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
Variation in anomalies can occur
Congenital (at or before birth)
Hereditary (by genetic makeup)
A congenital anomaly is sometimes the result of hereditary and may not show up until?
Years after birth
Familial tendency
When an anomaly occurs more frequently than usual in one family
Developmental anomaly
When the condition results during the formation and development of a dental structure
Most commonly supernumerary tooth is
Mesiodens (midline of maxillae) tooth erupting between max centrals
1st most common congenitally missing teeth
Maxillary third molars
(2nd most common max lateral incisors)
If primary teeth are congenitally missing, will permanent replacements also be missing?
Yes
What are the most common twinning abnormalities, both demonstrating enlarged crowns
Fusion and gemination
Which teeth are most commonly affected by dens in dente
Maxillary lateral incisors
Dilaceration refers to distortion in root or crown of angle rage ____? Most common in?
45-90
Mandibular third molars
Genination
Double fused teeth; one bud but 2 crowns
*single root, common pulp, notched incisally
Bifid tooth/bifurcated crown
A tooth split into 2 crowns with one root
Twinning
Occurs when a single tooth germ splits forming 2 almost identical teeth but remaining fused as one
Fusion of tooth germs involves ONLY
Dentin
Fusion or growing together of two teeth at the root ONLY VIA CEMENTUM
Concresence
First appears as radiololucent area and later radiopaque as it becomes mineralized
Hypercementosis
Generalized cementum deposition is a feature of a condition known as ____ of bone
Pagets disease
Enamel pearls are found
On distal 3rd molars and buccal root furcation of molars. Not found on single rooted teeth
Enamel hypoplasia inhibits
Enamel formation
Enamel hypocalcification is caused by a condition that inhibits the calcification of enamel. What are the most common forms
Enamel fluorosis
Turners tooth
Anelogenesis imperfecta
Turners tooth is most common on
Maxillary incisor
Amelogenesis imperfecta is characterized by
Thin enamel stained various shades of yellow and brown and easily fractures away
What is the most unique feature of dentinogenesis imperfecta
Pulp chambers and root canal are usually completely filled in with dentin
Most common malformed anterior tooth is
Maxillary lateral incisor (peg shaped)
The most common tooth with cusp variations
Mandibular second premolars
The most common tooth with accessory cusps or tubercles
Maxillary molars
Maxillary first premolars
Usually have 2 roots but 40% have 1 root
DICOM data
Universal format for handling storing and transmitting 3d images
Cone beam computed tomography (CBCT)
Term used to describe computer assisted digital imagine in dentistry