There are a variety of situations that require a tooth to be restored with a dental crown. The following are the most common: Large filling: When a tooth has a cavity or fracture that involves half the width of the tooth or more, it needs to be covered with a crown. This is because the remaining tooth around the large filling is so weak that it is prone to fracture. Sometimes a large filling that has been in the mouth for a while will need to be replaced with a crown because the tooth shows signs of stress and cracks around the filling.
How marijuana affects the mind. Marijuana reaches the same pleasure centers in the brain that are targeted by heroin, cocaine and alcohol. Depending on the quantity, quality and method of consumption, marijuana can produce a feeling of euphoria â or high â by stimulating brain cells to release the chemical dopamine.
Researchers for the first time comprehensively describe existing abnormalities in brain function and structure of long-term marijuana users with multiple magnetic resonance imaging (MRI) techniques. Marijuana. The effects of chronic marijuana use on the brain may depend on age of first use and duration of use. The effects of chronic marijuana use on the brain may depend on age of first use and duration of use, according to researchers at the Center for BrainHealth at The University of Texas at Dallas.