and methodsBite force was measured and analyzed in 20 young adults with healthy permanent dentition and normal stomatognathic function using a bite force recording system. Study models of the mandibular dental arch were scanned with CCD cameras, and X, Y and Z coordinates of the cusp tips of the molars were recorded. Their occlusal curvatures were analyzed using a three-dimensional measurement system.ResultsBite force showed significant positive correlations (0.52 < R < 0.57) with the radius of the anteroposterior occlusal arc of the molar region and the radii of the translateral occlusal arcs in the second premolar, first molar and second molar regions, and showed significant positive correlation (R = 0.71) with the radius of the occlusal sphere of the molar region.Conclusions It was suggested that occlusal curvatures is related with the magnitude of bite force, and that the three dimensional spherical analysis of occlusal curvatures is useful predictor of the masticatory function.
    Orthodontic Waves 09/2012; 71(3):79–84.
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    ABSTRACT: Abstract Objective: To determine the root-crown (R/C) ratio and dental root length of teeth in patients with open bite and seek any relationships with occlusal contact (OC) and the mandibular plane (Mp) angle. Materials and Methods: Thirty-one patients with open bite with negative overbite of at least four anterior teeth and 31 control patients with clinically normal overjet and overbite were enrolled. R/C ratios, dental root length, OC, and Mp angle were measured using panoramic radiographs, dental casts, and cephalograms, respectively. Mean differences between the groups, and variations between the R/C ratio or root length and Mp angle in patients with open bite were statistically analyzed. Results: R/C and OC ratios from the incisors to premolars were significantly lower for patients with open bite than for controls, and some teeth had short dental roots. Relationships between low R/C ratio or root length and high Mp angle were significant in patients with open bite. Conclusion: Patients with open bite, especially those with a high Mp angle, have an unfavorable R/C ratio and short dental roots in some teeth, which may be related to the loss of OC.
    The Angle Orthodontist 08/2012; · 1.18 Impact Factor

Publication Stats

2k Citations
327.19 Total Impact Points

Institutions

  • 2006–2014
    • Kagoshima University
      • • Graduate School of Medical and Dental Sciences
      • • Department of Dental Anesthesiology
      • • Department of Orthodontics and Dentofacial Orthopedics
      • • Department of Orthodontics
      Kagosima, Kagoshima, Japan
  • 2000–2007
    • Okayama University
      • • Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences
      • • Department of Orthodontics and Dentofacial Orthopedics
      Okayama-shi, Okayama-ken, Japan
  • 2001–2004
    • Osaka University
      • Department of Orthodontics and Dentofacial Orthopedics
      Ibaraki, Osaka-fu, Japan
  • 2003
    • Université du Québec à Montréal
      Montréal, Quebec, Canada
  • 1997–2002
    • Nara Medical University
      • Department of Oral and Maxillofacial Surgery
      Nara-shi, Nara, Japan
    • Osaka Dental University
      • Department of Orthodontics
      Ōsaka, Ōsaka, Japan
  • 1994–2001
    • Kyoto University
      • • Department of Cardiovascular Medicine
      • • Graduate School of Medicine / Faculty of Medicine
      Kyoto, Kyoto-fu, Japan
  • 1990–2000
    • Kansai Medical University
      Moriguchi, Ōsaka, Japan
  • 1998
    • Nippon Kayaku Co., Ltd.
      Edo, Tōkyō, Japan
  • 1987–1992
    • Nihon University
      • Department of Pediatrics
      Tokyo, Tokyo-to, Japan