intraoral projection Flashcards
BID-beam indicating device
collimates and directs X-ray beam (cone) (can also be rectangle)
Central ray of x ray beam
define position of beam vertically and horizontally
vertical angulation
movement of BID up or down in relation to occlusal plane
horizontal angulation
movement of BID around patients head in relation to sagittal plane
positive vs negative vertical angulation
positive=beam pointing down
negative=beam pointing up
most accurate vertical angulation
BW’s
what do bite wings eval?
- bone height
- interprox lesions
- depth of rest/caries
- assessment of rest margins
FMX
20 radiographs
PA’s on top and bottom
BW in middle
rules for PA
must show the entire crown and roots
2 mm beyond root apices
rules for BW
equal distribution of both arches
rules for canine
- canine must be centered in image
- 2 mm of apical bone visible above the root apex
- lateral canine contact open
head position for occlusal plane of teeth radiograph
parallel to floor
sagittal plane radiograph head position?
perpendicular to floor
paralleling technique
most anatomically accurate
-extension cone, right angle, long cone
bisecting angle
inherit distortion
pt managment
2 fundamental principles of paralleling technique
- image receptor is positioned parallel to long axes of teeth
- central ray of x ray beam is directed perpendicular to teeth and image receptor
to obtain a parallel relationship bw teeth and image in maxillary teeth?
incisal edges/buccal cusps engage biteblock in first or second groove (outer edge of bite block)
-receptor in center of oral cavity
in order to achieve parallelism between image receptor and teeth, the OBJECT RECEPTOR DISTANCE will have to be increased in the _______
maxillary arch (tooth placement in first or second groove)
PA anterior instrument
straight ring
-anterior arm most bent
PA posterior instrument
offset sing
horizontal block
ring bitewing instrument
straight ring
no bends
looks like airplane
to achieve parallel relationship bw teeth and image receptor in mandibular teeth—
incisal edges or buccal cusps should engage MIDDLE of biteblock
correct horizontal angulation
image receptor placed parallel to lingual surfaces and beam should be directed thru contacts of teeth and perpendicular to image receptor
correct horizontal angulation–
open contacts
correct vertical angulation
results in radiographic image that is close to same length as the tooth
incorrect vertical angulation
results in a radiographic image that is not the same length as the tooth
- foreshortening
- elongation
foreshortened image
excessive vertical angulation
elongated image
insufficient vertical angulation
cotton rolls are never used with —
bitewing technique
never place a cotton roll where?
on same side as plate
make sure image receptor is centered within ?
the ring
cone cut
when the central ray is not directed through the center of the region being radiographed
advantages of paralleling technique?
- accuracy (reduces distortion)
- simplicity (eliminates need to determine horizontal and vertical angulation)
- duplication (comparison of serial radiographs has validity)
disadvantages of paralleling technique
- image receptor placement may be difficult
- discomfort
typical results of paralleling tech
- no anatomic structures projected over roots
- roots approx same length
- cusp tips same height
- alveolar crest below CEJ
foreshortened image
- elongated palatal root
- foreshortened buccal roots
- alveolar crest not below CEJ
- cusp tips not superimposed
- zygomatic process and zygomatic bone projected over roots
elongated image
- roots stretched off the image
- crowns moved up in image
- biteblock and alignment rod moved up in image
bisecting angle technique
- plate must be placed along lingual
- plane of plate and long axis form an angle at the point where plate contacts tooth
- imaginary line bisects the angle formed by plate and long axis of tooth
- central ray directed perpendicular to imaginary bisector
advantages and disadvantages of bisecting tech
- helpful for gagging, small, shallow floor, large tongues
- image distortion
what is ideal for patients with moderate to severe bone loss?
vertical bitewing
vertical bitewing series
seven plates used to cover midline, canine, premolar, and molar areas
bitewing plate holder
device used to position an intraoral plate in the mouth
bitewing tab
heavy paperboard tab or loop fitted around an image receptor to stabilize it during exposure
bitewing tech with tabs
- x ray beam is angled positively at 6-8 degrees
- center BID directly over image receptor
diagnostic criteria for all intraoral radiographs
- density, contrast, definition, detail
- least amount of distortion
- FMX must include all tooth-bearing areas
- PA–entire crowns and teeth+2mm
- open contacts
types of image receptor holders
styrofoam
EEZEE-grip
endoray
unibite
