ly from the contra-angle and from a separate water syringe (4) are used to prevent burning of the bone.

Since the alveolar crest is the narrowest portion of the residual ridge, the groove entrance (5) should be centered on it or prefer-ably lingual to it. Wherever possible, in the mandible, the bur should not be angled but the groove should be made closer to the lingual border routinely (6) in order to provide a generous amount of bone labially to resist anterior thrusts of the tongue, occlusal impact and eccentric anamolies. An implant seated in such a site has more bone support labially than does a natural incisor. This extra bone is greatly needed labially, which nature did not provide in the tooth-filled arch. This greater bulk of labial bone is effectively counterbalanced by the harder nature of the lingual bone.

Caution: To avoid bending the post, the inexperienced operator may decide to angle the channel straight downward (7). This sometimes is unwise, depending upon the severity of the labial concavities as well as the lingual plate without angulating the bur slightly toward the labial might result in lingual perforation (8) of the bone by the blade and also ending up with a severe crossbite (9). Creating a groove more labially may cause a labial plate fracture near the shoulder of the blade where the labial portion of the ridge crest flanking the blade becomes extremely fragile (10). Thus, this straight upward angulation would also necessitate using a shallower implant, sacrificing the advantages of placing as deep-bodied an implant in the bone as is possible.

The groove required for the bladevent may be made in several ways. Many operators prefer to sweep the bur along the ridge (11) , making a shallow groove 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

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