Cyst coming from an unerupted permanent tooth is
**Core Concept**
A cyst associated with an unerupted permanent tooth is a type of odontogenic cyst, specifically a dentigerous cyst. This cyst forms around the crown of an unerupted tooth, usually a wisdom tooth, due to the accumulation of fluid between the tooth and its surrounding bone.
**Why the Correct Answer is Right**
The dentigerous cyst arises from the epithelial attachment to the unerupted tooth, which is a remnant of the enamel organ. This cyst is also known as a follicular cyst and is the most common type of odontogenic cyst. The cystic space fills with fluid, leading to expansion of the surrounding bone and potential displacement of the tooth.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a radicular cyst, also known as a periapical cyst, forms at the apex of a non-vital tooth, not around an unerupted tooth.
**Option B:** This option is incorrect because a lateral periodontal cyst is a non-odontogenic cyst that occurs in the periodontal ligament, not associated with an unerupted tooth.
**Option C:** This option is incorrect because an odontogenic keratocyst, now known as a keratocystic odontogenic tumor, is a type of odontogenic cyst that is aggressive and has a distinctive histological appearance, not specifically associated with an unerupted tooth.
**Clinical Pearl / High-Yield Fact**
It's essential to differentiate between various types of odontogenic cysts and tumors, as their treatment and prognosis can vary significantly.
**Correct Answer: D. Dentigerous cyst.**