Evaluating the implant candidate 215

lems when trying to fit conventional dentures. Not only must the shape of the denture accommodate a torus, making the denture difficult to fit, but the danger of irritating the thinly stretched tissues over a torus is great. An implant-supported fixed denture which is much less bulky than a conventional denture, would be a real boon to such a patient.

Malignant tumors of the jawbone rarely originate there; they either spread into the bone from cancerous lesions of the soft tissues or have metastasized there. Because of this, the types will be discussed elsewhere in this chapter. (See also pp. 222 and 237.)

Examining the periodontium

The condition of the soft tissues around the teeth is usually very indicative of many existing clinical conditions. It may not only provide a clue to the conditions but also suggest the proper avenue for their cure.

The color, form, and texture of the gingival tissues should be examined, as well as the amount of bleeding and type of exudate, if any. The degree of pocket depth and contour around each of the remaining teeth and the relationship of pocket base to the zone of alveolar mucosa should also be evaluated.

The thickness of the fibromucosal tissue covering the alveolar bone in the edentulous area of the maxilla and mandible is of extreme importance when diagnosing a case for implants. Many times the tissue covering the molar and tuberosity areas in the maxilla is often as thick as 5 or 6 mm. This extreme thickness will result in too much mobility for a scalloped template and will require too long a neck on a blade-vent, a vent-plant, or a spiral-shaft implant. As for triplant pins, which are much longer than all other types of implants, too much of their length will be lost in soft tissue, not set in bone. Therefore extremely thick fibromucosal tissue should be "thinned out" at least 3 months before implants are inserted. As an alternative, because "thinning" can be a painful procedure if not done correctly, a blade implant with an extremely long neck can be used.

The fibromucosa's thickness can be evaluated when injecting a local anesthetic into the various areas at right angles to the underlying bone. Radio-graphic interpretation can also be of great assistance in determining this thickness. The thickness of the tissue buccally, labially, lingually, and palatally must also be determined in order to reduce the danger of labial or lingual perforations by the implant inter-

vention procedure. However, it is Linkow's belief that the tissues should always be incised and retracted so that the implant can be placed directly into the bone.

Periodontal diseases

Periodontal diseases include a number of disorders that can be classified as inflammatory, de-generative, or neoplastic. All of these types can occur simultaneously in the same tissue.

Inflammatory diseases are caused by irritants, including mineral deposits (calculus or tartar), faulty margins of dental restorations, and food impaction. The principal irritant is the concentrated bacterial mass adhering to the roots of the teeth. Damage to the gingival tissues is caused by the toxic products of the bacteria. The most common inflammatory periodontal diseases are gingivitis and periodontitis.

Gingivitis, or inflammation of the gum, is the simplest form of periodontal disease. It is characterized by occasional bleeding, changes in the contour of the soft tissues, and pathologic deepening of the gingival sulcus forming the periodontal pocket. Simple gingivitis can be easily cured and is rarely a contraindication for an implant intervention. However, if the patient continually subjects himself to those conditions that promote gingivitis, despite adequate warnings from his dentist, he may not be acceptable as a candidate.

Periodontitis, commonly called pyorrhea, involves the destruction of the tooth's supporting tissues. The condition results when the superficial inflammation of gingivitis spreads down along the periodontal ligament and into the supporting bone. This extension produces a deeper and more severe periodontal pocket that in itself complicates the approach to therapy by retaining and absorbing the accompanying bacterial infection. The condition must be cured and the situation reevaluated before considering implants.

Those diseases in which the deeper periodontal structures, primarily the connective tissues, undergo noninflammatory changes that lead to the functional impairment and eventual cellular death are classified as degenerative diseases. Included in the category of degenerative diseases are gingivosis, periodontosis, and those conditions arising from periodontal and occlusal trauma.

Neoplastic diseases include all tumorous diseases affecting the periodontal tissues. Fortunately, how-ever, malignant neoplasms seldom occur in the peri-