The ductus arteriosus is a hole that allows the blood to skip the circulation to the lungs. However, when the baby is born, the blood must receive oxygen in the lungs and this hole is supposed to close. If the ductus arteriosus is still open (or patent) the blood may skip this necessary step of circulation. The open hole is called the patent ductus arteriosus.
Caring for a Bleeding Tooth. Some people mistakenly think that while brushing, a bleeding tooth is perfectly normal. It is not. Anytime there is any bleeding in the mouth, it is almost always a sign of periodontal disease. Even if you brush fairly hard, it should not cause healthy teeth and gums to bleed.
A dead pulp means a dead tooth. In many cases, a non-vital dead tooth is removed. Causes of Dead Tooth. There are two known causes of a dead tooth â tooth decay and dental trauma. Tooth Decay. Tooth cavity or bacterial infection, if not treated, can get near the nerve or the pulp, causing the nerve to die.