Yes, rotten teeth can make you very sick. Think about it, the teeth are rotten because the enamel is no longer there to protect the teeth from bacteria. That bacteria that has infected your teeth can travel through your digestive tract to your intestines where it can multiply like mad, or it can gain access directly to your bloodstream through the tiny capillaries inside your mouth (your mouth is very vascular, that's why it can bleed easily, but heal quickly). Once bacteria makes it to your blood it has a free ride to any organ in your body. The most frequent and serious systemic infection from rotten teeth is called pericarditis. It's an infection surrounding the outer layers of your heart. Obviously you'd be facing serious bodily consequences at that point. In conclusion, do what your dentist tells you and brush your freakin teeth dude.
