Occlusal Radiography Flashcards
Occlusal radiographs image receptor size
7x5cm
Occlusal radiograph image receptor size in children
5x4cm
Oblique occlusals indications (like large periodicals)
- Periapical type assessment when periapicals not possible
- Pathology too large to be seen on a periapical (oblique shows 4 anteriors periodical shows 3)
- Trauma - fractures to teeth and alveolus
What are dental alveoli?
Tooth sockets
What type of radiograph would be used to view a supernumerary tooth?
Oblique occlusal
What should the X-ray beam be perpendicular to?
Object plane + image receptor
List some projection geometry issues (3)
- Image receptor + object not in contact
- Beam of X-rays not parallel
- X-ray beam might not be perpendicular to object plane and image receptor
List of some projection geometry solutions - Bisecting Angle Technique (3)
- Image receptor + object partly in contact but not parallel
- Image receptor + object close together at crowns but apart at apices
Explain the bisecting angle technique
Image receptor and tooth touch at crown but apart at apex
In the bisecting angle technique, what happens if the X-ray beam is at 90 degrees to long axis of the tooth?
Elongated image
In the bisecting angle technique, what happens if the X-ray beam is at 90 degrees to the plane of the image receptor
Short image (foreshortened)
If a pt has proclined incisors how must you adapt the vertical angle?
Increase it
If a pt has retroclined incisors how must you adapt the vertical angle?
Decrease it
What head position should the patient be in for an occlusal radiograph?
Sitting up
How are head positions for radiographs altered?
By degree of mouth opening
What position should the patients be in for a maxillary occlusal? (2)
MAXILLA:
- Ala-tragus line horizontal (parallel to floor)
- Upper teeth stable
What does ala-tragus line mean?
Ala - nose
Tragus - ear (in front of external auditory meatus)
What position should the patient be in for a mandibular occlusal? (3)
MANDIBLE:
- Corner of mouth-tragus line horizontal (parallel to floor)
- Teeth apart
- Head tilted back
How are storage phosphor plates used?
- Go in between upper and lower teeth
- Held in place by biting (can be damaged)
Why do storage phosphor plates have a plastic cover over them?
So the sensor itself doesn’t come into contact with saliva + protect from toothmarks
Oblique occlusal guideline vertical angle:
UPPER ANTERIOR
60 degrees
Oblique occlusal guideline vertical angle:
UPPER OCCLUSAL CENTRED ON CANINE
55 degrees
Oblique occlusal guideline vertical angle:
UPPER OCCLUSAL CENTRED ON PREMOLAR
50 degrees
Oblique occlusal guideline vertical angle:
UPPER OCCLUSAL CENTRED ON MOLAR
45 degrees
Oblique occlusal guideline vertical angle:
LOWER ANTERIOR OCCLUSAL
40 degrees to occlusal plane
Oblique occlusal guideline vertical angle:
LOWER OCCLUSAL CENTRED LATERALLY
35 to occlusal plane
What does the orientation of the image receptor depend on? (2)
- Size of mouth
2. Patient tolerance
Mandibular true occlusal indications (NOT used often) (4)
- Detection of submandibular duct calculi
- Assessment of bucco-lingual position of un-erupted teeth **
- Evaluation of pathological bunco-lingual expansion **
- Horizontal displacement of fractures **
** = can use CBCT
Why do we not use MAXILLARY true occlusals? (2)
- Can’t get X-ray source that close to maxilla
- Have to go through more dense boney structure
What is the term for when a molar and premolar are facing each other very closely?
Kissing teeth
What position should the patient be in for a mandibular true occlusal?
Head tipped as far back as comfortable
