A 16-year-old male visited a dentist for a routine checkup. Oral examination revealed a brown discoloration on one maxillary central incisor.
Joen Iannucci Haring, DDS, MS
The patient stated that the brown discoloration had been present for as long as he could remember. Although he previously had seen a dentist for regular dental examinations and routine restorative dental treatment, no cause of the discoloration had ever been discussed. When questioned about a history of trauma to the primary or permanent maxillary incisors, the patient recounted that the primary incisors had been fractured in a bicycle accident.
The patient appeared to be in an overall good state of health at the time of the dental visit. No significant problems were noted during the medical history, and no medications were being taken by the patient at the time of the dental examination.
No unusual or abnormal findings were identified during the extraoral examination. Intraoral examination revealed a brown discoloration on the facial surface of tooth #9 (see photo). Further examination revealed no other teeth in the dentition with a similar appearance. Examination of the oral soft tissues revealed no unusual findings, and no bony abnormalities were noted.
Based on the clinical information presented, which of the following is the most likely clinical diagnosis?
* ectopic enamel
* Turner`s hypoplasia
* amelogenesis imperfecta
* dentinogenesis imperfecta
* internal resorption
Enamel hypoplasia can be defined as incomplete development of enamel; this condition results from a disturbance in enamel deposition during amelogenesis. Focal enamel hypoplasia involving a single tooth is relatively common.
The term, Turner`s hypoplasia, refers to a form of focal enamel hypoplasia that affects the crowns of permanent teeth. Turner`s hypoplasia occurs when localized inflammation (periapical inflammatory disease) or trauma occurs to a deciduous tooth and causes damage to the underlying permanent tooth. The term, Turner`s tooth, refers to the investigator that first reported this defect in the literature.
Turner`s hypoplasia is classified as an environmental defect (vs. a hereditary defect) of enamel. The developing ameloblasts found in the tooth germ are very sensitive to external stimuli. The defects that result depend on the phase of ameloblast production at the time of the insult, as well as the duration of the insult.
With Turner`s hypoplasia, a common cause of the enamel defects is periapical disease (an abscess, for example) linked to a carious deciduous tooth. The permanent bicuspids are most frequently involved because of their relationship to the overlying deciduous molars (teeth that are prone to caries involvement). Defects seen in response to periapical disease are less likely to be found on the anterior teeth because the anterior deciduous teeth are relatively caries-resistant.
Traumatic injury to deciduous teeth may also result in Turner`s hypoplasia. Because traumatic injury to deciduous teeth occurs in approximately 45 percent of children, Turner`s hypoplasia is not uncommon. In one study of 255 traumatized primary teeth, 23 percent of the corresponding permanent teeth demonstrated defects. The maxillary central incisors are the teeth most often affected. The facial surface of the maxillary central incisors are most frequently affected because of the position of the primary apices relative to the forming tooth bud.
The clinical appearance of Turner?s hypoplasia varies depending on the timing (state of development of the permanent tooth) and the severity of the damage. The enamel defects that result may range in color from white and yellow to brown. The involved areas may affect a limited region or the entire crown.
The diagnosis of Turner?s hypoplasia is made based on the clinical appearance and history of periapical involvement or trauma to the primary tooth. Most defects in enamel classified as Turner?s hypoplasia present cosmetic rather than functional problems. Treatment may include the placement of a composite restoration, a porcelain veneer, or full porcelain crown for a more esthetic appearance.
Joen Iannucci Haring, DDS, MS, is an associate professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.