Journal of Hard Tissue Biology
Online ISSN : 1880-828X
Print ISSN : 1341-7649
ISSN-L : 1341-7649
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Original
  • Xiaoyun Ma, Mengjiao Zhu, Xiaohui Mi, Fengshan Chen
    2020 Volume 29 Issue 2 Pages 55-62
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    Fibroblast growth factor 23 (FGF23), which belongs to FGF family, regulates the serum phosphate concentration and plays an essential role in bone development. Our previous study has reported a mutation of FGF23 c.35C>A in the mandibular prognathism (MP) pedigree. The aim of this article was to determine the effect of FGF23 c.35C>A mutation in alveolar bone remodeling during orthodontic tooth movement (OTM). An orthodontic spring was performed in an OTM mouse model for 7 days. Micro-computed tomography (micro-CT) was used to measure the amount of OTM and observe the periodontal ligament (PDL) after mechanical loading, hematoxylin-eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) staining, Runx2 immunostaining. The reverse transcription polymerase chain reaction (RT-qPCR) was also performed to determine mRNA levels. The mutation of FGF23 c.35C>A decreased the OTM, the mRNA expression levels of RANKL, RANK and the count of osteoclasts in compression side (CS). In contrast, the count of osteoblasts in tension side (TS), the mRNA expression levels of COL1A1, OCN were increased when compared to FGF23-WT group after OTM. In summary, we ascertained the obstruction of FGF23 c.35C>A in orthodontic tooth movement, which might due to the stimulation of osteogenesis and the inhibition of bone resorption.

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  • Satoru Matsuo, Masako Toda-Nakamura, Kyoko Oka, Hiroshi Kajiya, Kayoko ...
    2020 Volume 29 Issue 2 Pages 63-70
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    Cyclophosphamide (CPA) is a commonly used chemotherapeutic agent to treat cancer. Among its many side effects is the well-known consequence on tooth development when administered at early ages. This study elucidated the effects of CPA on development of the mandibular molar in mice. Mice received a single intraperitoneal injection of CPA at different doses and development times. CPA treatment led to weight loss and alopecia but had no effect on disturbances in tooth eruption or crown shape. However, at higher doses, there was arrested root development and early apical foramen closure histologically related to the formation of the cervical loop structure in the apical portion of the root. In cell culture experiments, the Hertwig’s epithelial root sheath cell line (HERS01a) was cultured with or without CPA. At high doses of CPA, HERS01a cells showed decreases in E-cadherin expression, while N-cadherin expression was upregulated, indicating that this cadherin switch may promote an epithelial-to-mesenchymal transition (EMT)-like phenomenon. These findings suggest that administration of high doses of CPA can lead to arrested root development of the molars and an EMT-like phenomenon.

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  • Chengdong Piao, Zhengwei Li, Jie Ding, Daliang Kong
    2020 Volume 29 Issue 2 Pages 71-76
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    This study aims to compare the bone mechanical properties of adipose-derived mesenchymal stem cells (ADMSCs) and raloxifene in treating osteoporosis and to provide related biomechanical basis. The serum of animal model of osteoporosis was sampled after ADMSCs or raloxifene intervention and measured BALP, TRACP -5b, MMP -9, and Cath-K the femur was taken for compression test, tibia for shock test, vertebrae for bone mineral densitytest, humerus for histomorphometric index test. In Group AMSCs, BMD and BALP were higher than those in Group MOD, in Group RAL, TRACP-5b, MMP-9 mL-1 and Cath-K were lower than those in Group MOD with significant differences (p < 0.05). In Group AMSCs, BMD, BALP, and such mechanical performance indexes as maximum compressive load, maximum stress, maximum strain, elastic modulus, shock energy, and shock toughness were significantly larger than Group MOD and Group RAL (p < 0.05). After AMSCs intervention, the bone quality can be improved, and the compression and shock mechanical properties can be restored.

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  • Yoshitomo Honda, Anqi Huang, Jianxin Zhao, Xiaoyu Han, Yuji Kurushima, ...
    2020 Volume 29 Issue 2 Pages 77-84
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    The potential of plant-derived polyphenols in bone tissue engineering has not been fully realized owing to difficulties in maintaining their stability in affected parts. Catechins, such as epigallocatechin gallate (EGCG), are not fully utilized in bone regenerative medicine. Here, we demonstrated that chemical and non-chemical modifications of gelatin with EGCG resulted in distinct bone-forming abilities in critical-sized bone defects (9 mm) in rat calvaria. We prepared two EGCG-containing gelatin sponges: vacuum-heated gelatin sponges modified chemically with EGCG (AC-vhEGCG-GS) and vacuum-heated gelatin sponges with EGCG (no chemical modification; NC-vhEGCG-GS). Both sponges were characterized using scanning electron microscopy and degradability and EGCG-retention tests. The bone-forming ability of the sponges were estimated using micro-computed tomography and hematoxylin-eosin staining; the quality of newly formed bone (collagen maturation) was determined using picrosirius red staining and polarized microscopy. Both sponges had a spongy and soft texture with macropores ranging 50-150 µm with negligible differences in degradability. The NC-vhEGCG-GSs released all their EGCG content within 1 h, whereas AC-vhEGCG-GSs retained 75% of the EGCG for up to 24 h. In addition, AC-vhEGCG-GSs resulted in a significantly greater bone formation than NC-vhEGCG-GSs 4 w after implantation, with negligible differences in collagen maturation. These results suggest that the chemical modification of gelatin with EGCG might be a promising strategy to fully utilize the pharmacological effects of EGCG for natural polymer-based sponges. Moreover, the release rate of EGCG from gelatin is possibly a screening parameter affecting the function of EGCG in vivo.

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  • Munetaka Naitoh, Shoko Tamaki Takada, Satoshi Nishida, Hiroyuki Nawa, ...
    2020 Volume 29 Issue 2 Pages 85-90
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    Supernumerary teeth are most commonly located in the maxillary incisor region. Recently, their directions and crown shapes were observed in detail using cone-beam computed tomography (CBCT), and their sizes were measured. Here, the root shapes and courses of the root canal of supernumerary teeth in the maxillary incisor region were assessed using CBCT. A total of 126 supernumerary teeth were assessed. The root shape, root curvature, and root canal deformity were evaluated. Also, delayed eruption of the permanent incisor and a median diastema were evaluated as complications caused by supernumerary teeth. The bifurcated-root type was noted in only 4.0%. Root curvature was observed in 27.4%, and root canal deformity was observed in 12.4%. Significant differences in root lengths were noted in root curvature and root canal deformity. Delayed eruption was observed in 12.9%, and a median diastema was observed in 25.0%. In conclusion, the root shapes and courses of the root canal of supernumerary teeth in the maxillary incisor region could be observed in detail using CBCT. The bifurcated-root type was rare. Root curvature was frequent in the inverted and horizontal types. Root canal deformity was frequent in the inverted type.

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  • Hua Song, Shiqi Suo, Chao Ning, Yang Zhang, Weidong Mu, Song Chen
    2020 Volume 29 Issue 2 Pages 91-98
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    To investigate the clinical efficacy of autologous bone marrow mesenchymal stem cells transplantation in patients with acute spinal cord injury. The clinical manifestations of these patients are abnormal sensation and motor functions that dominated by damaged nerve segment. A total of 36 patients with acute spinal cord injury were randomly divided into control group (n=18, treated with decompression + internal fixation + conventional medical treatments) and experimental group (n=18, control group’s treatment + autologous bone marrow mesenchymal stem cells injection in the subarachnoid space). The total effective rate in the observation group was higher than control group (P=0.045). After 12 months of treatment, the SCIM-III score, ASIA exercise score, Botsford score, and ASIA sensory score were significantly higher than those before treatment in both groups, and the increase in the observation group was more obvious (P<0.05). The time for muscle strength and muscle function recovery and independent walking in the observation group were less than those of the control group (P<0.05). Autologous bone marrow mesenchymal stem cells transplantation can improve the therapeutic effect and nerve function, promote the recovery of motor function, sensory function and spinal cord injury without disorder in humoral immune function.

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  • Fang Zhang, Shan Zhang, Yue Hu, Nannan Wang, Li Wu, Meng Ding
    2020 Volume 29 Issue 2 Pages 99-104
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    We aimed to study the role of the PI3K/AKT signaling pathway in the proliferation, migration and odontogenic differentiation of human dental pulp stem cells (hDPSCs). hDPSCs were cultured in vitro and treated with LY294002 (LY), an inhibitor of the PI3K pathway. Cell proliferation and migration were detected by CCK8 assay and scratch assay respectively. The levels of PI3K and AKT pathway downstream proteins AKT, phosphorylated AKT(p-AKT) as well as odontogenic differentiation marker DSPP were measured by Western blot at 6, 12, 24, 48 and 72 h. Blank control, mineralization induction, LY and mineralization induction + LY groups were set. After 14 days of mineralization induction, the formation of mineralized nodules was detected by alizarin red staining. At 24, 48 and 72 h, the optical densities of LY group were significantly lower than those of control group (P<0.05). Compared with 0 h after scratching, the cells in each group migrated at 24 h. Compared with control group, the number of migrating cells in LY group was significantly lower. After 14 days of mineralization induction, the mineralization induction group had most mineralized nodules, with the highest density. The protein levels of p-AKT and AKT remained almost unchanged at 0, 6, 12, 24, 48 and 72 h. After addition of LY294002, the protein level of p-AKT decreased from 6 to 72 h, that of AKT did not change significantly, and that of DSPP reduced. The PI3K/AKT signaling pathway can promote the proliferation, migration and odontogenic differentiation of hDPSCs.

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  • Masashi Takagi, Keiichi Kanayama, Keisuke Mukai, Hirotsugu Morinaga, A ...
    2020 Volume 29 Issue 2 Pages 105-110
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    A bone substitute, beta-tricalcium phosphate, was combined with a basic fibroblast growth factor to create a fibroblast growth factor/tricalcium phosphate complex. This complex was then implanted into canine mandibles to evaluate the usefulness of this treatment in bony defects around dental implants. Four beagles received implants that were installed into fresh extraction sockets of third and fourth mandibular premolars. All surgical procedures were performed under general anesthesia with intravenous sodium thiopental. Gingival incisions were performed mesially from the second premolar and distally to molars. Full-thickness buccal and lingual flaps were raised. After vertical interradicular sectioning, each root was carefully elevated and then gently extracted. Buccal bone defects adjacent to extraction sockets with a height of 7 mm and 3 mm in the mesio-distal direction were created on third and fourth premolars, respectively, using round burs with sterile saline irrigation. These defects were then assigned to the control, fibroblast growth factor, tricalcium phosphate complex, or fibroblast growth factor/tricalcium phosphate group. Animals were sacrificed 4 weeks after surgery. Tissue blocks were fixed in 4% paraformaldehyde and then scanned with micro-computed tomography before sectioning for light microscopy. New bone height and bone mineral density in sites were significantly larger in tricalcium phosphate and fibroblast growth factor than in tricalcium phosphate groups. New bone height was also significantly larger in tricalcium phosphate and fibroblast growth factor/tricalcium phosphate groups than in fibroblast growth factor and control groups. These results indicate that fibroblast growth factor/tricalcium phosphate complex is useful as a growth factor carrier and scaffold for bone augmentation around dental implants.

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  • Mikako Inazumi, Masanori Takekawa, Kumiko Oka, Naohiro Shibayama
    2020 Volume 29 Issue 2 Pages 111-122
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    We examined whether the effect of adipose tissue-derived stem cell (ADSC) transplantation improved bone wounds healing irradiation. ADSCs were harvested from F344 rats and the cells cultured until the second passage for transplantation. Before ADSC transplantation, a single dose of 15 Gy irradiation was administered to the head of every rat using 137Cs gamma-ray irradiation system, except for the rats of the control group. Two weeks after the irradiation, ADSCs were seeded on a carrier (collagen sponge) and transplanted into the bone defects formed on the rat parietal bones (the irradiation transplant group). This group was compared with two other groups: the carrier only group (without ADSCs) implanted after irradiation (the irradiation group) and; the group in which the carrier was implanted without irradiation (the control group). The results were obtained by histological, immunohistochemistry and ultrastructural observation. We examined the effects of ADSC transplantation on the delay of bone wound healing after irradiation. The new bone formation area of the irradiation group was significantly suppressed (p <0.05) as compared with the other groups. The vascular density at the site of new bone formation in the irradiation group decreased as compared with the other groups. In the irradiation transplant group, the BrdU positive cells were arranged like osteoblasts at the newly formed bone area and were also seen in the vascular wall and the interstitial tissue at the bone defect site. In the irradiation transplant group, VEGF positive cells appeared in blood vessels and the interstitial tissue in the bone defect area, whereas in the other groups, they were hardly found. ADSCs improved bone wound healing after irradiation by direct differentiation of bone forming cells and vascular endothelial cells. In addition, ADSCs have a paracrine effect which induces cell differentiation into VEGF positive cells which acts on angiogenesis.

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  • Nguyen Dien Bien, Kei-ichiro Miura, Yoshinori Sumita, Yuya Nakatani, R ...
    2020 Volume 29 Issue 2 Pages 123-130
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    Bone morphogenetic protein-2 (BMP-2) has diverse functions and is especially important in bone and cartilage development. Recombinant human BMP-2 (rhBMP-2) is an osteoinductive growth factor that has been clinically applied as a bone graft substitute. However, high-dose rhBMP-2 can cause complications such as induction of significant swelling that can endanger the patient’s life. Atelocollagen sponge (ACS) is the commercially provided standard carrier of rhBMP-2 in clinical applications. However, a large concentration of rhBMP-2 is required to be clinically effective with ACS as the carrier. Octacalcium phosphate/collagen (OCP/Col) has been shown to be an excellent bone substitute compared with other bone substitute materials such as hydroxyapatite or β-tricalcium phosphate due to its biological properties. In this study, we evaluated the use of OCP/Col as a carrier to minimize the effective dose of rhBMP-2. ACS or OCP/Col discs impregnated with different rhBMP-2 concentrations were implanted in mice calvarial bone defects. Morphological analysis with micro-CT both at 4 and 6 weeks post-implantation showed homogenous hard tissue formation in the defects of the OCP/Col group at all rhBMP-2 concentrations tested (0, 0.25, 0.50, or 1.00 μg). In contrast, ACS alone or with 0.25 μg of rhBMP-2 showed almost no bone formation. However, bone mineral density in all groups of ACS and OCP/Col was not dependent on rhBMP-2 concentration. Histological evaluation indicated that bone formation progressed depending on rhBMP-2 concentration in the defects of both the ACS and OCP/Col groups, although the newly formed bone area was significantly higher in the OCP/Col group than in the ACS group. These results indicate that OCP/Col could be an effective carrier of rhBMP-2, minimizing the application dose of rhBMP-2 in clinical settings and avoiding the complications caused by high-dose rhBMP-2.

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Clinical Note
  • Keisuke Matsumoto, Kazuya Inoue, Naoko Imagawa, Yoichiro Nakajima, Hir ...
    2020 Volume 29 Issue 2 Pages 131-134
    Published: 2020
    Released: April 20, 2020
    JOURNALS FREE ACCESS

    The success rate of dental implants depends largely on osseointegration of the implant. One method for evaluating osseointegration that has garnered attention is measurement of the implant safety quotient (ISQ) using resonance frequency analysis, but there have been few studies that have observed chronological changes in ISQ in the same implant type. Here, we observed chronological changes in ISQ in high-temperature acid-etched implants. The implants that were studied were 43 Swiss Precision and Innovation implants (SPI® implant, Thommen Medical, Grenchen, Switzerland) with a diameter of 4.0 mm that were placed at our clinic in 2017–2018 by the same technician. ISQ was measured at primary and secondary surgery using an Osstell IDx tooth contact analysis device (Osstell AB, Gothenburg, Sweden). Secondary surgery was carried out 6 months after placement in the maxilla and 3 months after placement in the mandible. The ISQ and change in ISQ thus obtained were investigated by placement site. ISQ at primary surgery was significantly higher in the mandible than the maxilla (p<0.001). Change in ISQ from primary to secondary surgery tended to be greater in the maxillary anterior tooth region and the maxillary molar region than the mandibular anterior tooth region and the mandibular molar region. By comparing ISQ from primary to secondary surgery using a single implant type, it was observed that ISQ and change in ISQ varied according to placement site.

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