We talked about the apex of the tooth is (root’s tip), so I want to discuss terms that you will hear often when talking about the apex of a tooth. These include a “closed apex” and an “open apex.

Closed Apex this is the apex in its normal form where it is connected to the tooth without any gaps in the connection. This is a fully formed healthy tooth that is not diseased at the apex. When an Apex is open, and it becomes closed, it is called a sealed apex. This occurs when the dentist goes in and must seal the apex closed so the gaps won’t lead to an infection. This is typically done during root canals and is sometimes the entire need for a root canal.

Open Apex

An open apex is when there is a gap in the pulp that is connecting the tooth to the jaw. The tooth can still get some nutrients if there is a connection. Immature and under-developed teeth have an open apex naturally, so when people typically talk about an open apex in a diseased tooth, they are referring to teeth that have dying or dead pulp (called a necrotic open apex).
An open apex can also occur because of blunt trauma creating an artificial gap in the tooth that may heal on its own or with assistance. An unsuccessful healing gap in the tooth’s pulp will most often lead to an abscess, so when an open apex occurs in blunt force trauma dentists will often want to do a root canal immediately to prevent further complications (infected roots in extreme cases can kill you).