**Core Concept**
EDTA (ethylenediaminetetraacetic acid) is a chelating agent used in endodontics to remove smear layers and enhance the removal of infected dentin. Its introduction in endodontics revolutionized the treatment of root canals by improving the cleaning efficacy and reducing the risk of reinfection.

**Why the Correct Answer is Right**
EDTA works by chelating calcium ions, which are essential for the formation of the smear layer. By removing the smear layer, EDTA allows for better penetration of irrigants and ultimately, a more thorough cleaning of the root canal. The use of EDTA in endodontics is a significant advancement in the field, enabling dentists to provide more effective treatment for patients with infected teeth.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because EDTA was not introduced by this individual. While the person might have made significant contributions to endodontics, they are not credited with the introduction of EDTA.
**Option B:** This option is incorrect because EDTA was introduced to endodontics for its chelating properties, not for its antibacterial effects. While EDTA might have some antibacterial properties, its primary use in endodontics is for chelation.
**Option C:** This option is incorrect because EDTA was not introduced by this individual. This person might have made significant contributions to dentistry, but they are not credited with the introduction of EDTA in endodontics.

**Clinical Pearl / High-Yield Fact**
When using EDTA in endodontics, it's essential to use it in conjunction with a surfactant (such as sodium hypochlorite) to enhance its chelating properties and prevent the formation of a new smear layer.

**Correct Answer: C. Endre Nygaard.**