## Core Concept
A periapical granuloma is a type of lesion that occurs at the apex of a tooth root, typically as a result of pulp necrosis and subsequent infection. It is characterized by the presence of granulation tissue, which consists of a mixture of inflammatory cells, fibroblasts, and newly formed blood vessels. The typical features of a periapical granuloma are important to understand for dental diagnosis and treatment planning.

## Why the Correct Answer is Right
Periapical granulomas are usually associated with the following features: they are usually small (less than 1 cm in diameter), are often asymptomatic but can cause tenderness to percussion, and are composed of granulation tissue. They are a common cause of periapical radiolucency seen on dental radiographs. Understanding these characteristics helps in distinguishing them from other periapical lesions like cysts or tumors.

## Why Each Wrong Option is Incorrect
Without the specific details of options A, B, C, and D, it's challenging to provide a direct explanation for each. However, we can infer based on common characteristics and misconceptions about periapical granulomas:
- **Option A:** If this option suggests that periapical granulomas are usually large (over 1 cm), it would be incorrect because they are typically small.
- **Option B:** If this option states that periapical granulomas are usually asymptomatic, this could be correct and not the answer we're looking for.
- **Option C:** If this option mentions that periapical granulomas are composed of granulation tissue, this would be correct and not the exception.
- **Option D:** If this option claims that periapical granulomas are usually painful, this could be considered incorrect because while they can cause tenderness, they are often asymptomatic.

## Clinical Pearl / High-Yield Fact
A key point to remember is that periapical granulomas are potentially reversible if the source of the infection (the non-vital tooth) is addressed through root canal therapy or extraction. They are a common reason for periapical radiolucencies and their resolution can often be seen after appropriate dental treatment.

## Correct Answer: D.