Evaluating the implant candidate 207

Fig. 6-8. The large radiolucent lesion is a median palatine cyst. Clinically it appears as a hard swelling covered by pale, intact mucosal tissues. (From Kolas, S., and others: Radio-graphic patterns of resorption seen in some gnathodental hard-tissue disturbances, Dent. Clin. N. Amer., November, 1968.)

Fig. 6-9. The pear shape is characteristic of a globulomaxillary cyst. (From Kolas, S., and others: Radiographic patterns of resorption seen in some gnathodental hard-tissue disturbances, Dent. Clin. N. Amer., November, 1968.)

Furthermore, there have been some reports that a squamous cell carcinoma has developed from such a lesion.

When the site of a single follicular cyst has healed, an implant intervention may proceed. How-ever, the dentist should proceed with great caution in a patient with multilocular cysts, not only because of local conditions but because of those elsewhere in the body.

Dental cysts. The most common cyst of the jaws is the dental cyst, and it occurs more frequently in the maxillae than in the mandible. The patient is usually between 30 and 40 years old.

The dental cyst is a discontinuity of the lamina dura. It usually originates from the apex of the tooth, though it may also arise from the side. It may be small or large, enveloping the roots of several teeth adjacent to that from which it arose. It is usually solitary, but more than one may occur in a mouth with teeth in poor condition.

In radiographs the dental cyst is seen as a rounded radiolucent area with a smooth outline. It is often difficult to distinguish it from a dental granuloma or some other type of cystic lesion. The dental cyst is usually asymptomatic, but the tooth from which it arose may be sensitive to percussion. This tooth is usually nonvital and may have been periodically painful. The cyst does not distort the jaw.

Such a cyst should be entirely removed along with the extracted tooth. Although the dental cyst will not develop into an ameloblastoma, any residual tissue may persist as a cyst and will then have to be removed.

As with any nonrecurring lesion, as soon as the site heals implantation is usually possible. If the cyst is small and entirely removed, a blade may be used to span a fresh empty site.

Nonodontogenic cysts. Nonodontogenic cysts, as the name implies, do not develop from teeth or tooth follicles but arise in the maxilla only. One group apparently arises from epithelial tissues that became sealed within the maxillary fissures during the fusion of the facial processes. For this reason these cysts are also called fissural cysts. What stimulates the trapped epithelial cells to proliferate and form cysts is unknown, and the cyst usually does not develop until adolescence or adulthood.

Fissural cysts may be subdivided according to their locations. Thus one occurring in the midline of the palate is called a median palatine cyst. This appears as a hard swelling covered by pale, but