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ABSTRACT: Despite efforts in peripheral nerve injury and regeneration, it is difficult to achieve a functional recovery following extended peripheral nerve lesions. Even if artificial nerve conduit, cell components and growth factors can enhance nerve regeneration, integration in peripheral nerve repair and regeneration remains yet to be explored. For this study, we used chitosan/gelatin nerve graft constructed with collagenous matrices as a vehicle for Schwann cells and transforming growth factor-β1 to bridge a 10-mm gap of the sciatic nerve and explored the feasibility of improving regeneration and reinnervation in rats. The nerve regeneration was assessed with functional recovery, electrophysiological test, retrograde labeling, and immunohistochemistry analysis during the post-operative period of 16 weeks. The results showed that the internal sides of the conduits were compact enough to prevent the connective tissues from ingrowth. Nerve conduction velocity, average regenerated myelin area, and myelinated axon count were similar to those treated with autograft (p > 0.05) but significantly higher than those bridged with chitosan/gelatin nerve graft alone (p < 0.05). Evidences from retrograde labeling and immunohistochemistry analysis are further provided in support of improving axonal regeneration and remyelination. A designed graft incorporating all of the tissue-engineering strategies for peripheral nerve regeneration may provide great progress in tissue engineering for nerve repair.
Cell biochemistry and biophysics 06/2013; · 3.34 Impact Factor
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ABSTRACT: Apert syndrome is a common craniosynostosis caused by gain-of-function missense mutations of fibroblast growth factor receptor 2 (FGFR2). Mice with the FGFR2 S252W mutation can elucidate the mechanism by which the human Apert syndrome phenotypes arise. However, many studies have focused on mutant skull and long bone malformation, only few studies have focused on mandible changes. Bone formation and micro-architecture between 28- and 56-day-old mutant mice and controls were compared to investigate the changes in the mandibular micro-architecture caused by the Fgfr2(S252W/+) mutation to provide a basis for exploring the pathogenesis and therapeutic measures of human Apert syndrome. Fgfr2(S252W/+) mutant mice were established, and their general characteristics, including weight, naso-anal length, and calcium and phosphate content in serum and bone were tested. Calcein labeling, tartrate-resistant acid phosphatase staining and toluidine blue staining were used to detect osteoblast and osteoclast activities. H&E staining and micro-CT detection were used to test micro-architecture changes. The changes in mineral apposition rate and micro-architecture of the Fgfr2(S252W/+) mice were statistically significant; however, the magnitude of the micro-architecture became less with age. The Fgfr2(S252W/+) mutation may retard mandibular bone formation, decreased bone volume, and compromised skeletal architecture by regulating both osteoblastogenesis and osteoclastogenesis. © 2013 Wiley Periodicals, Inc.
American Journal of Medical Genetics Part A 03/2013; · 2.39 Impact Factor
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ABSTRACT: Several populations of stem cells, including those from the dental pulp and periodontal ligament, have been isolated from different parts of the tooth and periodontium. The characteristics of such stem cells have been reported as well. However, as a common progenitor of these cells, ectomesenchymal stem cells (EMSCs), derived from the cranial neural crest have yet to be fully characterized. The aim of this study was to better understand the characteristics of EMSCs isolated from rat embryonic facial processes. Immunohistochemical staining showed that EMSCs had migrated to rat facial processes at E11.5, while the absence of epithelial invagination or tooth-like epithelium suggested that any epithelial-mesenchymal interactions were limited at this stage. The p75 neurotrophin receptor (p75NTR), a typical neural crest marker, was used to select p75NTR-positive EMSCs (p75(+) EMSCs), which were found to show a homogeneous fibroblast-like morphology and little change in the growth curve, proliferation capacity, and cell phenotype during cell passage. They also displayed the capacity to differentiate into diverse cell types under chemically defined conditions in vitro. p75(+) EMSCs proved to be homogeneous, stable in vitro and potentially capable of multiple lineages, suggesting their potential for application in dental or orofacial tissue engineering.
Biochemical and Biophysical Research Communications 09/2012; 427(1):5-10. · 2.48 Impact Factor
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ABSTRACT: OBJECTIVES: This study aimed to investigate the root canal morphology of mandibular first premolar teeth in a population from southwestern China by micro-computed tomography (micro-CT). MATERIALS AND METHODS: Human mandibular first premolars (115) were selected and prepared for micro-CT analysis with a slice thickness of 30 μm. Details of root canal orifices, canals, accessory canals, apical foramina-apical delta intercanal communication, loops and isthmuses, and mesial invagination were analyzed from reconstructed three-dimensional (3D) images. RESULTS: Canal patterns categorized according to the classification defined by Vertucci (Endod Top 10:3-29, 2005) as types I (65.2 %), III (2.6 %), V (22.6 %), and VII were identified (0.9 %). Accessory canals were present in 35.7 % of the samples and were predominantly located in the apical third of the root. A single apical foramen was observed in 50.4 % of the samples and two or three foramina in 28.7 % and 14.8 %, respectively. Apical delta was identified in 6.1 % of the samples and the prevalence of intercanal communication and loops was 3.5 % and 7 %, respectively. Mesial invagination of the root was identified in 27.8 % of the samples, the majority of which contained multiple canals. CONCLUSIONS: The data obtained in this study revealed complex root morphology with high prevalence of multiple canals, more than half of which exhibited type I canal patterns. CLINICAL RELEVANCE: Micro-CT was used as a noninvasive technique for 3D investigation of root canal morphology in the mandibular first premolars of a population from southwestern China. Furthermore, data obtained revealed complex anatomy of various types.
Clinical Oral Investigations 07/2012; · 2.36 Impact Factor
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ABSTRACT: To observe the changes of surface morphology and temperature of dental pulp cavity in vitro after irradiated by Er:YAG laser with different energy and irradiation time.
All of the 96 samples from 24 teeth in vitro were collected from dental clinical departments then divided into two groups (group A and group B) randomly. We chose the energy of 20 Hz, and 1, 2, 3, 4, 5, 6 W to treat the samples in group A and group B and the irradiation time was 10s or 20s. We recorded the temperature changes of dental pulp cavity by digital thermometer and observe the morphology of tooth enamel by scanning electron microscope (SEM).
With the extension of irradiation time and increasing of energy, the temperatures of dental pulp cavity were significantly increased after the treatment of Er: YAG laser. The two groups of tooth enamel surface morphology were changed after irradiated by Er: YAG laser with different energy and irradiation time. However, there was no melting and carbonation on the surface of tooth enamel after the treatment of Er:YAG laser in two groups.
The temperatures of dental pulp cavity were increased after irradiated by increasing laser energy density fom 1 W to 6 W. No melting or carbonized phenomenon was found in enamel within the energy of 1 W to 6 W. All the data would provide evidences for clinical treatment of cavity.
Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 04/2012; 30(2):206-8.
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ABSTRACT: Little is known about the lingual canal in the Vertucci type V mandibular first premolar. This study investigated the location of the lingual canal orifice and the curvature of the lingual canal by using micro-computed tomography.
One hundred fifteen mandibular first premolars were scanned by micro-computed tomography, reconstructed 3-dimensionally by using Mimics 10.01 software, and displayed in parallel projection mode. Twenty-six teeth with Vertucci type V canal were selected for further study. The lingual canal orifice was located by measurements made in both lingual and proximal views. The angle alpha (α) between the start of the lingual canal and the main canal and the angle beta (β) of the curvature of lingual canal were also measured.
In proximal view, 69% of lingual canals were located in the middle third of the tooth and the remainder in the apical third. In lingual view, 73% were located in the middle third of the root and the remainder in the coronal third. Mean angle α and angle β were 33.54° and 26.66°, respectively, in proximal view and 8.31° and 11.31°, respectively, in lingual view (P < .05). The highest values of angles α and β were observed in proximal view (65.24°and 43.39°, respectively). In most cases, angles α and β were severely curved in proximal view and straight or only slightly curved in lingual view.
Detailed information on the lingual canal is essential for successful endodontic treatment in patients with mandibular first premolar. The view used for imaging influences the information obtained.
Journal of endodontics 03/2012; 38(3):309-12. · 2.95 Impact Factor
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ABSTRACT: To compare the consistency of root canal configuration types of mandibular first premolar by using micro-CT and radio visio graphy (RVG).
One hundred extracted mandibular first premolars with complete dental root and apex which received no endodontic treatment were randomly selected. Each tooth was radiographed with RVG through a buccolingual and mesiodistal direction, and then scanned with micro-CT and reconstructed. The classifications of the root canal types according to Vertucci's type with the two methods were compared.
The canal patterns were classified as type I (67%), type III (3%), type V (18%), type VII (2%), additional type (10%) with micro-CT and canal patterns as type I (71%), type III (2%), type V (23%), type VII (1%), additional type (3%) with RVG. 63% of teeth showed one canal in both micro-CT and RVG. Only 25% of teeth were diagnosed as complex canal by the same canal type in both micro-CT and RVG. The Kappa value between micro-CT and RVG was 0.541 which suggested that the two kinds of methods had intermediate consistency. 82.8% of the premolars with root groove had two or more than two canals.
Although RVG can basically reflect the root canal system type of the mandibular first premolars in vitro, it offers poor accuracy images to complex root canals. Micro-CT three-dimensional images could clearly and precisely display the root canal system morphology of the mandibular first pre-molars in vitro.
Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 02/2012; 30(1):57-60.
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ABSTRACT: Adipose tissue-derived stem cells (ADSCs), which are easily harvested and show excellent pluripotency potential, have generated considerable interest in regenerative medicine. In this study, the differentiation of ADSCs was assessed after treatment with dental follicle cell conditioned medium (DFCCM) containing dentin non-collagenous proteins (dNCPs). ADSCs exhibited a fibroblast-like morphology and high proliferative capacity. However, after treatment with dNCPs/DFCCM, ADSCs changed from a fibroblast-like to cementoblast-like morphology and significantly lost their proliferative capacity. Alkaline phosphatase activity and in vitro mineralization behaviour of ADSCs were significantly enhanced. Mineralization-related markers including cementum attachment protein, bone sialoprotein, osteocalcin, osteopontin and osteonectin were detected at mRNA or protein levels, whereas dentin sialophosphoprotein and dentin sialoprotein were not detected, implying a cementoblast-like phenotype. These results demonstrate that ADSCs acquired cementoblast features in vitro with dNCPs/DFCCM treatment and could be a potential source of cementogenic cells for periodontal regeneration.
Biochemical and Biophysical Research Communications 06/2011; 409(3):583-9. · 2.48 Impact Factor
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Na Liu,
Songtao Shi, Manjing Deng,
Liang Tang,
Guangjing Zhang,
Ning Liu,
Bofu Ding,
Wenjia Liu,
Yali Liu,
Haigang Shi,
Luchuan Liu,
Yan Jin
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ABSTRACT: Periodontal ligament stem cells (PDLSCs), a new population of mesenchymal stem cells (MSCs), have been isolated from the periodontal ligament (PDL). The capacity of multipotency and self-renewal makes them an excellent cell source for bone regeneration and repair. However, their bone-regeneration ability could be awakened in inflammatory microenvironments, which may be the result of changes in their differentiation potential. Recently, genetic evidences has shown that the Wnt pathway plays an important role in bone homeostasis. In this study we have determined the specific role of β-catenin in osteogenic differentiation of PDLSCs obtained from inflammatory microenvironments (P-PDLSCs). The inflammatory microenvironment, while inhibiting osteogenic differentiation potential, promotes proliferation of MSCs. A higher the level of β-catenin in P-PDLSCs than in H-PDLSCs (PDLSCs obtained from a healthy microenvironment) resulted in the same disparity in canonical Wnt signaling pathway activation between each cell type. Here we show that activation of β-catenin suppresses the noncanonical Wnt/Ca(2+) pathway, leading to increased proliferation but reduced osteogenic differentiation of P-PDLSCs. Downregulation of the levels of β-catenin by treatment with dickkopf-1 (DKK-1) leads to activation of the noncanonical Wnt/Ca(2+) pathway, which, in turn, results in the promotion of osteogenic differentiation in P-PDLSCs. Interestingly, β-catenin can affect both the canonical Wnt/β-catenin pathway and the noncanonical Wnt/Ca(2+) pathway. Our data indicate that β-catenin plays a central role in regulating osteogenic differentiation of MSCs in inflammatory microenvironments. Given the important role of Wnt signaling in osteogenic differentiation, it is possible that agents that can modify this pathway may be of value in bone regeneration by MSCs in chronic inflammatory microenvironments.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 06/2011; 26(9):2082-95. · 6.04 Impact Factor
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ABSTRACT: The purpose of this study was to investigate the effect of pulse Nd:YAG laser on human dentine adhesion by optimizing the laser parameter combination and comparing it with other pretreatment methods for dentine adhesion.
In recent decades, many scholars have been seeking an optimal method to enhance the bond strength of resin to human dentine. However, little improvement has been achieved. In this study, pulse Nd:YAG laser was studied as a pretreatment method for dentine adhesion.
Two-hundred ten freshly extracted, caries-free human premolars were used in this study, which was conducted after approval from the IRB. Ninety of them were selected and randomly divided into nine groups, according to parameter combinations of pulse Nd:YAG laser. Tensile-bond strength was tested, and the laser parameter combination was optimized for later experiments. The other teeth were randomly divided into six groups: laser-irradiated, acid-etched, laser + acid, 10-3 solution, laser + 10-3 solution, and negative control (unconditioned). Each group had 20 specimens: 10 for tensile-bond strength tests and the other 10 for microleakage examination. After the bond-strength test, the fractured surfaces were examined under scanning electronic microscopy.
The bond strengths fluctuated with different laser-parameter combinations applied and showed significant differences in different laser-parameter groups (p < 0.01). The highest mean of tensile-bond strength was found in the group irradiated with the parameter combination of 1 W/15 Hz. In the contrasting experiments, the laser-irradiated group, the 10-3 solution group, and the laser + 10-3 solution groups showed higher tensile-bond strength and lower microleakage than did the other three groups (p < 0.05).
Pulse Nd:YAG laser, 10-3 solution, and their combination showed favorable effects on bond strength and adaptation of resin to human dentine and can be used to pretreat dentine surfaces before adhesion. The optimal parameter combination of pulse Nd:YAG laser was determined to be 1 W/15 Hz in this study.
Photomedicine and laser surgery 10/2010; 28(6):741-6. · 1.76 Impact Factor
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ABSTRACT: Cranial neural crest-derived ectomesenchymal cells represent a population of pluripotent stem cells giving rise to many of the various oro-facial and dental tissues. The factors determining the terminal fate of these cells are still unclear. The potentiality of human embryonic ectomesenchymal cells from the first branchial arch have been investigated when isolated and grown in a three-dimensional (3D)-collagen gel culture system in the presence of dentin matrix-derived non-collagenous proteins (DNCP) and TGFbeta-1. Functional differentiation of cells showing some characteristics of odontoblast-like cells could be observed when the cells were cultured with DNCP+TGFbeta-1 or DNCP, however, only cytological differentiation was observed during culture with TGFbeta-1 alone. The characteristics of these cells was assessed by morphological appearance, expression of the odontoblast phenotype marker dentin sialophosphoprotein (DSPP), increased alkaline phosphatase levels and formation of mineralised nodules in vitro. The results indicate that these embryonic cells from the first branchial arch are capable of responding to the inductive stimulus of DNCP or DNCP+TGFbeta-1 when isolated and grown in the 3D collagen gel culture system. The capacity of the isolated cells to differentiate into mineralizing cells showing some characteristics of odontoblast-like cells under these growth conditions highlights the potential of such approaches for tissue engineering strategies for hard-tissue regeneration after injury.
Archives of Oral Biology 12/2005; 50(11):937-45. · 1.60 Impact Factor
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ABSTRACT: To investigate the possibility of ectomesenchymal stem cell of human embryo facial process in differentiating into osteoblasts.
Ectomesenchymal stem cells of human embryo facial process were isolated and cultured in mineralized promoting solution containing 10 mmol/L beta-glycerophosphate, 100 microg/ml ascorbic acid and 10 nmol/L dexamethasone supplemented with 15% FBS. The morphological change was observed by phase contrast microscopy. The characteristics of cells was identified by immunohistochemistry assay. Alkaline phosphatase activity was tested and the form of mineralized nodules was tested with Von Kossa staining. The expression of osteocalcin was identified by RT-PCR.
There were significant changes in the shape of the cells after 3 days cultured in mineralized promoting solution. The cells became larger and the shape changed from fibroblast-like to multilateral. The result for anti-collogen type I staining was positive. The alkaline phosphatase activity increased. Mineralized nodules were formed after cultured 25 days by Von Kossa staining. RT-PCR assay showed induced cells expressed osteocalcin.
Ectomesenchymal stem cells of human embryo facial process can be induced to differentiate into osteoblasts by mineralized promoting solution.
Zhongguo xiu fu chong jian wai ke za zhi = Zhongguo xiufu chongjian waike zazhi = Chinese journal of reparative and reconstructive surgery 08/2004; 18(4):314-7.
