CHAPTER 14 Causes of implant failure

An implantologist must be familiar with many kinds of implants. He must not only know the various types of screw, pin, blade, and subperiosteal implants but also when to use each and how to insert it most advantageously. The experiences of skilled operators using well-designed implants have provided ample, well-documented evidence that implants function in accordance with the biomechanical principles typical of the site and are compatible with the tissues. Not only are they functionally and scientifically acceptable, they have provided thou-sands of patients with esthetically superior replacements for lost teeth.

Despite the obvious advantages of dental implants, strong opposition persists. Because of the number of failures, resistance to the widespread use of implants has been considerable. Granted, there have been numerous failures. Many of these can be explained by the facts that early implant designs were unsuitable, operative techniques were not perfected. and the many considerations in candidate evaluation were unknown or overlooked. Today, however, the skillful operator is well aware of these factors. Most experienced implantologists freely admit that if an implant intervention fails, the fault lies not in the idea of using a dental implant but in inaccurate patient evaluation, inappropriate choice of implant, or poor operative technique.

Without discussing the often obvious errors resulting from inexperience, this chapter will concentrate on the major areas wherein a skilled operator might make a mistake. These areas concern preoperative evaluation, implant design and instrumentation, and operative techniques.

PREOPERATIVE EVALUATION

The value of accurately diagnosing both systemic and local conditions cannot be underestimated. The difference between a relatively uncomplicated, logi-

tally sequential implantation and a disrupting series of patch and repair efforts often begins here. A few minutes reviewing a patient's general health and examining his remaining teeth and gums can set the initial stages for success or failure. Careful radio-graphic studies, in addition to examination by eye and hand, will help the evaluation.

Poor health

Naturally any chronic, severe systemic condition, such as blood or bone dyscrasias, uncontrolled diabetes, or severe allergies, contraindicates an implantation. Some conditions, such as a history of heart disease, make the patient a risky candidate. The obvious dangers here, difficulties in anesthetizing the site or overexcitability during the operation, are not the only considerations. Possible postoperative infection and its consequences should also be estimated.

After explaining the procedure, which should be done with any presenting candidate, the patient's reactions should be evaluated. The neurotic patient, particularly one tending to hypochondria, should perhaps be avoided. His fears, although imaginary, may actually provoke adverse physiologic reactions. He can "worry" the implant by unnatural biting, probing, poking, and "testing." Even the best-seated implant will not heal under such treatment.

The patient whose mouth bears evidence of poor oral hygiene might also be an unsuccessful candidate. If such a patient, despite prior warnings that poor oral hygiene could result in severe periodontal problems or the eventual loss of his natural teeth, presents himself for implantation with problems arising from these forewarned conditions, he should be rejected as a candidate. If he did not care enough to prevent the problems, it is overly optimistic to assume that he will take proper care of his implants. Those patients who are unaware that their problems were initiated by poor oral hygiene and who show a

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