A 4-year-old presents with Labia lingual caries affecting only maxillary incisors and involving molars The number of Streptococcus mutans Colony forming units (CFU) per unit of saliva will be
**Core Concept**
The question is testing the understanding of the relationship between Streptococcus mutans and dental caries. Streptococcus mutans is a bacterium that plays a key role in the development of dental caries by producing acid from the fermentation of carbohydrates. It is particularly associated with the early stages of caries.
**Why the Correct Answer is Right**
The correct answer is based on the concept that the higher the number of Streptococcus mutans Colony Forming Units (CFU) per unit of saliva, the higher the risk of developing dental caries. This is because Streptococcus mutans is able to adhere to tooth surfaces and produce acid, leading to the demineralization of tooth enamel. The presence of Streptococcus mutans in the saliva is a key factor in the initiation of dental caries.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not provide a specific value or relationship between Streptococcus mutans CFU and dental caries risk.
* **Option B:** This option is incorrect because it suggests a lower number of CFU is associated with a higher risk of dental caries, which is the opposite of the correct relationship.
* **Option C:** This option is incorrect because it suggests a specific value (10^5) without providing any context or explanation for why this value is relevant to the relationship between Streptococcus mutans CFU and dental caries risk.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the presence of Streptococcus mutans in the saliva is a significant risk factor for dental caries, particularly in children. Regular oral hygiene practices, such as brushing and flossing, can help reduce the number of Streptococcus mutans CFU and prevent dental caries.
**Correct Answer: D. 10^7**