Microarray illustrates enhanced mechanistic action towards osteogenesis for magnesium aluminate spinel ceramic-based polyphasic composite scaffold with mesenchymal stem cells and bone morphogenetic protein 2.

Spinel (magnesium aluminate MgAl2 O4 ) ceramic-based polyphasic composite scaffold has been recently reported for craniofacial bone tissue engineering. Improving the osteogenic effects of such composite scaffolds with bone morphogenetic proteins (BMP2) is an intensely researched area. This study investigated the gene interactions of this scaffold with BMP2 and mesenchymal stem cells (MSCs). Human bone marrow MSCs were cultured in 3 groups: Group 1-Control (BMSCs), Group 2-BMSC with BMP2, and Group 3-BMSC with scaffold and BMP2. After RNA isolation, gene expression analysis was done by microarray. Differentially expressed genes (DEGs) (-1.0 > fold changes>1 and p value <.05) were studied for their function and gene ontologies using Database for Annotation, Visualization and Integrated Discovery (DAVID). They were further studied by protein-protein interaction network analysis using STRING and MCODE Cytoscape plugin database. Group 3 showed up regulation of 3222 genes against 2158 of Group 2. Group 3 had five annotation clusters with enrichment scores from 2.08 to 3.93. Group 2 had only one cluster. Group 3 showed activation of all major osteogenic pathways: TGF, BMP2, WNT, SMAD, and Notch gene signaling with effects of calcium and magnesium released from the scaffold. Downstream effect of all these caused significant activation of RUNX2, the key transcriptional regulator of osteogenesis in Group 3. STRING and MCODE Cytoscape plugin demonstrated the interactions. The enhanced MSC differentiation for osteogenesis with the addition of BMP2 to the polyphasic composite scaffold proposed promising clinical applications for bone tissue engineering.

Comparative evaluation of the tensile bond strength of two silicone based denture liners with denture base resins.

BACKGROUND: To evaluate and compare tensile bond strength of two silicone based liners with heat cure and heat cure high impact denture base resin at baseline and after storage in artificial saliva for 30 and 60 days. METHOD: Heat cure conventional and high impact acrylic blocks (120 blocks each) prepared with final test specimen of two blocks of each resin with a liner. The baseline samples and those tested after 30 and 60 days interval stored in artificial saliva in thermal incubator, all were pulled apart in UTM at 20 mm/min. The tensile bond strength and mode of failure (adhesive/cohesive) were assessed. Mean, SD determined and analysis using one way ANOVA and paired 't' test. RESULTS: The highest mean tensile bond strength (1.028 MPa) and the least i.e. 0.289 MPa was observed with Permaflex silicone liner against heat cure PMMA after storage in artificial saliva at 37 ± 1 °C. CONCLUSION: The study rejected the null hypothesis because storage time in artificial saliva affected the bond strength of the resilient liners examined. The results revealed a statistically significant difference (p < 0.05) of artificial saliva storage on the bond strength of both the liners. After storage in artificial saliva for 30 days and 60 days at 37 ± 1 °C, all the specimens showed a significant reduction in the tensile bond strength.

Does Hollowing of Complete Denture Enhance Retention? - A Pilot Study.

INTRODUCTION: Prosthetic rehabilitation is an extremely challenging task in extreme resorption cases of the maxillary denture-bearing area. Reducing the weight of a maxillary obturator has been seen as beneficial. But whether reducing the weight of conventional complete denture also increases retention or not, is still very dubious. The aim of this pilot study was to determine the effect of maxillary denture weight on denture retention and stability. MATERIALS AND METHODS: For this study, a total of 10 patients were considered for the pilot study (06 female and 04 male) with an average age of 70 y. Each patient was provided with two sets of maxillary complete dentures, one hollow labeled as A and one conventional maxillary denture labeled as B. RESULTS: It was shown that mean values for retention using MKIS for retention for hollow dentures (A) was 7.8 and for conventional dentures (B) it was 8.2 and the stability for maxillary dentures was more with conventional dentures (B) than hollow maxillary dentures (A) and it was significant as p-value was 0.015 (p<.1). CONCLUSION: The denture retention and stability, chewing and comfort values of conventional dentures and hollow dentures were slightly better for conventional dentures.

Transparent magnesium aluminate spinel: a prospective biomaterial for esthetic orthodontic brackets.

Adult orthodontics is recently gaining popularity due to its importance in esthetics, oral and general health. However, none of the currently available alumina or zirconia based ceramic orthodontic brackets meet the esthetic demands of adult patients. Inherent hexagonal lattice structure and associated birefringence limits the visible light transmission in polycrystalline alumina and make them appear white and non transparent. Hence focus of the present study was to assess the feasibility of using magnesium aluminate (MgAl2O4) spinel; a member of the transparent ceramic family for esthetic orthodontic brackets. Transparent spinel specimens were developed from commercially available white spinel powder through colloidal shaping followed by pressureless sintering and hot isostatic pressing at optimum conditions of temperature and pressure. Samples were characterized for chemical composition, phases, density, hardness, flexural strength, fracture toughness and optical transmission. Biocompatibility was evaluated with in-vitro cell line experiments for cytotoxicity, apoptosis and genotoxicity. Results showed that transparent spinel samples had requisite physico-chemical, mechanical, optical and excellent biocompatibility for fabricating orthodontic brackets. Transparent spinel developed through this method demonstrated its possibility as a prospective biomaterial for developing esthetic orthodontic brackets.

Laser ionization mass spectrometry in oral squamous cell carcinoma.

Biomarker research in oral squamous cell carcinoma (OSCC) aims for screening/early diagnosis and in predicting its recurrence, metastasis and overall prognosis. This article reviews the current molecular perspectives and diagnosis of oral cancer with proteomics using matrix-assisted laser desorption ionization (MALDI) and surface-enhanced laser desorption ionization (SELDI) mass spectrometry (MS). This method shows higher sensitivity, accuracy, reproducibility and ability to handle complex tissues and biological fluid samples. However, the data interpretation tools of contemporary mass spectrometry still warrant further improvement. Based on the data available with laser-based mass spectrometry, biomarkers of OSCC are classified as (i) diagnosis and prognosis, (ii) secretory, (iii) recurrence and metastasis, and (iv) drug targets. Majority of these biomarkers are involved in cell homeostasis and are either physiologic responders or enzymes. Therefore, proteins directly related to tumorigenesis have more diagnostic value. Salivary secretory markers are another group that offers a favourable and easy strategy for non-invasive screening and early diagnosis in oral cancer. Key molecular inter-related pathways in oral carcinogenesis are also intensely researched with software analysis to facilitate targeted drug therapeutics. The review suggested the need for incorporating 'multiple MS or tandem approaches' and focusing on a 'group of biomarkers' instead of single protein entities, for making early diagnosis and treatment for oral cancer a reality.