Dental Radiology - Paralleling and Bisecting (2) Flashcards
the bisecting technique requires film to be placed
against the lingua surface of the tooth and 1/8 inch above incisal/occlusal edge
what is the rule of isometry
two triangles are equal if they have 2 equal angles and share a common side
the long axis of the tooth is the
line going straight through the tooth
the imaginary bisector is the line that
bisects the triangle, between film and long axis of the tooth
what forms the angle contacting the tooth
imaginary bisector, long axis of tooth and point of receptor
how is the central beam directed when using bisecting technique
its directed so its perpendicular with the imaginary bisector
what size receptor is used for all periodicals in bisecting
size 2
phalangioma
image of a finger is present in radiograph
is the finger holding method recommended
no, risk of unnecessary radiation exposure (alara)
what alignment devices can be used when bisecting
rinn bite block, disposable bite block, snap a ray
what are the two types of PID angulations
horizontal (side to side) and Vertical (up and down)
is horizontal angulation different depending on technique used?
no
how is the central ray directed for horizontal angulation
through the inter proximal contact areas
the tube head facing receptor head on is for ___ angulation
horizontal
what happens if HA is not correctly positioned
overlapping, blurred enamel, pulp cavity isn’t clear
vertical angulation is the positioning of
PID in a vertical (up and down) angles
when paralleling, vertical angulation puts the central ray perpendicular to the
receptor and long axis
when bisecting, vertical angulation puts the central ray perpendicular to the
imaginary bisector
VA of maxilla positions PID above the occlusal and central ray is directed ___
downward toward mandible
maxilla VA is a ___ angle
positive
Mandibular VA is a ___ angle
negative
VA of the mandible positions the PID below the occlusal and the central ray is directed ___
upward to chin
maxillary canine PA’s would be taken at a angle of
+45 - +55
mandibular canine PAs would be taken at an angle of
-20 > -30
a PA taken at a +40-50 angle would be of which tooth
maxillary incisors
-15 > -25 angle would be for a
mandibular incisor
maxillary molars PA are taken at a ___ angle
+20 - +30 angle
+30 - +40 angle would be for a
maxillary premolar PA
0 > -5 angle is for __ molars
mandibular
what is a foreshortened image
a radiograph taken at to high of an angle, causing teeth to look short
what is a elongated image
a radiograph taken at a low (flat) angle causing teeth to look longer
angulations only apply to which type of film
Periapical bisecting
vertical angulation is
central ray perpendicular to the imaginary bisector creating a right angle
horizontal angulation is
central ray directed in between contact areas
what is the exposure sequence of bisecting
anteriors then posteriors
posterior exposure sequence of bisecting
maxillary right and mandibular right first, (start with premolars then move to molars) repeat on left side
which technique is preferred if possible
paralleling
bitewing using bisecting technique is completed by
placing receptor parallel to upper and lower teeth, stabilized by Pt bite. PID is placed with a +8-10 angulation
why is there an +8 -10 angulation on a bisecting bitewing
due to the curve of spee
is it possible to get all open contacts on one bitewing film
no
how many total BWs are needed for a mouth
4, 2 on each side
the receptor is placed ___ for a bitewing
horizontally
Molar view BW shows
all molars, and the distal of 2nd premolar
Premolar view BW shows
premolars, and the distal of first molar and canine
what size receptor would you use on a child BW with primary dentition
0
size 1 receptors are used for BW on
children with mixed dentition
what size receptor is used on all adult BW
size 2
what is a full mouth series
14-20 images showing all tooth bearing areas
what would a FMS on a edentulous patient consist of
PA’s only
BW and PA’s make up a
full mouth series
Paralleling technique is used to
expose accurate and reliable PA and BW image receptor
parallel means
seperated by same distance and never intercept
perpendicular is
intersecting to form or at a right angle
long axis of tooth
to divide a tooth in equal halves
central ray is the
central portion of primary beam
bisect
to divide into two equal parts
how is a paralleling receptor placed
parallel to long axis and receptor, central beam perpendicular to contact areas
what differs paralleling from bisecting
the use of beam alignment devices
for anterior exposure, if you use a size 1 film how many placements are needed
7-8, 4 max - 3 or 4 mand
for anterior exposure with size two films how many placements needed
6, 3 max and 3 mand
what is the recommended anterior sequence for both paralleling and bisecting
start at 1.3 (max right) and go to 3.3 (max left), then move down to 3.3(mand left) over to end at 4.3 (mand right)
posterior exposure sequence for paralleling is
start at quad 1 (max right) premolars, then molars. Move down to quad 3 (mand left) premolars > molars, Reassemble RINN, move to quad 2 (max left) premolars>molars, down to finish in quad 4 (mand right) premolars then molars.
the posterior exposure sequence in paralleling mimics the shape of an
X
size 1 film for paralleling is used for anteriors and is placed
vertically
Size 2 film is placed horizontally for paralleling and is used for
posteriors
What is a blue RINN device used for
anterior PAs
what is a yellow RINN device used for
posterior PA’s
Red RINN devices are only used for
bitewings
Yellow RINN’s for max right (Q1) and Mand left (Q3) are shaped with the
elbow on the right and pins on the left
Yellow RINN’s for max left (Q2) and mand right (Q4) are shaped with the
elbow on the left and pins on the right
can the tongue be in-between receptor and teeth for paralleling
yes
what are the 2 most likely spaces in the mouth to trigger gag reflux
the soft palate and posterior third of tongue
the white side of film is always facing towards the
tubehead
