Apex of the tooth root

The apex of the tooth (Latin apex dentis) is the anatomical tip of the root of the tooth. This area is the transition zone of the pulp cavity to the periodontal tissue and is of key interest for endodontic treatment.

Anatomy and pathophysiology

In the area of the apex there is a large apical opening through which blood vessels and nerve fibers of the pulp pass. It is in the apical zone of the root that apical periodontitis begins: when the pulp dies, the infection enters the periodontal tissues through the apex, causing the development of an apical granuloma, abscess or cyst.

In the anatomy of the apex, three structures are distinguished: the radiologic apex (the apex proper), the large apical opening, and the apical constriction (apical narrowing). The apical constriction – the area with the smallest diameter of the root canal – is considered to be the physiologic level for root canal treatment and filling.

Between it and the large apical foramen, the canal is funnel-shaped and difficult to access for treatment. Often the apical foramen is displaced relative to the root axis, so the radiologic apex and apical constriction often do not coincide.

Clinical significance

For successful endodontic treatment, the doctor must accurately determine the position of the apical constriction. The filling of the canal should be made strictly to this boundary. If the material is not brought to the apical constriction, bacteria can remain in the canal, and if the material is taken out of the structure, it can cause chronic irritation of the periodontal tissues.