A. Another integral part of the master plan of tooth form and arrangement is the location of the height of contour on the facial and lingual surfaces on the crowns of teeth. The height of contour, which is also known as the crest of curvature, is the greatest area of contour inciso(occluso) cervically on the facial and lingual surfaces, and is best observed by viewing these surface outlines from a proximal aspect. Actually, mesial and distal surfaces also have heights of contour, and they are normally located at the contact areas.
B. The importance of these contours to the physiology and state of health of the periodontium is also critical. As with embrasure form, these contours aid in the proper protection and stimulation of the gingival tissue. If the contour is excessive, the flow of food material will be deflected away from the gingiva, and inadequate stimulation of these tissues may result in their breakdown. On the other hand, when an insufficient contour does not provide adequate protection, the overstimulation or insult to the gingival tissues may also result in their deterioration. Once again, the implications to the dentist of restoring correct contours should be obvious.
and lingual surfaces of the teeth are as follows:
1. Facial surfaces - The height of contour on the facial surfaces of all anterior and posterior teeth is located in the cervical third.
2. Lingual surfaces:
a. Anterior teeth - On the lingual surface of incisors and canines, the height of contour is found in the cervical third.
b. Posterior teeth - The lingual height of contour for premolars and molars is located in the middle or occlusal third.
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