The spread of the COVID-19 virus has brought forward a global pandemic that has halted many businesses and placed restrictions on daily activities. Vaccination of residents is crucial for a small country like Qatar to contain the spread of the virus. This study will aim to investigate and report the general outlook of Qatari residents toward the vaccine, the points of hesitancies, and how the contact tracing application (Ehteraz) can play a role in promoting vaccination. A questionnaire survey was given, and respondents answered a series of background questions and questions related to vaccine hesitancy and the effectiveness of the Ehteraz application. A broad search strategy was used to identify the main contributors to willingness and hesitancy with the COVID-19 vaccination. Regression models and test-train machine learning techniques were used for analysis. The results showed that dominance analysis was effective in highlighting the main barriers and promoters in taking the vaccine and that respondent's characteristics can be used to predict vaccination attitude.

Aim:The current study was conducted to evaluate the effectiveness of ginger and rosemary herbals versus sodium fluoride in remineralization of incipient enamel caries.Methodology: white spot lesions in anterior teeth of post orthodontic debanding patients received randomly two types of remineralizing agents, either ginger and rosemary gel or sodium fluoride varnish (bifluorid 10). White spot lesions were evaluated at base line one month and after 3, 6 months follow up periods by two blinded assessors to assess white spot lesion progression by Kavo DIAGNOdent.Results: Mann-Whitney test showed that there at baseline, sodium fluoride varnish group yielded similar readings as ginger and rosemary gel group (P=0.060). While at 1 month, ginger and rosemary gel group showed significantly higher readings compared to sodium fluoride varnish group (P<0.001). However, there were no statistically significant differences in readings of both groups at 3 months (P=0.302) and 6 months (P=0.070). Conclusion:Fluoride varnish and ginger and rosemary gel can decrease post-orthodontic white spot lesions. The herbals ginger and rosemary may be preferable for prevention purposes on initial remineralization of enamel lesions as more natural products are preferred today.

Objective: evaluate the microhardness and depth of cure of sonic bulk fill resin composite material for cementation of CAD/CAM composite block with different thicknesses versus the traditionally used dual cured resin cement by assessing microhardness at the top and bottom and calculating bottom/top ratio to determine the depth of cure.Materials and methods: CAD/CAM resin composite blocks (Grandio) restorative materials were used in the present study. For cementation options, two resin materials were selected: SonicFill 2 bulk fill resin composite (Kerr) and Dual-link universal Resin cement (Bisco). Four sections were prepared from each CAD/CAM blocks thickness of 1 mm, 1.5 mm, 2 mm and 3 mm respectively. Sectioned specimens of each CAD/CAM blocks were then divided according to their thickness into three groups (n=5).Portions of each composite cement were placed on a 1-mm thick transparent glass slide and squeezed to a 100µm film thickness Each specimen was covered with one of the CAD-CAM composite block slabs or left uncovered (control) and then light-cured for 40 sec that was positioned perpendicularly on top and in direct contact with the CAD-CAM slabs or the top glass (control).Micro-hardness was obtained for the top and bottom surface of specimens. The mean microhardness values and hardness ratio % of the specimens were calculated and tabulated. Microhardness measurements were performed twice; one immediately and after 24 hours. Statistical analysis was performed. Significance of the difference within the same group was evaluated using one way analysis of variance (ANOVA) test, followed by Tukey's post hoc test when ANOVA indicated a significant difference. T test was used to compare between both groups. The level of significance was set at P < 0.05.Results: Immediately, in control, a higher mean value was recorded in Sonicfill group, with a statistically significant difference (p=0.011). In 1 mm, 1.5 mm, 2mm, a higher mean value was recorded in SonicFill 2 group, with a statistically significant difference (p=0.003, p=0.00, p=0.00 respectively). In 3 mm resin cement recorded a mean value of 0.495±0.012.After 24 hours, in (408)

Objective: to evaluate the internal fit of all ceramic restoration fabricated by two CAD/CAM milling systems using cone beam CT (CBCT). Materials and methods:A total number of 20 all ceramic restorations were manufactured in this study, and were equally divided into two main groups (n=10) according to the type of CAD/ CAM system used in the manufacturing process. Group I (Cerec in-lab system) and group II (Everest system) using the e.max CAD blocks specified for each milling system. specially designed stainless steel die was manufactured with specified dimensions. The die was scanned, the all ceramic restoration was designed and milled according to the different CAD/CAM milling systems used, and then crystallization procedure was carried. Duplication of the metal die into epoxy resin dies was performed and the final all ceramic restorations were the placed over the epoxy resin dies and examined for internal gap measurement using cone beam computed tomography (CBCT). Numerical data were explored for normality using Kolmogorov-Smirnov test of normality. Normally distributed (parametric data), were presented as mean, standard deviation and were compared between groups using independent t test. Non-parametric data were compared between groups using Mann Whiney U test. Gingival, axial and occlusal segments were compared using Friedman test and Wilcoxon signed rank test. The significance level was set at p < 0.05. Statistical analysis was performed with SPSS 18.0 for windows.Results: Comparison between groups using the mean of the 3 successive sections in buccolingual section revealed that a higher mean value was recorded in Cerec for each of the gingival, axial and occlusal segments, with no statistically significant difference between groups (p=0.138, p=0.06, p=0.276 respectively), while in mesio distal section a higher mean value was recorded in Cerec in the gingival and axial segments, with no significant difference between groups (p=0.296,

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objective: This study was conducted to assess the shear bond strength of orthodontic brackets bonded with total etch adhesive systems containing silver nanoparticles (AgNPs) and interfacial analysis using Environmental Scanning Electron Microscope (ESEM). materials and methods:The AgNPs was synthesized and characterized by (UV-Vis) spectroscopy and Transmission Electron Microscope (TEM). Adper Single Bond 2 was used as the total etch (TE) adhesive. 48 teeth were divided into 40 teeth for shear bond strength test and 8 teeth for ultra-morphologic examination. For shear bond strength test 40 teeth were randomly divided into two equal groups according to the addition of silver nanoparticles, (TE) teeth were bonded with adhesive not containing silver nanoparticles and (TES) teeth were bonded with adhesive containing silver nanoparticles. Each group was subdivided into 2 subgroups: C 1 (10 specimens): 24 hours aging period. C 2 (10 specimens): 3months aging period. Finally two representative samples of each group were analyzed using an (ESEM) for interfacial analysis. result: After 24 hours aging, there was non-significant difference between mean shear bond strength values of the adhesive contain silver nanoparticles (5.09± 1.69) and the nanoparticles free adhesive (4.69± 1.42). Also after 3 months aging there was non-significant difference between both adhesives with (6.31±1.12) and without (5.14± 1.16) addition of silver nanoparticles. conclusions:The addition silver nanoparticles to total-etch adhesive systems did not hinder bonding of resin composite to enamel. Silver nanoparticles didn't antagonize penetration of resin tags into enamel. Bonding of brackets with resin composite using total etch adhesive system containing and non-containing Silver nanoparticles doesn't deteriorate with time.

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