Evaluating the implant candidate 203

The condition of existing restorative and/or prosthetic appliances should be considered. Naturally, if the patient has a poorly fitting or badly worn restoration, it should be replaced. If the underlying soft tissues show signs of pontic impingement or other forms of irritation, the offending area should be relieved or the restoration substituted. It may also be advisable to remove existing appliances in good condition and to include the affected areas in the implant restoration.

Any corrective treatment or restorative work on remaining teeth should be done before the implant intervention. Uncorrected problems may either en-danger the implant restoration or necessitate its removal to correct the situation, an unnecessarily troublesome postoperative complication. If bone or the soft tissues are injured during treatment, sufficient time for healing should be allowed before the intervention.

Diseases of the teeth and supporting bone

Pathologic conditions of the teeth and supporting bone may result from infections, trauma, hereditary factors, or environmental conditions. Such familiar disorders as dental caries will not be included in this discussion, as it is assumed that the reader is well aware of their causes and treatment. Emphasis will instead be on those conditions that affect the bone that supports teeth. The material in this section is limited to bone lesions arising primarily in the jaws and usually confined there. Lesions that more commonly arise elsewhere in the body but that can also be found in the jaws are discussed under Bone Dyscrasias, pp. 229-239.

Several generalizations may be made about implant prognosis when the patient has an alveolar bone defect or lesion. First, implants must be placed in healthy bone. This means that the pathologic condition must be alleviated before implantation. Sometimes only limited treatment is necessary, and implantation is then soon possible. Other lesions tend to recur, contraindicating implants for as long as there is a suspicion of possible resurgence of the condition. Second, the extent of the lesion affects the possibility of implantation. Small localized lesions that can be removed without much bone dam-age usually do not contraindicate implants. In some cases, a blade may even be used immediately to span a small defect. Larger lesions requiring bolder surgery may contraindicate implants until some bone fill-in has taken place. Extensive lesions that cause bone deformities and require radical surgery may forever contraindicate implants because of difficulties in finding adequate implant sites and in fitting and balancing the restoration. These generalizations, and others specific to the particular type of pathologic condition, will be detailed in discussion of the condition.

Acute alveolar abscess. An acute alveolar abscess, also called an acute rarefying osteitis, may result when disease-causing microorganisms reach the apex of a tooth via its pulp canal, which has been ex-posed by caries, or, in the case of a dead tooth, via its periodontal membrane. Rarely they may be circulated there in the blood from other parts of the body. Having reached the apex, the organisms provoke an intense inflammatory reaction in the periodontal membrane and adjacent bone.

Fig. 6-2. A swelling that is warm and tender to the touch may signify a periapical abscess. (From Bhaskar, S. N.: Synopsis of oral pathology, ed. 3, St. Louis, 1969, The C. V. Mosby Co.)