Which of the following is NOT a characteristic of Down's syndrome?

In the context of Down's syndrome, the characterization of macrodontia is not typically associated with this condition. Down's syndrome is primarily characterized by several distinct features, including macroglossia, which is an enlarged tongue commonly observed in individuals with the condition. They can also experience immunological challenges, leading to decreased neutrophil function and an increased risk for periodontal disease.

While certain dental anomalies are observed in patients with Down's syndrome, such as microdontia (smaller than normal teeth), macrodontia (larger than normal teeth) is not a recognized characteristic. Thus, choosing macrodontia as the answer highlights that it does not fit within the commonly recognized features associated with Down's syndrome, differentiating it from the other options that are indeed relevant to the condition.