What may result in black lines across the x-ray film?

Black lines across the x-ray film can result from excessive bending of the film during the processing or handling stages. When the film is bent too much, it can create areas where the emulsion is compromised or unevenly exposed, leading to the development of black lines after processing. This occurs because the pressure from bending may cause the latent image to be improperly formed or affect the chemical processing uniformity.

Understanding how physical handling of the film can impact its image quality is essential for maintaining diagnostic accuracy in dental radiography. Other factors, while significant in their own contexts, do not typically lead to the specific issue of black lines. For instance, double exposure generally results in overlapping images rather than lines, cone cutting leads to incomplete images on the film edges, and underexposure typically causes overall light images rather than distinct lines on the film.