A developed radiographic film shows multiple dark lines scattered across the image with no corresponding anatomical structures. What is the most likely cause?

Multiple dark lines scattered across a radiographic film that follow a crease or geometric pattern are the classic artifact of FILM BENDING. When a periapical or bitewing film is bent sharply during placement in the mouth, the silver halide crystals in the emulsion are physically disrupted at the crease. During development, these disturbed crystals reduce preferentially, producing dark (radiolucent) lines on the developed film. These lines do not correspond to any anatomical structures. Developer contamination produces dark spots or staining, not linear creases. Overlapping produces blurred or superimposed contact images. Double exposure produces a ghost superimposition of two anatomical areas. Digital sensors are more rigid and less prone to this artifact, though bending artifacts can still occur with some sensor types.