Parts of Teeth
a. Crown: Each tooth is divided into the crown and the root (or roots). The crown is that part of the tooth which is covered by enamel. The term clinical crown is often used to refer to that part of the tooth which is visible in the mouth. It seldom conforms exactly to that part covered by enamel. In this subcourse, the term crown will refer to the anatomic crown or that portion of the tooth actually covered by enamel. That portion of the tooth where the crown and the root join is commonly called the cervix (neck) of the tooth. The junction between the enamel of the crown and cementum of the root is called the cementoenamel junction (CEJ) or cervical line.
b. Root. The root (or roots) is that part of the tooth which is covered by cementum. It is mostly embedded in the bony process of the jaw. The tip (or end) of the root is called the apex. A small opening which passes though the apex is called the apical foramen. Through this opening, the blood vessels and nerves pass to and from the dental pulp. Often, there are additional small openings near the root apex called supplementary foramina.
c. Gingival Tissue and the Crown. In young persons, part of the enamel of a tooth is normally covered by gingival (gum) tissue. Only the clinical crown is exposed. On older persons, it is common for the tooth’s enamel to be completely exposed above the gingiva (the anatomical crown) and even to have part of the root surface showing.