American Board of Orthodontics (ABO) Practice Exam

Dentin Dysplasia Type II is characterized by specific morphological features, particularly regarding the shape of the pulp chambers within the teeth. The thistle tube-shaped pulp chambers are distinctive for Type II and are typically more elongated, resembling a thistle tube, which is a key differentiator from Type I. In contrast, Dentin Dysplasia Type I usually presents with irregular pulp chambers and can have a more crescent or fan-like appearance, not the elongated shape found in Type II.

Both types do affect the dentin and may result in abnormalities connected to the pulp, but the structural design of the pulp chambers is a hallmark sign of Type II. This is significant in a clinical setting because the appearance of the pulp can impact treatment decisions for affected individuals.

The other characteristics mentioned in the other answer choices do not accurately represent the distinctions between Type I and Type II. Therefore, recognizing the thistle tube-shaped pulp chambers is essential for understanding the nuances that differentiate Dentin Dysplasia Type II from Type I.