Crown Surface Form

A. Introduction:

The geometric configuration of all the crown surfaces of teeth (except incisal and occlusal i can be placed in one of three general categories: triangular, trapezoidal, or rhombr

B. Facial and Lingual Surfaces:

From the facial and lingual aspects, all permanent teeth in the mouth can be roughly described as trapezoidal. The incisal (occlusal) side forms the base of the trapezoid, while the cervical represents the shorter parallel side. Arrangement of these trapezoidal shaped crowns side by side in the dental arches creates interproximal spaces between the teeth, as well as one contact area between each pair of adjacent teeth. Since the shorter parallel side of the trapezoid is at the cervical, there is adequate space available for bony support around the roots of each tooth.

C. Mesial and Distal Surfaces:

1. Anterior teeth: As viewed from their proximal surfaces, the crowns of permanent anterior teeth exhibit a triangular shape, with the base of the triangle at the cervical, and the apex at the incisal. This shape readily fits into the prescribed function of the anterior teeth, since the apex at the incisal functions as a wedge in tearing, biting, and incising food material, while the wider cervical base provides the necessary strength for the crown form.

2. Maxillary posterior teeth: The crowns of permanent maxillary posterior teeth have proximal surfaces which are roughly trapezoidal in shape, with the base at the cervical, and buccal and lingual sides constricting toward the occlusal. This general shape also provides a wedge form which aids in the distribution of forces during mastication, and facilitates the self-cleaning process of the teeth.

3. Mandibular posterior teeth: From the proximal aspect, permanent mandibular posterior teeth are roughly rhomboidal. with the crowns inclined toward the lingual. This form and inclination allows for proper interlocking of the mandibular and maxillary posterior teeth during mastication.





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