Characterization of osteogenic cells grown over modified graphene-oxide-biostable polymers.

Graphene is an excellent filler for the development of reinforced composites. This study evaluated bone cement composites of graphene oxide (GO) and poly(methyl methacrylate) (PMMA) based on the proliferation of human bone marrow mesenchymal stem cells (hBMSCs), and the anabolic and catabolic effects of the incorporation of GO on osteoblast cells at a genetic level. Surface wettability and roughness were also evaluated at different GO concentrations (GO1: 0.024 wt% and GO2: 0.048 wt%) in the polymer matrix. Fabricated specimens were tested to (a) observe cell proliferation and (b) identify the effectiveness of GO on the expression of bone morphogenic proteins. Early osteogenesis was observed based on the activity of alkaline phosphatase and the genetic expression of the run-related transcription factor 2. Moreover, bone strengthening was determined by examining the collagen type 1 alpha-1 gene. The surface roughness of the substrate material increased following the addition of GO fillers to the resin matrix. It was found that over a period of ten days, the proliferation of hBMSCs on GO2 was significantly higher compared to the control and GO1. Additionally, quantitative colorimetric mineralization of the extracellular matrix revealed greater calcium phosphate deposition by osteoblasts in GO2. Furthermore, alizarin red staining analysis at day 14 identified the presence of mineralization in the form of dark pigmentation in the central region of GO2. The modified GO-PMMA composite seems to be promising as a bone cement type for the enhancement of the biological activity of bone tissue.

Surface wettability and nano roughness at different grit blasting operational pressures and their effects on resin cement to zirconia adhesion.

This study analyzed the effect of grit blasting pressures on resin cement to zirconia (ZrO2) adhesion using enclosed mold shear bond test (EM-SBS). ZrO2 blanks were pre-treated with Rocatec™ Soft as follows: group 1: control, group 2: specimens treated at 80 kPa, group 3: at 180 kPa, group 4: at 280 kPa, and group 5: at 380 kPa. Monobond® N and Multilink® Speed were used as the silane and resin cement, respectively. Next, the blanks were assigned into three sub-groups (n=8, N=108) according to storage conditions. A non-linear relation was observed between EM-SBS and contact angle versus grit blasting pressure (r=-0.542, p=0.01). According to ANOVA (p<0.05), the EM-SBS values with both 180 kPa (17.4±6.7 MPa) and 280 kPa (19.4±4.8 MPa) were statistically higher after 12,000 thermo-cycles. Relatively equal thermo-cycled bond strength might also be achieved with intermediate (180 kPa) grit blasting pressure instead of the recommended 280 kPa.

Sociodemographic Characteristics as Predictors of Satisfaction in Public and Private Dental Clinics.

OBJECTIVE: This study aimed to investigate influence of multiple sociodemographic characteristics on the patient satisfaction levels in outpatient public and private dental practices of Riyadh, Saudi Arabia. METHODS: Questionnaire-based survey data were collected from 500 patients, 250 each from the public and private dental clinics of Riyadh, Saudi Arabia from September to December, 2017. Questions related to demographic factors and service attributes were included. A Likert scale of 5-points was used to measure satisfaction levels. Data was analyzed to calculate the descriptive and inferential statistics (analysis of variance and multiple regression analysis) to find the statistical difference (p < 0.01). RESULTS: Satisfaction level differed significantly by education level (P< 0.001) and the type of clinic (P<0.001). The multiple regression analysis suggest that all variables influenced satisfaction, except age and marital status. The satisfaction score was higher by 27% for private clinics compared to public clinics. CONCLUSION: This study was exploratory and revealed an effect of individual variables on overall satisfaction score of the services attributes. Future plans for patient care could be developed with the help of this research.