rig. 5-123. Over 2 years later the implants are still functioning, although the bone around the superficial threads has resorbed.

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The evolution of dental implants 199

porary fixed splint for at least 1 month. If the implant is to be used as an abutment, it is prepared like any other natural tooth and immediately incorporated in a splint. Follow-up x-rays show that there is adequate condensation of bone around the implant (Fig. 5-121).

A biologic implant made from an animal tooth is prepared for transplantation in approximately the same manner, except that the root portion is usually reshaped to form threads. To insert the implant, a 2.5-mm. helical bur is used to prepare the site to its proper depth. Then a tap corresponding in size and shape to the threaded implant is used. The implant is screwed into position (Fig. 5-122). Because of its

Fig. 5-124. An animal biologic implant with a metal core. A, The implant just after insertion; B, the implant 6 months later. Note that very little alveolar bone resorption has taken place. C and D, A human biologic implant. C, The tooth immediately after insertion into its carefully prepared socket. D, After 3 months bone has regrown around the implant. E, The spirals of an animal donor tooth are widely spread to permit good bone regrowth around the implant.