Biomimetic, biodegradable and osteoinductive treated dentin matrix/α-calcium sulphate hemihydrate composite material for bone tissue engineering.

It is still a huge challenge for bone regenerative biomaterial to balance its mechanical, biological and biodegradable properties. In the present study, a new composite material including treated dentin matrix (TDM) and α-calcium sulphate hemihydrate (α-CSH) was prepared. The optimal composition ratio between TDM and α-CSH was explored. The results indicate that both components were physically mixed and structurally stable. Its compressive strength reaches up to 5.027 ± 0.035 MPa for 50%TDM/α-CSH group, similar to human cancellous bone tissues. Biological experiments results show that TDM/α-CSH composite exhibits excellent biocompatibility and the expression of osteogenic related genes and proteins (ALP, RUNX2, OPN) is significantly increased. In vivo experiments suggest that the addition of TDM for each group (10%, 30%, 50%) effectively promotes cell proliferation and osteomalacia. In addition, 50% of the TDM/α-CSH combination displays optimal osteoconductivity. The novel TDM/α-CSH composite is a good candidate for certain applications in bone tissue engineering.

TSF/FHA induces osteogenic differentiation of Mc3t3 cells via Pygo2 dependent Wnt/ß-catenin signaling pathway.

OBJECTIVES: This study aimed to investigate whether tussah silk fibroin (TSF)/fluoridated hydroxyapatite (FHA) can promote osteogenic differentiation of Mc3t3 cells and explore the role of Wnt/ß-catenin signaling in this process. METHODS: TSF/FHA was gained via freeze drying technique and cyclic phosphate immersion method. The relative expression levels of bone-related genes and proteins of Mc3t3 cells seeded on different materials were examined by RT-qPCR and Western blotting. Knockdown or overexpression of Pygo2 in Mc3t3 cells was achieved using lentiviral transfection. Cell proliferation, the expression of bone-related genes and proteins were subsequently examined. Animal experiment was also performed to observe the osteogenesis effect. RESULTS: Different ratios of fluorine of TSF/FHA accelerated the osteogenic differentiation of Mc3t3 cells and increased the Pygo2 expression. The Wnt/ß-catenin signaling pathway was activated after TSF/FHA induction, accompanied by the increased expression of related genes. In SD rats with skull defect, the newly formed bone increased significantly and the Pygo2 overexpressing Mc3t3 cells promoted osteogenesis. However, Pygo2 knockdown markedly compromised the osteogenesis of Mc3t3 cells after TSF/FHA induction. CONCLUSION: TSF/FHA facilitates osteogenic differentiation of Mc3t3 cells via upregulating Pygo2 and activating Wnt/ß-catenin signaling pathway.

α-Hemihydrate calcium sulfate/n-hydroxyapatite combined with metformin promotes osteogenesis in vitro and in vivo.

This study aimed to examine the effects of loading different concentrations of metformin onto an α-hemihydrate calcium sulfate/nano-hydroxyapatite (α-CSH/nHA) composite. The material characteristics, biocompatibility, and bone formation were compared as functions of the metformin concentration. X-ray diffraction results indicated that the metformin loading had little influence on the phase composition of the composite. The hemolytic potential of the composite was found to be low, and a CCK-8 assay revealed only weak cytotoxicity. However, the metformin-loaded composite was found to enhance the osteogenic ability of MC3T3-E1 cells, as revealed by alkaline phosphate and alizarin red staining, real-time PCR, and western blotting, and the optimal amount was 500 µM. RNA sequencing results also showed that the composite material increased the expression of osteogenic-related genes. Cranial bone lacks muscle tissue, and the low blood supply leads to poor bone regeneration. As most mammalian cranial and maxillofacial bones are membranous and of similar embryonic origin, the rat cranial defect model has become an ideal animal model for in vivo experiments in bone tissue engineering. Thus, we introduced a rat cranial defect with a diameter of 5 mm as an experimental defect model. Micro-computed tomography, hematoxylin and eosin staining, Masson staining, and immunohistochemical staining were used to determine the effectiveness of the composite as a scaffold in a rat skull defect model. The composite material loaded with 500 µM of metformin had the strongest osteoinduction ability under these conditions. These results are promising for the development of new methods for repairing craniofacial bone defects.

R-Spondin 2 Induces Odontogenic Differentiation of Dental Pulp Stem/Progenitor Cells via Regulation of Wnt/ß-Catenin Signaling.

Odontoblast cells generated from human dental pulp stem/progenitor cells (hDPSCs) secrete reparative dentin in responds to an injury. Endogenous Wnt signaling is also activated during this process, and these Wnt-activated cells are responsible for the following repair response. R-spondin 2 (Rspo2) is a potent stem cell growth factor, which strongly potentiates Wnt/ß-catenin signaling and plays a vital role in cell differentiation and regeneration. However, the role of Rspo2 during odontoblast differentiation in hDPSCs has not yet been completely understood. This study investigated the effects of Rspo2 on hDPSCs to provide therapeutic insight into dentin regeneration and reparative dentin formation. HDPSCs were extracted from human molars or premolars. Immunofluorescence staining and flow cytometric analysis were used to detect the mesenchymal stem cell markers in hDPSCs. EdU assay and Cell Counting Kit-8 (CCK-8) were performed to explore cell proliferation. The odontogenic differentiation levels were determined by measuring the mRNA and protein expression of DSPP, DMP-1, ALP, and BSP. Immunofluorescence staining was performed to detect the localization of ß-catenin. The biological effects of Rspo2 on hDPSCs was investigated using the Lentivirus-based Rspo2 shRNA and recombined human Rspo2 (rhRspo2). Recombined human DKK-1 (rhDKK-1) and recombined human Wnt3a (rhWnt3a) were used for further investigation. The cells generated from human dental pulp expressed mesenchymal stem cell markers Vimentin, Stro-1, Nestin, C-kit, CD90, and CD73, while were negative for CD3, CD31, and CD34. The mRNA expression levels of the odontogenic-related genes DSPP, DMP-1, ALP, and BSP were upregulated in the rhRspo2 treated cells. Silencing Rspo2 suppressed the proliferation and differentiation of the hDPSCs. Blockade of Wnt signaling with DKK-1 inhibited Rspo2-induced activation of Wnt/ß-catenin signaling and cell differentiation. The combined use of rhWnt3a and rhRspo2 created a synergistic effect to improve the activation of Wnt/ß-catenin signaling. Rspo2 promoted the proliferation and odontogenic differentiation of hDPSCs by regulating the Wnt/ß-catenin signaling pathway.

Chinese dental students' knowledge and attitudes toward HIV/AIDS.

BACKGROUND/PURPOSE: Oral care is vital to human immunodeficiency virus (HIV)-positive individuals. As future dentists, it is pertinent that dental students have sufficient knowledge and a positive approach toward this disease. The purpose of this study was to assess HIV/AIDS-related knowledge and attitudes among clinical dental students in central China. MATERIALS AND METHODS: This survey was conducted on 103 dental students in the final year of a 5-year program. A structured questionnaire with 50 questions examining their knowledge under various categories and 17 questions examining their attitudes toward the disease was employed. RESULTS: The survey was completed by 92.2% (95/103) of the students. The results revealed that more than half of the respondents demonstrated a good level of knowledge, although few exhibited an excellent level. The mean scores on knowledge was 79.41 ± 6.3 out of a maximum possible score of 100, and there was no significant difference regarding sex. Despite their good level of knowledge, the majority (93.68%) displayed a negative attitude (nonprofessional attitude) toward HIV/AIDS. CONCLUSION: These findings might help to define strategies to improve the quality of education among Chinese dental students and suggests that there is a need to address student misconceptions and attitudes toward the disease.

[Quality assessment on reports of randomized controlled trials of oral and maxillofacial surgery in China].

OBJECTIVE: To evaluate the report quality of randomized controlled trials (RCT) of oral and maxillofacial surgery in China during 2000-2009. METHODS: A comprehensive electronic search was carried out through Chinese Biomedical Literature Database (CBM), VIP Database for Chinese Technical Periodicals (VIP) and China National Knowledge Infrastructure (CNKI), and 19 kinds of journals of stomatology in China were also hand-searched. We identified RCT published between 2000 and 2009, and classified into oral and maxillofacial surgery and labeled "random" and assessed the quality of these reports using the consolidated standards of reporting trials (CONSORT) statement. RESULTS: 53 RCT articles were included. Reporting quality of the 53 articles was not high and the CONSORT score was 8.2 +/- 2.5. CONCLUSION: The reporting quality of RCT of oral and maxillofacial surgery in China is poor. The CONSORT statement should be used to standardize the reporting of RCT.

[Assessment of reporting quality of randomized controlled trial related to dentine hypersensitivity].

OBJECTIVE: To assess the reporting quality of randomized controlled trials (RCT) related to dentine hypersensitivity which were published between 2000 and 2009 in nineteen Chinese stomatological journals, learn the current status and the influence factors of reporting quality of the dentine hypersensitivity RCT, and determine whether they can provide high quality evidence clinically. METHODS: A handsearching of nineteen Chinese stomatological journals to identify dentine hypersensitivity RCT which were published between 2000 and 2009 and labeled "random". Assess the reporting quality of these RCT by Consolidated Standards of Reporting Trials (CONSORT) statement and then analyze the influence factors of reporting quality by univariate and multivariate analyses. RESULTS: We identified 61 dentine hypersensitivity RCT, among which 45 belonged to journals of Chinese scientific study statistical source and 16 belonged to journals of non-statistical source. The reporting quality of dentine hypersensitivity RCT was not high at large and the CONSORT score was 8.1 +/- 2.4 on average. Multiple linear regression showed that the score of improved Jadad scale (t=4.656, P=0.000) was the main influence factor of reporting quality of dentine hypersensitivity RCT. The better the intrinsic authenticity was, the higher the reporting quality would be. CONCLUSION: Currently, reporting quality of Chinese dentine hypersensitivity RCT needs to be improved. In order to improve the reporting quality of dentine hypersensitivity RCT, experts in stomatology should not only improve experimental design before experiments, but also write papers in accordance with CONSORT statement.