Natsumi Tsuka

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.

Effects of Mandibular Advancement on Growth after Condylectomy

Previous studies have indicated that an injured condyle during adolescence is a causative factor for reduced mandibular growth and resulting asymmetry of the mandible. The aim of this study was to examine the nature of mandibular growth after unilateral condylectomy and to elucidate the effects of mandibular advancement. Sixty growing mice were subjected to unilateral condylectomy, and then one-half of them underwent treatment with a functional appliance. After 4 wks, a unilateral condylectomy produced reduced growth of the mandible and a subsequent lateral shift to the affected side. However, reduced growth and a lateral shift of the mandible were eliminated by a functional appliance, and prominent regeneration of the condyle was also demonstrated. It was shown that mandibular advancement provides for the regeneration of cartilaginous tissues on injured condyles and recovery of reduced mandibular growth, leading to correction of the lateral shift of the mandible.

Correction of severe open bite using miniscrew anchorage.

This report describes the treatment of a case of severe open bite with posterior crossbite. While treating open bite, the outcome may not always be successful with orthodontic therapy alone. In such cases, surgical therapy is often chosen to gain a stable occlusion. Skeletal anchorage systems such as miniscrews are now frequently used for correcting severe malocclusion. In this report, we treated an open bite by intruding the molars with miniscrews placed bilaterally in the interdental space between both the upper and lower posterior teeth. The active treatment period was 36 months and the patients teeth continued to be stable after a retention period of 36 months.

Expression of Sox 9 and type II and X collagens in regenerated condyle

The present study was designed to examine the expression of Sox 9 and type II and X collagens in regenerated condyle resulting from the use of a functional appliance. Ninety, 3-week-old, mice were divided equally into the following groups: two experimental groups (condylectomy group and condylectomy with functional appliance group) and the corresponding control group. In the condylectomy group, a unilateral condylectomy was performed on the right side. In the condylectomy with appliance group, the mandible was repositioned in a forward direction using a functional appliance after unilateral condylectomy. The expression of Sox 9 and type II and X collagens in the condyle was determined immunohistochemically 4 weeks after surgery. In mice with a condylectomy, the expression was minimal. On the other hand, these factors were highly expressed in the condylectomized side with the appliance. It is thus speculated that cartilaginous regeneration is due to the expression of chondrogenic factors, such as Sox 9 and type II and X collagens. It is also suggested that condyle regeneration results from an optimal intra-articular environment with appropriate joint spaces achieved by condylar repositioning.

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.

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