Comparative Analysis of Stress and Deformation between One-Fenced and Three-Fenced Dental Implants Using Finite Element Analysis.

Finite element analysis (FEA) has always been an important tool in studying the influences of stress and deformation due to various loads on implants to the surrounding jaws. This study assessed the influence of two different types of dental implant model on stress dissipation in adjoining jaws and on the implant itself by utilizing FEA. This analysis aimed to examine the effects of increasing the number of fences along the implant and to compare the resulting stress distribution and deformation with surrounding bones. When a vertical force of 100 N was applied, the largest displacements found in the three-fenced and single-fenced models were 1.7469 and 2.5267, respectively, showing a drop of 30.8623%. The maximum stress found in the three-fenced and one-fenced models was 13.518 and 22.365 MPa, respectively, showing a drop of 39.557%. Moreover, when an oblique force at 35° was applied, a significant increase in deformation and stress was observed. However, the three-fenced model still had less stress and deformation compared with the single-fenced model. The FEA results suggested that as the number of fences increases, the stress dissipation increases, whereas deformation decreases considerably.

Downregulation of Jumonji-C domain-containing protein 5 inhibits proliferation by silibinin in the oral cancer PDTX model.

Dysregulation of histone demethylase Jumonji-C domain-containing protein 5 (JMJD5) has been identified as a great effect on tumorigenesis. Silibinin is a commonly used anti-hepatotoxic drug and exhibits anticancer effect in various cancers. However, the antitumor mechanism between silibinin and JMJD5 in oral squamous cell carcinoma (OSCC) remains unclear. In this study, the clinical significance of JMJD5 on OSCC patients was assessed through tissue microarray. Furthermore, mice bearing patient-derived tumor xenografts (PDTXs) and tongue cancer cell lines were treated with silibinin and evaluated for tumor growth and JMJD5 expression. High expression of JMJD5 in oral cancer was significantly associated with tumor size (P = 0.0241), cervical node metastasis (P = 0.0001) and clinical stage (P = 0.0002), was associated with worse survival rate compared with that of the total cohort (P = 0.0002). Collectively the data indicate that JMJD5 expression may be suitable for detection of unfavorable prognosis in OSCC patients, based in part on its apparent role as a marker of metastasis. In addition, silibinin inhibits cancer growth in vitro and in PDTX models. Furthermore, metastasis-associated protein 1 (MTA1) could regulate the expression for JMJD5 and had a positive correlation with JMJD5. Moreover, silibinin could downregulate JMJD5 and MTA1 in oral cancer. Present study thus identifies that JMJD5 might be an essential prognostic indicator and therapeutic target against OSCC progression. In addition, silibinin is a potential candidate among novel chemotherapeutic agents or adjuvants for modulating JMJD5 in OSCC, through a mechanism likely involving MTA1/JMJD5 axis.

Autophagy and apoptotic machinery caused by Polygonum cuspidatum extract in cisplatin­resistant human oral cancer CAR cells.

Polygonum cuspidatum (Hu Zhang) is a traditional Chinese medicine (TCM) and has been revealed to exert anticancer, anti­angiogenesis, anti­human immunodeficiency virus (HIV), anti­hepatitis B virus, anti­microbial, anti­inflammatory, and neuro­protective bio­activities. However, the effect of P. cuspidatum extract (PCE) on drug­resistant human oral cancer cells regarding cell death is not fully understood yet. The present study was undertaken to explore the induction of autophagic and apoptotic cell death and to investigate their underlying molecular mechanisms in PCE­treated cisplatin­resistant human oral cancer CAR cells. Our results revealed that PCE was determined via HPLC analytic method, and it was revealed that resveratrol may be a major compound in PCE. The data also demonstrated that PCE reduced CAR cell viability in a concentration­ and time­dependent response via an MTT assay. PCE had an extremely low toxicity in human normal gingival fibroblasts (HGF). Autophagic and apoptotic cell death was found after PCE treatment by morphological determination. PCE was revealed to induce autophagy as determined using acridine orange (AO), LC3­GFP, monodansylcadaverine (MDC) and LysoTracker Red staining in CAR cells. In addition, PCE was revealed to induce apoptosis in CAR cells via 4',6­diamidino­2­phenylindole (DAPI)/terminal deoxynucleotidyl transferase dUTP nick­end labeling (TUNEL) double staining. PCE significantly stimulated caspase­9 and ­3 activities as revealed using caspase activity assays. PCE markedly increased the protein levels of Atg5, Atg7, Atg12, Beclin­1, LC3, Bax and cleaved caspase­3, while it decreased the protein expression of Bcl­2 in CAR cells as determined by western blotting. In conclusion, our findings are the first to suggest that PCE may be potentially efficacious for the treatment of cisplatin­resistant human oral cancer.

Effects of Osseointegration by Bone Morphogenetic Protein-2 on Titanium Implants In Vitro and In Vivo.

This study designed a biomimetic implant for reducing healing time and achieving early osseointegration to create an active surface. Bone morphogenetic protein-2 (BMP-2) is a strong regulator protein in osteogenic pathways. Due to hardly maintaining BMP-2 biological function and specificity, BMP-2 efficient delivery on implant surfaces is the main challenge for the clinic application. In this study, a novel method for synthesizing functionalized silane film for superior modification with BMP-2 on titanium surfaces is proposed. Three groups were compared with and without BMP-2 on modified titanium surfaces in vitro and in vivo: mechanical grinding; electrochemical modification through potentiostatic anodization (ECH); and sandblasting, alkali heating, and etching (SMART). Cell tests indicated that the ECH and SMART groups with BMP-2 markedly promoted D1 cell activity and differentiation compared with the groups without BMP-2. Moreover, the SMART group with a BMP-2 surface markedly promoted early alkaline phosphatase expression in the D1 cells compared with the other surface groups. Compared with these groups in vivo, SMART silaning with BMP-2 showed superior bone quality and created contact areas between implant and surrounding bones. The SMART group with BMP-2 could promote cell mineralization in vitro and osseointegration in vivo, indicating potential clinical use.

A comparison of epithelial cells, fibroblasts, and osteoblasts in dental implant titanium topographies.

The major challenge for dental implants is achieving optimal esthetic appearance and a concept to fulfill this criterion is evaluated. The key to an esthetically pleasing appearance lies in the properly manage the soft tissue profile around dental implants. A novel implant restoration technique on the surface was proposed as a way to augment both soft- and hard-tissue profiles at potential implant sites. Different levels of roughness can be attained by sandblasting and acid etching, and a tetracalcium phosphate was used to supply the ions. In particular, the early stage attaching and repopulating abilities of bone cell osteoblasts (MC3T3-E1), fibroblasts (NIH 3T3), and epithelial cells (XB-2) were evaluated. The results showed that XB-2 cell adhesive qualities of a smooth surface were better than those of the roughened surfaces, the proliferative properties were reversed. The effects of roughness on the characteristics of 3T3 cells were opposite to the result for XB-2 cells. E1 proliferative ability did not differ with any statistical significance. These results suggest that a rougher surface which provided calcium and phosphate ions have the ability to enhance the proliferation of osteoblast and the inhibition of fibroblast growth that enhance implant success ratios.

A Strong Promoter Provided with the Gene Encoding Arginyl-tRNA Synthetase(argS) from Escherichia coli.

Previous studies showed that the gene argS encoding the arginyl-tRNA synthetase(ArgRS) from Escherichia coli(E.coli), was overexpressed 1 000 folds in the E.coli transformant TG1/pUC-argS, while the gene leuS, encoding the leucyl-tRNA synthetase(LeuRS) from E.coli, was only overproduced 35-fold in the same case. To investigate why the expression of these two aminoacyl-tRNA synthetase genes is so different, a fused gene (termed parg-leuS) was constructed by replacement of the 5' flanking region of leuS to 5' flanking region of argS. In the E.coli transformant TG1/pUC-parg-leuS, the activity of LeuRS was only improved 8.5-fold, which was much lower than that of the transformant harboring the recombinant plasmid pUC18-leuS or pKK-leuS. However, by RNA dot hybridization the amount of mRNA produced in the transcription of parg-leuS was about 5 times than that of the wild type leuS, and was similar to that of pKK-leuS, suggesting that the promoter of argS is very strong. Analysis of the secondary structure around the initiation codon among three mRNAs showed that the secondary structure of the mRNA from parg-leuS was the strongest of the three mRNAs. From the results, it could be deduced that expression of the fused gene parg-leuS might be controlled at the translational level and the strong secondary structure of this mRNA may hinder translation initiation and result in a low translation efficiency.