Biomedical Research ; trends ; China ; Dental Pulp ; physiology ; Humans

OBJECTIVETo investigate the effect of Notch signaling pathway on human dental pulp cells.

METHODSThe γ-secretase inhibitor N-[N-(3, 5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester(DAPT) was applied to inhibit the Notch signaling pathway of human dental pulp cells. The solvent dimethly sulfoxide (DMSO) served as the negative control.Senescence conditions were evaluated by cells morphology changes, the alkaline phosphatase (ALP) expression and its activity, senescence-associated β-galactosidase (SA-β-Gal) expression and the senescence related gene p53 expression.

RESULTSAfter inhibition of the Notch signaling pathway, morphology changes, including flatter cells, larger plasma area, were seen in the 10th passage human dental pulp cells. ALP expression and activity showed a significant decrease at the 8th passage after inhibition (35.36 ± 2.55) U/g, compared with the negative control group[(49.76 ± 4.30) U/g] (t = 4.989, P = 0.008).SA-β-Gal-positive cells could be seen as early as the 8th passage and more positive cells were evident at the 10th passage. The relative expression level of p53 gene was elevated in the 10th passage cells (1.7 ± 0.4) compared with the negative control group(1.0) (t = 3.581, P = 0.012).

CONCLUSIONSHuman dental pulp cells became senescent at earlier passages after inhibition of Notch signaling pathway.Notch signaling pathway may affect life cycle of human dental pulp cells.

Cells, Cultured ; Dental Pulp ; metabolism ; Epithelial Cells ; Humans ; Receptors, Notch ; physiology ; Signal Transduction

OBJECTIVETo test the capacity of the stem cells derived from human exfoliated deciduous teeth in in vitro differentiation into osteoblasts.

METHODSStem cells were isolated from the exfoliated deciduous teeth of healthy children and sorted into CD34(+)/CD117(+) cells and the remaining mixed cells using flow cytometry. After in vitro cell culture, the differentiation capacity into osteoblasts of the two groups of cells was evaluated by detecting the markers of osteoblasts using immunocytochemical techniques and fluorescent quantitative PCR. Mineralization assay was performed to identify the cell differentiation.

RESULTSThe cells isolated by typsin digestion grew in the manner of fibroblasts. After a 30-day culture of the two groups of cells, immunocytochemistry detected the expressions of osteoblast markers RUNX-2, OC, and BSP. After 40 days of cell culture, the mRNA expressions of RUNX-2, OC and BSP genes were significantly different between the two groups. At day 50 of cell culture, the CD34(+)/CD117(+) cells exhibited positivity for von Kossa's staining and alizarin red staining, but the mixed cells showed negative staining results.

CONCLUSIONThe purified CD34(+)/CD117(+) stem cells derived from exfoliated deciduous teeth of healthy children possess the capacity to differentiate into osteoblasts and form calcium deposits and mineralized nodules in vitro.

Cell Differentiation ; physiology ; Cells, Cultured ; Child ; Dental Pulp ; cytology ; Humans ; Osteoblasts ; cytology ; Osteogenesis ; physiology ; Stem Cells ; cytology ; Tooth, Deciduous ; cytology

Therapeutic dentin regeneration remains difficult to achieve, and a majority of the attention has been given to anabolic strategies to promote dentinogenesis directly, whereas, the available literature is insufficient to understand the role of inflammation and inflammatory complement system on dentinogenesis. The aim of this study is to determine the role of complement C5a receptor (C5aR) in regulating dental pulp stem cells (DPSCs) differentiation and in vivo dentin regeneration. Human DPSCs were subjected to odontogenic differentiation in osteogenic media treated with the C5aR agonist and C5aR antagonist. In vivo dentin formation was evaluated using the dentin injury/pulp-capping model of the C5a-deficient and wild-type mice. In vitro results demonstrate that C5aR inhibition caused a substantial reduction in odontogenic DPSCs differentiation markers such as DMP-1 and DSPP, while the C5aR activation increased these key odontogenic genes compared to control. A reparative dentin formation using the C5a-deficient mice shows that dentin regeneration is significantly reduced in the C5a-deficient mice. These data suggest a positive role of C5aR in the odontogenic DPSCs differentiation and tertiary/reparative dentin formation. This study addresses a novel regulatory pathway and a therapeutic approach for improving the efficiency of dentin regeneration in affected teeth.
Animals ; Cell Differentiation/physiology* ; Cells, Cultured ; Complement C5a/metabolism* ; Dental Pulp/physiology* ; Dentin ; Mice ; Receptor, Anaphylatoxin C5a ; Stem Cells

Deletion or mutation of dentin matrix protein 1 (DMP1) leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate (Pi) or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmp1-null (Dmp1(-/-)), Klotho-deficient (kl/kl), Dmp1/Klotho-double-deficient (Dmp1(-/-)/kl/kl) and wild-type (WT) mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography (μCT), scanning electron microscopy (SEM), histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmp1(-/-) (a low Pi level) or kl/kl (a high Pi level) mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice (a high Pi level) displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment (a high Pi level).
Ameloblasts ; pathology ; Amelogenesis ; physiology ; Animals ; Apoptosis ; physiology ; Cell Differentiation ; physiology ; Dental Enamel ; pathology ; Dental Pulp ; pathology ; physiology ; Dental Pulp Cavity ; pathology ; Dentin ; abnormalities ; pathology ; Dentinogenesis ; physiology ; Extracellular Matrix Proteins ; genetics ; physiology ; Glucuronidase ; genetics ; Homeostasis ; physiology ; Hyperphosphatemia ; physiopathology ; Immunohistochemistry ; Mice ; Mice, Knockout ; Microscopy, Electron, Scanning ; Odontoblasts ; pathology ; Odontogenesis ; physiology ; Ossification, Heterotopic ; genetics ; pathology ; Phosphates ; physiology ; Tooth Calcification ; physiology ; X-Ray Microtomography

Tooth loss compromises human oral health. Although several prosthetic methods, such as artificial denture and dental implants, are clinical therapies to tooth loss problems, they are thought to have safety and usage time issues. Recently, tooth tissue engineering has attracted more and more attention. Stem cell based tissue engineering is thought to be a promising way to replace the missing tooth. Mesenchymal stem cells (MSCs) are multipotent stem cells which can differentiate into a variety of cell types. The potential MSCs for tooth regeneration mainly include stem cells from human exfoliated deciduous teeth (SHEDs), adult dental pulp stem cells (DPSCs), stem cells from the apical part of the papilla (SCAPs), stem cells from the dental follicle (DFSCs), periodontal ligament stem cells (PDLSCs) and bone marrow derived mesenchymal stem cells (BMSCs). This review outlines the recent progress in the mesenchymal stem cells used in tooth regeneration.
Adult Stem Cells ; physiology ; Bone Marrow Cells ; cytology ; Dental Papilla ; cytology ; Dental Pulp ; cytology ; Dental Sac ; cytology ; Humans ; Mesenchymal Stromal Cells ; physiology ; Multipotent Stem Cells ; physiology ; Periodontal Ligament ; cytology ; Regeneration ; physiology ; Tissue Engineering ; Tooth ; physiology ; Tooth, Deciduous ; cytology

OBJECTIVETo investigate the role of pulp in the root resorption of primary teeth without permanent tooth germs.

METHODSThe animal model without permanent tooth germs was established by surgery in Beagle dog. The root resorption was observed by taking periapical radiographs periodically. The samples of mandibular bone and pulp at different resorption stages were collected. The distribution of odontoclasts and the activating factor was analyzed by histological staining and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). The role of pulp in the root resorption of primary teeth was tested by early pulpectomy.

RESULTSIn the root resorption of primary molars without permanent teeth germs, a large number of odontoclasts were present on the pulpal surface of the root canal. Semi-quantification RT-PCR showed that the ratios of the expression of receptor activator of NF-κB ligand (RANKL) mRNA and β-actin in the pulp of permanent teeth and primary teeth without permanent teeth germ during different periods of root resorption are 0.1314, 0.1901, 0.2111 and 0.6058 (P > 0.05). The root resorption of primary teeth without permanent teeth germs in test groups was about 5 weeks later than that of control group.

CONCLUSIONSThe pulp of primary tooth played an important role in the root resorption of primary tooth without permanent tooth germ.

Actins ; metabolism ; Animals ; Dental Pulp ; metabolism ; physiology ; Dental Pulp Cavity ; metabolism ; Dogs ; Male ; Molar ; Osteoclasts ; cytology ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Root Resorption ; metabolism ; Tooth Germ ; Tooth, Deciduous ; physiology

The purpose of this study was to evaluate the effect of age on the ratio of pulp cavity/tooth width (P/T ratio) in healthy cats. The dental radiographs of 32 cats (16 males and 16 females) were generated with a digital dental X-ray unit with the animals under general anesthesia. Standardized measurement of the canine teeth was performed by drawing a line on the radiograph perpendicular to the cementoenamel junction (CEJ) of the tooth. There was an inversely proportional correlation between chronological age and the P/T ratio. Moreover, a strong Pearson squared correlation (gamma2 = 0.92) was identified by the curved regression model. No significant differences in the P/T ratio based on gender or breed were found. These results suggest that determination of age by P/T ratio could be clinically useful for estimating the chronological age of cats.
Age Determination by Teeth/*veterinary ; Animals ; Cats/*physiology ; Dental Pulp Cavity/anatomy & histology/*radiography ; Female ; Male ; Tooth/anatomy & histology/*radiography

The aim of this article was to examine the research articles regarding biological and mechanical properties of cryopreserved teeth for potential use in tooth transplantation. A systematic review of literatures was performed by Pubmed searching with assigned key words from January 1, 1990 to June 8, 2009. All articles were examined for inclusion criteria. Secondary search was conducted by hand-search through references of included articles from primary search. A total of 24 articles were obtained from both primary and secondary search and used as fundamental articles in this review. Periodontal ligament tissues of cryopreserved teeth were able to maintain their biological properties resulted in a satisfactory healing of periodontium. Dental pulp tissues, however, may be compromised by limitation of permeability of cryopreservative agent into pulp cavity. Therefore, an endodontic treatment of transplanted cryopreserved teeth was recommended. Cryopreserved teeth had comparable mechanical properties to those of normal teeth. Importantly, the success of cryopreserved tooth transplantation treatment in orthodontic patients was reported. The cryopreserved teeth for tooth banking have a potential clinical application for treatment of missing teeth. Case selection, however, is critical for treatment success. More studies and data regarding masticatory function and periodontal healing of transplanted cryopreserved teeth are needed.
Cryopreservation ; methods ; Dental Enamel Permeability ; Dental Pulp ; blood supply ; cytology ; physiopathology ; Dentin Permeability ; Humans ; Periodontal Ligament ; physiology ; Tissue Banks ; Tooth ; transplantation

OBJECTIVETo observe the process of pulp revitalization of immature permanent teeth after pulpectomy.

METHODSThirty-two single-rooted teeth with open apices from 4 Beagle dogs aged 4 months were included in the study. The pulpal tissues of 8 front teeth with single root of each dog were removed, and a blood clot was produced to the level of the cementoenamel junction followed by a double seal of mineral trioxide aggregate and composite resin. At day 7, 14, 21 and 28, respectively after operation, the dog was sacrificed, and then longitudinal paraffin sections were made for histologic investigation.

RESULTSAfter 7 days, about one thirth of the pulp chamber had an ingrowth of new tissue. After 14, 21, 28 days, there were more and more new tissue in the chamber. This new tissue consisted of well-organized and well-vascularized connective tissue. Hard tissue was too observed in the root canal. In some cases, the newly generated hard tissue even deposited against the canal dentinal walls.

CONCLUSIONSThe pulp of immature permanent teeth can revitalize after removal of the original pulp tissue under suitable conditions.

Animals ; Bone Regeneration ; Connective Tissue ; growth & development ; Dental Pulp ; blood supply ; growth & development ; Dental Pulp Cavity ; blood supply ; growth & development ; Dentition, Permanent ; Dogs ; Incisor ; blood supply ; growth & development ; Male ; Neovascularization, Physiologic ; physiology ; Pulpectomy