DANB CDA Exam 145 Questions And Answers

Periapical radiographs are used to display the location, outlines, and distance from the central jaw arch of the teeth into the surrounding tissue area. The entire tooth and root of all required teeth on a given periapical, including minimally 2 mm of the periapical bone below the apex of the teeth, are required. Sensor positoning devices such as the RINN XCP or Snap-a-Ray are utilized during periapical exposures.

Bitewing radiographs are used to show the entire coronal portion of the tooth or at a minimum, the visible part of the tooth covered by enamel as well as a surrounding bone. Bitewing images are useful for observation of calcium deposits, configuration of the pulp area, decay, periodontal issues, and other anomalies that are not clinically visible.

Occlusal radiographs look at the cutting-edge surfaces of the teeth and the planes in the mouth. Occlusal images can be taken on both the maxillary and mandibular arch. Adult occlusal sensors are captured using size 4 sensors while pediatric occlusal images are captured with size 2 sensors. This type of imaging is useful for observation of obvious abnormalities in the oral cavity as they show large areas of the exposed arch and also allow a 3D view of that area.

In general dentistry, it is common to expose patients to what is known as a full mouth series. This set of dental images can also be referred to as a full mouth survey or a complete mouth survey. The two types of images that are found in a full mouth series are periapical images and bitewing images. In a standard adult FMX there are 14 periapical images and 4 bitewing images. This allows for the dentist to have a full view of the mouth including all of the teeth in the dentition as well as their surrounding structures and bone. The dental team can adjust the number and types of images found in a full mouth series.

A maxillary topographic projection is a type of occlusal radiograph designed to document a large portion of the upper jaw. For a maxillary topographic projection, the sensor is positioned in the mouth on the tongue with the active part of the sensor facing upward towards the maxilla and the inactive part of the sensor down towards the tongue. The dental operator will then ask the patient to bite down gently which will hold the sensor in place. The ala-tragus line should be parallel to the ground, and the midsagittal plane should be at right angle to the ground.

an imaginary line drawn from the ala of the nose to the tragus of the ear that is used as a reference to establish the correct occlusal plane in dentistry
Ala = the outer side of the nostril
Tragus = the small cartilage bump in front of the ear canal

an imaginary vertical line that divides the body into equal left and right halves
It is used as a reference position to make sure the head is straight and not tilted when taking X-rays.
It runs through:
- middle of the nose
- center of the forehead
- middle of the chin

A mandibular cross-sectional projection is a type of occlusal radiograph used to document the presence of anomalies including calcium stones or calcified areas in the salivary glands found in the lower jaw area. Settings are similar to those used for mandibular symphysis projections, but the head is tilted much further back until the plane of the maxillary teeth is actually upright and perpendicular to the floor. The sensor is placed with the active part of the sensor facing downwards toward the tongue and the inactive part facing upwards towards the roof of the mouth. The middle part of the x-ray beam is directed at right angles to the occlusal sensor by positioning the position indicator device close to the lower chin but not touching it.

A mandibular symphysis projection is a type of occlusal radiograph designed to document a large area of the incisor region of the lower jaw. The sensor is placed the same as other mandibular occlusal projections with the active side of the sensor facing downwards towards the tongue. When exposing the projection, the patient's head is inclined backward to form a 45° angle between the floor and the biting surface plane. The midline plane should be perpendicular ot the ground. The bisecting angle technique is employed to center the x-ray beam. This translates to an angle between the sensor and x-ray of about 55° and a vertical angulation of about -20°. The beam indicating device is usually placed against the chin.

Posterior occlusal topographic projections can be taken for both the upper and lower jaws. For the maxillary jaw, this type of image is useful to view the sinus and other structural areas near the upper dentition. In this case, the sensor is placed lengthwise along the midline on one side of the face, the patient bites down on it, and the positioning device directs the x-ray beam at about a 55° angle through the profile near the premolar region. For the mandible, separate projections for each side of the mouth are usually unnecessary, but if they are required the sensor can again be placed on one side with the long edge positioned anteroposteriorly along the center.