200 Theories and techniques of oral implantology

snug fit, it may not be necessary to immediately splint it, although this is usually advisable (Fig. 5-123).

According to Chercheve and Bordon, biologic implants are well tolerated by the tissues and provide adequate support for a prosthesis if the following conditions are met.

The donor tooth must be of recent extraction and ready for insertion with the metal pin in place and the tooth already irradiated. This presents difficulties, as tooth "banks" have not been established nor are the facilities for obtaining, preparing, and storing the teeth readily available.

The seat for the implant must be carefully pre-pared. This is more of a problem with human teeth than with animal teeth, as these latter have taps corresponding in size and shape to the trimmed do-nor teeth. Because the human donor tooth may not be anatomically correct for the transplant site, the operator must carefully estimate the width and depth of the site from radiographic studies and compare them with the shape of the donor tooth. Not all donor teeth are appropriate for all transplant sites. If there appears to be enough bone to support the tooth,

drilling must proceed cautiously and gradually, with numerous try-ins of the tooth, until the site is suit-able. This is time-consuming and leaves a lot of room for miscalculations and errors such as over-drilling, perforating the cortical plates of bone, and creating an unbalanced or overly large site.

In most cases the implant must be immediately stabilized by splinting or wiring it to other teeth. Chercheve and Bordon claim that this is sometimes not necessary when animal teeth have been snugly inserted. Linkow, however, disagrees. Because creating the site kills osteocytes not only in the walls of the socket but up to several cells away, bone resorbs away from the site. Thus a snug implant loosens after a few days, and a loose implant impedes the kind of healing necessary to bind an implant.

Chercheve and Bordon are pleased with the results of their experiments with biologic implants so far (Fig. 5-124). Although the treated teeth show no rejection phenomena, bone tends to resorb down-ward from the alveolar crest. Progressive mobilization results but eventually equalizes somewhere between the crown-and-root ratio in those implants that contain the metallic core.