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In some individuals, the central incisors may be separated from the nasal cavity (8) by only a thin plate (9) of bone; in others, there is a good amount of bone (10) between the two. Naturally, the latter individual has the decided advantage after tooth loss. More support remains for the lip, and there is generous bone for an endosteal implant. The two examples cited, however, are extremes. Most cases fall somewhere in between, and usually an adequate amount of bone remains in the remodeled socket.

Labial bone below the nose and extending bilaterally into the canine pillar area is usually as dense as mandibular bone except in the symphyseal area. It is to be remembered, however, that the residual socket bone and the subnasal bone are responsive to trauma. A poorly fitting removable appliance or a full maxillary denture opposed by natural anterior mandibular teeth can cause extensive resorption in this area, compounding surgical and prosthodontic problems.

The Palate

Palatal anatomy should be reviewed for two reasons. Firstly, the palate may serve as an implant site; and secondly, the soft tissues overlying the maxillary alveolar crest should be reflected towards the midline with a minimum amount of damage. This involves knowing the character of the tissues; the origins and pathways of the vital blood vessels, nerves, and glands; and the structural peculiarities of different sections of the arch. Knowing where to anticipate problems helps to avoid them or cope with them.

The palate forms the roof of the oral cavity and separates it from the nasal cavity. It consists of the hard palate, comprised by the palatine processes of the maxillae and the horizontal plates of the palatine bones, and of the palatine velum, a movable, thick fold of mucous membrane. The vertical part of the palatine velum, or soft palate, forms the posterior wall of the oral cavity, and curves down laterally as the palatine pillars.

The Hard Palate

The hard palate is a relatively narrow plate of bone that arches downward to meet the maxillary alveolar process. The palate may be almost flat or form a deep vault or may have an

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