CHAPTER 1 Current implant techniques

an overview

The dental implants discussed in this book may be broadly classified into two groups—the endosseous and the subperiosteal. In the first group, the endosseous, the principle is to set into bone an implant to which a fixed or removable partial denture can be attached. The second group, the subperiosteal, involves placing over bone a device whose protruding parts serve as attachments for a removable denture.

The choice of implant, endosseous or subperiosteal, depends upon the structure of the jaws. The groups do not compete with one another. One can-not possibly be successful when use of the other is indicated.

To use any kind of endosseous implant, there must be an adequate amount of alveolar bone into which to insert the implant. Otherwise, the implant may be driven into a maxillary sinus or the mandibular canal—accidents to be carefully avoided.

If the alveolar bone has been resorbed, a subperiosteal implant should be employed. There is no danger to vital structures within the bone because this kind of implant does not penetrate the bone. However, the subperiosteal implant technique does require revealing the bone by retracting the soft tissues overlying it, and the operator should be aware of the anatomy and physiology of these tissues.

In order to give the reader a general idea of the wide range of possibilities inherent in both endosseous and subperiosteal implants, a brief discussion of some of the most commonly and successfully used techniques follows. Because this initial presentation is simple, it should not be assumed that an implant intervention is simple. As will be demonstrated later, a great deal of care must be taken in evaluating the candidate, choosing the suitable approach and the materials needed to execute this approach,

performing the implant intervention itself, and following it up. The information herein is only a frame-work; it was designed to provide a basic grasp of the techniques that will be discussed in greater de-tail in separate chapters.

For convenience, this introductory material will be divided into two broad headings, endosseous implants and subperiosteal implants.

ENDOSSEOUS IMPLANTS

The concept underlying endosseous implants is to set directly into bone metal supports that can serve as abutments for a fixed or removable denture. This involves creating an anchorage point that is stable and compatible with the tissues into which it has been set. Stability results when bone grows around and possibly into the implant, separated by a fibrous tissue membrane.

Today four basic implant designs are used in endosseous implant interventions (Fig. 1-1). The four designs are the spiral-shaft implant, the vent-plant implant, the tripod implant (or triplant), and the blade implant. The spiral-shaft and the vent-plant are similar in that they rely on tissue regrowth for complete stability. The tripod implant, which is totally unlike the other two in design, is stable as soon as the three pins forming it are fastened together. The blade, completely different from all others in design and concept, is neither screwed nor drilled into the bone but is tapped into place.

In order to explain the characteristics of each design and its insertion, sample cases illustrating the techniques of inserting each will be given. For the spiral-shaft and vent-plant, the example will be in-stalling a fixed splint secured to two implants and to existing anterior teeth, which will serve as natural

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