What causes a ghost image of the anterior teeth in a periapical radiograph of molars?

A ghost image of the anterior teeth in a periapical radiograph of molars typically occurs when the film is double exposed. This phenomenon happens when the radiographic film is exposed to X-rays more than once without being processed in between. The result is that images from two different exposures overlap, causing confusion in interpreting the radiographs.

When the anterior teeth are radiographed first, and then the same piece of film is used again, the previously recorded image of the anterior teeth remains visible in addition to the newly captured image of the molars. Hence, it creates a superimposed, less distinct image where the anterior teeth appear ghosted.

Insufficient exposure time may lead to underexposed images but does not amount to the specific scenario of overlapping images that result in ghosting. Incorrect film placement could lead to inadequate coverage of the teeth and hence poor images but would not create a ghost image specifically. Using a worn-out film might affect the overall quality and clarity of the radiograph, but it would not directly result in ghost images unless it somehow created a double exposure effect unintentionally, which is less likely than a true double exposure.