Apex of the Tooth Root

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

Anatomy and pathophysiology

In the apex area, 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 starts to develop: 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. The apical foramen is often displaced relative to the axis of the root, so the radiological apex and the apical constriction often do not coincide.

Clinical significance

For successful endodontic treatment, the dentist must accurately identify where the apical constriction is located. Canal filling should be performed strictly to this boundary. If the material does not reach the apical constriction, bacteria may remain in the canal, and if the material extends beyond the constriction, it may cause chronic irritation of periodontal tissues.