198 Theories and techniques of oral implantology

titanium, Vitallium, or some other biologically inert metal—is inserted in the canal. The metal core ensures that if the natural tooth implant resorbs, there will be some form of implant abutment left to sup-port a restoration. Also, the length of the metal core helps retain a good root-to-crown ratio if the root partially resorbs. The prepared tooth is then irradiated with cobalt to desensitize it and to reduce possible rejection phenomena. The treated tooth is stored in its own container filled with a sterile normal saline solution.

To insert a human biologic implant, radiographic

studies are made of the proposed site to determine whether or not there is enough alveolar bone in which to seat the implant. Any residual root tips are cleared from an otherwise healthy area. A helical bur is used to prepare the site for the donor tooth. The prepared site is then cleansed and treated with an antibiotic paste, and the biologic implant is pressed manually into position (Fig. 5-120) . If the site is not deep or wide enough, the implant is re-moved and the hole enlarged with a 2.5-mm. helical bur. The reseated implant is then rotated to its proper position and immediately stabilized with a tern-

Fig. 5-120. A biologic implant from a human donor is inserted for a trial fit. If the site is not appropriate, further drilling is done until a snug fit is achieved.

Fig. 5-121. Nearly 4 years after its insertion, the human biologic implant is still providing adequate support for the fixed partial denture. Note how bone has filled in around the root, which shows little evidence of resorption.

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Fig 3-122 Two biologic implants from animal donors that have been reshaped to form threads.