MAXILLARY SECOND MOLAR

The maxillary second molar (tooth #2 or #15), illustrated in figure 4-42, is the seventh tooth from the midline. The second molars are often called 12-year molars because they erupt when a child is about 12 years old.

Because it has the same function as the maxillary first molar, its physical characteristics are basically the same. The second molar is smaller, the occasional fifth cusp of Carabelli does not appear, and there is a marked reduction in the size of the distolingual cusp.

MAXILLARY THIRD MOLAR

The maxillary third molar (tooth #1 or #16), illustrated in figure 4-43, is the eighth tooth from the midline. Third molars are often called wisdom teeth

Figure 4-42.\Surfaces of maxillary second molar.

Figure 4-43.\Surfaces of maxillary third molar.

because they erupt when the young adult is passing into manhood or womanhood. The tooth is much smaller than the maxillary first or second molars, with an occlusal outline that is nearly circular.

Occlusal Surface

Numerous fissures and grooves cover the occlusal surface. There is no distinct oblique ridge.

Root Surface\The root may have from one to as many as eight divisions. These divisions are usually fused and very often curved distally.

MANDIBULAR FIRST MOLAR

The mandibular first molar (tooth #19 or #30), illustrated in figures 4-44 and 4-45, is the sixth tooth from the midline. It is the first permanent tooth to erupt.

Facial Surface\The facial surface has two grooves: the facial groove, which is an extension of the facial groove from the occlusal surface and the distofacial groove, an extension of the distofacial groove from the occlusal surface.

Occlusal Surfaces\The occlusal surface has five cusps (fig. 4-45). The fifth cusp is called the distal cusp.

Roots \The tooth has two roots, a mesial and a distal.

MANDIBULAR SECOND MOLAR

The mandibular second molar (tooth #18 or #31), illustrated in figure 4-46, is the seventh tooth from the midline.

Figure 4-44.\Surfaces of mandibular first molar.

Figure 4-45.\Features of an occlusal surface of mandibular first molar.

Figure 4-46.\Surfaces of mandibular second molar.

Facial Surface\The facial surface has only one groove, the facial groove, which arises on the occlusal surface, extends over the facial margin onto the facial surface.

Occlusal Surfaces\The greatest difference between the occlusal surfaces of the mandibular first and second molars is that the occlusal surface of the second molar has no fifth cusp.

Roots\The mandibular second molar has two roots that are smaller than those of the first molar.