Technique Basics (Ch 16-24) Flashcards
Ch 16- Introduction to Radiographic Examinations Ch 17- Paralleling Technique Ch 18- Bisecting Technique Ch 19- Bite-wing Technique Ch 20- Exposure and Technique Errors Ch 21- Occlusal and Localization Techniques Ch 22- Panoramic Imaging Ch 23- Extraoral Imaging Ch 24- Imaging of Patients with Special Needs
What is an intraoral radiographic examination?
a radiographic inspection of the teeth and intraoral adjacent structures
What are intraoral receptors?
receptors placed inside the mouth to examine the teeth and supporting structures
What are the three types of intraoral radiographic examinations?
-periapical
-interproximal
-occlusal
What is the purpose of a periapical radiographic examination?
to examine the entire tooth and supporting bone
What is a periapical receptor?
the type of imaging receptor used for periapical radiographs
What are the two techniques that can be used for a periapical radiographic examination?
-paralleling technique
-bisecting technique
What is the purpose of an interproximal radiographic examination?
to examine the crowns of both the maxillary and mandibular teeth on a single image
What type of image receptor is used for an interproximal radiographic examination?
bite-wing receptor
What is a bite-wing receptor?
the type of imaging receptor used for bite-wing radiographs
What technique is used for an interproximal radiographic examination?
bite-wing technique
What is the purpose of an occlusal radiographic examination?
to examine large areas of the maxilla or mandible in one image
What type of image receptor is used for an occlusal radiographic examination?
occlusal receptor
What technique is used for an occlusal radiographic examination?
the occlusal technique
What is a full mouth series (FMX) of radiographs?
a series of intraoral dental radiographs that show all the tooth-bearing areas of the maxilla and mandible
What are considered tooth-bearing areas?
the regions of the maxilla and mandible where the 32 teeth of the human dentition are normally located
What are dentulous areas?
areas where teeth are present
What are edentulous areas?
areas where teeth are not present
How many radiographs are typically taken in a full mouth series for an adult with no missing teeth?
18 radiographs
List some general diagnostic criteria for intraoral radiographs.
-must display optimal density, contrast, definition, and detail
-must display the least amount of distortion possible
-must be of the same size and shape as the object being radiographed
-FMX must include all tooth-bearing areas, including dentulous and edentulous regions
-periapical images must show the entire crown and root of the teeth being examined, as well as 2-3mm beyond the apices
-bite-wing images must show open contacts or interproximal tooth surfaces that are not overlapped
When taking a periapical radiograph, how far below the apex of the tooth should be captured in the image?
2-3mm
What is an extraoral radiographic examination?
a radiographic inspection of large areas of the skull or jaws
What are extraoral receptors?
the type of imaging receptor used for extraoral radiographs
List some examples of extraoral radiographs.
-panoramic
-cephalometric
-transcranial
-tomographic
What does the term parallel mean?
moving or lying in the same plane, always separated by the same distance and not intersecting
What does the term intersecting mean?
to cut across or through
What does the term perpendicular mean?
intersecting at or forming a right angle
What is a right angle?
an angle of 90 degrees formed by two lines perpendicular to each other
What is the long axis of the tooth?
an imaginary line that divides the tooth longitudinally into two equal halves
What is the central ray?
the central portion of the primary beam of x-radiation
With the paralleling technique, how is the receptor placed intraorally in relation to the long axis of the tooth being radiographed?
parallel
With the paralleling technique, how is the central ray directed in relation to the receptor and the long axis of the tooth?
perpendicular
Is a beam alignment device necessary for the paralleling technique?
yes; the patient cannot hold the receptor
What is object-receptor distance?
the distance between the receptor and the object being radiographed
What is target-receptor distance?
the distance between the source of x-rays and the receptor
During the paralleling technique, in order to compensate for image magnification caused by an increased object-receptor distance, how should the target-receptor distance be influenced?
increased
What is a beam alignment device, and what is its purpose?
a device used to align the position-indicating device in relation to the tooth and receptor; helps to position the intraoral receptor and retain/stabilize the receptor during exposure and reduce the chances of movement
What are the three components of the Rinn XCP instruments?
-plastic bite block
-plastic aiming ring
-metal indicator arm
What is the color coding system used with the Rinn XCP instruments?
blue = anterior
yellow = posterior
red = bite-wing
How do beam alignment devices help to prevent a patient’s exposure to excess radiation?
by holding the receptor in place and stabilizing it during exposure in order to prevent movement, and therefore, the need for a retake of the radiograph
What is an exposure sequence?
a definite order for periapical receptor placement and exposure that must be followed in the placement and exposure of intraoral radiographs
When using the paralleling technique, what is required to be captured when radiographing a maxillary canine using an anterior periapical receptor?
-the entire crown and root of the canine
-the interproximal alveolar bone and mesial contact of the canine
When using the paralleling technique, what is required to be captured when radiographing maxillary incisors using an anterior periapical receptor?
-the entire crown and root of the one lateral and one central incisor
-the interproximal alveolar bone between the central and lateral and the surrounding regions of bone
-the mesial and distal contact areas of the central and lateral incisor
-the mesial contact of the adjacent central incisor
-the mesial contact of the adjacent canine
When using the paralleling technique, what is required to be captured when radiographing mandibular incisors using an anterior periapical receptor?
-the entire crowns and roots of four mandibular incisors
-contacts between all teeth
When using the paralleling technique, what is required to be captured when radiographing mandibular canines using an anterior periapical receptor?
-the entire crown and root of the canine
-the interproximal alveolar bone
-the mesial and distal contacts
When using the paralleling technique, what is required to be captured when radiographing maxillary premolars using a posterior periapical receptor?
-the entire crowns and roots of the first and second premolars
-the alveolar crests and surrounding bone
-the contact areas
-the distal contact of the maxillary canine
When using the paralleling technique, what is required to be captured when radiographing maxillary molarsusing a posterior periapical receptor?
-the entire crowns and roots of the first, second, and third molars
-the alveolar crests and surrounding bone
-the contact areas
-the tuberosity region
-the distal contact of the maxillary second premolar
When using the paralleling technique, what is required to be captured when radiographing mandibular premolars using a posterior periapical receptor?
-the entire crowns and roots of the first and second premolars
-the alveolar crests and surrounding bone
-the contact areas
-the distal contact of the mandibular canine
When using the paralleling technique, what is required to be captured when radiographing mandibular molars using a posterior periapical receptor?
-the entire crowns and roots of the first, second, and third molars
-the alveolar crests and surrounding bone
-the contact areas
-the distal contact of the mandibular second premolar
If a patient has a shallow palate and the paralleling technique cannot be properly accomplished, how should the vertical angulation change to compensate for the lack of parallelism?
the vertical angulation can be increased by 5-15 degrees more than the beam alignment device indicates; however, image distortion will occur
What is a torus?
a bony growth seen in the oral cavity
What is the plural of the term torus?
tori
What is a maxillary torus?
a nodular mass of bone seen along the midline of the hard palate
What is a mandibular torus?
bony growths along the lingual aspect of the mandible
What is the palate?
the roof of the mouth
When using the paralleling technique, how should the image receptor be placed to compensate for maxillary torus?
the receptor must be placed on the far side of the torus; not on the torus
When using the paralleling technique, how should the image receptor be placed to compensate for mandibular torus?
the receptor must be placed between the tori and the tongue; not on the tori
If a patient cannot tolerate the placement of a periapical receptor when radiographing the mandibular premolars using the paralleling technique, how should the receptor placement be modified?
the receptor should be placed under the tongue to avoid impinging on muscle attachments and the lingual gingiva
What is the primary advantage of the paralleling technique?
to produce a radiographic image without dimensional distortion
What is the advantage of the accuracy when using the paralleling technique?
the image has dimensional accuracy and is highly representative of the actual tooth; there is maximum detail and definition
What is the bisecting technique?
an intraoral radiographic technique used to expose periapical receptors where the receptor is placed along the lingual surface of the tooth, the central ray is directed perpendicular to the imaginary bisector formed by the receptor and the long axis of the tooth, and the receptor holder or the patient’s finger is used to stabilize the receptor
What does the term angle mean?
a figure formed by two lines diverging from a common point
What does the term bisect mean?
to divide into two equal parts
What geometry principle is the bisecting technique based on?
the rule of isometry
What is the rule of isometry?
two triangles are equal id they have two equal angles and share a common side; this is what the bisecting technique is based on
How is the receptor placed when using the bisecting technique?
along the lingual surface of the tooth so that where the receptor touches the tooth, the plane of the receptor and the long axis of the tooth form an angle
What is the imaginary bisector?
an imaginary plane that divides in half the angle formed by the receptor and the long axis of the tooth in order to create two equal angles and provide a common side for the two imaginary equal triangles
How is the central ray directed when using the bisecting technique?
perpendicular to the imaginary bisector
What does the term angulation mean?
the alignment of the central ray beam in the horizontal and vertical planes
What is used to assist with proper angulation when exposing an intraoral radiograph?
beam alignment devices
What is horizontal angulation?
the positioning of the position indicating device and direction of the central ray beam in a horizontal or side-to-side plane
How is correct horizontal angulation achieved when exposing intraoral radiographs?
the central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth
What occurs as a result of incorrect horizontal angulation in intraoral imaging?
incorrect horizontal angulation
What is vertical angulation?
positioning of the position indicating device in a vertical or up-and-down plane
What is the necessary vertical angulation when using the paralleling technique?
the vertical angulation of the central ray is directed perpendicular to the receptor and the long axis of the tooth
What is the necessary vertical angulation when using the bisecting technique?
the vertical angulation is determined by the perpendicular positioning of the central ray to the imaginary bisector
What results from correct vertical angulation in intraoral images?
the dental image is that of the same length as that of the tooth
What results from correct horizontal angulation in intraoral images?
the contact areas of the teeth appear opened and the result is diagnostic
What results from incorrect horizontal angulation in intraoral images?
the contact areas of the teeth appear overlapped and thus nondiagnostic
What results from incorrect vertical angulation in intraoral images?
the dental image is not the same length as that of the tooth and appears elongated or foreshortening and therefore nondiagnostic
What are forshortened images?
radiographic images that appear shortened
What is forshortening?
a term describing images of teeth that appear too short as a result of excessive vertical angulation
What are elongated images?
radiographic images that appear too long
What is elongation?
a term used to describe the images of teeth that appear longer than the actual teeth, as a result of insufficient vertical angulation
What are the recommended degrees of vertical angulation for maxillary canines when using the bisecting technique?
+45 to +55 degrees
What are the recommended degrees of vertical angulation for mandibular canines when using the bisecting technique?
-20 to -30 degrees
What are the recommended degrees of vertical angulation for maxillary incisors when using the bisecting technique?
+40 to +50 degrees
What are the recommended degrees of vertical angulation for mandibular incisors when using the bisecting technique?
-15 to -25 degrees
What are the recommended degrees of vertical angulation for maxillary premolars when using the bisecting technique?
+30 to +40 degrees
What are the recommended degrees of vertical angulation for mandibular premolars when using the bisecting technique?
-10 to -15 degrees
What are the recommended degrees of vertical angulation for maxillary molars when using the bisecting technique?
+20 to +30 degrees
What are the recommended degrees of vertical angulation for mandibular molars when using the bisecting technique?
-5 to 0 degrees
List some advantages of using the bisecting technique.
-can be used without a beam alignment device when a patient has anatomy that does not allow for placement (shallow palate, tori, etc)
-decreased exposure time when using a short 8-inch position indicating device
What is the primary disadvantage of using the bisecting technique?
dimensional distortion
What is the common term used for “caries?”
decay
List the anatomy included on a bite-wing radiograph.
-crowns of maxillary and mandibular teeth
-interproximal areas of teeth
-areas of crestal bone
What is the bite-wing technique?
a method used to examine the interproximal surfaces of teeth
What does the term interproximal mean?
between two adjacent areas
What is alveolar bone?
bone that supports and encases the roots of teeth
What is crestal bone/alveolar crest?
the coronal portion of alveolar bone found between teeth
What are contact areas of teeth?
-the area of a tooth that touches an adjacent tooth
-the area where adjacent tooth surfaces touch each other
How is a horizontal bite-wing receptor placed in the mouth?
the receptor is placed with the long portion of the receptor in a horizontal position
How is a vertical bite-wing receptor placed in the mouth?
the receptor is placed with the long portion of the receptor in a vertical position
How do opened contacts appear on a dental image?
thin radiolucent lines between adjacent tooth surfaces
What are overlapped contacts on a dental image?
the area where contact area od one tooth is superimposed over the contact area of an adjacent tooth
What are the three basic principles of the bite-wing technique?
-the receptor is placed in the mouth parallel to the crowns of both the maxillary and mandibular teeth
-the receptor is stabilized when the patient bites on the bite-wing tab or the bite-wing beam alignment device
-the central ray of the x-ray beam is directed through the contacts of the teeth, using a vertical angulation of +10 degrees
What two options can be used in the bite-wing technique to stabilize the receptor?
-bite-wing beam alignment device
-bite-wing tab
When using the bite-wing technique, is the receptor placed parallel or perpendicular to the crowns of the teeth
parallel
How is the bite-wing receptor stabilized in the mouth?
by the patient biting on either the bite-wing tab or the bite-wing beam alignment device
What is the recommended vertical angulation needed of the central ray for the bite-wing technique?
+10 degrees
What is a bite-wing tab?
a heavy paperboard tab or loop that is fitted around an intraoral receptor and used to stabilize the receptor when using the bite-wing technique; an alternate stabilizing option for the bite-wing intraoral receptor
In the bite-wing technique, the _____ of the position indicating device is critical to the success of a diagnostic image.
angulation
What is the correct horizontal angulation of the central ray when using the bite-wing technique?
the central ray is directed perpendicular to the curvature of the arch and through the contact areas of the teeth
When using the proper horizontal angulation during the bite-wing technique, is the central ray directed parallel or perpendicular to the curvature of the arch?
perpendicular
What is the result of incorrect horizontal angulation of the central ray when using the bite-wing technique?
an undiagnostic image due to overlapped/unopened contact areas
What is positive (+) vertical angulation?
when the position-indicating device is positioned above the occlusal plane and the central ray is directed downward
What is negative (-) vertical angulation?
when the position-indicating device is positioned below the occlusal plane and the central ray is directed upwards
When using the bite-wing technique, what is the basic rule for the receptor placement?
the bite-wing receptor must be positioned to cover the prescribed areas of the teeth that are being examined
When using the bite-wing technique, what is the basic rule for the receptor position?
the bite-wing receptor must be positioned parallel to the crowns of both the maxillary and mandibular teeth and must be stabilized when the patient bites on either the bite-wing tab or the bite-wing beam alignment device
When using the bite-wing technique, what is the basic rule for the vertical angulation of the central ray?
the central ray of the x-ray beam must be directed at +10 degrees
When using the bite-wing technique, what is the basic rule for the horizontal angulation of the central ray?
the central ray of the x-ray beam must be directed through the contact areas of the teeth
When using the bite-wing technique, what is the basic rule for receptor exposure?
the x-ray beam must be centered on the receptor to ensure that all areas of the receptor are exposed
All vertical angulations above the occlusal plane are termed _______.
positive
All vertical angulations below the occlusal plane are termed _______.
negative
How is zero vertical angulation achieved?
when the position-indicating device and the central ray are parallel to the floor
Why is it common practice to expose two bite-wing radiographs on each side of the mouth?
to compensate for the curvature of the arch, which can often make it impossible to open all posterior contact areas on one bite-wing image
Define the term: receptor placement
the specific area where the receptor must be positioned before exposure
How can you accommodate edentulous spaces when exposing bite-wing radiographs?
placing a cotton roll in the missing area(s) to support the bite-wing tab or the beam alignment device
How can you accommodate for tori when exposing bite-wing radiographs?
place the receptor between the tori and the tongue- not on the tori
True or false: Exposure factors should be set after placing the receptor in the mouth
False
True or false: Angulations should be set prior to placing the receptor in the mouth
True
What is the appearance of an unexposed receptor?
the image appears clear
What is the cause of an unexposed receptor?
the receptor was not exposed to x-radiation
How would you attempt to prevent an unexposed receptor error?
make sure the x-ray machine is turned on and during exposure, listen for the audible exposure signal
What is the appearance of an overexposed receptor?
the image appears dark
What is the cause of an overexposed receptor?
the receptor was overexposed to radiation due to excessive exposure time, kilovoltage or milliamperage settings, or a combination of these factors
How would you attempt to prevent an overexposed image error?
check the exposure settings on the x-ray machine prior to exposing the image
What is the appearance of an underexposed receptor?
the image appears light
What is the cause of an underexposed receptor?
the receptor was underexposed to radiation due to inadequate exposure time, kilovoltage or milliamperage, or a combination of these factors
How would you attempt to prevent an underexposed receptor error?
check the exposure settings on the x-ray machine prior to exposing the image
What can result from improper receptor placement for a periapical image?
a nondiagostic image caused by improper placement of the receptor over the required area, inadequate coverage of the apices, or a dropped receptor corner
How would you attempt to prevent missing the apical structures when exposing a periapical image?
make sure that no more than 1/8 of an inch of the receptor edge extends beyond the incisal-occlusal surfaces of the teeth
What is the appearance of a dropped receptor corner when exposing a periapical image?
the occlusal plane appears tipped or tilted
What is the cause of a dropped receptor corner when exposing a periapical image?
the edge of the receptor was not placed parallel to the incisal-occlusal surfaces of the teeth, due to the patient not closing firmly on the bite block in order to hold the receptor against the tooth
How would you prevent a dropped receptor corner error when exposing a periapical image?
make sure that the edge of the receptor is placed parallel to the incisal-occlusal surfaces of the teeth as the patient bites their teeth together
Define the term: cone-cut
the clear, unexposed area on a radiograph when the position-indicating device is misaligned and the x-ray beam is not centered over the receptor and only a partial image is captured
What is the appearance of an image that has been cone-cut?
a clear, unexposed area is seen on the image
What is the cause of a cone-cut error from the position-indicating device?
the position-indicating device was not properly aligned with the beam alignment device, and the x-ray beam did not expose the entire receptor
How would you attempt to prevent a cone-cutting error when using a beam alignment device with an aiming ring?
ensure that the position-indicating device and the aiming ring are aligned
How would you attempt to prevent a cone-cutting error when you are not using a beam alignment device with an aiming ring?
ensure that the x-ray beam is centered over the receptor and the entire receptor is covered by the diameter of the position-indicating device
What is the appearance of an incorrect receptor placement when exposing a premolar bite-wing?
the distal surfaces of the maxillary and mandibular canines are not visible on the image
What is the cause of incorrect receptor placement when exposing a premolar bite-wing?
the bite-wing receptor was positioned too far posteriorly in the mouth and the front edge of the receptor was not placed at the midline of the canines
How would you attempt to prevent incorrect receptor placement when exposing a premolar bite-wing?
ensure the anterior edge of the bite-wing receptor is positioned at the midline of the mandibular canine
What is the appearance of incorrect receptor placement when exposing a molar bite-wing?
the third molar regions are not visible in the image
What is the cause of incorrect receptor placement when exposing a molar bite-wing?
the bite-wing receptor was positioned too dar anteriorly in the mouth and the front edge of the receptor was not placed at the midline of the mandibular second premolar
How would you attempt to prevent incorrect receptor placement when exposing a molar bite-wing?
ensure that the anterior edge of the of the bite-wing receptor is positioned at the midline of the mandibular second premolar
In the case that third molars are not present, does the position of the bite-wing receptor change when exposing a molar bite-wing?
No- with or without third molars present, the center of the bite-wing receptor must always be centered on the mandibular second premolar
What is the cause of a cone-cut error from the beam alignment device?
the position- indicating device was not properly aligned with the beam alignment device and the x-ray beam did not expose the entire receptor
How would you attempt to prevent a cone-cut error from the beam alignment device?
ensure that the position-indicating device and the aiming ring of the receptor are aligned
How would you attempt to prevent a cone-cut error when not using a beam alignment device?
ensure that the x-ray beam is centered over the receptor and that the entire receptor is covered by the diameter of the position-indicating device
Define the term: phalangioma
a radiographic error that occurs when the finger-holding method is used with the bisection technique, causing the distal phalanx of the finger to be seen on the image
What is the appearance of a phalangioma error on an image?
an image of the patient’s finger is seen on the radiograph
What is the cause of a phalangioma error on an image?
the patient’s finger was incorrectly positioned in front of the receptor, instead of behind it, when using the finger-hold method
How would you attempt to prevent a phalangioma error when exposing a radiograph?
if using the finger-holding method, endure that the patient’s finger that is being used to stabilize the receptor is placed behind the receptor and not in front of it
What is the appearance of a movement error when exposing a radiograph?
blurred images are seen on the radiograph
What is the cause of a movement error when exposing a radiograph?
either the tubehead or the patient moved during the exposure of the receptor
How would you attempt to prevent a movement error when exposing a radiograph?
ensure that the tubehead and the patient’s head are stabilized, and instruct the patient to remain still while exposing the radiograph
What is the appearance of a film bending error on an image?
the images appear stretched and distorted
What is the cause of a film bending error on an image?
the film was bent excessively because of the curvature of the patient’s hard palate
How would you attempt to prevent a film bending error when exposing a radiograph?
always check film placement prior to exposure and ensure that, if the film is bent due to the curvature of the hard palate, use cotton rolls with the paralleling technique, or switch to using the bisecting technique
What is the appearance of a film creasing error on an image?
a thin radiolucent line is seen on the image
What is the cause of a film creasing error on an image?
the film was creased prior to or during placement of the receptor
How would you prevent a film creasing error when exposing a radiograph?
do not bend or crease the film excessively, and if needed, gently soften the corners of the film before placing it in the patient’s mouth
What is the appearance of a double exposure error on an image?
a double image is seen on the radiograph
What is the cause of a double exposure error on an image?
the same receptor was used twice in the patient’s mouth
Why is a double exposure error imperative to prevent it from occurring?
it requires two retakes, one for each of the two areas previously radiographed, which doubles the radiation dosage unnecessarily to the patient
How would you attempt to prevent a double exposure error when exposing an image?
always separate the exposed and unexposed receptors; once a receptor has been exposed, place it in a designated area away from the unexposed receptors
What is the appearance of a reversed film error when exposing a radiograph?
light images with a herringbone pattern are seen on the radiograph
Define the term: herringbone pattern
a radiographic error that occurs when the film is placed backward in the patient’s mouth and then exposed
What is the cause of a reversed film error when exposing a radiograph?
the film was placed in the mouth backward/reversed and then exposed
How would you attempt to prevent a reversed film error when exposing a radiograph?
always confirm the front and back sides of the receptor before placing it in the patient’s mouth and place the correct side of the receptor adjacent to the teeth being captured
What are occlusal surfaces?
the chewing surfaces of posterior teeth
List some areas that can be located with the use of occlusal imaging.
-retained roots of extracted teeth
-supernumerary, unerupted, or impacted teeth
-foreign bodies in the maxilla or mandible
-salivary stones in the duct of the submandibular gland
-lesions in the maxilla or mandible
List some areas that can be evaluated with the use of occlusal imaging.
-the extent of lesions in the maxilla or mandible
-the boundaries of the maxillary sinus
-fractures of the maxilla or mandible
-cleft palate
-measure changes in the size and shape of the maxilla or mandible
How is the receptor placed in the mouth when using the occlusal technique?
between the occlusal surfaces of the maxillary and mandibular teeth
How is the receptor stabilized when using the occlusal technique?
when the patient gently bites on the surface of the receptor
What are the three types of maxillary occlusal projections?
-topographic
-lateral (right or left)
-pediatric
What area is captured when exposing a maxillary topographic occlusal projection?
the palate and the anterior teeth of the maxilla
What area is captured when exposing a maxillary lateral occlusal projection?
the palatal roots of maxillary molars or to locate foreign bodies or lesions in the posterior maxilla
What area is captured when exposing a maxillary pediatric occlusal projection?
the anterior teeth of the maxilla in children ages 5 years or younger
What are the three types of mandibular occlusal projections?
-topographic
-cross-sectional
-pediatric
What area is captured when exposing a mandibular topographic occlusal projection?
the anterior teeth of the mandible
What area is captured when exposing a mandibular cross-sectional occlusal projection?
the buccal and lingual aspects of the mandible or to locate foreign bodies or salivary stones in the region of the floor of the mouth
What area is captured when exposing a mandibular pediatric occlusal projection?
the anterior teeth of the mandible in children ages 5 years or younger
Define the term: localization technique
a radiographic method used to locate the position of a tooth or an object in the jaws
What is the correct vertical angulation for a maxillary topographic occlusal projection?
+65 degrees
What is the correct vertical angulation for a maxillary lateral occlusal projection?
+60 degrees
What is the correct vertical angulation for a maxillary pediatric occlusal projection?
+60 degrees
What is the correct vertical angulation for a mandibular topographic occlusal projection?
-55 degrees
What is the correct vertical angulation for a mandibular cross-sectional occlusal projection?
90 degrees
What is the correct vertical angulation for a mandibular pediatric occlusal projection?
-55 degrees
List the two basic techniques used to localize the depth of an object.
-buccal object rule
-right-angle technique
What is the buccal object rule?
a localization technique that governs the orientation of structures portrayed in two images exposed at different angulations in order to determine the buccal-lingual relationship of an object
What is the right-angle technique?
a localization technique in which the orientation of structures can be seen in two different radiographs- one periapical and one occlusal
Which two types of radiographs will be evaluated when using the right-angle localization technique?
one periapical and one occlusal
When following the buccal object rule, what type of angulation is used when trying to locate two vertically aligned objects?
horizontal angulation
Using the buccal object rule, what type of angulation is used when trying to locate two horizontally aligned objects?
vertical angulation
When following the buccal object rule, how is an object determined to be lingually positioned?
when the object appears to have moved in the same direction as the shift of the position-indicating device
When following the buccal object rule, how is an object determined to be buccally positioned?
when the object appears to have moved in the opposite direction as the shift of the position-indicating device
What mnemonic phrase can be used to help remember the buccal object rule, and what does it stand for?
-SLOB
-Same = Lingual / Opposite = Buccal
What two types of images are exposed when using the right-angle technique?
one periapical and one occlusal
How is the periapical receptor positioned when using the right-angle technique?
using the proper periapical technique and angulation to show the position of the object being examined in both superior-inferior and anterior-posterior relationships
How is the occlusal receptor positioned when using the right-angle technique?
directing the central ray at a right angle/perpendicular (90 degrees) to the receptor in order to show the position of the object being examined in both the buccal-lingual and anterior-posterior relationships
Which of the two localization techniques is commonly used to locate objects in the mandible?
the right-angle technique
What is considered a “panoramic view?”
a wide view
What is the purpose of panoramic imaging?
to examine the upper and lower jaws on a single projection
Is a panoramic image an intraoral or extraoral radiographic technique?
extraoral
List some diagnostic purposes for exposing a panoramic image.
-to evaluate impacted teeth
-to evaluate eruption patterns, growth, and development
-to detect diseases, lesions, and conditions of the jaw
-to examine the extent of large lesions
-to evaluate trauma
Define the term: tomography
an imagining technique that allows the imagine of one layer or section of the body while blurring the the images of structures in another plane
What is the rotation center in panoramic imaging?
the pivotal point or axis around which the receptor and the x-ray tubehead rotate around a patient during exposure
List the three rotation centers used in panoramic x-ray machines.
-double-center rotation
-triple-center rotation
-moving center rotation
How is a double-center rotation center used on a panoramic x-ray machine?
there are two rotation centers- one for the right side and one for the left side
How is a triple-center rotation center used on a panoramic x-ray machine?
there are three centers of rotation used to create an uninterrupted radiographic image of the jaws
How is a moving-center rotation center used on a panoramic x-ray machine?
they rotate around a continuously moving center that is similar to the dental arches, creating an uninterrupted image of the jaws
What two aspects of the rotation centers on panoramic x-ray machines influence the size and shape of the focal trough?
the location and number of rotational centers
In panoramic imaging, what is the theoretical concept used to determine where the dental arches must be positioned in order to obtain the clearest image?
the focal trough
Define the term: focal trough
a three-dimensional curves zone in which structures are clearly demonstrated on a panoramic image
How do structures positioned within the focal trough appear on a panoramic image?
well-defined
How do structures positioned inside or outside the focal trough appear on a panoramic image?
blurred/indistinct and not readily visible
Is the focal trough more narrow or broader the closer the rotation center is to the teeth?
more narrow
In most panoramic machines, is the focal trough more narrow in the anterior or posterior region?
anterior region
List the three main components of a panoramic machine.
-x-ray tubehead
-head positioner
-exposure controls
How does a panoramic collimator differ from a collimator used for intraoral radiography?
the panoramic collimator is a lead plate with an opening in the shape of a narrow vertical slit; an intraoral collimator is a lead plate with a small round or rectangular opening in the middle
What is the function of the panoramic collimator?
to restrict the size and shape of the x-ray beam
Does the panoramic tubehead rotate in front of or behind the patient’s head during exposure?
behind the patient’s head
Does the panoramic receptor rotate in front of or behind the patient’s head during exposure?
in front of the patient’s head
Which part of the panoramic x-ray unit aligns the patient’s teeth in the focal trough?
the head positioner
Which exposure factor is fixed and cannot be changed by the operator on a panoramic unit?
the exposure time
List two common patient preparation errors in panoramic imaging.
-ghost images
-lead apron artifact
Define the term: ghost image
a radiopaque artifact on an image due to a radiodense object being penetrated twice by the x-ray beam
List some examples of objects that can result in a ghost image if not removed prior to the exposure of a panoramic x-ray
eye glasses, jewelry, dentures, hairpins
How does a ghost image appear on a panoramic image?
it resembles its real counterpart and is found on the opposite side of the image; however, it is indistinct, larger and higher than the actual counterpart
How do you prevent a ghost image error when exposing a panoramic radiograph?
ensure that all radiodense objects are removed from the head and neck area prior to positioning the patient
What is the cause of a lead apron artifact on a panoramic image?
the lead apron is incorrectly placed on the patient, or a thyroid collar is used
How does a lead apron artifact appear on a panoramic image?
a radiopaque artifact that results in an undiagnostic area in the image
Can a lead apron with a thyroid collar be used when exposing a panoramic x-ray?
no
How can the position of the patient’s lips negatively affect the panoramic image?
if the lips are not closed on the bute block during exposure, it results in a dark radiolucent shadow that obscures the anterior teeth
How can the position of the patient’s tongue negatively affect the panoramic image?
if the tongue is not in contact with the palate during exposure, it results in a dark shadow that obscures the apices of the maxillary teeth
What is the result of the Frankfurt plane being positioned upward in a panoramic image?
-the hard palate and floor of the nasal cavity appear superimposed over the roots of the maxillary teeth
-the maxillary incisors appear blurred and magnified
-a reverse smile line (curved downward) is seen
How do you prevent the Frankfort plane from being incorrectly positioned when positioning a patient for a panoramic image?
ensure that the patient is positioned so that the Frankfort plane is parallel to the floor
What is the result of incorrectly positioning the patient so the teeth are aligned in the focal trough when taking a panoramic radiograph?
the teeth appear blurred
What is the result of incorrectly positioning the patient so that the teeth are anteriorly positioned in the focal trough when taking a panoramic radiograph?
the anterior teeth appear “skinny” and out of focus in the image
How would you prevent incorrectly aligning the anterior teeth in the focal trough when taking a panoramic radiograph?
ensure the patient is positioned with the anterior teeth in an end-to-end position in the groove in the bite block
What is the result of incorrectly positioning the patient so that the teeth are posteriorly positioned in the focal trough when taking a panoramic radiograph?
the anterior teeth appear “fat” and out of focus in the image
What is the result of misaligning the midsaggital plane when positioning a patient for a panoramic radiograph?
the ramus and posterior teeth appear unequally magnified- the side farthest from the image receptor appears magnified and the side closest to the image receptor appears smaller
How would you prevent misaligning the midsagittal plane when positioning a patient for a panoramic radiograph?
position the patient’s head so that the midsagittal plane is perpendicular to the floor while the midline is centered on the bite block
What is the result of misaligning the sine when positioning a patient for a panoramic radiograph?
the spine appears as a radiopacity in the center of the image
How would you prevent misaligning the spine when positioning a patient for a panoramic radiograph?
ensure the patient is standing or sitting as tall as possible with their back kept straight
What is the advantage of the field size in a panoramic image?
the entire maxilla and mandible are shown, which allows for more anatomic structures to be evaluated; areas can be shown on a panoramic that may not be seen on an intraoral image
Explain the advantage of the simplicity of taking a panoramic image.
the exposure is relatively simple, takes minimal time, and is easy and comfortable for patients
Explain the disadvantages of panoramic image quality.
the images are not as sharp as an intraoral image and therefore, cannot be used to diagnose caries, periodontal disease, or periapical lesions
