Yayoi Matsuda

Cryopreservation of periodontal ligament cells with magnetic field for tooth banking

The purpose of this study was to establish a long-term tooth cryopreservation method that can be used for tooth autotransplantation. Human periodontal ligament (PDL) cells were frozen in 10% dimethyl sulfoxide (Me(2)SO) using a programmed freezer with a magnetic field. Cells were cryopreserved for 7 days at -150 degrees C. Immediately after thawing, the number of surviving cells was counted and the cells were cultured; cultured cells were examined after 48 h. Results indicated that a 0.01 mT of a magnetic field, a 15-min hold-time, and a plunging temperature of -30 degrees C led to the greatest survival rate of PDL cells. Based on these findings, whole teeth were cryopreserved under the same conditions for 1 year. The organ culture revealed that the PDL cells of cryopreserved tooth with a magnetic field could proliferate as much as a fresh tooth, although the cells did not appear in the cryopreserved tooth without a magnetic field. Histological examination and the transmission electron microscopic image of cryopreserved tooth with a magnetic field did not show any destruction of cryopreserved cells. In contrast, severe cell damage was seen in cells frozen without a magnetic field. These results indicated that a magnetic field programmed freezer is available for tooth cryopreservation.

Association between root resorption incident to orthodontic treatment and treatment factors.

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 Students 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.

Effects of long-term occlusal hypofunction and its recovery on the morphogenesis of molar roots and the periodontium in rats.

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.

Effects of vascular endothelial growth factor-C and -D on osteoclast differentiation and function in human peripheral blood mononuclear cells

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.

A newly developed snack effective for enhancing bone volume

BackgroundThe incidence of primary osteoporosis is higher in Japan than in USA and European countries. Recently, the importance of preventive medicine has been gradually recognized in the field of orthopaedic surgery with a concept that peak bone mass should be increased in childhood as much as possible for the prevention of osteoporosis. Under such background, we have developed a new bean snack with an aim to improve bone volume loss. In this study, we examined the effects of a newly developed snack on bone volume and density in osteoporosis model mice.MethodsOrchiectomy (ORX) and ovariectomy (OVX) were performed for C57BL/6J mice of twelve-week-old (Jackson Laboratory, Bar Harbar, ME, USA) were used in this experiment. We prepared and given three types of powder diet e.g.: normal calcium diet (NCD, Ca: 0.9%, Clea Japan Co., Tokyo, Japan), low calcium diet (LCD, Ca: 0.63%, Clea Japan Co.,) and special diet (SCD, Ca: 0.9%). Eighteen weeks after surgery, all the animals were sacrified and prepared for histomorphometric analysis to quantify bone density and bone mineral content.ResultsAs a result of histomorphometric examination, SCD was revealed to enhance bone volume irrespective of age and sex. The bone density was increased significantly in osteoporosis model mice fed the newly developmental snack as compared with the control mice. The bone mineral content was also enhanced significantly. These phenomena were revealed in both sexes.ConclusionIt is shown that the newly developed bean snack is highly effective for the improvement of bone volume loss irrespective of sex. We demonstrated that newly developmental snack supplements may be a useful preventive measure for Japanese whose bone mineral density values are less than the ideal condition.

RANKL and OPG expression: Jiggling force affects root resorption in rats

OBJECTIVE To immunohistochemically investigate the longitudinal changes in root resorption by jiggling force in experimental animal models. MATERIALS AND METHODS Fifty-six 12-week-old male Wistar rats were used. The maxillary first molars were alternately moved in the buccal and lingual direction in 28 rats (experimental group) using an experimental appliance to produce jiggling forces of 10 g. In another 28 rats (control group), the maxillary first molars were moved in only the lingual direction with a force of 10 g. After 1, 3, 7, 10, 14, 17, and 21 days, the maxillae were resected and subjected to immunohistochemical analysis. The resorption area was quantified histomorphometrically and the number of odontoclasts on the root surface was counted. Expression of RANKL and OPG was also examined by immunohistochemical staining. RESULTS The root resorption area and the number of odontoclasts were significantly greater in the experimental group than in controls. Odontoclasts were detected in the resorption lacunae and PDL in the experimental group, whereas osteoclasts were located only along the alveolar bone in controls. OPG was detected on the alveolar bone in the experimental group and on the root surfaces of the controls. CONCLUSIONS Jiggling force is a critical factor in severe root resorption, affecting RANKL and OPG expression, which accelerates and inhibits odontoclastic induction, respectively.

Influences of abnormal root shape and the amount of tooth movement on the prevalence of root resorption in open bite

Recently, many reports have been made about severe root resorption in open-bite cases during orthodontic treatment. However, no information is available for the association of the prevalence of root resorption with root shape in open-bite cases. The purposes of the this study were to clarify the prevalence and degree of root resorption immediately after orthodontic treatment and to investigate the association with root shape and the amount of tooth movement in patients with normal and open bites. Seventy-five patients treated with multibracket appliances were divided into normaland open-bite groups. The normal-bite group comprised 49 patients and the open-bite 26. The root shape before treatment and the severity of root resorption after treatment were classified according to Malmgren and coauthors. Next, positional changes of the maxillary and mandibular central incisors before and after treatment and its association with root resorption were evaluated. Prevalences of abnormal root shape and root resorption were significantly higher in the open-bite group than in the controls. In the open-bite group, the amounts of lingual movement and extrusion of the maxillary central incisors were significantly greater than in the controls and exhibited a close association with high prevalence of root resorption. From these results, open-bite patients are shown to be involved with a higher risk of root resorption because of abnormal root shapes and greater amounts of tooth movement.

A clinical survey for the association between root resorption incident to orthodontic treatment and host factors

Introduction: The purpose of this study was to clarify the prevalence and degree of root resorption induced by force application during orthodontic treatment. Association between the root resorption and host factors was statistically examined. Materials and methods: In this study, 243 subjects (72 male and 171 female subjects) were randomly selected from patients treated with multibracket appliances at the Orthodontic Department of Hiroshima University Hospital. The severity of root resorption was classified into five groups according to an index score from 0 to 4 defined by Malmgren et al., using pretreatment and post-treatment dental radiographs. Results: Root resorption was found in 78% patients, and prominent, in particular, in the upper and lower incisors and canines. The prevalence of severe root resorption was significantly higher in the teeth with short roots than in those with normal roots. The prevalence was also significantly higher in male than in female patients, and in patients with maxillary protrusion and age>20 years when active treatment was started. Moreover, teeth with trauma tended to exhibit a higher prevalence of root resorption than those without. Conclusions: Maxillomandibular incisors, teeth with short roots, male sex, maxillary protrusion, and age >20 years are risk factors for severe root resorption.

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 osteopetrotic (op/op) mice

OBJECTIVE 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. DESIGN 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. RESULTS 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. CONCLUSIONS 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.

A case of bimaxillary protrusion treated with two-jaw surgery and genioplasty

A 22-year-old female patient visited our clinic with a chief complaint of antero-posterior direction. The maxillary incisors exhibited average labio-lingual inclination, and the mandibular incisors were labially inclined. The maxillary dental midline was shifted by 2.0 mm to the right from the facial midline. This patient was diagnosed as having bimaxillary protrusion and indicated for orthognathic surgery with presurgical and postsurgical orthodontic treatment. Prior to the operation, two mandibular first premolars were extracted and edgewise appliances placed on the maxillary and mandibular dentitions. The total presurgical treatment time was approximately 1 year. During surgery, two maxillary first premolars were extracted and maxillary anterior alveolar osteotomy was executed to move the dento-alveolar segment backward. Le Fort I osteotomy was preformed for the impaction of anterior and posterior segments, and the bones were fixed with titanium plates. Bilateral intraoral vertical ramus osteotomy (IVRO) was executed for counterclockwise rotation of the mandible, then advanced sliding genioplasty was performed along the mandibular plane. Postsurgical orthodontic treatment was continued for 23 months, and lingual bonded retainers and wraparound retainers were used for the retention. A remarkable improvement of gummy smile was achieved by Le Fort I osteotomy and IVRO with maxillary anterior alveolar osteotomy. Moreover, excellent lateral facial proportion was acquired by genioplasty. Orthognathic surgery provides harmony in occlusion and facial profile. DOI: 10.1016/j.odw.2010.11.013