Dental radiographs Flashcards
Importance of dental rads
Essential for proper assessment of oral cavity
Enable us to view that which is not visible or probable
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 full mouth rads
Periodontal disease
Missing teeth
Resorptive lesions
Oral tumors
Gingival inflammation
Malformed teeth
Discoloured teeth
Dental extractions
Dental trauma
Contraindications for full mouth rads
Critical patients may have difficulty with anesthetic
Protective measure for dental rads
Weal lead aprons/collars
Stand behind screen when possible
Maintain safe distance from beam
0.6 meters recommended
NEVER stand in path of beam
Films are never held by hand- use positioning devices
Wear dosimeter
Equipment in dental rads
Standard much more difficult to use
Lots of patient moving required
Less detail- reduces quality of image
Needs to take measurements and sue technique chart- be prepared for adjustments
Dental machines are more simplified
Preset settings for species/tooth
Little manual adjustments needed
Move machine around patient
The dental unit consists of
Generator
Extension arm
Scissor arm
X-ray tube- has collimator cone
The dental unit
X-ray tube is stationary anode encased in tube at the end of the scissor arm
Rotates around the stem
One side of the tube will have an angle meter
Useful for setting up views
kVp and mA usually fixed, but time can be varied
May have settings for both film and digital
Dental x-ray imaging film
kV required for imaging teeth generally much higher
No intensifying screens
4 sizes
0, 1, 2, 4
2 and 4 most common
Have a convex dot on front in specific corner
Helps determine left/right once film developed
Keep dot facing the tube and at front of the mouth
Can be processed manually or through automatic processor
Need system for labelling, mounting, and storing
Computed radiography on dentals
CR processor similar to standard CR used in whole body radiographs
Plates are flexible and come in sizes 0-4
Have an “a” in corner that acts as a left/right marker
“a” is always placed away from the tube and rostral
Direct digital imaging in dentals
Image receptor is a size 2 sensor
Attached directly to computer
Must protect from liquids
Place in plastic sleeve over sensor
Can use a single layer of plain vet wrap over plastic sleeve for protection or to avoid slippage or some systems come with a rubber protector
Radiographic technique for teeth
Keep distance between patient and tube as short as possible
Under 10cm
Use small focal spot
Always center cone on tooth in question
No collimator light so need to view from many angles to ensure centered
Place film correctly
Correct side towards x-ray unit
Correct anatomy
Appropriate tooth including full crown and root and maximum support bone
Radiographic log for teeth
All exposures must be recorded in log book
Each machine requires separate book
Require patient ID, client, date, area imaged, settings
If machine has present mA and kV, you only need to record seconds for each exposure as long as state presets at beginning of log
Each series given accession number, NOT the patient
Crown is
supragingival (above gums)
Four basic tooth types
Incisors
Canines
Premolars
Molars
Dental formual
Illustrates how many of each tooth type are present in half the dog or cats mouth
Presented in a fraction with maxillary teeth above and mandibular teeth shown below, using the following conventions
Permanent: upper case (I,C,P,M)
Deciduous: lower case (i,c,p,m)
Dental formula for dogs
Deciduous: 2 x (i3c1p3m0/i3c1p3m0) = 28 total
Permanent: 2 x (I3C1P4M2/I3C1P4M3) = 42 total
Dental formula for cats
Deciduous: 2 x (i3c1p3m0/i3c1p2m0) = 26 total
Permanent: 2 x (I3C1P3M1/I3C1P2M1) = 30 total
Nomenclature on teeth
Anatomical system for notation
Uses combination of short forms for tooth type and the numbers of those teeth in their group to designate a specific tooth
Permanent teeth: I, C, P, M
Deciduous teeth: i, c, p, m
Numbers: ie – premolars 1-4
Number is placed on left for left-sided tooth and on right for right sided tooth
Number is superscript for maxillary tooth and subscript for mandibular tooth
Modified triadan system is
Uses 3 numbers
1st digit identifies quadrant of tooth
Next 2 digits identify the specific tooth
Numbering starts at front of mouth at central incisors
System allows identical teeth to have identical numbers in different species
Advantages and disadvantages of modified triadan system
Advantages: can be used with any computer, not as cumbersome when recording in patient file
Disadvantages: not intuitive, need to learn the numbering system
Roots of various teeth
Very important to know structure and number of tooth roots
Vital to determine tooth angle and to decide when to change the direction of x-ray beam to isolate roots
Lingual is
towards tongue
Lower arcade only
Palatal is
towards palate
Upper arcade only
Labial is
towards lips
Incisors and canines
Buccal is
Towards teeth
Occlusal is
chewing surface, towards opposite arcade
Mesial is
toward middle/center
Tooth surface description and radiographic angles
Apical and coronal are
Apical – toward root of tooth
Coronal– toward crown of tooth
Normal Radiographic Anatomy in Dogs and Cats is important why in dental
Important to be able to distinguish between mandible and maxilla when viewing radiographs
Important to become familiar with orientation of teeth and anatomical differences in root and crown structure
More familiar you are with these areas, easier is to distinguish between teeth on radiograph
Viewing dental rads
Film always exposed with convex dot at dorsal end of mouth
Results in views on right side having dot in different location from those on left side
Once film developed, hold with convex dot raised towards you – as it was placed in the mouth
Orient radiograph so cusps of maxillary teeth are pointing down toward the floor and cusps of mandibular teeth are pointing up toward the ceiling
Parallel technique
Used for caudal mandibular teeth (premolars and molars) as well as nasal cavity
Involves placing dental film directly behind and parallel to the tooth and then directing the x-ray beam perpendicular to film
Bisecting angle technique
For majority of the teeth, film cannot be placed directly behind due to anatomic structure
Bisecting angles are based on geometric theory of isometric triangles
Lay film far enough inside animal’s mouth that tooth root structure will be projected on film
Imaginary lines drawn along axis of tooth and plane of film
Imaginary lines are two sides of your triangle, third being the imaginary line between the ends of first two lines
Point where these two lines meet will create an angle
Bisecting angle cuts your triangle into 2 equal halves
Central beam aimed perpendicular to the line bisecting the angle created between the line of the tooth and the line of the film
Positioning for maxillary premolars and molars
Can be done in lateral or ventral recumbence
Opposite edge of film should be touching hard palate
Tips of teeth should be at edge of film closest to cone to allow ample space for roots to “fall onto” film
Tube head placed 90 degrees to bisecting angle of target teeth and film
May need multiple x-rays for multi-rooted teeth
Maxillary premolars
Maxillary 4th premolar (108/208) is triple rooted with one large distal root and two smaller mesial roots
Mesial roots superimpose each other if beam directed from lateral aspect
If this happens, it is hard to evaluate both roots
SLOB rule is and when to use it
To visualize both roots, two radiographs are taken at oblique angles
Vertical position fixed, tube moved horizontally
Horizontal tube shift results in film with overlapped roots moved apart
SLOB – “Same Lingual Opposite Buccal”
When the root “moves” in same direction as tube – it is lingual or palatal
When the root “moves” in the opposite direction as tube, it is labial or buccal
Helps identify particular root when directed from mesial or distal aspect
Maxillary incisors positioning
Patient in sternal or lateral recumbency
Foam or towel under mandible to keep parallel
Film placed parallel to hard palate
Use bisecting technique
Tube head is 90 degrees to bisecting angle of target teeth and film
Maxillary canines positioning of patient and tube head
Patient in sternal recumbency
Foam or towel under mandible to keep parallel
Film placed parallel to hard palate
Use bisecting angle technique
Canine teeth curve distally so you need to visualize the curvature of the root to accurately reflect the long axis of the tooth in order to properly find bisecting angle
From true lateral adjust tube head to 30 degrees and center on middle of canine
Mandibular incisors patient positioning and tube head
Patient in dorsal or lateral recumbency
Tips of incisors should be at rostral edge of film to allow ample space for roots
Choose film size where both canine teeth are touching/biting film
Size 4 for most medium to large dogs
Use bisecting angle technique
Tube head 90 degrees to bisecting angle
Center cone between the six incisors
Cone in slight rostrocaudal direction
Mandibular canines patient and tube head positioning
Choose film size where both canine teeth are touching the film (biting on it)
Center in middle long axis of canine tooth and center of incisors (to get both canines)
If you are only attempting to get one canine, then center centrally on that tooth
Use bisecting angle technique
Mandibular premolars 1 and 2 patient and tube head positioning
Film should be resting on both the first and second premolars, behind the canine tooth, facing the floor of the mandible
Tips of premolars should be at edge of film closest to you to allow ample space for roots
Cone directed laterally and centered at tooth/teeth to be radiographed
Bisecting angle technique used
Premolar 2 and 3 patient and tube head positioning
Film placed between tongue and mandible, parallel to long axis of teeth
Push film down until can feel the film pop out under ventral mandible
Can use gauze/paper towel to keep film pushed down or can be placed diagonally if needed
Cone is directed laterally and centered on tooth/teeth to be radiographed
Cone is perpendicular to film
Parallel technique used
Feline radiographs mouth rads are different from dogs how
Anatomical differences between canines and felines allow for some modifications of views
Maxillary canine and incisor teeth are more upright than in dogs
Important when estimating long axis of tooth for bisecting angle technique
Follow the crown as root follows same angle
Prominent zygomatic arch makes maxillary premolars and molars most difficult area to image
Will superimpose over teeth, negating diagnostic value of radiograph
Cannot use traditional bisecting angle technique for these teeth – use modified technique
Complete dental series includes
Obtained with 6 views** (Not 6 exposures)
Right and left posterior maxilla
Right and left posterior mandible
Anterior maxilla
Anterior mandible
Larger patients will require additional films to cover all the teeth
Rules for successful positioning of tube head
Closer the object being radiographed is to the film, the sharper and more accurate the image
Use the longest film focal distance practical
Make sure you are aiming at subject AND sensor/film
Complications in dental rads
Root cutoff – film not pushed in far enough
Cone cutoff – cone not centered on tooth
Blurred image
Patient or tube moved during exposure
Tongue movement under light anesthesia
Double image
Movement or pressing exposure button twice
Not keeping proper track of already exposed films/plates
Elongation of tooth is caused by
result of central ray’s being at a right angle to long axis of tooth instead of to bisecting angle
Image is stretched out and may not have captured entire tooth on film
Foreshadowing is caused by
result of central ray’s being at right angle to film instead of to bisecting angle
Tooth will appear to have crown overlapping on the root
Elongated images look like and can be fixed by
Appear LONGER than actual tooth
Caused by too little vertical angulation
To correct: increase vertical angulation
Move tube head away from film
Increase your angle
Foreshortened images appear and are fixed
Appear SHORTER than actual tooth
Caused by too much vertical angulation
To correct: reduce vertical angulation
Move tube head towards film
Reduce your angle
Root is
subgingival (below gums)
Apacial delta is
top of root where blood supply and nerves end
Pulp chamber is
inner part of tooth
Dentin is
bulk of tooth
Cumentum is
outer covering of root
