Occasionally, in situations where the posterior crest is only a millimeter or two above the canal and due to an extreme concavity beneath the mylohyoid ridge blades are inserted near the external oblique ridge rather than on the lingual side of the ridge to avoid a paresthesia, figs. 243, 244. This case worked out exceptionally well, figs. 245, 246, 247. However, I do not recommend placing a bladevent extremely buccal to the ridge as there is usually no attached gingivae in this area and a cross-bite occlusion often results.

It is not always possible to line up the blade posts so that the corresponding crowns of the restorations will fit directly over them, fig. 248. Fig 249 shows how the posterior crown was con-

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