Prevention of Odontogenic .Cystsand Tumors
When impacted teeth are retained within the alveolar process, the associated follicular sac is also retained. Although in most patients the dental follicle maintains its original size, it may undergo cystic degeneration and become a dentigerous cyst or keratocyst. If the patient is
closely followed, the dentist can diagnose the cyst before it reaches large proportions (Fig. 9-11). However, unrnonitored cysts can reach enormous sizes (Fig. 9-12). As a general guideline, if the follicular space around the crown of the tooth is greater than 3 mm, the ‘diagnosis of a dentigerous cyst is a reasonable one. In the same way that odontogenic cysts can occur
around ‘impacted teeth, odontogenic tumors can arise from the epithelium contained within the dental follicle. The most common odontogenic tumor to occur in this region is the ameloblastoma. Usually, ameloblastomas in
this area must be treated aggressively by excision of the overlying soft tissue and of at least a portion of the mandible. Occasionally, other odontogenic tumors may occur in conjunction with impacted teeth (Fig. 9-13). Although the overall incidence of odontogenic cysts and tumors around impacted teeth is not high, 10 the overwhelming majority’ of pathologic conditions of the mandibular third molar are associated with unerupted teeth. It is therefore recommended that impacted teeth be removed to prevent the occurrence of cysts and tumors.