pointed seating instrument must be used, a finger is needed to hold down the untapped post (17) .

Anterior Support Only — The Toroplant

When the only possible implant sites are anterior, a special subperiosteal implant — the toroplant — can be used. The toroplant is suggested principally for two categories of patient: those whose residual ridge cannot support a balanced complement of anterior and posterior implants because extensive sinus invagination prohibits inserting a bladevent into the tuberosity or extending a pterygoid implant's struts over it; and those patients whose general health contraindicates the more complicated and, therefore, more traumatic surgery required for a pterygoid extension implant. A severe bleeder or a diabetic is a poor candidate for surgery requiring optimal healing conditions.

The toroplant permits using a palateless, removable denture when the patient cannot tolerate a conventional denture because of a flat maxillary landscape; loose, irritated, or diseased soft tissues; or palatal obstructions, such as a large torus. Because sup-port is limited to the anterior region, the restoration should be carried out only through the first molar.

The toroplant includes an anterior palatal (pre-maxillary) portion (1), from which extends bilaterally along the palatal surface of the alveolar bone a posterior strut (2) and an anterior labial strut (3) that passes over the ridge in the cuspid area and bifurcates high on the ridge into short lateral arms, or wings which should join with each other beneath the anterior nasal spine (4). The labial struts bear the posts (5). These are fabricated directly on the implant, as is the modified Dolder or Andrews bar (6) ex-tending posteriorly from each.

The labial struts can be modified to accommodate accessory anterior support. In a totally edentulous arch, bladevents may be used on each side of the midline. In a partially edentulous arch, either natural teeth or a tooth complemented by a bladevent can be included in the labial extensions as they pass over the ridge. The restoration is borne on a modified Dolder or Andrews bar extending from the anterior abutments.

The toroplant for the totally edentulous upper arch is the basic, and simplest, form of toroplant design. As are all other subperiosteal implants, this one is designed by the implantologist directly on a stone model cast from an impression of the exposed sites.

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