radiographs Flashcards
What are radiographs?
Images created using x-ray photons
How are radiographs produced?
x-ray photons pass through an object and interact with a receptor
3 ways x-rays can interact with matter
transmit, absorb, scatter
Which interactions cause attenuation (reduce in amplitude) of x-ray photons?
absorption and scattering
term referring to darker areas
radiolucent
term referring to lighter areas
radiopaque
What happens to the x-rays to causes more radiolucent areas?
less attenuation of x-rays (more transmission, less absorption and scattering)
What happens to the x-rays to causes more radiopaque areas?
more attenuation of x-rays (less transmission but more absorption and scattering)
Materials that are more radiopaque
enamel, dentine, bone, some fillings
Why are radiographs useful?
Assess anatomy and pathology of hard tissues not visible to naked eye. Assess caries, bone loss
How will caries appear in a radiograph?
more radiolucent compared to rest of tooth (caries decreases radiodensity)
Types of intra-oral radiographs
bitewing, periapical, occlusal radiographs
Types of extra-oral radiographs
panoramic radiograph, lateral cephalogram
Type of cross-sectional radiograph
cone beam computed tomography (CBCT)
What does a bitewing show?
View of multiple upper and lower side teeth (premolars and molars). shows crowns, part of roots (not apex), some interdental bone
Use of bitewing
shows interdental caries
How can you reduce overlap between adjacent teeth in a bitewing?
Take more than one bitewing
What does a periapical radiograph show?
Full-length view of a particular tooth/teeth in one dental arch. Shows height of bone support around tooth.
Why may the receptor be a different size for anterior and posterior teeth?
Anterior teeth may require a smaller receptor to fit the curvature of the arch
What does a panoramic radiograph show?
entire dentition, jaws, mid-face. Can be full or sectional
Disadvantage of a panoramic radiograph
worse resolution than intra-oral radiographs
What does an occlusal radiograph show?
one dental arch (mandibular or maxillary) that can be seen from different viewpoints
Different angles of occlusal radiograph
anterior / lateral and true / oblique
What does cone beam computed tomography show?
cross-sectional imaging of the teeth/jaws (3D scan)
When is cone beam computed tomography used?
when routine dental imaging cannot provide the required information e.g. implant planning, fractures
Disadvantages of cone beam computed tomography
high radiation dose, low resolution, high cost
Advantages of a radiographic assessment
visualise caries, reveal RCT, depth of restoration
Limitations of a radiographic assessment
superimposition (2 distinct restorations may appear joined, buccal-lingual position of structures unknown.
how should you arrange multiple radiographs for viewing?
position radiographs as if you are facing the patient
Examples of anatomical features that can indicate which teeth are shown
crown morphology, root morphology, curve of Spee, surrounding non-dental anatomy
Aspects of tooth morphology that can identify teeth in radiographs
crown shape, number of cusps, number of roots
Which teeth have 1 root?
incisors, canines, some premolars
Which teeth have 2 roots?
some premolars, lower molars
Which teeth have 3 roots?
upper molars
What is the curve of Spee?
Normal anatomical upwards curvature of the occlusal plane posteriorly
Examples of non-dental anatomy used to identify maxillary teeth
maxillary sinus, nasal cavity, maxillary tuberosity
Examples of non-dental anatomy used to identify mandibular teeth
inferior alveolar canal, mental foramen, inferior border of mandible, external oblique ridge.
Location of mental foramen
below mandibular premolars
