Chapter 18 Bisecting Technique Radiology

what is the proper direction of the central ray in the bisecting technique

90 degrees to the imaginary bisector

significance of the shaded areas

It is the plane of the receptor

B

Long axis of the tooth

which beam alignment device is recommended for use with the bisecting technique because it aids in the alignment of the PID and reduces patient exposure

Rinn BAI instruments

film exposed to light appears

black

what condition is detected by the primary use of bite wing images

caries

A

central ray

unexposed receptor appears

clear

describe correct and incorrect horizontal angulation

correct: PID in side-side plane resulting in open contacts incorrect: results in overlapping (unopened contacts)

describe correct and incorrect vertical angulation

correct: PID in up-down plane, determined by the imaginary bisector resulting in dental image that is the same length as the tooth. incorrect: not same length of the tooth (ex. foreshortening- excessive vertical angulation)

an overexposed image appears

dark

too little vertical angulation results in images that are

elongated

errors that can occur with the bisecting technique

elongation, overlapped contacts, cone cut, phalangioma

primary use of the bite wing radiograph image

examination of the interproximal areas of the teeth

too much vertical angulation results in images that are

foreshortened

what type of movement is determined by the side to side movement of the PID

horizontal angulation

B

identify the correct vertical angulation

C

identify the vertical angulation that results in elongation

when does a cone cut result

if the beam is not centered over the film

C

imaginary bisector

an underexposed image appears

light

reversed film appears

light

what happens to the dental image when a short (8 in) PID is used?

magnification

how is the patients head positioned before exposing mandibular periapicals with the bisecting technique

mandibular: parallel to the floor midsagital: perpendicular to the floor

incorrect horizontal angulation results in images that are

overlapped

when the central ray of the xray is not directed through the contact areas of the teeth, what is seen on the resulting image

overlapped contacts

errors that can occur with the bitewing technique

overlapped contacts and cone cut

what does the term bite wing refer to

patient "bites" on a "wing" (tab) to stabilize film

D

plane of the receptor

advantages of the bisecting technique

shorter exposure time

what size receptor is reccomended for use with the bite wing techique in a pediatric patient with primary dentition

size 0

what size receptor is reccomended for the use with the bite wing technique in the adult patient

size 2

what size receptor is used with the bisecting technique

size 2

what size receptor is used to include all the posterior teeth in all one bite wing exposure

size 3

relationship of the receptor to maxillary and mandibular teeth in the bite wing technique

the receptor and teeth are parallel to each other

distance between the receptor and the tooth in bisecting technique

the receptor is placed as close as possible to the tooth

why is a 10+ degree vertical angulation is used with the bite wing technique and a bite tab

to compensate for the slight bend of the upper portion of the receptor and the slight tilt of maxillary teeth

do the disadvantages of the bisecting technique outweigh the advantages?

true

rule of isometry

two triangles are equal if they have two equal angles and share a common side

how is the patients head positioned before exposing a bite wing receptor

upper arch parallel to the floor midsagital plane perpendicular to the floor

what type of angulation is determined by the up and down movement of the PID

vertical angualtion

C

which angle is bisected correctly?

B

which central ray is correctly positioned perpendicular to the imaginary bisector

B

which position indicating device is aligned correctly

none

which vertical angulation results in foreshortening

correct vertical angulation used with the bite wing technique and the bite tab

+10 degrees

correct receptor placement

-anterior bite wings must be placed vertically -posterior bite wings may be placed horizontally -posterior bite wings may be placed vertically

correct about the exposure sequence for a CMRS that includes periapical and bite wing exposures

-anterior periapicals are always exposed first -posterior periapicals are exposed after anterior periapicals -bite wings are exposed last

modifications in bitewing that are used for patients with edentulous spaces or bony growths

-cotton roll is placed in the area of missing teeth -receptor must be placed between the tori and the tongue -with large tori the receptor is pushed away from the teeth

patient and equipment preparations that must be completed before using the bisecting technique

-infection control procedures -prepare treatment areas and supplies -seat patient -explain procedures -make chair and headrest procedures -place lead apron on -remove intaoral objects and glasses -set exposure factors -assemble beam alignment devices over a covered work area

exposure sequence for the 14 periapical placements using the bisecting technique

-max canine -max incisor -mand canine -mand incisor -max premolar -max molar -mand premolar -mand molar

how is the patients head positioned before exposing maxillary periapicals with the bisecting technique

-maxillary: parallel to the floor -midsagital: perpendicular to the floor

5 rules of the bisecting technique

-receptor must cover the the prescribed area of interest -receptor must be positioned with 1/8th of an inch extending beyond the incisal or occlusal surfaces -the central ray must be directed perpendicular to the imaginary bisector that divides the angle formed by the tooth and the receptor -central ray must be directed through the contact area between the teeth -xray beam must be centered over the receptor to ensure all areas of the receptor are exposed

basic rules of bitewing technique

-the receptor must cover the prescribed area of interest -the receptor must be positioned parallel to the crowns of max and mand teeth and stabilized by the tab or the beam alignment device -the vertical angulation must be angled at 10+ degrees for receptors using bite tabs -central ray must be directed through the contact areas between teeth for receptors using bite tabs -xray beam must be centered over the receptor to ensure all areas are exposed