Bisecting Technique

Question 1

Bisection of the angle

Answer 1

Receptor is no longer parallel to the teeth as in PT

Based on the theory of the equilateral triangle (two triangles have a common side, but are equal triangles)

Question 2

General rule of BAT

Answer 2

The CR is directed perpendicular to an imaginary line which bisects the long axis of the tooth and the receptor (angle bisector)

Question 3

Advantages of BAT

Answer 3

More comfortable

use of short cone- less radiation

Question 4

Disadvantages of BAT

Answer 4

More distortion

Difficult technique

Question 5

Placement of the receptor tube head

Answer 5

Place receptor so it is centered over the area of interest or specific tooth
Vertical placement of the receptor is approx 1/8-1/4” above or below the occlusal line

Question 6

Vertical angulation of tube head

Answer 6

Occlusal plane parallel to the floor
Angulations above occlusal= +
Angulations below occlusal= -
Angulation will vary w/ eat patient
If receptor holder is used, angulation will decrease

Question 7

Angulation errors in BAT

Answer 7

Too little V. angulation= elongation

Too much V. angulation= foreshortening

Question 8

Advantages of a bite block holder

Answer 8

Patients hand no exposed to radiation
When patient occludes on bite block, less of a chance of receptor movement

Vertical angulation decreases b/c there is less of an angle

Question 9

Disadvantages of bite block holder

Answer 9

W/ some patients it is difficult to position

Increase in discomfort

Question 10

What is the holder of choice for bisecting?

Answer 10

Snap-a-ray

Question 11

Snap-a-ray technique

Answer 11

Place receptor in holder
Have patient occlude LIGHTLY
Anterior- have pt. hold holder w/ slight pressure up or down)
Posterior- Patient occludes on bite block

Question 12

Minimum # of exposures in a FMS

Answer 12

14 to survey both arches
7max CCP=9max
7man CCP= 7man
Bite-wing should accompany PA (not included in 14)

Question 13

Positioning for cuspid shots

Answer 13

Place CR btw the contact point of the cuspid and 1st bicuspid to prevent overlapping
Alternatives- oblique receptor placement/cross arch receptor placement

Question 14

Oblique receptor placement reasons and positioning

Answer 14

Reason: difficulty placing receptor high enough due to low palate
Positioning: use diamond shape, positioning edge of receptor below the occlusal line not more than 1/8”

Question 15

Cross arch receptor placement reason/positioning

Answer 15

Reason: Arch too narrow for standard or oblique receptor placement
Positioning: Pace receptor on the occlusal surface of teeth in vertical alignment with cuspid
Angulation will increase

Question 16

Placement rules for occlusal expoures

Answer 16

For maxillary, occlusal plane parallel to floor
For mandibular, pt. is reclined
For topographical, rules of BAT followed

Question 17

Cross sectional exposures

Answer 17

CR is directed toward area of interest and perpendicular to receptor

Result= circular or eliptical appearance of teeth

Question 18

Steps for maxillary topographical

Answer 18

Anterior exposure of the maxillary arch

• max arch parallel to floor
• no.2 receptor or occlusal film in the mouth
• cone placed above the bridge of nose
• CR is directed in center
• Bisect the angle

Question 19

Steps for mandibular topographical

Answer 19

Anterior exposure of mandibular arch

• Plane of occlusion, head tilted 45 degree angle to plane of floor
• No. 2 receptor
• center of cone placed at the tip of patients chin
• bisect the angle

Question 20

Maxillary crossectional

Answer 20

• occlusal plane parallel to the floor

- CR perpendicular to film

Question 21

Mandibular crossectional

Answer 21

• Pt. is totally reclined
• No. 2 receptor or occlusal film
• cone placed 1” posterior to tip of chin
• tube head angled at 0 degrees, CR at right angle to receptor

Question 22

Indications for size 2 anterior occlusals in place of PA’s

Answer 22

to see unerupted toot position

Question 23

Indication for size 2, 4 crossectional exposures

Answer 23

Impacted or supernumerary teeth
Fractures
Foreign bodies
Cyst
Odontomas
Osteomyelitis 
Malignancies etc.

Question 24

Panorex

Answer 24

Excellent supplement

View of overall jaw development and development of permanent teeth

Question 25

What happens to the dental image when a short PID is used

Answer 25

Distortion will occur. Causes an increased divergence of x-rays resulting in image magnification

Question 26

Which size receptor is used with the bisecting technique?

Answer 26

Size 2

Question 27

How is the patient’s head positioned before exposing maxillary periapical images with the bisecting technique?

Answer 27

The maxillary arch is parallel to the floor And the sagittal is perpendicular to the floor

Question 28

How is the patient’s head position before exposing mandibular periapical image with the bisecting technique

Answer 28

Mandibular Arch is parallel to the floor

Question 29

What describes the proper direction of the central ray in the bisecting technique

Answer 29

90° to the imaginary bisector

Question 30

What describes the distance between the receptor and the tooth in the bisecting technique

Answer 30

The receptor is placed as close as possible to the tooth on the lingual surface

Question 31

What is the advantage of the bisecting technique

Answer 31

Shorter exposure time

Question 32

True or false. The disadvantages of the bisecting technique outweigh the advantages

Answer 32

True

Question 33

What is the rule of isometry

Answer 33

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

Question 34

Five rules for the bisecting technique

Answer 34

Receptor placement
Receptor position
Vertical angulation 
Horizontal angulation
Receptor exposure