Lecture 5: Radiographs Flashcards
why take intraoral radiographs
Look beyond the obvious
Examine dentition and supporting structures
Prepare better treatment plans
Have a more successful outcome
Healthier patient and a happier client
Less time under general anesthesia = quicker recovery time
Indications for radiographs
As part of the legal medical record, they are used to document the assessment and treatment of all types of dental and oral diseases:
Determine whether a visibly “missing tooth” is truly missing
Evaluate for abnormal root structure
Periodontal disease
Exodontics
Endontics
Oral abnormalities
Tooth resorption
Trauma
Missing teeth can be
Edentulous – tooth is absent
Fractured below the gumline (root retained)
Unerupted – no crown in the mouth but tooth visible on radiographs under the gumline
Impacted – unerupted or partially erupted tooth that is prevented from erupting further by other structures
Embedded – tooth is covered in bone and unlikely to erupt into the oral cavity
Evaluation for abnormal root structure in radiographs can be
Dilacerated roots – abnormally shaped/curved
More or fewer roots than expected
Ankylosis – fusion of the root to the bone
Endodontics is radiographed why
Evaluate the effectiveness of endodontic therapy and study radicular (root) health and size before, during, and after therapy
Exodontics is evaluated by radiographs by
Before extractions for diagnosis and evaluation of possible complications
During the procedure to determine the presence of retained roots and other complications
After to ensure completeness of the procedure
Contraindications of radiographs
Critical patients may have difficulty undergoing anesthesia, which is necessary to allow proper patient positioning
Protective measures for dental radiogrpahs
Wearing lead safety aprons, collars, and goggles(if available)
Standing behind screens
Maintaining a safe distance from the beam emitted (0.6 meters minimum recommended)
NEVER stand in the path of the beam
Films are never held by hand instead positioning aids are used
Wear dosimeter
Placing the film in the mouth
Side with raised dot or “a” is facing toward x-ray unit
Most x-ray film is labeled to indicate which side should face the x- ray tube
Place far enough in mouth to get maximum amount of root and support bone possible
Place outer edge of film at tip of tooth of interest
Parallel technique is
Used for distal mandibular teeth (premolars and molars) and nasal cavity
Film is placed parallel to structure being radiographed
When radiographing a single tooth, the film packet is placed parallel to the long axis of the tooth
In the lower jaw, place it between the tongue and the mandible
The central beam is projected at a right angle to the film packet
Bisecting angle technique is
Used in areas of the mouth where the parallel technique cannot be used
The bisecting angle is obtained by visualizing an imaginary line that bisects the angle formed by the x-ray film and the structure being radiographed
Bisect means to cut in half
Lay film far enough inside the animal’s mouth so that the tooth root structure will be projected on the film
Imaginary lines are drawn along the long axis of the tooth and the plane of the film
The point where these two lines meet will create an angle – the bisecting line cuts this angle in half
Central beam is aimed perpendicular to the line bisecting the angle created between the line of the tooth and line of the film
Principles of bisecting technique
For this to work three lines are drawn:
Line A is the long axis of the tooth
Line B is the angle of the film.
Line C bisects Line A and B
The beam is then directed at
90 degrees to Line C
Maxillary cheek teeth are radiographed by
Animal in lateral or sternal recumbency
Place film across the maxilla, parallel to the hard palate
Long end of the film is oriented from the muzzle to the back of the mouth
Central beam is aimed 90o to the bisecting angle of the target teeth and film
Practically: tube head will align with the eye when radiographing #108 and 208
Rostral maxillary teeth are radiographed by
Patient in sternal recumbency
Film is place parallel to the hard palate (oriented rostral-caudal)
Central beam is aimed 90o to the bisecting angle of the target teeth and film
The canine teeth are best evaluated by placing the machine head 45o from the front of the patient
Rostral mandibular teeth are radiographed by
Animal in dorsal recumbency with palate parallel to the tabletop
Place film parallel to the mandible
Central beam is aimed 90o to the bisecting angle of the target teeth and film
Just like in the upper jaw, canines are best evaluated by placing the machine head 45o from the front of the patient
Mandibular cheek teeth are radiographed by
Usually use parallel technique
Can also use bisecting angle technique as for the other teeth with the patient in lateral or dorsal recumbency
Complete dental rads include
Obtained with 6 views
Right and left posterior maxilla
Right and left posterior mandible
Anterior maxilla
Anterior mandible
Depending on the size of the patient, to obtain these views it usually requires:
10 – 18 radiographs in the dog
6 – 8 radiographs in the cat
Marking radiographs
As with all parts of the medical record, should be labelled appropriately with owner and pet information
Direct digital radiography allows you to mark the image as it is exposed
How to tell what direction the film is in
When the images are oriented correctly, you can easily distinguish right and left sides of the mouth from the lateral views:
Tooth roots project upwards in the maxilla
Tooth roots project downwards in the mandible
The direction the nose points is the side of the mouth being radiographed
Where should the dimple of the film be located
The dimple of the film should always be positioned the same during each procedure
When viewing the films, the concave surface of the dimple should be facing you
If the distal teeth are on the left, then that is the left side of the jaw
If the distal teeth are on the right, then that is the right jaw.
Blurred image can be caused by
Patient or tube moved during exposure
Tongue movement under light anesthesia can cause a blurred image
Double image can be caused by
Movement
Pressing the exposure button twice
Confusion with exposed films
Elongated image can be caused by
The tooth on x-ray will appear longer than the actual tooth
Caused by too little vertical angulation
Correction:
vertical angulation increased
steeper angle or closer to “12 o’clock”
Foreshortened image is caused by
Tooth on x-ray will appear shorter than actual tooth
Caused by too much vertical angulation
Correction:
vertical angulation is reduced
Reduce the angle or closer to “3 or 9 o’clock”
How to visualize the 3rd root in 208 and 108
pping of dental structures (SLOB rule)
When two roots of a triple rooted tooth are superimposed on the radiograph it is difficult to evaluate both roots – 108/208
In order to visualize the roots, you need to take an oblique radiograph:
Keep the plate/film in the same position
Vertical position of the x-ray tube is fixed
The tube is moved horizontally
Horizontal tube shift will result in a film with the overlapped roots moved apart
What is the SLOB rule
When the root “moves” in the opposite direction to the tube shift, then the root is labial or buccal
If the root “moves” in the same direction as tube, it is lingual or palatal
SLOB = Same Lingual, Opposite Buccal
108 and 208:
If you move the tube mesially, the palatal root will appear mesial (forward) on the x-ray
If you move the tube distally, the palatal root will appear distal (caudal) on the x-ray
Can demo this on your fingers! (right hand = 108, left is 208)
What should a normal young patients radiographs look like
Dentinal wall is thin and pulp chamber is large
Apex may be open depending on age
Lamina dura may be seen (boney white line next to the dark line of the periodontal space)
Periodontal ligament is located in the periodontal space (lamina lucida)
What does normal older patient radiographs look like
Decreased pulp chamber size with increased dentin
Lamina lucida becomes narrower with age and eventually disappears
Apex delta (foramen) is usually not seen
Thinning of alveolar crest may occur
