T Kawata

Kanagawa Dental University, Йокосука, Kanagawa, Japan

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Publications (78)96.89 Total impact

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    ABSTRACT: Malocclusions, such as an open bite and high canines, are often encountered in orthodontic practice. Teeth without occlusal stimuli are known as hypofunctional teeth, and numerous atrophic changes have been reported in the periodontal tissue, including reductions in blood vessels in the periodontal ligament (PDL), heavy root resorption, and reduced bone mineral density (BMD) in the alveolar bone. Low Level Laser (LLL) has been shown to have a positive effect on bone formation and the vasculature. Although the recovery of hypofunctional teeth remains unclear, LLL is expected to have a positive influence on periodontal tissue in occlusal hypofunction. The aim of the present study was to elucidate the relationship between LLL and periodontal tissue in occlusal hypofunction. Twenty-four male rats aged 5 weeks were randomly divided into control and hypofunctional groups. An anterior metal cap and bite plate were attached to the maxillary and mandibular incisors in the hypofunctional group to simulate occlusal hypofunction in the molars. LLL irradiation was applied to the maxillary first molar through the gingival sulcus in half of the rats. Rats were divided into four groups; control, control+LLL, hypofunctional, and hypofunctional+LLL. Exposure to LLL irradiation was performed for 3 minutes every other day for 2 weeks. Animals were examined by Micro-CT at 5 and 7 weeks and were subsequently sacrificed. Heads were resected and examined histologically and immunohistologically. The hypofunctional group had obvious stricture of the PDL. However, no significant differences were observed in the PDL and alveolar bone between the hypofunctional+LLL and the control groups. In addition, the expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF)-positive cells were higher in the hypofunctional + LLL group than in the hypofunctional group. These results indicated that LLL enhanced the production of bFGF and VEGF in the periodontal tissue of hypofunctional teeth.
    PLoS ONE 01/2014; 9(6):e100066. · 3.53 Impact Factor
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    ABSTRACT: Mesenchymal stem cells (MSCs) can be used for the regeneration of various tissues and cryopreservation of MSCs is so important for regenerative medicine. The purpose of this study was to evaluate the influences of cryopreservation on MSCs by use of a programmed freezer with a magnetic field (CAS freezer). MSCs were isolated from bone marrow of rat femora. The cells were frozen by a CAS freezer with 10% dimethyl sulfoxide (Me2SO) and cryopreserved for 7 days at a temperature of -150°C. Immediately after thawing, the number of survived cells was counted. The cell proliferation also examined after 48h culture. Next, MSCs were frozen by two different freezers; CAS freezer and a conventional programmed freezer without magnetic field. Then, osteogenic and adipogenic differentiations of cryopreserved cells were examined. As a result, survival and proliferation rates of MSCs were significantly higher in CAS freezer than in the non-magnetic freezer. Alizarin positive reaction, large amount of calcium quantification, and greater alkaline phosphatase activity were shown in both the non-cryopreserved and CAS groups after osteogenic differentiation. Moreover, Oil Red O staining positive reaction and high amount of PPARγ and FABP4 mRNAs were shown in both the non-cryopreserved and CAS groups after adipogenic differentiation. From these findings, it is shown that a CAS freezer can maintain high survival and proliferation rates of MSCs and maintain both adipogenic and osteogenic differentiation abilities. It is thus concluded that CAS freezer is available for cryopreservation of MSCs, which can be applied to various tissue regeneration.
    Cryobiology 08/2013; · 2.14 Impact Factor
  • Orthodontic Waves 03/2013; 72(1):41.
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    ABSTRACT: Condylar regeneration with the use of functional appliances after condylectomy has been validated. However, the process during treatment remains unclear. In this study, we evaluated the condylar regeneration process and then examined mandibular growth and masticatory muscle activity after regeneration in growing rats. Seventy-five male Wistar rats aged 4 weeks were equally divided into 3 groups: unilateral condylectomy group, unilateral condylectomy + appliance group, or control group. The use of a functional appliance following condylectomy promoted mandibular growth and regeneration of the condyle 1 week after condylectomy. Condyle regeneration showing normal morphology was finally achieved 8 weeks after condylectomy. Asymmetrical masticatory muscle activity was observed after condylectomy. However, the use of a functional appliance produced symmetrical masticatory muscle activity. These results indicate a favorable regeneration process in the condylectomized area due to the use of a functional appliance. In addition, due to condylar regeneration, symmetrical masticatory muscle activity was achieved.
    Journal of dental research 02/2013; · 3.46 Impact Factor
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    ABSTRACT: The purpose of the present study was to clarify the prevalence and degree of root resorption induced by orthodontic treatment in patients with and without open bite. One hundred and eleven patients treated with multibracket appliances were retrospectively selected from the patients and divided into non-open bite (NOB) and open bite (OB) groups. The severity of root resorption and the root shape were classified into five groups on periapical radiographs before and after treatment. Moreover, only in the OB group, all teeth were sub-divided into functional and hypofunctional ones that are occluding and non-occluding.As the results of multiple linear regression analysis of patient characteristics and clinical variables with the number of overall root resorption, the independent variables that were found to contribute significantly to root resorption were bite and abnormal root shape. The prevalences of root resorption evaluated in the number of patients were significantly higher in OB group than in NOB group, and those in the number of teeth were significantly higher in OB group than in NOB group, in particular anterior and premolar teeth. The prevalence of resorbed teeth with abnormal root shapes was also significantly higher in OB group than in NOB group. On the other hand, in OB group, the prevalences of root resorption and teeth with abnormal root shape were significantly greater in hypofunctional teeth than in normal functional teeth.There are more teeth with root resorption and abnormal root shape in open bite cases than in normal bite cases, and more teeth with abnormal root shapes and root resorption in hypofunctional teeth than in functional teeth.
    The European Journal of Orthodontics 01/2013; · 1.08 Impact Factor
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    ABSTRACT: In order to determine a suitable condition for osteoblasts cryopreservation, murine osteoblasts were freezed by programmed freezer with a magnetic field (CAS freezer). After 7 days cryopreservation at -150°, the number of survival cells immediately after thawing and the growth rate of cultured cells for 48 hours were examined. Gene and protein expression of alkaline phosphatase (ALP), osteopontin (OPN) and bone sialoprotein (BSP) were compared between cryopreserved and non-cryopreserved groups. As a result, a plunging temperature of -30°, a hold-time at -5° for 15 minutes and a 0.1 mT of magnetic field led to the largest survival and growth rate. Moreover, there was no significant difference in ALP, OPN and BSP mRNA and protein expression between cryopreserved and control groups. From these results, it was suggested that the CAS freezer is available for osteoblast cryopreservation and bone tissue banking can be established in the future.
    Cryo letters 01/2013; 34(1):10-9. · 0.84 Impact Factor
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    ABSTRACT: Abstract Objectives: To investigate the effects of long-term, artificially created, hypofunctional occlusion and its recovery on the morphology of rat molar roots. Material and Methods: Eighteen 5-week-old Wistar-strain male rats were randomly divided according to their periodontal conditions into normal, hypofunctional, and recovery groups (n  =  6 in each). In the experimental hypofunctional and recovery groups, a bite-raising appliance was set to produce hypofunction at the molar region. All groups were analyzed at 16 weeks of age using three-dimensional micro-computed tomography. Root length, width, and area as well as the thickness and the area of the periodontal ligament (PDL) space of the maxillary first molar were calculated. Results: Roots were longer and narrower in the hypofunctional group than in the control group. The mesial root in particular showed a dramatic change. Root area also decreased significantly in the hypofunctional group compared to the other groups. Moreover, the PDL thickness and area decreased significantly in the hypofunctional group compared to the control group, but increased in the recovery group compared to the hypofunctional group. Conclusions: These findings suggest that root size and PDL structure may be reduced due to disuse atrophy resulting from a defect in occlusal function, but may be recovered following a gain of occlusal stimuli.
    The Angle Orthodontist 11/2012; · 1.18 Impact Factor
  • Article: Reply.
    The European Journal of Orthodontics 11/2012; · 1.08 Impact Factor
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    ABSTRACT: OBJECTIVE: The purpose of this study was to clarify the interaction of vascular endothelial growth factors (VEGFs)-C and -D with cell surface foetal liver kinase-1 (Flk-1) and fms-like tyrosine kinase-4 (Flt-4) receptors in the induction and activity of osteoclasts in cultured human peripheral blood mononuclear cells (PBMCs). DESIGN: PBMCs were cultured on chamber slides or on ivory discs for 2 or 3 weeks in the presence of macrophage-colony stimulating factor (M-CSF), VEGF-A, -C or -D, or placental growth factor (PlGF) with or without receptor activator of nuclear factor kappa-B ligand (RANKL). The number of osteoclasts in each group was counted and the area of ivory resorption was measured. In addition, osteoclast differentiation was further analysed under the same conditions, but with the addition of specific neutralizing antibodies against Flk-1 and Flt-4. RESULTS: RANKL was essential for the induction of osteoclasts in PBMCs. However, significant differences were found in the number of osteoclasts induced by VEGF-A, -C, -D or M-CSF with RANKL compared with control groups lacking or containing RANKL. Blocking of either Flk-1 or Flt-4 resulted in a reduction in the enhancement of osteoclast differentiation in PBMCs by VEGF-C or -D with RANKL. The osteoclasts induced by VEGF-A, -C, -D or M-CSF with RANKL formed significantly larger resorption lacunae than those formed by osteoclasts induced by RANKL alone. CONCLUSIONS: This study showed that VEGF-C and -D play a role in the induction of osteoclast differentiation through both Flk-1 and Flt-4 receptors and influence the area of the ivory resorption in PBMCs.
    Archives of oral biology 07/2012; · 1.65 Impact Factor
  • Orthodontic Waves 03/2012; 71(1):40.
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    02/2012; , ISBN: 978-953-51-0026-3
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    ABSTRACT: Our recent studies showed that a programmed freezer with a magnetic field (CAS freezer) is helpful in the survival of periodontal ligament (PDL) cells after cryopreservation. The theory is that a magnetic field can prevent the cluster from growing by causing it to vibrate. In this letter, we commented in detail on the influence of a magnetic field during cryopreservation.
    Cryobiology 02/2012; · 2.14 Impact Factor
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    ABSTRACT: This case report describes the treatment of a case involving a skeletal Class II facial profile with a gummy smile. While treating a facial profile and a gummy smile, the outcome may not always be successful with orthodontic therapy alone. For this reason, surgical therapy is often chosen to gain an esthetic facial profile and a good smile. However, sometimes the patients reject surgical treatment and an alternative method must be considered. Skeletal anchorage systems such as miniscrews are now frequently used for correcting severe malocclusion that should be treated by surgical therapy. In this case report, we treated a skeletal Class II malocclusion with a convex profile and a gummy smile using miniscrews, which were placed in the upper posterior and anterior areas. The active treatment period was 3.5 years, and the patient's teeth continued to be stable after a retention period of 36 months.
    The Angle Orthodontist 01/2012; 82(1):170-7. · 1.18 Impact Factor
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    ABSTRACT: The purpose of this study was to examine the effect of a new cryopreservation method with a magnetic field on periodontal regeneration in vitro and in vivo. Human periodontal ligament cells were frozen in 10% dimethyl sulfoxide by using a programmed freezer with a magnetic field. Cells were cryopreserved for 3 days at -150°C. Immediately after thawing, collagen type I and alkaline phosphatase gene expression were determined by real-time polymerase chain reaction. Incisors were extracted from 15-week-old Wistar rats and cryopreserved or dried for 3 days. Then the incisors were replanted into the same sockets. Ninety days after transplantation, they were observed under light microscopy. There was no difference in the messenger RNA expression of collagen type I between the cryopreserved and the control groups. The expression of alkaline phosphatase messenger RNA in the cryopreserved group was slightly decreased compared with the control group. There was no progressive root resorption in the teeth that were replanted immediately (control group) or cryopreserved. However, there was widespread root resorption and ankylosis in the dried teeth. These results show that a magnetic field programmed freezer can be successfully used for cryopreservation of teeth.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 12/2011; 140(6):799-805. · 1.33 Impact Factor
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    ABSTRACT: Expression of osteoclasts in osteopetrotic (op/op) mice is substantially reduced by the absence of functional macrophage colony-stimulating factor (M-CSF). However, it has been reported that osteoclasts do gradually appear in the bones of op/op mice and spontaneously correct the osteopetrosis. Age-related production of osteoclasts and the changes of serum levels of vascular endothelial growth factor (VEGF) and receptor activator for nuclear factor (NF)-κB ligand (RANKL) in op/op mice were examined. The number of femoral osteoclasts, and the serum levels of VEGF, both gradually increased in op/op mice after birth and reached a peak in 120- and 60-day-old mice, respectively. However, the serum levels of RANKL showed an inverse relationship to osteoclast number. These findings suggest that the appearance of osteoclasts may be influenced by the serum levels of VEGF and that the serum levels of RANKL may be influenced by the appearance of osteoclasts.
    Archives of oral biology 10/2011; 57(4):352-6. · 1.65 Impact Factor
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    ABSTRACT: The purpose of this study was to clarify the prevalence and degree of root resorption induced by orthodontic treatment in association with treatment factors. The files of 243 patients (72 males and 171 females) aged 9-51 years were randomly selected from subjects treated with multi-bracket appliances. The severity of root resorption was classified into five categories on radiographs taken before and after treatment. The subjects were divided into extraction (n = 113 patients, 2805 teeth) and non-extraction (n = 130 patients, 3616 teeth) groups and surgical (n = 56 patients, 1503 teeth) and non-surgical treatment (n = 187 patients, 4918 teeth) groups. These subjects were also divided into two or three groups based on the duration of multiloop edgewise archwire (MEAW) treatment, elastic use, and total treatment time: 0 month (T1; n = 184 patients, 4831 teeth), range 1-6 months (T2; n = 37 patients, 994 teeth), more than 6 months (T3; n = 22 patients, 596 teeth); range 0-6 months (n = 114 patients, 3016 teeth) more than 6 months (n = 129 patients, 3405 teeth); range 1-30 months (n = 148 patients, 3913 teeth) and more than 30 months (n = 95 patients, 2508 teeth). The prevalence of overall and severe root resorption evaluated by the number of subjects and teeth was compared with a chi-square test. A Student's t-test for unpaired data was used to determine any statistically significant differences. The prevalence of severe root resorption based on the number of teeth was significantly higher in the group with extractions (P < 0.01). Longer use of a MEAW appliance and elastics also produced a significantly higher prevalence of root resorption (P < 0.05). On the other hand, the prevalence of severe root resorption was not significantly different between the subjects treated with or without surgery, but there was a significant increase when treatment time was prolonged (P < 0.05). A significant difference was found in the amount of root movement of the upper central incisors and the distance from their root apices to the cortical bone surface (P < 0.05). These are regarded as essential factors in the onset of root resorption. These results indicate that orthodontic treatment with extractions, long-term use of a MEAW appliance and elastics, treatment time, and distance of tooth movement are risk factors for severe root resorption.
    The European Journal of Orthodontics 08/2011; 34(3):350-6. · 1.08 Impact Factor
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    ABSTRACT: To investigate how mandibular and femoral growth is affected when sex hormone- specific receptor antagonist is administered in growing mice. Forty C57BL/6J mice were used in this experiment. At 5 days of age, the mice received daily injection of estrogen receptor alpha (ERα), beta (ERβ), or androgen receptor (AR) antagonists, and their body weight was assessed every 4 days. One, four and eight weeks after the initial injection, radiographs of the mandible and femur were taken and measured. Analyses of variance and pairwise comparisons (Fisher) were performed to examine the differences in values measured among the groups. Mandibular growth was affected by ERβ antagonist injection in male mice at 4 and 8 weeks. In female mice, the growth was affected during all the experimental period, when ERβ was administered. Moreover, at 8 weeks, mandibular growth was also affected in male and female mice injected with ERα antagonist and in male mice injected with AR antagonist. Femoral growth was affected during all the experimental period in male and female mice injected with ERβ antagonist. Moreover, at 8 weeks, the growth was affected in male and female mice injected with ERα antagonist and in male mice injected with AR antagonist. Growth of the mandible and femur in mice, in part, is induced in response to the stimulation of ERβ in chondrocytes before and during early puberty. In late and after puberty, the growth is induced by the stimulation of ERα in male and female mice and that of AR in male mice.
    Orthodontics and Craniofacial Research 05/2011; 14(2):63-9. · 1.19 Impact Factor
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    ABSTRACT: The objective of this study was to evaluate the effects of condylectomy and of a functional appliance on the mineral content, density, and area of the mandibular cortical bone in a growing mouse model. In the condylectomy group, a unilateral condylectomy was performed on the right side of the mouse mandible. In the condylectomy + appliance group, a functional appliance was used to reposition the mandible after the unilateral condylectomy. All mice were killed 4 wk after surgery. Each mandible was then subjected to analyses of cortical bone mineral content (CRT_CNT), cortical bone density (CRT_DEN), and cortical bone area (CRT_A) by peripheral quantitative computed tomography (pQCT). The CRT_CNT, CRT_DEN, and CRT_A values were significantly lower in the condylectomized mandible (right side) than in the non-condylectomized mandible (left side). However, in the condylectomized animals in which a functional appliance was used, the CRT_CNT, CRT_DEN, and CRT_A values became higher than those in the mice treated with condylectomy alone. No significant differences were found in the CRT_CNT, CRT_DEN, and CRT_A between non-condylectomized (left side) mandibles, mandibles treated with condylectomy + functional appliance (right side), and control mandibles. It was thus shown that a functional appliance used to reposition the condylectomized mandible forward in a symmetric position induced improvement of the cortical bone in a mouse model in terms of cortical bone mineral content, density, and area.
    European Journal Of Oral Sciences 04/2011; 119(2):136-40. · 1.42 Impact Factor
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    ABSTRACT: At the present time, there are no reports in the literature on the treatment of temporomandibular joint disorder (TMD) by intrusion of molars using mini-screws. This case report describes the treatment for a female patient, aged 19 years seven months, with a TMD and an excessive lower anterior facial height. Overjet and overbite were +5.0 mm and +0.5 mm, respectively. The patient had a history of orthodontic treatment in which her first premolars were all extracted. During the first orthodontic treatment, a clockwise mandibular rotation was observed as a result of the increase of posterior dentoalveolar height. She had temporomandibular joint (TMJ) pain during mouth opening and complained of difficulty in eating due to masticatory dysfunction. The pretreatment Schuller views of both TMJ showed a posterior condyle position. In order to correct the overjet, molar relationship and the mandibular condyle position, a miniscrew was inserted into the palatal region of the upper first molar to intrude the upper posterior teeth. As the upper molars were intruded, the overjet was decreased, and a class I molar relationship was achieved by a counterclockwise mandibular rotation. After one year of treatment, an acceptable occlusion was achieved, and the condyle moved into centric position in the glenoid fossa. The patient's teeth continued to be stable, and she had no pain in TMJ after a retention period of three years. The result of this treatment showed that molar intrusion using miniscrew anchorage is effective for treatment of a TMD patient with a posterior condyle position.
    Cranio: the journal of craniomandibular practice 04/2011; 29(2):155-63. · 1.11 Impact Factor
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    ABSTRACT: Sex hormones are important for bone growth. However, the mechanism by which sex hormone receptors influence bone growth remains unclear. In orthodontic treatment, there is a need to develop an indicator of bone maturity to accurately predict the beginning and end of growth. This indicator might be developed from the screening of sex hormones. The purpose of this study was to investigate the role of each sex hormone receptor on bone growth in newborn mice. Five-day-old C57BL/6J mice were used in this experiment. Forty mice underwent an orchiectomy (ORX), ovariectomy (OVX), or sham surgery. One week after surgery, the femur and the mandible were resected for immunohistochemical staining. Alternatively, 80 mice were daily injected with antagonist against receptors oestrogen alpha (ERα), beta (ERβ), or androgen receptor (AR). One week after the first injection, radiographs of the femur and mandible were taken and then measured. Analysis of variance and pairwise comparisons (Fisher) were performed to examine the differences in values measured among the groups In the sham-operated male and female mice, ERβ was found to be more prominent than ERα and AR during all experimental periods. In the ORX and OVX groups, the expressions of all receptors were significantly reduced in comparison with the sham-operated control group throughout the experiment. Moreover, femur and mandibular growth were significantly affected in the group injected with ERβ antagonist. The deficiency of any sex hormone leads to reduced bone growth. In particular, a disturbance in ERβ produces a greater aberrance in both male and female mice immediately after birth.
    The European Journal of Orthodontics 02/2011; 33(5):564-9. · 1.08 Impact Factor

Publication Stats

383 Citations
96.89 Total Impact Points

Institutions

  • 2014
    • Kanagawa Dental University
      • Department of Orthodontics
      Йокосука, Kanagawa, Japan
  • 1999–2013
    • Hiroshima University
      • • Department of Orthodontics and Craniofacial Developmental Biology
      • • Faculty of Dentistry
      Hiroshima-shi, Hiroshima-ken, Japan