<P> Placing the photographic film or sensor outside the mouth, on the opposite side of the head from the X-ray source, produces an extra-oral radiographic view . </P> <P> A lateral cephalogram is used to evaluate dentofacial proportions and clarify the anatomic basis for a malocclusion, and an antero - posterior radiograph provides a face - forward view . </P> <P> Panoramic films are extraoral films, in which the film is exposed while outside the patient's mouth, and they were developed by the United States Army as a quick way to get an overall view of a soldier's oral health . Exposing eighteen films per soldier was very time consuming, and it was felt that a single panoramic film could speed up the process of examining and assessing the dental health of the soldiers; as soldiers with toothache were incapacitated from duty . It was later discovered that while panoramic films can prove very useful in detecting and localizing mandibular fractures and other pathologic entities of the mandible, they were not very good at assessing periodontal bone loss or tooth decay . </P> <P> There is increasing use of CT (computed tomography) scans in dentistry, particularly to plan dental implants; there may be significant levels of radiation and potential risk . Specially designed CBCT (cone beam CT) scanners can be used instead, which produce adequate imaging with a stated tenfold reduction in radiation . Controversy surrounds the degree of radiation reduction though as the highest quality cone beam scans use radiation doses not dissimilar to modern conventional CT scans . </P>

What is a pa x ray in dentistry
find me the text answering this question