Too much development time.
Use of a developing solution that is too warm.
Movement of the patient, film, or tube during exposure.
Exposure of film to light during storage.
Leaving film unprotected in the x-ray room during operation of the x-ray machine.
Use of film that has been exposed to heat or chemical fumes.
Use of improperly mixed or contaminated developer.
Defective safelight. (para 3-15)
Median palatal suture
Nasal fossae (paraS 3-25a-d)
Coronoid process of the mandible
Zygomatic process and nasal septum
Mental foramen (paraS 3-27a-c)
Border of the mandible
External oblique ridge
Mylohyoid ridge (paraS 3-28a-e)