Enamel pearl
Enamel pearls are developmental variations of teeth that present as beads or nodules of enamel in places where they are not normally observed.
Appearance and Location
Enamel pearls most commonly present as spheroid in shape, but can also be conical, cylindrical, oval, teardrop, and irregularly shaped. They vary in size with an average diameter of 1.7mm.Enamel pearls are most frequently found in the root furcation of molars, and are not commonly seen in teeth with a single root, such as incisors and canines.
Mechanisms of Formation
Several theories of enamel pearl development exist, although no definitive mechanism has been established. Enamel pearls are composed primarily of enamel, but most also have a core of dentin within them.The most widely accepted theory suggests enamel pearls are formed from remnants of Hertwig’s epithelial root sheath (HERS), which adhere to the tooth surface after root development. During normal tooth development, after dentin formation is initiated on the root surface, the root sheath disintegrates and moves away from the root allowing the cells of the dental sac to contact predentin. This begins the differentiation of cementoblasts which in turn deposit cementum. However, when HERS remains adherent to the root surface, these fragments have the potential to develop into functional ameloblasts, which then deposit enamel onto the root surface, thereby forming enamel pearls. This theory is considered inconclusive as it does not account for the dentin component seen in some enamel pearls.
Alternative theories propose that enamel pearl formation is akin to the development of supernumerary tubercles or cusps, thus pearl formation must occur during initial dentin formation. Intradental enamel pearls may form during tooth formation, when ameloblasts are invaginated inside the developing dentin. Inner enamel epithelium cells may similarly invade connective tissue of the dental papilla, resulting in an internal enamel pearl.