miR-379-5p regulates the proliferation, cell cycle, and cisplatin resistance of oral squamous cell carcinoma cells by targeting ROR1.

OBJECTIVE: To analyze the regulatory mechanism microRNA miR-379-5p in oral squamous cell carcinoma (OSCC). METHODS: We collected serum samples from patients with OSCC and examined the expression of miR-379-5p and receptor tyrosine kinase-like orphan receptor 1 (ROR1) by real-time polymerase chain reaction and western blot. OSCC cells were purchased for molecular research, cell multiplication was tested using the BrdU assay, cell cycle was tested using flow cytometry, and resistance to cisplatin (DDP) was assessed using the MTT assay. RESULTS: miR-379-5p expression was downregulated and ROR1 expression was upregulated in the serum of OSCC patients, and the area under the curve for OSCC identified by miR-379-5p and ROR1 was not less than 0.800. In the cell function test, overexpression of miR-379-5p could suppress the proliferation, cell cycle, and DDP resistance of OSCC cells. miR-379-5p could negatively regulate ROR1. Inhibition of ROR1 expression had a similar effect after the re-expression of miR-379-5p. Co-overexpression of miR-379-5p and ROR1 counteracted the above inhibitory effects on the proliferation, cell cycle, and DDP resistance of OSCC cells. CONCLUSION: miR-379-5p in OSCC regulates the proliferation, cell cycle, and DDP resistance of tumor cells by targeting ROR1.

Erythropoietin induces the osteogenesis of periodontal mesenchymal stem cells from healthy and periodontitis sources via activation of the p38 MAPK pathway.

Erythropoietin (Epo), a hematopoietic hormone, has multiple biological functions. Recently, the positively osteogenic effects of Epo on mesenchymal stem cells (MSCs) have attracted broad interest. However, the effects of Epo on the osteogenesis of human periodontal ligament tissue­derived mesenchymal stem cells (hPDLSCs) and periodontitis mesenchymal stem cells (pPDLSCs) from patients with periodontitis remain unknown. In the present study, osteogenic effects of Epo on hPDLSCs and pPDLSCs were investigated, and the results suggested that the effects were mediated by promoting the expression of runt related transcription factor 2, alkaline phosphatase (ALP) and osteocalcin. Using Alizarin Red and ALP staining, it was demonstrated that Epo exerted positive osteogenic effects on hPDLSCs and pPDLSCs. Additionally, Epo upregulated the proliferation of hPDLSCs and pPDLSCs, based on flow cytometric analyses of the cell cycle. To determine the underlying mechanism, the role of the p38 mitogen­activated protein kinase (MAPK) pathway, which is associated with the osteogenesis of hPDLSCs and pPDLSCs, was investigated further. Epo increases p38 phosphorylation (the target of the MAPK pathway) in hPDLSCs and pPDLSCs. Furthermore, when the cells were treated with SB203580, an inhibitor of the p38 MAPK pathway, the osteogenic effects of Epo on hPDLSCs and pPDLSCs were attenuated. In conclusion, Epo may upregulate the bone formation ability of hPDLSCs and pPDLSCs via the p38 MAPK pathways.

Ameloblasts serum-free conditioned medium: bone morphogenic protein 4-induced odontogenic differentiation of mouse induced pluripotent stem cells.

Induced pluripotent stem (iPS) cells possess the ability of self-renewal and can differentiate into cells of the three germ layers, both in vitro and in vivo. Here we report a new method to efficiently induce differentiation of mouse iPS cells into the odontogenic lineage. Using ameloblasts serum-free conditioned medium (ASF-CM), we successfully generated ameloblast-like cells from mouse iPS cells. Importantly, culturing mouse iPS cells in ASF-CM supplemented with BMP4 (ASF-BMP4) promoted odontogenic differentiation, which was evident by the upregulation of ameloblast-specific as well as odontoblast-specific genes. On the other hand, culturing mouse iPS cells in ASF-CM supplemented with noggin (ASF-noggin), an inhibitor of BMP4, abrogated this effect. These results suggest that mouse iPS cells can be induced by ASF-BMP4 to differentiate into ameloblast-like and odontoblast-like cells. The results of our study raise the possibility of using patient-specific iPS cells for tooth regeneration in the future. Copyright © 2016 John Wiley & Sons, Ltd.

The Effects of Diamond-Like Carbon Films on Fretting Wear Behavior of Orthodontic Archwire-Bracket Contacts.

This study aims to assess the effects of diamond-like carbon (DLC) films on fretting wear behavior of orthodontic archwire-bracket contacts. 'Mirror-confinement-type electron cyclotron resonance (MCECR) plasma sputtering' was utilized to deposit carbon films on stainless steel archwires and brackets. Nanostructure of carbon films such as the bonding structure, cross-sectional thickness and surface roughness were studied. The fretting wear behavior of various archwire-bracket contacts were investigated by using a self-developed tester in ambient air and artificial saliva. The results indicated that DLC-coated wires showed significantly low friction coefficient than the uncoated wires independently of the applied environments. Nevertheless, the DLC-coated and uncoated brackets showed no significant differences in the friction coefficient. Microscopic analysis showed that low wear took place for the DLC-coated surfaces. It is proposed that the application of DLC coating on archwires can decrease the orthodontic fretting wear and coefficient of friction. Unfortunately it does not affect the frictional properties for brackets at present.

Cyclic mechanical stretch promotes energy metabolism in osteoblast-like cells through an mTOR signaling-associated mechanism.

Energy metabolism is essential for maintaining function and substance metabolism in osteoblasts. However, the role of cyclic stretch in regulating osteoblastic energy metabolism and the underlying mechanisms remain poorly understood. In this study, we found that cyclic stretch (10% elongation at 0.1 Hz) significantly enhanced glucose consumption, lactate levels (determined using a glucose/lactate assay kit), intracellular adenosine triphosphate (ATP) levels (quantified using rLuciferase/Luciferin reagent) and the mRNA expression of energy metabolism-related enzymes [mitochondrial ATP synthase, L-lactate dehydrogenase A (LDHA) and enolase 1; measured by RT-qPCR], and increased the phosphorylation levels of Akt, mammalian target of rapamycin (mTOR) and p70s6k (measured by western blot analysis) in human osteoblast­like MG­63 cells. Furthermore, the inhibition of Akt or mTOR with an antagonist (wortmannin or rapamycin) suppressed the stretch-induced increase in glucose consumption, lactate levels, intracellular ATP levels and the expression of mitochondrial ATP synthase and LDHA, indicating the significance of the Akt/mTOR/p70s6k pathway in regulating osteoblastic energy metabolism in response to mechanical stretch. Thus, we concluded that cyclic stretch regulates energy metabolism in MG­63 cells partially through the Akt/mTOR/p70s6k signaling pathway. The present findings provide novel insight into osteoblastic mechanobiology from the perspective of energy metabolism.

Bivariate optimization of orthodontic mini-implant thread height and pitch.

PURPOSE: Mini-implants have been used as anchorage for years, but failure is common in clinical practice. Mini-implant design is a critical factor affecting its stability. The aim of this study was to evaluate the effect of continuous and simultaneous variations of thread height and pitch on the biomechanical properties of an orthodontic mini-implant. METHOD: A 3D finite element model, composed of a posterior maxilla section and an orthodontic mini-implant, was created. Mini-implant thread height ranged from 0.10 to 0.40 mm, and thread pitch ranged from 0.50 to 2.00 mm. Effects of the implant thread height and pitch on the maximum Von Mises stresses in maxilla and mini-implant, as well as maximum displacements in the mini-implant, were evaluated by a finite element method. Bivariate analysis was used to determine the optimal range of thread height and pitch. RESULTS: Variation of thread height and pitch decreased the maximum Von Mises stresses in cortical bone, cancellous bone and mini-implant by 54.9, 78.4 and 23.6 %, respectively. The maximum displacement in the mini-implant decreased by 21.8 %. CONCLUSION: Maxillary stress and mini-implant stability were influenced by mini-implant thread height and pitch. Increased thread height with a thread pitch of 1.20 mm was better for orthodontic mini-implant in the maxillary posterior region. Thread height played a more significant role than the thread pitch in reducing maxillary stress and enhancing orthodontic mini-implant stability.

Effect of jaw opening on the stress pattern in a normal human articular disc: finite element analysis based on MRI images.

INTRODUCTION: Excessive compressive and shear stresses are likely related to condylar resorption and disc perforation. Few studies have reported the disc displacement and deformation during jaw opening. The aim of this study was to analyze stress distribution in a normal articular disc during the jaw opening movement. METHODS: Bilateral MRI images were obtained from the temporomandibular joint of a healthy subject for the jaw opening displacement from 6 to 24 mm with 1 mm increments. The disc contour for the jaw opening at 6 mm was defined as the reference state, and was used to establish a two dimensional finite element model of the disc. The contours of the disc at other degrees of jaw opening were used as the displacement loading. Hyperelastic material models were applied to the anterior, intermediate and posterior parts of the disc. Stress and strain trajectories were calculated to characterize the stress/strain patterns in the disc. RESULTS: Both the maximum and minimum principal stresses were negative in the intermediate zone, therefore, the intermediate zone withstood mainly compressive stress. On the contrary, the maximum and minimum principal stresses were most positive in the anterior and posterior zones, which meant that the anterior and posterior bands suffered higher tensile stresses. The different patterns of stress trajectories between the intermediate zone and the anterior and posterior bands might be attributed to the effect of fiber orientation. The compression of the intermediate zone and stretching of the anterior and posterior bands caused high shear deformation in the transition region, especially at the disc surfaces. CONCLUSIONS: The stress and strain remained at a reasonable level during jaw opening, indicating that the disc experiences no injury during functional opening movements in a healthy temporomandibular joint.

JNK and AKT/GSK3ß signaling pathways converge to regulate periodontal ligament cell survival involving XIAP.

Periodontal ligament cells (PDLCs) were incubated with H2O2 and the levels of XIAP protein, protein kinase B (AKT), phosphorylated forms of AKT (pAKT), c-Jun N-terminal kinase (JNK), and glycogen synthase kinase-3ß (GSK3ß) were determined by western immunoblotting or immunocytochemistry. After overexpression and knockdown of XIAP, the AKT, pAKT, JNK and GSK3ß levels were determined in PDLCs exposed to H2O2. We demonstrated that 72 h of 250 µM H2O2 exposure resulted in an increase in apoptosis. Meanwhile, XIAP levels were decreased with 72 h of 250 µM H2O2 exposure, while there were also a decrease of JNK2, AKT, pAKT, and GSK3ß levels. Such reductions induced by 72 h of 250 µM H2O2 treatment were partially recovered in PDLCs overexpressing XIAP. Interestingly, these reductions (except for pAKT) were mimicked by RNA interference of XIAP. These results suggest that, after 72 h of 250 µM H2O2 exposure, Akt, JNK, and GSK3ß intracellular kinase signaling pathways converge to regulate PDLC survival involving XIAP.

Low-intensity pulsed ultrasound accelerates tooth movement via activation of the BMP-2 signaling pathway.

The present study was designed to determine the underlying mechanism of low-intensity pulsed ultrasound (LIPUS) induced alveolar bone remodeling and the role of BMP-2 expression in a rat orthodontic tooth movement model. Orthodontic appliances were placed between the homonymy upper first molars and the upper central incisors in rats under general anesthesia, followed by daily 20-min LIPUS or sham LIPUS treatment beginning at day 0. Tooth movement distances and molecular changes were evaluated at each observation point. In vitro and in vivo studies were conducted to detect HGF (Hepatocyte growth factor)/Runx2/BMP-2 signaling pathways and receptor activator of NFκB ligand (RANKL) expression by quantitative real time PCR (qRT-PCR), Western blot and immunohistochemistry. At day 3, LIPUS had no effect on the rat orthodontic tooth movement distance and BMP-2-induced alveolar bone remodeling. However, beginning at day 5 and for the following time points, LIPUS significantly increased orthodontic tooth movement distance and BMP-2 signaling pathway and RANKL expression compared with the control group. The qRT-PCR and Western blot data in vitro and in vivo to study BMP-2 expression were consistent with the immunohistochemistry observations. The present study demonstrates that LIPUS promotes alveolar bone remodeling by stimulating the HGF/Runx2/BMP-2 signaling pathway and RANKL expression in a rat orthodontic tooth movement model, and LIPUS increased BMP-2 expression via Runx2 regulation.

Inflammatory environment induces gingival tissue-specific mesenchymal stem cells to differentiate towards a pro-fibrotic phenotype.

BACKGROUND INFORMATION: Human gingival tissues are prone to hyperplasia under inflammatory stimuli. We have identified gingival tissue-specific mesenchymal stem cells (GMSCs) and found their functional change being correlated with drug-induced gingival hyperplasia. However, whether these cells exhibit characteristics of pro-fibrotic phenotype under inflammatory condition remains unknown. RESULTS: GMSCs isolated from human normal gingival tissues (N-GMSC) and inflammatory gingival tissues (I-GMSC) were cultured in vitro, representative cytokines were added to simulate the in vivo inflammatory environment. Under the influence of the inflammatory cytokines, GMSCs exhibited higher rate of proliferation than those under normal condition, while their potential for osteogenic and adipogenic differentiation was suppressed. The expression of matrix metalloproteinases (MMP)-1, MMP-2, IL-1, IL-6, TNF-α and type 1 collagen was significantly higher in I-GMSCs than in N-GMSCs. Furthermore, compared with dental pulp stem cells, GMSCs showed different pattern of gene expression and extracellular matrix formation in inflammatory environment. CONCLUSIONS: Inflammatory microenvironment induces GMSCs to differentiate towards a pro-fibrotic phenotype, which could underlie the hyperplastic appearance of inflammatory gingiva.

Traumatic loss of a maxillary central incisor treated with nonextraction orthodontics.

This case report describes the orthodontic treatment of a girl who lost her maxillary left central incisor from trauma. The patient had a concave profile, a Class I molar relationship on the right side and a Class II molar relationship on the left side, with a slight maxillary retrusion, an anterior edge-to-edge bite, and a posterior crossbite. Therefore, the treatment consisted of rapid palatal expansion to widen the maxilla in a transverse direction along with reverse headgear to improve the incisor relationship. The crown of the left canine was modified to resemble the left lateral incisor, and a porcelain veneer was placed to make the left lateral incisor resemble the left central incisor. This case report illustrates how orthodontics alone can be used to treat a missing central incisor, without a bridge or an implant.

Combined degenerative and regenerative remodeling responses of the mandibular condyle to experimentally induced disordered occlusion.

INTRODUCTION: The purposes of this research were to investigate the long-term responses of mandibular condylar cartilage to experimentally induced disordered occlusion and to evaluate changes in the expression of the SDF-1/CXCR4 axis. METHODS: Experimentally induced disordered occlusions were created in 8-week-old female Sprague-Dawley rats by orthodontic methods. After 24 weeks, remodeling of the mandibular condylar cartilage was assessed by hematoxylin and eosin staining. Protein and mRNA expression of SDF-1, CXCR4, MMP9, IL6, OPG, and RANKL were investigated by means of immunohistochemical staining and real-time polymerase chain reaction. RESULTS: Obvious cartilage degenerative remodeling responses were observed; they appeared as uneven distributions of cellular disposition, loss of cartilage surface integrity, and cell-free areas. Regenerative responses presenting as thickening of the whole and the calcified cartilage layers in the experimental group were also observed. Compared with the age-matched controls, the protein and mRNA levels of SDF-1, CXCR4, MMP9, IL6, and OPG, but not RANKL, were increased in the experimental group (all, P <0.05). In addition, the mRNA level of RANKL/OPG showed a decreasing trend in the experimental group compared with the age-matched controls (P = 0.052). CONCLUSIONS: This study demonstrated that long-term experimentally induced disordered occlusion leads to a combined response in degeneration and regeneration of mandibular cartilage, accompanied by active interaction of the SDF-1/CXCR4 axis and local upregulation of MMP9, IL6, and OPG.

No significant association between p53 codon 72 Arg/Pro polymorphism and risk of oral cancer.

The genetic polymorphism of p53 codon 72 Arg/Pro has been implicated in oral cancer risk, but the results of previous studies remain controversial and ambiguous. To estimate the effect of the p53 codon 72 Arg/Pro polymorphism on the risk of oral cancer, a meta-analysis was performed. Based on a comprehensive search in PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases, we identified all available publications assessing the association between p53 codon 72 Arg/Pro polymorphism and oral cancer risk. The pooled odds ratio (OR) with its corresponding 95 % confidence interval (CI) was calculated to assess the association. Subgroup analyses by ethnicity and study quality were performed to further identify the correlation. Totally, 17 studies with 2,975 cases and 3,413 controls were included into this meta-analysis. There was no statistically significant association between the p53 codon 72 Arg/Pro polymorphism and oral cancer risk in all genetic contrast models (OR(Pro allele vs. Arg allele) = 1.05, 95 % CI 0.94-1.18, P(OR) = 0.379; OR(Pro/Pro vs. Arg/Arg) = 1.11, 95 % CI 0.89-1.40, P(OR) = 0.356; OR(Pro/Arg vs. Arg/Arg) = 1.10, 95 % CI 0.93-1.30, P(OR) = 0.256; OR(Pro/Arg + Pro/Pro vs. Arg/Arg) = 1.10, 95 % CI 0.93-1.31, P(OR) = 0.263; and OR(Pro/Pro vs. Arg/Arg + Pro/Arg) = 1.03, 95 % CI 0.90-1.18, P(OR) = 0.647). In the subgroup analysis of high-quality studies, we failed to find the susceptibility of p53 codon 72 Arg/Pro polymorphism to oral cancer. Moreover, the results were similar among Asians, Caucasians, and mixed populations when stratifying by ethnicity. Sensitivity analysis further confirmed the stability of the results. The present meta-analysis of currently available data shows no association between the p53 codon 72 Arg/Pro polymorphism and oral cancer risk.

Variability in permanent tooth size of three ancient populations in Xi'an, northern China.

OBJECTIVES: This paper compares permanent dental dimensions between three ancient populations that belonged to the same biological population throughout a temporal range of 2000 years to detect temporal trends and metric variation in dentition. MATERIALS AND METHODS: The samples analysed were dental remains of 4502 permanent teeth from 321 individuals, which were excavated from three archaeological sites: Chang'an (1000-1300 years BP), Shanren (2200 years BP) and Shaolingyuan (3000 years BP) in the Xi'an region (northern China). For each tooth three standard measurements were taken: Mesiodistal (MD) diameter of crown, labiolingual or buccolingual (BL) diameter of crown and length of root (LR). RESULTS: Three ancient population samples generally displayed the same dental dimensions (p>0.05), whereas some tooth types varied. The Shaolingyuan had larger canine and the smallest maxillary second molars and the Chang'an had the largest mandibular first molars in the MD dimension. The Shanren had the smallest maxillary third molars and mandibular central incisors, and the Chang'an had the smallest maxillary lateral incisors in the BL dimension. In the LR measures, statistically significant differences of five tooth types showed that the Chang'an were smaller than the Shaolingyuan and the Shanren. Comparisons of coefficients of variation for teeth showed that the length of root and third molar usually displayed greater variation. CONCLUSIONS: Decreasing or increasing trend for crown size does not occur between the ancient populations, while changes in crown size of a few tooth types fluctuate. The root size is more variable than the crown size and is likely to reflect a degenerated trend in a few tooth types.

Restoration of miR-34a in p53 deficient cells unexpectedly promotes the cell survival by increasing NFκB activity.

Upregulation of miR-34a by p53 is recently believed to be a key mediator in the pro-apoptotic effects of this tumor suppressor. We sought to determine whether restoration of miR-34a levels in p53 deficient cells could rescue the response to DNA damage. Compared with the p53 wildtype U2OS cells, miR-34a expression was much lower in p53 deficient Saos2 cells upon cisplatin treatment. Unexpectedly, delivery of miR-34a in Saos2 cells does not increase the cell sensitivity to apoptosis. This effect was mediated by direct downregulation of SirT1 expression by miR-34a, which in turn increased the NFκB activity. Inhibition of NFκB activity in Saos2 cells by Aspirin sensitized the miR-34a overexpressing cells to cell death. Thus, in tumors with p53 deficiency, miR-34a restoration alone confers drug resistance through Sirt1-NFκB pathway and combination of miR-34a and NFκB inhibitor could be considered as a promising therapeutic strategy.

Osteochondral angiogenesis in rat mandibular condyles with osteoarthritis-like changes.

OBJECTIVE: To investigate angiogenesis at the osteochondral junction and changes in expression of pro- and anti-angiogenic factors in rat mandibular condyles with osteoarthritis-like changes. METHODS: In order to evoke osteoarthritis-like lesions in mandibular condyles, disordered occlusion was created experimentally in rats. Osteochondral vascularity was assessed histologically at 20 and 24 weeks. Protein and mRNA levels of pro-angiogenic factors including vascular endothelial growth factor (VEGF), connective tissue growth factor (CTGF) and matrix metalloproteases 9 (MMP9), and anti-angiogenic factor chondromodulin-I (CHM-I) were investigated by means of immunohistochemical staining and real-time PCR. RESULTS: Osteochondral angiogenesis was demonstrated as increased numbers of vascular channels terminating in the calcified cartilage and non-calcified cartilage in 20- and 24-week experimental groups compared with controls (all P<0.05). In the experimental groups, VEGF, CTGF and MMP9 were highly expressed in the tissues adjacent to the osteochondral junction. However, CHM-I was more expressed in the superior but not deep hypertrophic chondrocytes. Compared to their age-matched controls, the protein levels of VEGF and CTGF were higher in 20-week experimental group, and the protein and mRNA levels of CTGF, MMP-9, and CHM-I increased in the 24-week experimental group (all P<0.05). CONCLUSION: In the present rat model, osteochondral angiogenesis was observed in mandibular condyles with osteoarthritis-like changes, accompanied with local upregulation of VEGF, CTGF and MMP9. Although the increase in CHM-I may moderate pro-angiogenic factors effects in the superior cartilage, the deficiency of deep hypertrophic chondrocytes to express CHM-I may permit vascular invasion into condylar cartilage.

Heterogeneous dental follicle cells and the regeneration of complex periodontal tissues.

Dental follicle cells (DFCs) are a heterogeneous population that exhibit a variety of phenotypes. However, it remains unclear whether DFCs can maintain stem cell characteristics, or mediate tissue-regeneration to form single or complex tissues in the periodontium, after long-term culturing. Therefore, DFCs were isolated from human impacted molars (HIM-DFCs), passaged >30 times, and then evaluated for their heterogeneity and multipotential differentiation. Morphology, proliferation, epitope profile, and mineralization characteristics of clones derived from single HIM-DFCs in vitro were also assayed. HIM-DFCs (passage #30) were found to be positive for the heterogeneous markers, Notch-1, stro-1, alkaline phosphomonoesterase (ALP), type I collagen (COL-I), type III collagen (COL-III), and osteocalcine. Moreover, passage #30 of the HDF1, 2, and 3 subclone classes identified in this study were found to express high levels of the mesenchymal stem cells markers, CD146 and Stro1. HDF3 subclones were also associated with the strongest ALP staining detected, and strongly expressed osteoblast and cementoblast markers, including COL-I, COL-III, bone sialoprotein (BSP), and Runx2. In contrast, HDF1 subclone analyzed strongly expressed COL-I and COL-III, yet weakly expressed BSP and Runx2. The HDF2 subclone was associated with the strongest proliferative capacity. To evaluate differentiation characteristics in vivo, these various cell populations were combined with ceramic bovine bone and implanted into subcutaneous pockets of nude mice. The 30th passage of subclone HDF1 and 3 were observed to contribute to fiber collagens and the mineralized matrix present, respectively, whereas HDF2 subclones were found to have a minimal role in these formations. The formation of a cementum-periodontal ligament (PDL) complex was observed 6 weeks after HIM-DFCs (passage #30) were implanted in vivo, thus suggesting that these cells maintain stem cell characteristics. Therefore, subclone HDF1-3 may be related to the differentiation of fibroblasts in the PDL, undifferentiated cells, and osteoblasts and cementoblasts, respectively. Overall, this study is the first to amplify HIM-DFCs and associated subclones with the goal of reconstructing complex or single periodontium. Moreover, our results demonstrate the potential for this treatment approach to address periodontal defects that result from periodontitis, or for the regeneration of teeth.

Effect of the cyclic stretch on the expression of osteogenesis genes in human periodontal ligament cells.

Periodontal ligament cells can potentially differentiate into osteoblast-like cells and influence the remodeling of periodontal tissues under mechanical strain conditions. In the present study, Gene chip technology was adopted to investigate the effect of the cyclic stretch on the expression of osteogenic-related genes in human periodontal ligament cells (HPDLCs). Cultured HPDLCs were subjected to 12% elongation cyclic stretch for 24 h using a Flexercell Strain Unit, and then GEArray Q series human osteogenesis gene expression profile chip with 96 spot array numbers was used to conduct parallel analyses on the change of the related gene expression in the osteogenic differentiation of HPDLCs stimulated by cyclic stretch. The results show that after the HPDLCs were stimulated by the cyclic stretch, the expression of 21 osteogenic-related genes was significantly upregulated, including 10 growth factor genes and their associated molecules, 10 extracellular matrix genes and their associated proteins, and 1 cell adhesion molecule. Two genes were significantly downregulated, including one growth factor gene and one cell adhesion molecule. Then the expressions of 10 candidate genes were validated using Real-time RT-PCR. These results indicate that cyclic stretch with 12% deformation can stimulate or inhibit some gene expression which was associated with the process of HPDLCs differentiation.

[Orthodontic retention and adjustment of the occlusion after orthognathic surgery].

OBJECTIVE: To investigate the orthodontic retention and adjustment of the occlusion after orthognathic surgery. METHODS: 18 patients were divided into three groups. Group I: Cases with skeletal Class I bimaxillary protrusion treated by subapical osteotomy; Group II: Cases with skeletal Class II mandibular retrusion treated by sagittal split mandibular advancement surgery; Group III: Cases with skeletal Class III treated by Le Fort I osteotomy on maxilla and sagittal split osteotomy on mandible. There were 6 patients in each group. Three kinds of orthodontic elastic tractions were used based on different categories of malocclusion and different types of operation. RESULTS: 18 patients attained functional occlusion after the orthodontic occlusion adjustment. There was no relapse and malocclusion by surgery. CONCLUSION: Intermaxillary elastics based on different categories of occlusion and different kinds of surgery can improve the occlusion after orthognathic surgery and attatin the functional occlusion.

Characterization of rat apical tissues in different root development stage.

In this study, we try to compare the histological characteristics and the odontogenic capability of apical tissues (AT) at different root development stages of rat molar teeth. AT of mandibular first molars from 8-day-old, 21-day-old, and 35-day-old Sprague-Dawley rats were selected as being representative of root-initiating, root-forming, and root-completing stages, respectively. Cell counting, flow cytometry assays, alkaline phosphatase activity, alizarin red staining, and reverse transcription polymerase chain reaction were performed to assess the proliferation and mineralization potential of apical tissue cells at different stages of root development in vitro. In vivo transplantation of apical tissue cells combined with ceramic bovine bone was used to characterize the differentiation capacity. It was shown that there was a structurally and functionally dynamic change in the apical tissue of developing tooth root of rats, of which the unique developmental potential will reduce gradually with the ending up of root development. The AT of root-initiating and root-forming stage exhibited much higher proliferation and tissue-regenerative capacity than those of root-completing stage. Our present results indicate that the apical tissue, with the sustainable developmental ability throughout almost the whole process of tooth development, can yet be regarded as a competent candidate source for root/periodontal tissues regeneration.