The anterior blades are inserted in the standard fashion: grooves are prepared, bladevents are curved to fit the socket, and finally tapped down until their posts touch the crest.

With the site still exposed and plastic copings over the blade-vents, an impression material' is molded over the anterior maxillary arch. Special attention is paid to the areas flanking the blade-vents (32, 33).

When the impression material is set, it is removed along with the plastic copings (34) over the implants. A bite is always taken with the impression material at the same time the bone impression is taken.

Caution: Impression material should not be packed into the grooves or under the implant posts. If it binds and sets under the posts, the implants can be dislodged. Foil, wax, or rubber dam material, cut to shape and with holes for the posts, can be laid over the site to protect the wound. Or, soft surgical wax can be packed into the groove and around the posts.

Prefabricated metal die pins are inserted in the impression, and a stone model cast from it. The dies become incorporated in this master model.

The toroplant subperiosteal implant is designed directly on

the stone model (36).2 The stone model bearing the implant

sketch is sent to a reliable laboratory which will cast the implant from the sketched design.

The fabricated toroplant should fit exactly over the exposed bone, snapping on over the abutment posts and ridge. The operator should not rock the toroplant on or force it into position. Undue pressure on the blades during insertion can fracture their bony sockets, or a poor fit can move them in much the same way as teeth are moved during orthodontia. If there is too tight a fit, the blade posts can be carefully tapered with a carbide fissure bur. The copings (37) over the bladevent posts must not intrude into crestal bone. They can be reduced, if necessary, with a bur outside the mouth. Some remodeling or reshaping of the bars and struts is also possible, but should not be necessary with a carefully planned and executed design.

Hard cement is inserted into the copings, and the implant is seated. Each coping bears a modified Dolder or Andrews bar (38), which will be incorporated within the restoration.

'Imput—Columbia Dentoform Corp.—N.Y. 'Park Dental Studios, N.Y. 'Howmedica—N.Y.

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