We continue our examination of tooth development by looking at the fourth stage, the bell stage. The most important function of this stage is the finalization of the shape of the crown. There are two developmental anomalies that occur in this stage. They are the formation of supernumerary (extra) teeth, or the development of an odontoma which is collected calcified tissue in the upper or lower jaw.
Apposition and maturation are the final stages of tooth development. The most significant development here is the secretion of the layers of the tooth which are the enamel, dentin, and cementum. Because this is such a critical stage it is prone to a number of anomalies. Enamel dysplasia, or imperfect enamel can occur two ways. The first is enamel hypoplasia, which results in the enamel layer of the tooth being pitted and grooved. Second, is enamel hypocalcification which relates to the quality of enamel maturation. This stage is also very vulnerable to illness. Fevers can produced malformed enamel or exposure to tetracycline can leave the enamel with a permanent gray tinge. Finally, ingestion of too much fluoride in this stage will cause white patches of hypomineralizaton. Amelogenesis imperfecta can also be a factor in the apposition and maturation stage. It causes the enamel to be thin or nonexistant, but this is a hereditary condition only.
Once the crown has fully formed then root development begins. There are a number of anomalies that can happen during this process. Root dilaceration is a severe bend in the root of a posterior tooth that usually results from trauma to the primary tooth. Dwarfed roots are more common in women and anterior teeth and are usually hereditary. Taurodontism produces an elongated pulp chamber and trifurcated roots. While this can occur naturally, it can also be the result of chemotherapy, osteomyelitis, or bone marrow transplants. Concrescence is the result of excess cementum, and leaves the root structure of one or more teeth joined by cementum. Concrescence can result from traumatic injury to the tooth or crowding during the apposition and maturation stages. An enamel pearl, a small, circular raised deposit of enamel on the root, can result from misplaced cells. Finally, supernumerary roots can form from trauma, pressure or metabolic diseases and are most commonly found on third molars or incisors.
This overview should help put perspective on any dental anomalies you need to discuss with your dentist.