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Figure 18: A facial view of teeth #5–8 after selective reduction on the
facial and lingual surfaces to remove excess tooth structure outside
the proposed arch form.
Figure 19: An incisal view of the preparations for teeth #5–8 after
depth cutting and two-plane reduction. This process is referred to as
“orthodontic tooth preparation.” Note that the prepared incisal edges
now follow a nice arch form that will be followed in the definitive restorations.
Compare this to the varied directions of the incisal edges in
the preoperative condition in Figure 16.
Figure 20: A facial view of the completed preparations. These
orthodontically prepared teeth are now ready to accept restorations
that will not only correct the clinical crown positions, but will also
be structurally sound and esthetic due to the space created for the
proper thickness of restorative material.
Figure 21: A facial view of the correction of the maxillary arch after
provisionalization with a rubberized urethane provisional material
(Tuff-Temp [Pulpdent Corporation; Watertown, Mass.]).
Interproximal reduction, or IPR, is performed in a similar
fashion to that of conventional orthodontics. The goal is to
separate the prepared teeth at the free gingival crest (Fig. 17).
The facial surfaces of the rotated teeth are reshaped in areas
that are facial to the proposed completed arch form (Fig. 18).
Lastly, depth cutting and two-plane reduction is performed
to allow for the proper positioning and thickness of the
definitive restorations (Fig. 19).
Figure 20 shows the completed preparations from the facial
view. Looking only at the final shape of the final preparations
of the teeth prior to master impression-making, one
would be hard-pressed to know how severe the preoperative
crowding and rotations were.
After making the master impression, taking a facebow
transfer and making interocclusal records, the preparations
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