Intraoral radiography is integral to nearly every dental procedure. The dentist is at a disadvantage without diagnostic images when treatment planning and providing treatment. It is critical that the dental professional acquiring the images be knowledgeable of proper technique and radiographic anatomy, available in Intraoral Radiographic Anatomy CE 601. The prescription of images is the responsibility of the dentist, whereas the acquisition of images is primarily the responsibility of the dental auxiliary. An overview of digital imaging and the latest advances in digital technology is available in Digital Imaging in Dentistry: Intraoral, Extraoral, and 3D Technology CE 512.
Each radiographic examination is unique, because every patient is unique: the size of the jaws, the number and position of teeth present, the presence or absence of palatal and/or mandibular tori, the morphology of the anterior lingual mandible (bone is upright or flares out creating a shelf), and, of course, the patient’s level of cooperation and ability to hold the sensor in proper position. When teeth are ‘out of alignment’ (mal-positioned) and overlapped, the interproximal contacts cannot be ‘opened’. It can be very difficult to image the apex of a very long rooted tooth, and some patients find the procedure uncomfortable.
There are two techniques associated with intraoral periapical imaging: the Paralleling Technique and the Bisected Angle Technique. The Bisected Angle Technique was introduced in 1904 and is based on the geometry of equilateral triangles. The operator must identify the long axis of the teeth and the long axis of the receptor (sensor or film) and place the x-ray beam at a right angle to an imaginary line that bisects those two planes. Charts with suggested vertical angulations are available in most dental imaging textbooks (Table 1 is representative). These vertical angulations are important to remember when exposing intraoral image receptors, even when using aiming instruments.
The Paralleling Technique was introduced in 1920 and is based on paralleling the receptor (sensor or film) to the long axis of the teeth and placing the x-ray beam at right angles to those paralleled lines. Paralleling is also known as the Right-Angle Technique and the Long-Cone Technique.