The evolution of dental implants 183

Fig. 5-93. Linkow's unilateral lingual finger implant, shown on a model prepared from a direct impression of the bone. The fingers follow the contours of the jaw and keep the implant immobile. (From Linkow, L. I.: Re-evaluation of mandibular unilateral subperiosteal implants: a 12 year report, J. Prosth. Dent. 17 [5] :512, 1967.)

Fig. 5-94. A, The mylohyoid ridge, a problem area for shaping an overall superiosteal implant, is gripped by the finger extensions. B, The implant straddles the site and is closely adapted to variations of the jawbone. (From Linkow, L. I.: Re-evaluation of mandibular unilateral subperiosteal implants: a 12 year report, J. Prosth. Dent. 17 [5] :512, 1967.

It gradually became clear to most implantologists, both European and American, that an implant fabricated from casts made of exposed bone fit better and gave greater retention than one made from surface models. Also, the lighter the implant and the more economically it utilizes local anatomy, the greater its chances of success. An example of how closely a subperiosteal implant can conform to its site is shown in Fig. 5-93. Here the major portion of the implant, Linkow's unilateral lingual-finger implant designed in 1956, snugly follows the overall shape of the crest of the jaw. Extending from the saddle-like framework are phalanges, or fingers, which follow the lingual curves of the bone below the mylohyoid ridge. The additional retention provided by such a device is evident in x-rays of sample cases (Fig. 5-94).

MISCELLANEOUS IMPLANTS

A few implants cannot be strictly categorized as either endosseous or subperiosteal implants. Among these are the following.

Intramucosal inserts

Intramucosal inserts are Vitallium buttons processed in a denture whose free ends, or heads, fit into slots made in the mucosa (Fig. 5-95). When the tissue heals around the buttons, its tenacity and

Fig. 5-95. An intramucosal insert, or button implant. The base is permanently embedded in the denture, with only the head and neck protruding. These buttons fit into slots made in the mucosa. (From Cranin, N.: The intramucosal insert—review and progress report, J.A.D.A. 62:658-665, 1961. Copyright American Dental Association. Reprinted by permission.)