The Hamular Notch

Posteriorly in the upper arch, where the tuberosity joins the pterygoid process of the sphenoid bone, lies a distinct cleft, familiar to dentists as the hamular notch (1). This area usually retains its distinct shape and depth even after extensive alveolar ridge re-sorption because it is formed by dense, compact bone. The notch marks where the posterior border of the tuberosity (2) joins the medial (3) and lateral (4) plates of the pterygoid process. Of these two plates, the more anterior — the medial — projects interiorly as a distinct, finger-like extension of bone — the pterygoid hamulus (5). When the mouth is wide open, the hamulus tip can be seen as a small bulge (6) slightly posteriorly and medially to the maxillary tuberosity (7), above the anterior pillar (glossopalatine muscle) (8) and tonsil (9).

The hamular notch area has previously concerned dentists mainly in relation to the posterior border of a denture. The area interests the implantologist because its distinct morphology and dense, compact bone can serve as a subperiosteal-type implant site. This implant, called the pterygoid extension implant because its most posterior portion is braced against the pterygoid process that forms the posterior wall of the cleft, provides the only posterior maxillary support possible in a maxilla with a severely ballooned sinus that has invaginated the crest anteriorly and maxillary tuberosity posteriorly. The pterygoid extension implant is fashioned to lodge in the hamular notch against the pterygoid process with a thick palatal arm extending forward over the dense palatal side of the alveolar crest, and a wider, fenestrated buccal arm wrapping over that part of the tuberosity that encloses cancellous bone, distal to the sinus. From this posterior portion a bar angles occlusally to pass forward well above the crest and connect with anterior sup-port, natural or artificial. This bar will bear the prosthesis, so that no force is applied to any part of the fragile ridge under or buccal to the sinus.

Using the pterygoid extension implant requires exposing the site to get a direct bone impression for fabricating the prosthesis, and then re-exposing the area to insert the fabricated implant. There are two very distinct landmarks to be avoided in either procedure.

The scalpel should never approach the greater (10) and lesser palatine foramina (11), nor their emerging vessels. The more

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