Effect of platelet-rich plasma on cell proliferation and osteogenic activity of pulp stem cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of different concentrations of platelet-rich plasma (PRP) on human dental pulp stem cells (hDPSC) proliferation and osteogenic differentiation activity so as to provide basis for future application of dental pulp stem cells and PRP in tissue engineering and bone repair therapy.</p><p><b>METHODS</b>hDPSC were isolated and cultivated in vitro. Flow cytometric analysis was carried out to test the expression of STRO-1.hDPSC were cultured in various concentrations of PRP (1%, 5%, 10%, 20%). At the 2nd and 6th day 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was tested. Osteogenic differentiation of hDPSC was assessed using alkaline phosphatase (ALP) staining and Alizarin Red staining at the 7th and 14th day.</p><p><b>RESULTS</b>Flow cytometric analysis demonstrated that 14.82% of hDPSC were STRO-1 positive. One percent to 20% PRP showed significant effect of promoting hDPSC proliferation. One percent to 10% PRP showed significant effect of promoting hDPSC osteogenic differentiation.</p><p><b>CONCLUSIONS</b>Certain concentrations of PRP can promote hDPSC proliferate and osteogenic differentiate, and this finding suggests future application of dental pulp stem cells and PRP in bone tissue engineering.</p>

Inflammation-related cytokines expression in periodontal ligament fibroblasts under mechanical stress / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the changes of inflammation-related cytokine expression profiles in human periodontal ligament fibroblasts (hPDLF) under mechanical stress.</p><p><b>METHODS</b>The periodontal ligament attached to the mid-third part of the fresh root of young premolars extracted for orthodontic treatment was scalped and removed. hPDLFs were cultured by the method of digesting by I-type collagenase combined with tissue adhering, and then isolated and purified by cells passages. hPDLFs were then divided into two groups, group with mechanical force and group without mechanical force and then cultured for 24 h. Employing cytokine-microarray analysis to assess, in a comprehensive manner compared to the hPDLFs culture system without a static force. The quantity of different cytokine-related genes in hPDLFs was analyzed by means of quantitative with the special primers of up-and down-regulated genes. The mRNA of inflammation-related cytokines was examined by real-time PCR, and the expression of the cytokines in hPDLFs detected by cytokine flowcytomix assay.</p><p><b>RESULTS</b>The relative expression of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, TNF-β and interferon (IFN)-γ mRNA in the hPDLFs with 24 h persistent-pressure (0.3633 ± 0.0874, 0.4200 ± 0.0285, 0.1697 ± 0.0284, 0.0983 ± 0.0131, 0.2840 ± 0.0676 and 3.1067 ± 0.2857) was significantly higher than the group without mechanical force (0.1173 ± 0.0176, 0.1691 ± 0.0174, 0.0117 ± 0.0021, 0.0243 ± 0.0050, 0.0000 ± 0.0000 and 0.1433 ± 0.0125), P < 0.05. The cell culture supernatant cytokines expression of IL-1β, IL-6, IL-8, TNF-α, TNF-β and IFN-γ after 48 h cultured [(18.21 ± 1.01), (1634.11 ± 472.41), (1461.47 ± 50.53), (20.71 ± 2.52), (884.11 ± 118.86) and (1461.47 ± 333.37) ng/L] was significantly higher than the group without mechanical force [(5.32 ± 4.97), (373.56 ± 155.92), (679.11 ± 141.42), (4.32 ± 0.73), (3.56 ± 0.92) and (204.11 ± 35.36) ng/L], P < 0.05. The relative mRNA and protein expression of IL-2, IL-4, IL-5, IL-10 and IL-12 showed no significant difference between the both groups.</p><p><b>CONCLUSIONS</b>Persistent static mechanical force could regulate the expression of some inflammation-related cytokines. These up-regulated cytokines may be invloved in remodeling of hPDLFs, bone resorption and periodontal microenvironment.</p>

Human dental pulp stem cell is a promising autologous seed cell for bone tissue engineering / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The seed cell is a core problem in bone tissue engineering research. Recent research indicates that human dental pulp stem cells (hDPSCs) can differentiate into osteoblasts in vitro, which suggests that they may become a new kind of seed cells for bone tissue engineering. The aim of this study was to evaluate the osteogenic differentiation of hDPSCs in vitro and bone-like tissue formation when transplanted with three-dimensional gelatin scaffolds in vivo, and hDPSCs may become appropriate seed cells for bone tissue engineering.</p><p><b>METHODS</b>We have utilized enzymatic digestion to obtain hDPSCs from dental pulp tissue extracted during orthodontic treatment. After culturing and expansion to three passages, the cells were seeded in 6-well plates or on three-dimensional gelatin scaffolds and cultured in osteogenic medium. After 14 days in culture, the three-dimensional gelatin scaffolds were implanted subcutaneously in nude mice for 4 weeks. In 6-well plate culture, osteogenesis was assessed by alkaline phosphatase staining, Von Kossa staining, and reverse transcription-polymerase chain reaction (RT-PCR) analysis of the osteogenesis-specific genes type I collagen (COL I), bone sialoprotein (BSP), osteocalcin (OCN), RUNX2, and osterix (OSX). In three-dimensional gelatin scaffold culture, X-rays, hematoxylin/eosin staining, and immunohistochemical staining were used to examine bone formation.</p><p><b>RESULTS</b>In vitro studies revealed that hDPSCs do possess osteogenic differentiation potential. In vivo studies revealed that hDPSCs seeded on gelatin scaffolds can form bone structures in heterotopic sites of nude mice.</p><p><b>CONCLUSIONS</b>These findings suggested that hDPSCs may be valuable as seed cells for bone tissue engineering. As a special stem cell source, hDPSCs may blaze a new path for bone tissue engineering.</p>

Clinical application and evaluation of the custom shade guide of tetracycline stained teeth / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical application of the custom shade guide of tetracycline stained teeth in color matching.</p><p><b>METHODS</b>Forty-two patients with 59 tetracycline stained teeth were included in this study. Color matching was performed with Shofu shade guide and custom shade guide of tetracycline stained teeth. According to the two results, two porcelain fused to metal crowns were fabricated for each tooth. Evaluations were made both visually by dentists and patients and with ShadeEye NCC.</p><p><b>RESULTS</b>Color difference between prostheses made according to custom shade guide and natural teeth was (7.80 +/- 4.70). Color difference between prostheses made according to Shofu shade guide and natural teeth was (10.68 +/- 4.70). Both visual evaluation and ShadeEye NCC evaluation showed that the custom shade guide provided a more accurate shade selection than the Shofu shade guide did, and the difference between the two shade guides was significant (t = 7.328, P < 0.001).</p><p><b>CONCLUSIONS</b>The custom shade guide of tetracycline stained teeth provided a standard for clinical shade matching for the tetracycline stained teeth and could be a supplement to Shofu shade guide.</p>

A three-dimensional finite element analysis on relationship between abutment undercut and retentive arm width of cast cobalt-chromium three-arm clasp / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the stress distribution on cast retentive clasp arms in dislodging denture, and to discuss the deepest undercuts of the second mandibular premolar (abutment) for cobalt-chromium alloy cast clasps with different widths.</p><p><b>METHODS</b>Three-dimensional finite element models of the abutment with different depths of undercuts and retentive arms with different widths were set up. Dynamic displacement load (3 mm/s) was exerted on the middle of the retentive arms to analyze the stress in retentive arms while they were being removed from the abutment.</p><p><b>RESULTS</b>The peak stress in retentive arms was positively correlated to the undercuts displaced by clasp tips, and those were not obviously related to the undercuts displaced by the middle of retentive arms. When width/thickness of retentive arms was 3, the increase of peak stress of retentive arms with similar locations of clasp tips was significantly related to the increase of the arm width. The deepest undercuts of the second mandibular premolar for cobalt-chromium alloy cast retentive arms with different widths of 1.8 mm, 1.6 mm, and 1.4 mm were 0.25 mm, 0.30 mm, and 0.35 mm respectively.</p><p><b>CONCLUSIONS</b>When width/thickness of the retentive clasp arm is fixed, the wider the arm is, the smaller depth it should be placed on the undercut of abutment. Retentive clasp arms with different widths should be placed on different depths of undercuts in order to prevent their permanent deformation.</p>

Three-year clinical observation and failure analysis of all-ceramic restorations made by chair-side computer aided design and computer aided manufacture system / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate 3-year clinical performance of restorations made by chair-side computer aided design and computer aided manufacture (CAD/CAM) system and analyze possible failure reasons.</p><p><b>METHODS</b>Thirty-two single-tooth large all-ceramic restorations were fabricated using a computer aided design and computer aided manufacture (CAD/CAM) system. Fourteen premolars and 18 molars were restored with machined porcelain blocks. Of these 11 inlays, 10 crowns, and 11 endocrowns were finished respectively. The integrity and marginal fitness were evaluated at 3 years after insertion.</p><p><b>RESULTS</b>Twenty-eight restorations were rated as good; 2 were fractured (1 molar-crown and 1 molar-inlay) and had to be replaced; and 2 were found marginal defects (1 molar-inlay and 1 premolar-inlay). The failures occurred mostly in the inlays and molars.</p><p><b>CONCLUSIONS</b>With proper indication selection and careful tooth preparation, restorations with chair-side CAD/CAM were clinical success both in function and esthetics.</p>