Coordination of tooth fit

=; A major finishing consideration in the horizontal plane is the

G"> coordination of tooth fit in the anterior and posterior areas.

^ The authors find that the anterior and posterior teeth fit well, with little or no adjustment, in approximately 20% of cases > (Fig. 10.4). However, in approximately 60% of cases m (Fig. 10.4), as the finishing stage approaches, it becomes clear that the crowns of the upper anterior teeth do not occupy enough space, relative to the crowns of the lower anterior teeth. The evidence may be seen in the following situations:

Cases where posterior space closure is difficult in the upper arch while maintaining the correct amount of overjet (3-4 mm).

Cases where the overjet is correct, but the buccal segments remain in a slight to moderate Class II position.

• Cases where complete space closure in the upper anterior segment is difficult while attempting to maintain the correct amount of overjet.

Fig. 10.4 Tooth size coordination.

In approximately 20% of cases (Fig. 10.4), the authors find an excess of upper anterior tooth substance, relative to the lower. In these cases, the crowns of the teeth in the upper anterior segment are disproportionally larger than the crowns of the teeth in the lower anterior segment, and the patient shows some excessive overjet when the posterior segments are in a Class I relationship. This is seen in the following situations: Fi9- 10.5

• In patients with large upper incisors

• In some Class III cases where upper incisors are proclined forward and lower incisors are retrodined.

These patients can be easily managed during finishing by canying out some enamel reduction in the upper anterior segment and then closing the residual space.

The challenge, then, is dealing with the 60% of cases that show a relative shortage of tooth mass in (he upper anterior segment. In (he horizontal plane, this difficulty relates primarily to the factors of tip in the anterior teeth, incisor torque, and tooth size (Fig. 10.5). Each of these will be discussed below.

Torque Tooth size

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