Ectopic enamel

Ectopic enamel refers to the presence of enamel in unusual locations, mainly the tooth root. The most widely known are Enamel pearls. These are hemispheric structures that may consist entirely of enamel or contain underlying dentin and pulp tissue. Most enamel pearls project from the surface of the root and are thought to arise from a localized bulging of the odontoblastic layer. This bulge may provide prolonged contact between Hertwig's root sheath and the developing dentin, triggering induction of enamel formation.

In addition to Enamel pearls, Cervical enamel extensions also occur along the surface of dental roots. These extensions represent a dipping of the enamel from the cementoenamel junction toward the bifurcation of molar teeth. This pattern of ectopic enamel forms a triangular extension of the coronal enamel that develops on the buccal surface of molar teeth directly overlying the bifurcation. The base of the triangle is continuous with the inferior portion of the coronal enamel; the leading point of the triangle extends directly toward the bifurcation of the tooth. These areas of ectopic enamel have been called Cervical enamel projections.

Clinical and Radiographic Features

Enamel Pearls

Enamel pearls are found most frequently on the roots of maxillary molars > mandibular molars. It is uncommon for maxillary premolars and incisors to be affected. Involvement of deciduous molars is not rare. 1-4 enamel pearls usually found on single tooth at furcation areas and on CEJ. Radiographically, pearls appear as well-defined, radiopaque nodules along the root's surface. Mature internal enamel pearls appear as well-defined circular areas of radiodensity extending from the dentinoenamel junction into the underlying coronal dentin.

The enamel surface of pearls precludes normal periodontal attachment with connective tissue, and a hemidesmosomal junction probably exists. This junction is less resistant to breakdown; once separation occurs, rapid loss of attachment is likely. In addition, the exophytic nature of the pearl is conducive to plaque retention and inadequate cleansing.

Cervical Enamel Extensions

Mandibular molars are affected slightly more frequently than maxillary molars. Cervical enamel extensions may occur on any molar, but they are seen less frequently on third molars. Because connective tissue cannot attach to enamel, these extensions have been correlated positively with localized loss of periodontal attachment with furcation involvement. Greater the degree of cervical extension, the higher the frequency of furcation involvement.

In addition to periodontal furcation involvement, cervical enamel extensions (in some cases) have been associated with the development of inflammatory cysts that are histop-athologically identical to inflammatory periapical cysts. The cysts develop along the buccal surface over the bifurcation and most appropriately are called buccal bifurcation cysts.

Treatment and Prognosis

When enamel pearls are detected radiographically, the area should be viewed as a weak point of periodontal attachment. Meticulous oral hygiene should be maintained in an effort to prevent localized loss of periodontal support. If removal of the lesion is contemplated, then the clinician must remember that enamel pearls occasionally contain vital pulp tissue.

For teeth with cervical enamel extensions and associated periodontal furcation involvement, therapy is directed at achieving a more durable attachment and providing access to the area for appropriate cleaning.Flattening or removing the enamel in combination with an excisional new attachment procedure and furcation plasty may accomplish this.