type of situation, the bone must firmly encase the single natural abutment, and the sinus be small.

The methods for inserting a single-tooth implant, whether it be to support a single-unit restoration or for inclusion in a multi-unit restoration, are very much the same.

Because the single-tooth implant is atypically tall, the operator must reflect an unusual amount of tissue to visualize the ridge, particularly the labial surface. Undercuts may occur at any level on the ridge, and labial concavities are typical in anterior situations.

The exceptionally deep groove must bisect the labio-palatal cortices at the narrowest diameter of the ridge, wherever it occurs. If the ridge is wide, the bur should be angled toward the harder bone of the palate.

The most desirable alignment for a single-tooth implant is along the arch line (15). Thus the broader surface of the implant faces the lateral forces (16) which are the major cause of dislodgement. However, to avoid the sinus, the longer surface may be set perpendicular (17) to the arch. Or, perhaps there is insufficient space between the roots of the teeth and the implant must be angled (18) to avoid impinging upon their periodontia. The implant socket may also be angled to avoid a flaw (19) in the ridge.

The 700 XXL bur is used to make the socket for this long implant. In particularly dense bone — which is not uncommon deep in the canine pillar (20) or near the nasal vestibulum and midline (21) — more than one fresh bur may be needed. Some bone is so dense that reducing the implant's height is preferable to intense, high-friction drilling. When the bone is very porous, a few millimeters should be left to be broken by the implant's legs as the implant is finally seated.

The teeth bordering the edentulous span may interfere with the head of the contra-angle, preventing the bur from reaching the desired depth. The bur can be locked further out of the contra-angle head; the standard contra-angle can be replaced with a pedoheaded contra-angle; or a straight handpiece (22) can be used to go between the teeth with a special bur to fit it. If neighboring teeth are to be prepared for full crowns, this can be done prior to starting the implant socket to make easier access for the implant groove.

Usually the bone between the crest of the ridge and the nasal vestibulum is tall enough to accept the manufactured size of a single-tooth implant. However, excessive resorption, or reduction of a knife-edge ridge to make it better accommodate an implant, may make the ridge shorter than the implant (23). The implant

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