The evolution of dental implants 173

Weinberg's implant straddled the crest of the bone under the periosteum. As the site healed, the periosteum grew over and through the holes in the lattice and reattached to the bone. Thus the implant was held tightly in place.

As pressure was exerted on the implant during mastication, the impact was to be dispersed over the metal and dissipated. Perhaps the idea of using four legs for the post was intended to help disperse the force of occlusal impacts. However, it is essential to closely suture the mucosa over a periosteal im-

plant. This must have been a problem around the legs of Weinberg's early implant, and he later modified his design by using a solid post (Fig. 5-73) .

Weinberg's implant was sometimes successful, but like most other meshwork implants it was prone to loosening and dislodgment. It is quite difficult to force a mesh or lattice to follow the contours of bone.

Aaron Gershkoff and Norman Goldberg of Providence, Rhode Island, were leading American pioneers in subperiosteal implant designs and tech-

Fig. 5-76. A, A later Gershkoff and Goldberg subperiosteal implant. A, Connecting bar; B, saddle over retromolar pad area; C, lingual extensions; D, connecting bar; E, supporting bars. (From Goldberg, N., and Gershkoff, A.: Implant dentures, Philadelphia, 1957, J. B. Lippincott Co.) B, Another one of Gershkoff and Goldberg's early mandibular subperiosteal Vitallium implants, cast without a surgical bone impression. Instead, the master stone model was trimmed to nearly duplicate the topography of the underlying bone revealed by the x-rays. (Courtesy Howmedica, Inc.)