Posterior_Direct_Restorations Salvatore_compressed

FIG 2-12 Maxillary right first premolar. (a) The central developmental groove is centered mesiodistally but located slightly palatally. The buccal cusp is slightly larger than the palatal cusp. In subtractive techniques, this will be the first groove to be defined; in additive techniques, the cusps will be defined as the result of moving masses closer together. M, mesial. (b) The central developmental groove extends in a buccal direction both mesially and distally, separating the buccal ridges from the palatal cusp as well as from the mesial

and distal marginal ridges. Two small supplemental grooves sometimes extend from the primary groove toward the palatal cusp. (c) The mesial interradicular concavity can extend to the mesial marginal ridge, creating a depression or break in the ridge. (d) Sometimes this break in the marginal ridge continues into the central developmental groove. (e) The triangular ridges of the cusps are not usually accentuated. When they are, the associated supplemental grooves must be exaggerated accordingly.

FIG 2-13 Maxillary right first (right) and second premolars.

FIG 2-14 Maxillary left first (left) and second premolars.

Maxillary second premolar

The maxillary second premolar is very similar to the first (Fig 2-15). However, the central developmental groove is shorter, and there are many more supplemental grooves extending from it than in the first premolar. This tooth is much more symmetric than the first premolar and significantly more rounded. Figure 2-16 shows anatomical references whose specificities and variants should be considered when modeling. Figures 2-17 and 2-18 provide additional views of the occlusal surfaces of maxillary premolars, highlighting the variations that occur naturally.

FIG 2-15 (a and b) Clinical photograph and illustration of the occlusal surface of a maxillary right second premolar. M, mesial.