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seated by continual trauma. And this is usually what happens when a patient with a totally edentulous upper arch is dismissed for several days with his bladevents protected by a hollowed out, re-lined conventional denture. The soft tissues are sore and swollen, so the denture is pulled off and reinserted, pulled off and reinserted. With the denture off, occluding knocks the unprotected bladevents labially. As the healthy tissues recede, the denture no longer fits and it slides and jars the implants. Because of the very real, difficulty to control threats to the bladevents, a toroplant-bladevent combination is not recommended for a totally edentulous arch unless the subperiosteal portion of the implant can be inserted within 24 hours.

The prognosis for a bladevent-toroplant is more optimistic in a partially edentulous arch. Here, a stable natural tooth or, preferably, teeth, counterbalancing a bladevent can significantly minimize trauma to the bladevent. The bladevent can be set out of occlusion, an obvious advantage.

Because it is certainly possible, and often beneficial, to include bladevents in a toroplant, the range of situations should be indicated.

The type of bladevents to be used anteriorly depends upon bone availability. Ideally, but rarely, in a totally edentulous area it may be possible to put two abutments on either side of the mid-line in the form of a double-posted blade (25), two single-posted blades (26), or a combination of both. In most cases, there is only enough room for one single-posted bladevent (27) on each side of the midline. Occasionally, one or two stable anterior teeth (28) on one side of the midline may be counterbalanced by a bladevent (29) with a corresponding number of posts. The number of abutments should balance, and all abutments will be covered by copings included in the toroplant.

Caution: A toroplant-bladevent combination can be used only when the ridge has diverging walls. It would be difficult to take an accurate impression — and impossible to insert a toroplant — over a bladevent set in a ridge with a severe undercut (30). Improperly angling the bladevent post (31) to align it with the axis of the ridge for the sake of slipping on a toroplant will result in excessive force against the anterior labial plate and its subsequent destruction. In all totally or partially edentulous situations with a severely undercut ridge, it is far better to eliminate the bladevent and cut a groove in the ridge to accept the labial strut.

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