LECTURE 3: FACIAL LANDMARKS Flashcards
making of radiographs of teeth and adjacent structures by the exposure of films to x-rays
DENTAL RADIOGRAPHY
picture on a film produced by the passage of x-rays through an object
RADIOGRAPH
STANDARD RADIOGRAPHIC PROCEDURES
→ area to be radiographed
→ film
→ x-ray beam
In STANDARD RADIOGRAPHIC PROCEDURES, All of these must be in proper relationship to create an accurate radiographic image sometimes called the ________
diagnostic image
imaginary beam of x-rays traveling directly through the center of the cone
CENTRAL BEAM OF RADIATION (CR)
used as a reference point when discussing the orientation of the x-ray beam, object, and film
CENTRAL BEAM OF RADIATION (CR)
very much used in periapical radiography (an intraoral technique used to take images of the tooth up to its surrounding periapical area)
FACIAL LANDMARKS IN ORAL RADIOGRAPHY
areas on the face that provide the radiographer with a quick reference in positioning the PID (directing of the central beam of the radiation)
FACIAL LANDMARKS IN ORAL RADIOGRAPHY
maxillary and mandibular molars
Outer Canthus of the Eye
maxillary and mandibular premolars
Inner Canthus (Pupil) of the Eye
maxillary and mandibular canines
Ala of the Nose
maxillary incisors
Tip of the Nose
mandibular incisors
Chin
The central beam (center of the cone) is directed at the level of beam
these:
→ ala tragus line for maxillary teeth
→ 1⁄2 inch from the lower border of the mandible for mandibular
teeth
direction or alignment of the central beam in a horizontal and vertical plane
CENTRAL RAY ANGULATION
tubehead and the PID are aligned to obtain the optimum angle at which the radiation is to be directed toward the film
CENTRAL RAY ANGULATION
In CENTRAL RAY ANGULATION there are (2) projections or angulations of the tubehead:
o vertical angulation
o horizontal angulation
(for successful exposure techniques, both angulations must be considered)
considered first
VERTICAL ANGULATION
positioning of the PID in an up and down plane in order to
direct the central rays of the x-ray perpendicular to the film
VERTICAL ANGULATION
controls the longitudinal dimensions of the resulting image
VERTICAL ANGULATION
measured in degrees that is found on the number scale
VERTICAL ANGULATION
begins at 0 degrees; scaled at 5 degrees
VERTICAL ANGULATION
TYPES OF VERTICAL ANGULATION
Zero
Positive
Negative
angulation when the PID and central rays are parallel to the floor or the occlusal plane
Zero
usually for mandibular molars
Zero
maxillary teeth
Positive
angulation above the occlusal plane from 0
degrees in which the tip of the PID is tilted downwards
Positive
angulation below the occlusal plane from 0 degrees in which the tip of the PID is tilted upwards
Negative
mandibular teeth
Negative
PROBLEMS OF INCORRECT VERTICAL ANGULATION
FORESHORTENING
ELONGATION
occurs if the vertical angulation is larger or greater than necessary
FORESHORTENING
image of the teeth appears smaller than normal
FORESHORTENING
occurs if the vertical angulation is less than necessary or inadequate
ELONGATION
image of the teeth appears larger/longer than normal
ELONGATION
→ side to side or horizontal movement of the tubehead or x-ray beam
→ positioning of the tubehead on a horizontal or side to side plane
HORIZONTAL ANGULATION
remains the same whether paralleling or bisecting angle technique is used
o there is no number value
HORIZONTAL ANGULATION
to direct the central rays of the x-ray beam perpendicular toward the surface toward the film surface and through the interproximal surfaces of the teeth
HORIZONTAL ANGULATION
correct horizontal angulation:
o open contact areas (radiolucent)
o x-ray beam was able to go perpendicular to the surface
and beam is able to reach the film through these contact areas
incorrect horizontal angulation
o overlapping (radiopaque)
o unless in cases of crowding of the teeth
True or false
Correct horizontal and vertical angulation of the x-ray beam is necessary to obtain radiographs of diagnostic quality.
True
incisors centered on?
midline
cuspid centered on ?
cuspid
premolar centered on?
second premolar
molar centered on
second molar
anterior films are positioned ?
vertically
posterior films are positioned
horizontally
(1) Seat the patient upright
(2) Adjust the patient’s head
(3) Place film properly
(4) Adjust the tip of the PID (distance)
(5) Determine vertical angulation
(6) Determine horizontal angulation
(7) Center beam on film; expose the film
GENERAL PROCEDURE TO DETERMINE VERTICAL and HORIZONTAL ANGULATIONS
