In 1981, Reagan persuaded Congress to reduce the top tax rate form 70% to 50% and to index tax brackets (so that inflation was taken into consideration). In 1986, the Tax Reform Act reduced the rate on the wealthiest Americans to 28%.
Causes. Cavities are caused by tooth decay â a process that occurs over time. Here's how tooth decay develops: 1  Plaque forms. 2  Your mouth naturally contains many types of bacteria. 3  Some thrive on food and drinks that contain certain forms of sugar.
The weakened enamel then collapses to form a cavity and the tooth is progressively destroyed. Caries can also attack the roots of teeth should they become exposed by gum recession. This is more common in older adults. Dental caries is caused by the action of acids on the enamel surface. The acid is produced when sugars (mainly sucrose) in foods or drinks react with bacteria present in the dental biofilm (plaque) on the tooth surface.