American Board of Orthodontics (ABO) Practice Exam

Dentin Dysplasia Type I is characterized by a specific root structure, which includes notably short roots that often appear surrounded by radiolucent areas on radiographic imaging. This condition is a genetic disorder affecting the dentin, the mineralized tissue that forms the bulk of the tooth beneath the enamel. In this type, the disruption in the normal development of the roots results in their significant reduction in length, and the surrounding radiolucency is indicative of changes in the supporting structures, such as the alveolar bone surrounding the roots.

The other characteristics listed do not align with Dentin Dysplasia Type I. For instance, elongated roots with normal pulp chambers generally suggest a healthy development without the dental dysplasia condition. An absence of roots entirely would indicate a more severe anatomical anomaly not specific to this type of dentin dysplasia. Lastly, having multiple branching canals is typically associated with more complex root canal systems, which is not a feature of Dentin Dysplasia Type I. Thus, the distinct presentation of short roots surrounded by radiolucent areas is a hallmark of this condition, leading to the identification of option A as the correct characterization.