498 Theories and techniques of oral implantology

was picked up with an accurate alginate impression. As for tissue healing, it was continuing uneventfully (Fig. 11-112).

The processed lower full arch porcelain-fused-tometal splint was affixed with hard cement (Fig. 11-113). All spot-grinding necessary for perfect occlusion was done (Fig. 11-114) .

A comparison between an immediate postoperative Panorex (Fig. 11-115) and one taken 6 months later (Fig. 11-116) shows an impressive amount of bone rehealing. Needless to say, the patient was de-lighted with her restoration.

Case 10

A full arch restoration for a maxillary knife-edge ridge

The true knife-edge ridge develops in the maxilla rather than the mandible. When a knife-edge ridge is seen in the mandible, it is usually the unresorbed mylohyoid ridge. The true ridge crest has resorbed

to a flatter, and many times concave, surface buccal to the mylohyoid ridge. The situation is camouflaged by the mucoperiosteal tissue over the bone and can-not be realized readily until the soft tissues have been incised and retracted.

In the maxilla, however, the alveolar bone resorbs in a buccopalatal or labiopalatal direction. Therefore the knife-edge of the ridge is the true ridge. Here too the situation is often camouflaged as a result of the extreme thickness of the fibromucosal tissue over the ridge.

Because of the tendency of the mucoperiosteum to camouflage the bone's morphology, it is now considered imperative to incise and retract the tissues in order to expose the underlying bony ridge, no matter what type of implant is contemplated. This not only avoids perforating the cortical plates, it also ensures that no epithelium will be pushed down to the artificial socket and proliferate there.

This case, accomplished on a 52-year-old woman,

Fig. 11-117. The patient had been unhappily wearing a removable prosthesis.

Fig. 11-118. Only two molar teeth remained. Note the thickness of the fibromucosal tissue, which often camouflages the morphology of the underlying maxillary ridge.

Fig. 11-119. Both molar teeth were prepared for full crown restorations.

Fig. 11-120. The incision was made from molar to molar along the crest of the ridge.