Posterior_Direct_Restorations Salvatore_compressed

FIG 2-27 (a and b) Illustration and clinical photograph of the occlusal surface of a mandibular left first molar. M, mesial.

FIG 2-28 Mandibular left first molar. (a) The central fossa is approximately centered mesiodistally but displaced slightly lingually. (b) The central fossa is the point of confluence of three grooves, forming a Y. The two buccal grooves house the centrobuccal cusp crest, while the lingual groove separates the lingual cusp crests. (c and d) Both buccal portions of the Y-shaped groove end in fossae. The other grooves, separating the mesiobuccal and distobuccal ridges, branch off from these. The buccolingual developmental grooves, together with the supplemental grooves, separate the cusps from one another. (e) The mesiodistal developmental grooves extend toward the mesial and distal marginal ridges. (f) The mesial marginal ridge extends toward the occlusal surface. (g) Sometimes there is a mesial fossa from which two supplemental grooves run toward the margin. (h) On other occasions, these supplemental grooves traverse the entire marginal ridge, creating breaks. These characteristics can be appropriately recreated to break up a marginal ridge that would otherwise look artificial.

FIG 2-29 Occlusal surface of a mandibular left first molar.

Mandibular second molar

The mandibular second molar has four cusps (Fig 2-30). The occlusal surface looks quite simple as it is only slightly lingualized and features cross-shaped developmental grooves separating the four cusps. Figure 2-31 shows anatomical references whose specificities and variants should be considered when modeling. The simplicity of a cross-shaped occlusal growth pattern is difficult to replicate in a natural-looking way

during restoration. Sometimes the cross-shaped pattern is more complex, and there are two triangular fossae from which the grooves run (Fig 2- 32).

FIG 2-30 (a and b) Clinical photograph and illustration of the occlusal surface of a mandibular left second molar.

FIG 2-31 Mandibular left second molar. (a) The occlusal surface looks relatively squareshaped. M, mesial. (b) The position of the central fossa is relatively centered in the occlusal surface, which looks slightly lingualized from an occlusal viewpoint. (c) Grooves defining the four cusps originate in the central fossa. (d) Mesial and distal marginal fossae, from which the supplemental grooves run, are located approximately 1.5 mm from the marginal ridge.