For example, repeated episodes of vomiting, which is common in people with bulimia, releases harmful stomach acids that wear away tooth enamel and lead to gingivitis and tooth decay. Other problems, such as poorly fitting fillings and braces, are another byproduct of such eating disorders.
Brushing after episodic vomiting is actually more harmful than one would think. The best practice is to rinse thoroughly with a neutral solution such as baking soda and water.