Early invading bacteria in carious lesions are called
**Core Concept**
The early invading bacteria in carious lesions are a critical component of the pathogenesis of dental caries. These bacteria are typically acidogenic, meaning they produce acid as a byproduct of their metabolism, which contributes to the demineralization of tooth enamel.
**Why the Correct Answer is Right**
The correct answer is **Streptococcus mutans**. These bacteria are known to be among the first to colonize tooth surfaces and are a primary cause of dental caries. They produce acid through the fermentation of sugars, which leads to a decrease in pH and the dissolution of calcium and phosphate ions from the tooth enamel.
**Why Each Wrong Option is Incorrect**
**Option A:** While **Lactobacillus** species are also involved in the carious process, they are not typically the first to invade carious lesions. **Lactobacillus** species are more commonly associated with the later stages of caries progression.
**Option B:** **Candida** species are opportunistic pathogens that can colonize tooth surfaces, but they are not typically considered early invaders in carious lesions. **Candida** species are more commonly associated with oral candidiasis.
**Option C:** **Porphyromonas gingivalis** is a bacterium associated with periodontal disease, not dental caries. While it can colonize tooth surfaces, it is not typically considered an early invader in carious lesions.
**Clinical Pearl / High-Yield Fact**
The presence of **Streptococcus mutans** in the oral cavity is a significant risk factor for dental caries, and its reduction through good oral hygiene practices and the use of fluoride can help prevent caries progression.
**Correct Answer:** C.