A radiolucency in the position of a missing mandibular third molar is likely to be what type of cyst?

• A. Odontogenic cyst
• B. Primordial cyst
• C. Radicular cyst
• D. Follicular cyst

Answer: (B)

In the context of a radiolucency observed in the location of a missing mandibular third molar, the classification of a primordial cyst is particularly relevant. Primordial cysts are formed from remnants of the dental lamina and can occur in places where teeth are absent, as typically seen after tooth extraction or congenital absence. Their appearance can often mimic other types of cysts, but their distinctiveness lies in their origin.

Specifically, since you are observing a radiolucency where a third molar should have developed, and that tooth is absent, the primordial cyst fits as it represents the cystic manifestation of the absence of a tooth from its developmental stage. In instances where there is no tooth present, such as in the case of an extracted or congenitally missing tooth, the possibility of a primordial cyst arises, as it can occupy that space.

This understanding helps clarify that while odontogenic, radicular, and follicular cysts are closely associated with teeth that are present, the primordial cyst stands out as it relates directly to the absence of the third molar, aligning perfectly with the situation described.