Learning objective: to study the peculiarities of the anatomical structure of frontal maxillary teeth, to learn to identify the distinctive features of teeth belonging to the right and left side.
CENTRAL UPPER INCISOR
The vestibular surface of this tooth is convex, trapezoidal in shape. There are two poorly pronounced grooves called medial and distal depressions; they are formed by three scallops: longitudinal, medial, and distal. The crown of the tooth has well-defined signs of the angle; the medial angle is acute, the distal one is blunt. The height of contour is well defined, there is a pronounced anatomical neck (fig. 10.1).
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The oral surface also has a trapezoidal shape. There are two medial and distal ridges that converge in the cervical region and form the cervical line. The anatomical neck of the tooth is clearly pronounced (fig. 10.2).
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From the lateral view the incisor is triangular in shape, palatine and ves-tibular contours are distinguishable (fig. 10.3).
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The cavity of the tooth is similar to its external outlines. Near the cutting edge, the cavity is slit-like, flattened in the vestibule-lingual direction, it narrows at the root and passes smoothly into the root canal.
The incisor has one root: straight, slightly flattened in the medio-lateral direction. The lateral surface of the root is more convex, with a shallow longitudinal groove. The root deviates laterally from the vertical axis. On the cross cut its shape is oval.
Distinctive signs:
► crown height 9-12 mm;
► crown width 8-9 mm;
► medio-distal diameter of the neck 6.3-6.9 mm;
► vestibulo-lingual diameter of the neck is 7.1-7.5 mm;
► root length 12-15 mm.
LATERAL UPPER INCISOR
The lateral upper incisor has vestibular surface of pentagonal shape. There are three ridges: longitudinal, medial, distal, converging in the cervical region. There is a medial depression. The distinctive signs of the crown angle are slightly less pronounced than in the first incisor (fig. 10.4).