Lecture 3 4/7/25 Flashcards
(41 cards)
What are the characteristics of dental radiology?
-dental rads have allowed for ID of significant problems in 27.8% of patients with clinically normal teeth
-incidental findings were found in 41.7% of patients with clinically normal teeth
-50% more information obtained in clinically diseased teeth with rads than without
What are the components of the radiograph equipment used for dentistry?
-control panel/interface
-generator/tube head/position indicating device
-film/digital sensors
-light box/computer software
What are the characteristic of the x-ray generator/control panel?
-sends energy/electrons to the tube head to produce x-rays
-radiographic exposure is controlled by kVp, MA, and time seconds/pulses
What is the purpose of the tube head?
where electrons are converted to x-rays and heat
What are the characteristics of the position indicating device?
-guides the direction of x-rays
-collimates and reduces collateral radiographic exposure
-length determines focal film distance; shorter requires less radiation but longer has better collimation
What are characteristics of film?
-D-speed film that comes in multiple sizes
-light box needed for viewing
-can use a manual chairside developing unit or automatic film processor
-low start up cost
-superior detail
-more radiation than digital versions
-unable to manipulate image
-takes longer to develop
-need physical storage space
What are the characteristics of direct digital radiography?
-uses sensor directly connected to software to produce image
-image available in seconds
-sensors have long life of use
-lowest levels of radiation
-high start up costs
-only available with size 2 sensors
What are the characteristics of computed digital radiography?
-photostimulable phosphor plate stores image
-processing into digital image via reader
-faster than film, slower than DR
-different plate sizes available
-plates have limited life span
-less radiation than film, more than DR
-high start up cost
What are the three principles behind radiographic safety recommendations?
-justification: exposure to radiation should not be done unless there is a positive net benefit
-optimization: should use the least amount of radiation to get the best possible effect
-limitation: dose equivalence limits are set for employees
How can radiation exposure be limited?
-have tube head checked for leakage during regular maintenance
-stand 6 feet away from tube head
-stand at a 90 to 135 angle from path of primary beam; not directly in front or behind
How should radiographic sensors be placed within the mouth?
-film and sensors both have a front and back; front side faces towards tubehead/beam
-need to place film/sensor to cover entire tooth; roots and crown
-need to be placed as close as possible to tooth
-cusp of tooth should be at edge of film/sensor to avoid wasted/undeveloped space
What are the techniques used for dental radiographs?
-parallel technique for mandibular molars
-bisecting angle technique for all other teeth
-sternal recumbency for maxillary radiographs
-dorsal recumbency for mandibular radiographs
What are the characteristics of parallel technique?
-sensor is placed parallel to tooth
-tubehead/beam is directed perpendicular to film/sensor
-creates minimal distortion
What are the characteristics of the bisecting angle technique?
-used when anatomical structures prevent use of parallel technique
-creates an image on the film that does not distort the target’s dimensions
-elongation or foreshortening of image can occur with incorrect positioning
What are the steps to the bisecting angle technique?
-sensor is placed as parallel to palate as possible
-angle between sensor and tooth is bisected/cut in half intraoral
-long axis of tube head is directed perpendicular to this new angle
How does vertical and horizontal technique change the radiographs?
-vertical angle changes lead to elongation or foreshortening of the tooth
-horizontal technique changes superimposition
What is the SLOB rule?
-“same lingual (palatal); opposite buccal”
-root that moves in same direction as tube head is the lingual/palatal root; one that moves in opposite direction is buccal root
What are the characteristics of labial mounting?
-look at rads as if you are facing patient
-images from patient’s right should be on your left; etc.
-crowns of maxillary teeth should point down while crowns of mandibular teeth should point up
-patient’s face will be pointing towards the side you are looking at
What are the characteristics of tooth crown anatomy?
-thin radiodense layer of enamel on outer surface
-middle layer is composed of moderately radiodense dentin
-inside is radiolucent pulp chamber
What are the characteristics of tooth root anatomy?
-outer layer of cementum is not usually visible on rads
-middle layer is composed of moderately radiodense dentin
-inside is the radiolucent root canal continuous with pulp chamber
What are the characteristics of tooth supporting structure anatomy?
-surrounding alveolar bone should sit 1-2 mm apical to the cementoenamel junction of the tooth
-the thin radiolucent line that surrounds tooth root is the soft tissue periodontal ligament
-the radiodense line that surrounds the PDL is the lamina dura, which is composed of the dense bone that forms the tooth socket
What is the chevron effect?
-effect created by the radiolucent periapical trabecular bone and vascular structures next to the denser alveolar bone
-commonly noted on the maxillary incisors and canines and the mandibular first molar
What is the appearance of the palatine fissures?
large symmetric radiolucent areas in the rostral maxilla, near the apical area of the incisors
What is the appearance of the conchal crest?
radiodense line that extends from the root of the canine to the 3rd premolar
