Fabrication of three-dimensional orthodontic force detecting brackets and preliminary clinical test for tooth movement simulation.

This study aimed to develop an ultraminiature pressure sensor array to measure the force exerted on teeth. Orthodontic force plays an important role in effective, rapid, and safe tooth movement. However, owing to the lack of an adequate tool to measure the orthodontic force in vivo, it remains challenging to determine the best orthodontic loading in clinical and basic research. In this study, a three-dimensional (3D) orthodontic force detection system based on piezoresistive absolute pressure sensors was designed. The 3D force sensing array was constructed using five pressure sensors on a single chip. The size of the sensor array was only 4.1 × 2.6 mm, which can be placed within the bracket base area. Based on the barometric calibration, conversion formulas for the output voltage and pressure of the five channels were constructed. Subsequently, a 3D linear mechanical simulation model of the voltage and stress distribution was established using 312 tests of the applied force in 13 operating modes. Finally, the output voltage was first converted to pressure and then to the resultant force. The 3D force-detection chip was then tested to verify the accuracy of force measurement on the teeth. Based on the test results, the average output force error was only 0.0025 N (0.7169%) (p = 0.958), and the average spatial positioning error was only 0.058 mm (p = 0.872) on the X-axis and 0.050 mm (p = 0.837) on the Y-axis. The simulation results were highly consistent with the actual force applied (intraclass correlation efficient (ICC): 0.997-1.000; p < 0.001). Furthermore, through in vivo measurements and a finite element analysis, the movement trends generated when the measured orthodontic forces that acted on the teeth were simulated. The results revealed that the device can accurately measure the orthodontic force, representing the first clinical test of an orthodontic-force monitoring system. Our study provides a hardware basis for clinical research on efficient, safe, and optimal orthodontic forces, and has considerable potential for application in monitoring the biomechanics of tooth movement.

Comparison of the Angiogenic Ability between SHED and DPSC in a Mice Model with Critical Limb Ischemic.

BACKGROUND: Regenerative medicine by using stem cells from dental pulp is promising for treating patients with critical limb ischemic (CLI). Here, we investigated the difference in the angiogenetic ability of stem cells from human exfoliated deciduous teeth (SHED) and human dental pulp stem cells (DPSC). METHODS: SHED and DPSC were harvested from dental pulp and analyzed in flow- cytometry for detecting the expression of surface markers. Levels of angiogenetic marker were examined by RT-PCR and Western-blot. Eighteen immunodeficient mice of critical limb ischemic model were divided into three groups: SHED, DPSC and saline, which was administered with SHED, DPSC or saline intramuscularly. Histological examination was performed to detect the regenerative results. RESULTS: A highly expression of CD146 was detected in SHED. Moreover, cells with negative expression of both CD146 and CD31 in SHED were more in comparison with those in DPSC. Expression of angiogenesis factors including CXCL12, CXCR4, Hif-1a, CD31, VEGF and bFGF were significant higher in SHED than DPSC by the RT-PCR and Western-Blot results. SHED induced more CD31 expression and less fibrous tissue formation in the critical limb ischemic model as compare with DPSC and saline. CONCLUSION: Both SHED and DPSC possessed the ability of repairing CLI. With expressing more proangiogenesis factors, SHED may have the advantage of repairing CLI.

Effects of Androgen Receptor Overexpression on Chondrogenic Ability of Rabbit Articular Chondrocytes.

BACKGROUND: The role of sex hormones and their receptors has drawn much attention in the process of cartilage regeneration. This study aimed to investigate the effect of androgen receptor (AR) on the chondrogenic ability of articular chondrocytes and the related mechanism. METHODS: Articular chondrocytes were isolated, cultured, identified by toluidine blue staining and then transduced with lentivirus carrying the AR gene. The cell viability was determined using Cell Counting Kit-8, and cell apoptosis was assessed by flow cytometry analysis. The effects of AR overexpression on the expression of cartilage-specific proteins and some signalling molecules were evaluated by real-time PCR and Western blotting. Using 24 New Zealand rabbits, the regeneration of rabbit articular cartilage defects was further investigated in vivo and evaluated histologically. RESULTS: The overexpression of AR significantly reduced the apoptosis rate of chondrocytes but did not affect their proliferation. The overexpression of AR also promoted the expression of Sry-related HMG box 9, collagen II and aggrecan, decreased the expression of matrix metalloproteinase-13, and downregulated p-S6 and RICTOR. The experimental group with AR-overexpressing chondrocytes exhibited superior regeneration of cartilage defects. CONCLUSION: AR overexpression can maintain the phenotype of chondrocytes and promote chondrogenesis in vitro and in vivo. mTOR-related signalling was inhibited.

Mechanical properties and cell compatibility of a chitosan-graphene oxide guided bone regeneration composite membrane / 中华口腔医学杂志

Objective@#To explore the feasibility of graphene oxide (GO)-chitosan (CS) guided bone regeneration composite membrane being used as a new guided bone regeneration (GBR) membrane by testing its tensile strength and its effect on the proliferation of human gingival fibroblasts (HGF).@*Methods@#The CS solution and GO solution were mixed in following ratios, ultrasonically crushed and dispersed, and formed into membranes by self-evaporation. Composite membrane with 0.5%, 1.0%, 2.0%, 4.0%, 6.0%, 8.0% GO in CS was prepared. The tensile strength of the composite membranes was tested by mechanical universal testing machine (n=6). The microstructure of the composite membrane with the best tensile strength was observed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction was used to characterize the ingredients of the material. A group of samples was prepared again with the proportion of the highest tensile strength composite membrane, and were immersed in a sodium hydroxide solution for acid removal. The tensile strength of the new group of samples was tested. The newly extracted impacted teeth were collected from the Department of Oral and Maxillofacial Surgery, Stomatologic Hospital and College, Anhui Medical University, and the gingival tissues remained on the teeth were taken for primary HGF and were cultured to P2 generation, which were identified by immunocytochemical staining methods. Cell counting kit-8 (CCK-8) was applied to detect cell counts in the blank control group, the pure CS membrane group, and the composite membrane group with the highest tensile strength (n=5) and all groups co-cultured with the HGF for 24 h and 48 h.@*Results@#After adding GO, the cross-section of the composite membrane was in an ordered layer structure. X-ray diffraction analysis showed that GO could be found in the composite membrane. The tensile strength increased with the increase of GO ratio. When the mass fraction of GO in CS was 4.0%, the tensile strength reached (134.8±7.3) MPa and the tensile strength reached (144.6±8.1) MPa after deacidification of the composite membrane. The CCK-8 test of HGF showed that there was no significant difference in absorbance between the pure CS membrane group and the GO/CS composite membrane group when they were compared with the blank control group (P>0.05).@*Conclusions@#When the mass fraction of GO in CS is 4.0%, the composite membrane has the best tensile strength. The composite membrane showes good cytocompatibility, which lays a foundation for further in vivo experiments and the development of a new generation of GBR membrane.

Effects of cellular microenvironment on the efficacy of biomacromolecular therapies / 国际生物医学工程杂志

Currently,with the rapid development of drug delivery technologies,more and more efforts are taken into the efficient therapies for various diseases by delivering biologically-active macromolecules into the target cells directly.Although a certain number of positive treatment results were obtained from the therapies by using the biomacromolecules to cure some diseases,the microenvironment around the target cell still has a great influence on the final treatment effect.Since many diseases and injuries interfere the normal architecture of the extracellular matrix (ECM),the cell adhesion to ECM and the subsequent cellular activities,the normal microenvironment of the cell plays a critical role in maintaining body balance,tissue regeneration and repair.Given these points,this paper reviews the effects of the cellular microenvironment constructed by ECM on the efficacy of bioactive macromolecules,and provides a theoretical basis for future drug design and synthesis of pharmaceuticals.

Investigation and analysis on the employment issues of postgraduates majoring in clinical science of stomatology / 中华医学教育探索杂志

Objective To investigate the preference of the postgraduates in school for work and their psychological changes based on the analysis of the employment status of postgraduates majoring in clinical science of stomatology in Anhui medical university in recent five years in an aim to provide preemployment counseling.Methods The employment status of postgraduates majoring in clinical science of stomatology in affiiated stomatological hospital of Anhui medical university in recent five years (2006 -2010) was summed up.Questionnaire of employment preference and the psychological pressure was conducted in 66 postgraduates majoring in clinical science of stomatology (2008 -2010 grade).Results The employment rate of provincial first-class hospitals was obviously decreased in the recent five years while that of municipal first-class hospitals was increased gradually.The number of postgraduates willing to work in the municipal first-class hospitals was reduced while that willing to future their study and work in the non first-class hospitals was increased.Psychological pressure was univcrsally existed in students and did not get released.Conelusion As the employment situation for postgraduates majoring in clinical science of stomatology changes,the preference for work and psychological pressure of the postgraduates also undergo corresponding changes.Targeted measures can be formulated to work out the problem based on the understanding of these changes.Meanwhile,adjustment should be made in the training methods and employment guidance for postgraduates majoring in clinieal science of stomatology.

IFN-γ enhances the anti-tumour immune response of dendritic cells against oral squamous cell carcinoma.

OBJECTIVE: To investigate the expression of antigen processing-1 (Tap-1) and Tapasin in oral squamous cell carcinoma (OSCC), and observe the immune response against OSCC by use of IFN-γ-antigen induced dendritic cells (DCs) in vitro and in vivo. DESIGN: Expression of Tap-1 and Tapasin in different cell lines was analysed. CAL27 cells were treated with IFN-γ. Antigen from the treated cells was presented by DCs. Pulsed DC was then co-cultivated with CD8+ T lymphocyte to induce antigen specific cytotoxic lymphocytes (CTLs). The immune response elicited by CTLs against OSCC was observed. RESULTS: A significant lower expression of Tap-1 and Tapasin was observed in OSCC cell lines. IFN-γ exerted time-dependent effect for increasing the expression of these genes. Antigen from the treated CAL27 cells was presented by DCs. CTLs were induced and generated a strong immune response in vitro and in vivo. CONCLUSIONS: Tap-1 and Tapasin were downregulated in OSCC. IFN-γ increased the expression of these genes. Use of IFN-γ-antigen induced DCs could induce stronger immune response in vitro and in vivo.