ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the effects of tumor necrosis factor-α (TNF-α) on osteogenic differentiation and Notch signaling pathway of periodontal ligament stem cells (PDLSCs) and to investigate the regulatory role of Notch signaling pathway on the osteogenic differentiation of PDLSCs under the influence of TNF-α.</p><p><b>METHODS</b>PDLSCs were obtained through enzyme digestion and tissue block method. The expression levels of stem cell surface markers CD105, CD90, CD146, CD45, and CD31 were detected by fluorescence activated cell sorter (FACS). PDLSCs were divided into experimental (10 ng·mL⁻¹ TNF-α) and control groups (0 ng·mL⁻¹ TNF-α). The proliferation ability of PDLSCs was detected using cell counting kit-8 (CCK-8). The effect of TNF-α on the osteogenic ability of PDLSCs were tested by measuring alkaline phosphatase (ALP) activity and conducting alizarin red staining and quantitative real-time polymerase chain reaction (PCR). We tested Notch signal pathway receptors Notch1, Notch2, ligand JAG1, JGA2, and downstream gene Hes-1. Changes in DLL1 expression were detected by quantitative real-time PCR.</p><p><b>RESULTS</b>FACS profiling showed that PDLSCs were strongly positive for CD105, CD90, and CD146 but negative for CD45 and CD31. CCK-8 results showed that TNF-α could promote the proliferation of PDLSCs (P<0.05). ALP activity in the experimental group was lower than that in the control group (P<0.05). Alizarin red staining showed that the experimental group had decreased mineralized nodules as compared with the control group. Quantitative real-time PCR results showed that the mRNA expression of osteogenic marker genes cementum attachment protein (CAP), osteopontin (OPN), and Runt-related transcription factor 2 (Runx2) significantly decreased in the experimental group as compared with those in the control group (P<0.05). The expression levels of Notch1, Notch2, JAG1, JGA2 and Hes-1 were significantly decreased (P<0.05), whereas those of Notch3 and DLL1 were increased in Notch signaling pathway-related molecules (P<0.05).</p><p><b>CONCLUSIONS</b>TNF-α can promote PDLSCs proliferation and inhibit bone differentiation and Notch signaling pathway expression, indicating that the Notch signaling pathway regulates PDLSCs osteogenic differentiation.</p>
ABSTRACT
BACKGROUND:One-piece glass fiber post-and-core achieves a good sealing between cast-post and core and provides a suitable elastic modulus of the glass fiber material. Therefore, selecting a reasonable bonding system for the CAD/CAM-fabricated fiber post-and-core with no ferrule effect has become an important issue in clinical practice. OBJECTIVE:To compare the bonding effects of three kinds of adhesive materials without ferrule effect in the CAD/CAM-fabricated dental restoration after bypass obturation of oval root canals. METHODS:Ninety extracted first mandibular premolars with the working length set to 14 mm were randomized into three groups (n=30 per group). The root canal was prepared with the ProTaper next nickel titanium system under a dental operating microscope. The bypass obturation with oval root canals was achieved using the warm gutta-percha vertical condensation technique. 1-4 # Pesso drills were used to remove the gum in the root canal, with the preparatory depth of 9 mm, but with no shoulder collar. CAD/CAM technology was used to prepare one-piece fiber post-and-cores which were bonded using the KetacTM Cem Easymix glass ion, ONE-STEP PLUS universal UV-curable adhesive and RelyXTM Unicem 2 self-adhesive resin cement in different groups. The bonding effect of three kinds of adhesive materials was analyzed by using a universal mechanical measuring instrument. RESULTS AND CONCLUSION:Compared with the KetacTM Cem Easymix glass ion group, the debonding force and micro-tensile strength were significantly stronger in the other two groups (P<0.05), while compared with the ONE-STEP PLUS universal UV-curable adhesive group, the debonding force and micro-tensile strength were slightly higher in the RelyXTM Unicem 2 self-adhesive resin cement group, but there was no significant difference between the two groups. To conclude, RelyXTM Unicem 2 self-adhesive resin cement in the absence of ferrule effect can achieve better bonding effect on the CAD/CAM-fabricated one-piece fiber post-and-core after bypass obturation of oval root canals.