**Core Concept**
Down's syndrome is a genetic disorder characterized by an increased risk of various health complications, including dental caries. The altered oral environment in patients with Down's syndrome, coupled with poor oral hygiene and reduced saliva production, contributes to an increased incidence of dental caries.

**Why the Correct Answer is Right**
The incidence of dental caries in patients with Down's syndrome is significantly higher due to several factors. Firstly, reduced saliva production leads to a decrease in the natural buffering capacity of saliva, making the oral environment more acidic and conducive to caries formation. Secondly, patients with Down's syndrome often have reduced oral hygiene practices, which can lead to an accumulation of plaque and bacteria on the teeth. This, in turn, can cause demineralization of tooth enamel and the formation of dental caries.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not take into account the specific oral health challenges faced by patients with Down's syndrome.
**Option B:** This option is incorrect as it does not accurately reflect the increased incidence of dental caries in patients with Down's syndrome.
**Option C:** This option is incorrect as it does not address the underlying oral health factors that contribute to the increased incidence of dental caries in patients with Down's syndrome.

**Clinical Pearl / High-Yield Fact**
Patients with Down's syndrome are at a higher risk of developing dental caries due to reduced saliva production and poor oral hygiene practices. Regular dental check-ups and oral hygiene education are essential in preventing and managing dental caries in this population.

**Correct Answer: D. 10-20% higher incidence than general population**