Which of the following represents a clear radiopaque structure in dental radiography?

In dental radiography, radiopaque structures are those that absorb more X-rays, causing them to appear lighter on the radiograph. Among the given options, cortical bone is an excellent example of a radiopaque structure due to its dense mineral content, primarily composed of calcium and phosphate. This density results in a significant absorption of X-rays, making cortical bone appear very white or light on dental images.

The pulp chamber contains soft tissue and is less dense, thus appearing radiolucent, or darker, on an X-ray. Enamel, while it is the hardest substance in the human body and does provide a certain degree of radiopacity, is still less radiopaque compared to cortical bone. The periodontal ligament is composed of soft connective tissue, which is also radiolucent and does not provide significant contrast on a radiograph.

Understanding these characteristics is essential for interpreting dental images properly, helping to distinguish between various anatomical features based on their radiographic appearance.