purpose:dental shade guides are commonly used for color determination and should be disinfected and sterilized. the purpose of this study was to evaluate the color change of vita 3d master shade tabs after disinfection and sterilization. material and methods:overall, 98 samples (shade tabs) were randomly selected from 14 new, unused vita 3d sets, including the following shades: 2m1, 3l1.5, 3m1,...

background: pancreatitis is most common complication of post-ercp and needs to admission at least for one day. the purpose of this study was to assess the efficacy of guide wire for better common bile duct (cbd) cannulation for reducing post-ercp pancreatitis. methods: from april 2010 through march 2011, the patients who needed ercp and referred to shahid beheshti and rouhani teaching hospital ...

The event study model is a powerful econometric tool used for the purpose of estimating dynamic treatment effects. One its most appealing features that it provides built-in graphical summary results, which can reveal rich patterns behavior. Another value picture estimated pre-event pseudo-“effects,” provide type placebo test. In this essay I aim to framework shared understanding these models. T...