The application of an intraoral banana peel suturing model in surgical training of dental students.

OBJECTIVES: This study investigated the application of an intraoral banana peel suturing model in helping students to acquire intraoral surgical techniques. METHODS: This is a self-control study conducted from January 2021 to March 2021. An intraoral banana peel suturing model was implemented to provide oral suture experience for undergraduates majoring in stomatology. The sutures students placed in the model were photographed and evaluated blindly by a professional team using an established scoring system. Training scores were recorded before (training 1) and after 2 months of training (training 2). Linear regression was used to examine factors related to the scores. Suturing training was conducted in the School and Hospital of Stomatology at Peking University. A total of eighty-two students in Peking University School and Hospital of Stomatology were in their fourth pre-clinical year and followed a workshop on surgical sutures according to the curriculum. All students who should take this course were included, and the response rate was 100%. RESULTS: The mean training 2 score (23.04 ± 3.83) was higher than the mean training 1 score (13.94 ± 3.15). The training 1 score was not significantly correlated with any of the students' general characteristics. The training 2 score was correlated with the training 1 score and the cumulative duration of practice outside of class. CONCLUSION: The intraoral banana peel suturing model can be used for suture training, and dental students' suture ability was improved after using the banana peel for suture practice.

[Clinical effect of a new low-shrinkage composite on restoring dental wedge-shaped defects].

PURPOSE: To evaluate the clinical effect of a new low-shrinkage composite FiltekTM P90 on restoring dental wedge-shaped defects. METHODS: Fifty-two patients with at least two equivalent non-carious cervical lesions on bilateral teeth (180 teeth with wedge-shaped defect) were enrolled in this study. Self-control design was used in this study. The teeth were randomly divided into experimental group which were restored with low-shrinkage composite FiltekTM P90 in one side, and the control group which were filled with FiltekTM Z350 XT composite resin in the other side. The modified USPHS/Ryge criteria were used to evaluate the treatment effects 6 months and 1 year after treatment. SPSS19.0 software package was used for statistical analysis. RESULTS: The 6-months successful rate in FiltekTM P90 group was 96.55% and 95.40% in control group. The 1 year successful rate in FiltekTM P90 group was 94.05% and 90.48% in control group. There were no significant differences in main indexes, including successful rates ,retention, marginal discoloration, marginal adaptation, surface texture, color match, secondary caries and postoperative sensitivity between the 2 groups (P>0.05). CONCLUSIONS: Low-shrinkage composite FiltekTM P90 is a good choice for treating dental wedge-shaped defects.

[Establishing a luciferase reporter system to evaluate osteogenic differentiation potential of human adipose-derived stem cells].

OBJECTIVE: Human adipose-derived stem cells (hASCs) are a highly attractive source in bone tissue engineering. To generate a luciferase reporter system that could be used to quantitatively and rapidly examine osteogenic differentiation potential of human adipose-derived stem cells (hASCs) in vitro, and eventually make it possible to monitor the osteogenic differentiation of transplanted cells in vivo. METHODS: The genomic DNA harboring promotor regions of osteocalcin and DNA sequences encoding luciferase genes were amplified by PCR and cloned into the pLVX-pTRE-puro vector to generate the OC(pro)-Luc-Puro construct. Then, the OC(pro)-Luc-Puro construct together with three assistant vectors: pMDLg/pRRE, pRSV-REV, and pVSVG, were transiently transfected into HEK293T cells followed by viral supernatants collection, filtration and concentration. Next, the hASCs stably expressing luciferase reporter gene driven by osteocalcin promotor were created with the lentivirus carrying OC(pro)-Luc-Puro cassette under puromycin selection. The OC(pro)-Luc-hASCs were then cultured in the absence or presence of osteogenic differentiation medium. On the 7th and 14th days, after osteogenic induction, cellular extracts were collected and analyzed by luciferase reporter assay. Meanwhile, alizarin red staining and quantification as well as quantitative reverse transcription PCR (qRT-PCR) analysis of osteogenic associated genes osteocalcin (OC), runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP) were used to assess the osteogenic differentiation ability of OC(pro)-Luc-hASCs. RESULTS: OC(pro)-Luc-Puro plasmid and OCpro-Luc-hASCs were successfully generated. On the 7th and 14th days after osteogenic induction, the luciferase activity of the cellular extracts from OC(pro)-Luc-hASCs was dramatically increased. Consistently, the extracellular matrix mineralization, as shown by Alizarin red S (ARS) staining and quantification was also markedly intensified and a marked increase of the mRNA expression levels of OC, Runx2 and ALP, although to variable extent, was observed upon osteogenic differentiation. These results indicated that the observations from traditional experiments examining hASCs osteogenic differentiation were largely in agreement with that of our luciferase reporter assay in OC(pro)-Luc-hASCs. CONCLUSION: We established a luciferase reporter system that could be used to rapidly, quantitatively and specifically determine osteogenic differentiation ability of hASCs. Comparing with the traditional time-consuming methods, the system we generated here was highly effective. This system not only can be used to examine ostogenic differentiation of hASCs in a high throughput manner, but also provides a way to monitor ostogenic differentiation of cells in vivo.

[Osteogenic capability of primary human adipose-derived stromal cells in vivo].

OBJECTIVE: To investigate the osteogenic capability of primary human adipose-derived stromal cells (hASCs) in vivo. METHODS: hASCs were isolated from adipose tissue by the method of collagenase digestion. After 7 and 14 days of osteogenic induction, alkaline phosphatase (ALP) staining and Alizarin Red staining were performed to test the osteogenic potential of hASCs in vitro. After 14 days of adipogenic induction, the adipogenic potential of hASCs was assayed by Oil Red O staining.In the in vivo part, 12 nude mice were used. Test group (scaffold with hASCs) and control group (scaffold only) were symmetrically implanted into the back of nude mice. After 4 weeks and 8 weeks of implantation, samples were collected. Histological and immunohistochemical staining were performed to investigate the osteogenic capability of hASCs. RESULTS: Approximately 6×10(7) hASCs could be isolated from 300 mL adipose tissue. ALP, Alizarin Red and Oil Red O staining of hASCs showed positive results after specific inductions. These results demonstrated the osteogenic and adipogenic potentials of hASCs in vitro. Bone-like tissue could be observed in the test group at 4 weeks and 8 weeks after the implantation. Immunohistochemical staining showed that there were positive results of osteocalcin, ALP and anti-human nuclei in the bone-like tissue areas. CONCLUSION: A large number of primary hASCs can be isolated from human adipose tissue; hASCs combined with scaffold show osteogenic capability in vivo.

[Application of human adipose-derived stromal cells in bone tissue engineering].

Human adipose-derived stromal cells (hASCs) can be obtained from adipose tissues that offer an abundant and easily accessible pool of stem cells. Thus, hASCs have become a highly attractive source of seed cells in bone tissue engineering and have promising prospects in bone regeneration. Since 2002, our research group has performed a series of experiments on hASCs and its application in bone tissue engineering, including: to substitute dexamethasone by 1,25 (OH)2 vitamin D3 to induce osteogenic differentiation of hASCs; to explore the effect of epigenetic regulation and to inflammation on the osteogenic differentiation of hASCs; to construct a novel and simple tissue engineered bone system by hASCs and human platelet-rich plasma (hPRP) and to investigate the bone formation capability of this tissue engineered bone and the stimulatory effect of simvastatin. Our results suggested that 1,25 (OH)2 vitamin D3 could replace dexamethasone to induce the osteogenic differentiation of hASCs; retinoblastoma binding protein 2 (RBP2), as one of histone demethylases, could regulate the osteogenic differentiation of hASCs epigenetically while tumor necrosis factor α (TNFα), as a inflammatory factor, could also influence the osteogenic differentiation of hASCs. Moreover, we found that in vivo bone formation could be detected by our novel tissue engineered bone composed with hASCs and hPRP; simvastatin could enhance the bone formation capability of this tissue-engineered structure.

[Inhibition of retinoblastoma binding protein 2 promotes osteogenic differentiation of human adipose-derived stromal cells].

OBJECTIVE: To explore the effect of retinoblastoma binding protein 2 (RBP-2), a histone H3K4 demethylase, on osteogenic differentiation of human adipose-derived stromal cell (hASC). METHODS: According to the GenBank sequence information of RBP-2, four different small interfering RNAs (siRNA) targeting RBP-2 gene were designed and the corresponding short hairpin RNAs (shRNA) were cloned into pLL 3.7 lentivirus RNA interference vector. The lentivirus with RBP-2-siRNA was packaged in 293T cells. The effective sequence was examined and selected by Western blotting and real-time PCR. The lentiviruses with efficient knockdown effects were used to infect hASC. On the 14th day after osteogenic differentiation, alkaline phosphatase (ALP) activities of hASC were quantitatively tested and at the same time, ALP staining and alizarin red staining were performed to assess the difference of osteogenic differentiation between the knockdown group and the control group. RESULTS: The recombinant lentivirus siRNA targeting RBP-2 was successfully constructed and the expression of RBP-2 mRNA and protein were dramatically suppressed by infection with RBP-2-siRNA lentivirus. On the 14th day after osteogenic induction, ALP activity of hASC in the knockdown group [(299.2 ± 22.7), (224.3 ± 17.7) U/g] was much stronger than that in the control group [(129.9 ± 12.9) U/g, P < 0.05] and the same result was achieved for the ALP staining and alizarin red staining. CONCLUSIONS: The constructed RBP-2-siRNA lentivirus could markedly decrease the expression of RBP-2 and promote osteogenic differentiation of hASC. It indicated that RBP-2 can repress the osteogenic differentiation of hASC.