molar to the lowermost aspect of the third molar on the opposite side. Figure 2-7 illustrates an edentulous mandibular arch.

EDENTULOUS MOUTH.

- Inscribe crossing lines (fig. 2-8) one extending from the maxillary right third molar to the mandibular left third molar and the other line from the maxillary left third molar to the mandibular right third molar.

PARTIALLY ERUPTED TOOTH.

- In the diagram of the tooth, draw an arcing line through the long axis. Figure 2-9 illustrates teeth #17 and #32 as partially erupted.

AMALGAM RESTORATIONS.

- In the diagram of the tooth, draw an outline of the restoration showing size, location, and shape, and block in solidly. The following are different types of amalgam restorations:

Occlusal (O): Chart along the grooves on the occlusal surface (fig. 2-10, teeth #l, #2, and #5).

Figure 2-7. - Missing teeth and edentulous mandibular arch.

Figure 2-8. - Edentulous mouth.