Quiz 3 Flashcards
Theory rule
The central ray is directed perpendicular to an imaginary line which bisects the long axis of the tooth and the film
Bisection of the angle technique (BAT)
Based on the theory of the equilateral triangle (2 triangles have a common side and 2 equal angles are equal triangles)
In the room:
Opening of cone parallel to bisector
Bisecting line (imaginary line):
Forms a right angle with the central rays
Vertical angulation governed by:
Cone
Film is placed:
Centered over the area of interest or a specific tooth
Vertical placement of film is approx. 3mm (1/4 inch) above or below occlusal line
Vertical angulation
1) is the up and down angulation of the cone tip
2) vertical angulation is a deviation from a line parallel to the floor
Occlusal plane should be ______ to the floor
Parallel
Ala/tragus line also called:
Frankford plane
Ala/tragus line _____ to the floor?
Parallel
If a film holder is used vertical angulation will….
Decrease because tooth and film are more parallel to each other
Horizontal angulation rule
Make sure that the central rays pass through the teeth parallel to the proximal surface
Bite wing front and back
Cone 1/4 anterior to film
Bite wing top and bottom
Middle of cone at occlusal plane
PA front and back
Cone 1/4 anterior to the film
PA top and bottom
Cone 1/4 above (for mandible) or below (for maxilla) the occlusal plane
Minimum # of films in a FMS?
14 to survey both arches 7 max and 7 man —-> CCP 9 max and 7 man
Bite wings should accompany PA films
Cuspid horizontal angulation revision:
Between the contact point of the cuspid and 1st bicuspid to prevent overlapping
Alternate placements of cuspid
Oblique film placement
Cross arch film placement
Oblique film placement
Reason: due to low palate may have difficulty in placing the film high enough in the palate to record apices
Positioning: use diamond shaped positioning; edge of the film below the occlusal line more than 1/8 inch
Cross arch film placement
Reason: if arch is too narrow for standard or oblique film placement
Placement: place the film on occlusal surfaces of the teeth in vertical alignment with the cuspid
Vertical angulation will increase
Advantages of bite block holder:
Patient hand and finger not exposed to radiation
When patient occludes on bite block less of a chance of film moving
Disadvantages
With some pt it is difficult to position
Increase discomfort
Occlusal exposures
Replaces PA in anterior
Maxillary topographical
Anterior exposure of the maxillary arch
Max. topographical steps:
Max arch parallel to floor No 2 film in the mouth or occlusal film placed horizontally White side up Instruct pt to close Cone placed approx. above the bridge of the nose CR is directed in the center Vertical angulation bisects the angle CR is at a right angle to the film
Mandibular topographical
Anterior exposure of the mandibular arch
Mandibular topographical steps
Plane of occlusion at 45 degree angle to floor (so radiation doesn’t hit their lap)
White side down on ant edge
Center of cone is placed at the tip of pt chin
-45 vertical angulation bisect the angle
Cross sectional maxillary
Occlusal plane parallel to the floor, CR perpendicular to film
Cross sectional exposure of mandibular arch
Pt is totally reclined
Occlusal film, white side down as far posterior as possible
Close
Cone places 1 inch posterior to too of the chin
Tube head angled at 0 degrees, CR at right angle to film
Panorex views
Overall jaw development
Development of permanent teeth
Endodontic exam:
Uses hemostat
Rinn snap a ray
Tongue depressor
Occlusal indication
Anterior occlusal in place of PA to see unerupted tooth position
Cross section exposures
Impacted or supernumerary teeth Fractures Foreign bodies Cyst Odontomas- tumors Osteomyelitis-bone inflammation Malignancies Size and shape of dental arch Presence of stones Tori Healing of cleft palate surgery Retained roots Unerupted teeth Foreign particles
