Orthopantomography a dental radiographic technique

1. PANORAMIC
RADIOGRAPHY

2. Pantomograph 1951

3. Pantomography
Rotational radiography

4. History
– Dr. H. Numata (1933)
– Dr. Y.V. Paatero (1946)

5. OPG
• Ortho - straight
• Panoramic - An obstructed or a
complete view of the object in every
direction
• Tomography – An exray technique for
making radiographs of layers of tissue
in depth, without the interference of
tissue above and below that level

6. Single image of facial structures that
includes maxillary
and mandibular arches
and their supporting
structures.

7. Advantages…
• Broad anatomic coverage
• Low patient radiation dose
• Convenience of examination
• Used in patients unable to open mouth

8. Panoramic X-ray procedure
• requires less time
• causes no discomfort
• is radiation hygienic
• is painless and non-traumatic

9. • Panoramic x-rays use
film/screen imaging
systems which require
82% less radiation than
an FMX
• Studies vary, but most
agree that the newest
panoramic x-rays
machines will produce a
film with the same
radiation as one to two
periapicals

10. • It is difficult for a
patient to
understand 16 to 22
different pictures of
their teeth
• A panoramic film
can be easily
understood and
helps to explain the
diagnosis and
treatment plan to
the patient

11. • The median time
required for X-ray
examination
– Intraoral full mouth
series 20 min
– two bitewings 5 min.
– panoramic: 3 min
• Some patients cannot
tolerate intra oral films: a
gagger or an
apprehensive patient.
• Quicker diagnostics for
an emergency patient.

12. Disadvantages
• Does not show fine anatomic
details
• Magnification
• Distortion
• Overlapped image of teeth
• Expensive

13. Indications
• Evaluation of trauma
• Third molars
• Large lesions
• Tooth development
• Developmental anomalies
• Intolerant to intraoral procedures

14. OPG IS A
SCREENING
RADIOGRAPH

18. Ext.
Auditory
meatus
Mandibular
condyle
Articular eminence
Coronoid
process
Zygomatic
bone
Ptregomaxillary Fissure
Inf. orbital rimFloor of Maxillary sinus
Ant. wall of Maxillary sinus
Hard palate
Nasal fossa
Inf. Orbital canal and foramen
Zyg.
process
of
Maxilla
Panoramic Innominate line
(Infra temporal surface of
Zyg. bone
Lat.
ptreg.
plate
Man. fossa
Inf. border of Mandible
C- Spine
Mental foramen
Hyoid bone Inf. Alveolar canalExt. oblique ridge
All this diagnostic information is missed in intraoral X-rays
Hard Tissue

19. Inf. nasal concha (turbinate)
Inf. nasal meatus
Dorsal surface of the tongue
Post. Wall of the pharynx
Soft palate
Lower lip
Upper
lip
Middle meatus
Ghost image of opposite Man.
Soft tissue (edentulous)
All this diagnostic information is missed in intraoral X-rays

20. Factors for interpretation
• Principles of image formation
• Techniques of patient positioning
• Radiographic appearance of
normal anatomic structures.

21. Primary slot
Aluminium filter
Secondary slot
Filament
Focal spot
mAkV
Anode (+) Cathode (-)
Radiation beam

22. Principles of Image formation
Film
Object
Source

23. Principle
• X ray source is rotated, so the central
ray constantly passes through the
centre of rotation of disc 1.
• Both disc 2 and the film collimator
rotate about the centre of disc 1.
• While disc 2 moves, film on this disc
rotates past the slit.

24. Rotating
X-ray source
Rotating and
moving receptor
Image layer
(focal trough)
Moving X-ray
beam

26. Focal trough
• Focal trough is a three dimensional
image layer in which structures are
reasonably well defined on panoramic
radiograph.

27. Focal troughFocal trough

28. Patient positioning
• Removal of all metallic objects
• Demonstrate the machine
• Draped with leaded apron
• Dental arches located in focal trough
• Midline positioning
• Chin placed in the chin rest
• Back and spine erect.