376 Theories and techniques of oral implantology

small rectangular seat for the horizontal bar the same size and depth as, or slightly larger than, the bar was then created in the crest of the ridge with a fissure bur.

The implant was once again tried in the mouth. (If the horizontal bar is not seated deeply enough and if its superior surface is protruding from the crest of the ridge, the site needs more attention. The implant must be removed and the template once

Fig. 9-139. Both bifid implants in place.

Fig. 9-140. A, A vent-plant is also used to help support the two bifid implants. B, The three implants in position.

again introduced to guide the spiraled bur to make deeper holes until the implant fits flush.)

Twist drills for the second bifid implant were then used in the cuspid area on the other side of the arch (Fig. 9-138), making sure that the pins went in the opposite direction from those of the first implant. The horizontal bar spanning the legs of this implant must also fit flush with the alveolar crest (Fig. 9-139).

To give added retention and to help prevent dislodgment by buccolingual movements of the tongue, a vent-plant was inserted midway between the bifid implants, ending deep into the cortical bone along the inferior border of the mandible (Fig. 9-140).

Before the soft tissues were sutured over the horizontal portions of both implants, a full lower plaster

Fig. 9-141. A plaster index is taken of the three implants as well as the rest of the lower arch. Duplicate implants were used in the index to facilitate laboratory procedures.

Fig. 9-142. The tissue was then sutured around the protruding shafts.