on each side of the midline anteriorly, and one double-posted implant bilaterally posteriorly.

The maxillary anterior implant socket for a single-posted bladevent is started about 2-3 mm away from the midline (1) , and follows the arch posteriorly. A 700 XL bur is used in a contra-angle (2). As with all friction-producing work on bone, copious amounts of water (3) are used to prevent burning.

Because the crest is the narrowest portion of the residual ridge, the socket entrance (4) should be centered on it or slightly palatal to it. Also, because this type of ridge is relatively wide, the bur should be angled slightly toward the palate (5) to provide a generous amount of bone labially as resistance against occlusal impact and anterior tongue thrust. An implant seated in such a site has more bony support labially than does a natural incisor. The greater bulk of labial bone is effectively counterbalanced by the harder nature of the palatal bone.

Caution: To avoid bending the post, the inexperienced operator may decide to angle the channel straight upward (6). This is unwise. The labial plate (7) could be fractured easily during drilling or, later, by occlusal impact. Such angulation would also necessitate using a shallower implant, sacrificing the advantages of placing as deep-bodied an implant in bone as is possible.

The implant socket may be made in several ways. Many opera-tors prefer to sweep the bur along the ridge (8), making a shallow cut first as a guide and gradually deepening the socket. This is a particularly sound approach in good bone.

A relatively inexperienced operator might prefer to mark the implant site with an indelible pencil and then drill a series of holes (9) along the marked line either to the entire depth of the socket or about halfway down. Then these holes are connected with gradually deepening, running sweeps of the bur (10).

In good bone, the depth of the channel or socket (11) equals the height of the blade, from its leading edge (12) to the bottom of its post (13). The 700 XL bur, which is longer than the body of the blade, is used to its entire depth. Often, the 700 XXL bur must be substituted in good bone to obtain the proper depth. If the channel is made deeper than necessary, there is little danger of the blade's sinking because its wedge shape (14) will brace it against the wall of the socket.

The socket should be no wider than the head of the bur. As injured bone cells whose processes have been disrupted by the

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