R: Intra-oral radiographic technique 1

Question 1

Intraoral
radiography types

Answer 1

Question 2

Basic
principles of
intraoral
radiography

Answer 2

Question 3

Differences in
long axes of
maxillary and
mandibular
teeth

Answer 3

 Maxillary teeth inclined outward
 Mandibular teeth- anteriors are
inclined outwards; premolar are
vertical; molars are tilted inwards

Question 4

Apices of teeth

Answer 4

0.25 inches from the
inferior border of
mandible

Question 5

Planes

Answer 5

Question 6

Patient
positioning

Answer 6

Upright
 Chair raised so that patient’s mouth is at
your elbow level
 Occlusal plane parallel to f loor-maxilla vs
mandible
 Sagittal plane perpendicular to the f loor

Question 7

Bisecting angle
technique

Answer 7

Principle of Isometry
 States that 2 triangles are equal if they have 2
equal angles and a common side

Central ray of the x ray beam is
directed perpendicular to the
line bisecting the angle formed
by the long axis of the tooth and
the long axis of the film
 Image on the film same length as
the tooth

Question 8

Average vertical angulations*

Answer 8

Question 9

Advantages of
bisecting angle
technique vs. Disadv

Answer 9

Ad:
Positioning of the sensor/film reasonably
comfortable for the patient
- Positioning simple and quick( for
experienced users)
- Diagnostic images can be obtained if the
angulations are assessed correctly
- Can be used when certain factors prevent
use of paralleling technique

Disad:
Too many variables- technique
sensitive
- Cannot be reproduced
- Shadow of the zygomatic arch overlaps
the maxillary teeth
- Horizontal and vertical angulation
assessed for each patient

Question 10

Principles of
paralleling
technique

Answer 10

• Based on the concept of parallelism
• Rules of paralleling technique
• Long axis of tooth and long axis of film
  parallel
• Long source to film distance; short tooth
  to film distance
• Central beam perpendicular to the tooth
  and film

Question 11

Film/sensor
holders for
paralleling
technique adv/disadv

Answer 11

Note:  Dentsply-Rinn
 Aiming or locator ring
 Holding devices retain the film or sensor in proper position and guide placement of the tube/BID

Ad:Geometrically accurate images
 Vertical and horizontal angulations
automatically determined
 Reproducible images
 Relative position of the sensor/film, teeth
and tube always maintained irrespective of
head position-useful in patients with
disabilities

Disad:
Positioning of the film/sensor can be
uncomfortable for the patient [gagging,
lower third molars]
 Positioning of the holder in patient’s mouth
can be difficult for inexperienced users
 Anatomy can make this technique
impossible to use

Question 12

Bitewing
radiographs

Answer 12

Patient ‘bites’ on a small ‘wing’(tab)-
thus called bitewing
 Horizontal and vertical bitewings

 Detection of interproximal caries
 Evaluation of periodontal condition
 Assessment of existing restorations
 Detection of secondary caries
 Detection of calculus deposits
interproximally

Question 13

Bitewing
radiograph-
technique

Answer 13

Patient position-anatomic landmarks
 Angulation of the tube head
 Film holding instruments
 Film placement-horizontal/vertical
bitewings
 Quality assessment-what is acceptable
Patient upright
 Ala tragal line parallel to the f loor
 Mid sagittal plane 90°
 5-10° positive vertical angulation
 0° horizontal angulation
 central ray through the contacts of teeth
 Point of entry
 central ray directed through the occlusal
plane