Rad Final Flashcards
Bisecting technique is based on a simple geometric principle known as ?
What does it state?
Rule of isometry
States that 2 triangles are equal if they have 2 equal angles and share a common side
In the bisecting technique the film must be placed on the
Lingual surface of the tooth
Where the film ____ the tooth, the plane of the film and the long axis of the tooth form and angle. What should we do with this angle
Contacts
Bisect this angle
The central ray is directed _____ to the bisector so 2 imaginary _____ triangles are formed
Perpendicular; equal
What is the finger holding method
Patients finger or thumb is used to stabilize the periapical film
Disadvantages of the finger holding technique
Unnecessary radiation
Distorted images
Inadequate exposure of prescribed area
Max Incisors vertical angulation of PID
+40-50
Mand incisors PID angulation
-15-25
Max canines PID angulation
+45-55
Mand canines PID angulation
-20-30
Max premolars PID angulation
+30-40
Mand premolars PID angulation
-10-15
Max molars PID angulation
+20-30
Mand molars PID angulation
-5-0
Incorrect vertical angulation results in an image that is
Foreshortened or elongated
In foreshortening the PID is angled too
Steep; short image; excessive vertical angulation
If an image is elongated the PID is too
Flat; long image; insufficient vertical angulation
Incorrect horizontal angulation results in
An overlapped image
Advantages of bisecting technique
Can be used without film holding device
Exposure time is reduced
Disadvantages of bisecting technique
Image distortion
Angulation problems
If film holder not utilized clients hand is exposed in finger holding
Describe the proper direction of the central ray in the bisecting technique
Central ray is directed at an angle of 90 degrees to the imaginary bisector
Impacted teeth occur where
One tooth is prevented from erupting due to being wedged up against a neighbouring tooth
If a tooth is not breaking through the gum because of being under bone it is classified as
Embedded
Dental anomalies can result from a combination of
Intrinsic and extrinsic factors