Topics to be covered
 Dental
film definition and composition
 Intraoral film packet components
 Intraoral films classification
Dental film
Definition
It is an image receptor in the form of photographic
plate, that receives the incident x-ray and records
the image of dental structures.
X – Ray Films Composition
* X-ray film has 2 major components: Emulsion & Base .

Film emulsion = Silver halide grains suspended in a Vehicle Matrix
made of Gelatin and both are coated on a Plastic Film Base .
*Base
- Made of cellulose acetate
- SKELETON: supports the emulsion layer, and provide
strength
- It is blue, transparent?????
- It has high melting point, dimensionally stable and
photographically inert and inflammable ?????
*Sub-coating
Thin layer of adhesive material that ensure good
adhesion between emulsion and base.
*Emulsion
The sensitive component of the film to x-ray and light.
The film may be single or double coated.
Ag halide crystals (80-90% Ag bromide + 1-10% Ag
iodide) absorb and store energy from radiation exposure
Gelatin matrix provide homogencity and even dispersion
of the crystals.
Which Component of the X- ray Film is Responsible
for Image Formation ?
Silver Halide Grains
Ag Br X-ray Ag+ Br- (latent image)
P
(visible image)
*Super coat
Thin, non abrasive transparent coating for
protection. Made of gelatin
Classification of dental films
1-Intraoral: placed inside the patient’s
mouth (teeth & supporting structures)
2-Extraoral: placed outside the patient’s
mouth(skull&jaws)
Intraoral films
Intraoral
film packet
Identification dote
2 black papers
surrounds film;
protects emulsion
film
single or double;
raised dot in one corner
lead foil
protects film from backscatter;
reduces patient exposure;
strengthens packet
Classification of IO films
according to:
1- Uses
2-Sizes
3- Speed
4- Material of packet
5- Number of films in each packet
6- leaded or not
7- Cassetted or not
1- According to use



Periapical
Bitewing
Occlusal
1-Periapical film
The film is held in the proper position using the
thumb, or index finger, or else use a film holder
Indications
•Widely used technique
•Periapical involvement.
•Endodontics.
•Periodontal evaluation.
•Caries detection.
•Impaction and supernumerary
teeth.
•Cr and Br.
•Periodic check-up.
2-Bitewing Film
tab
Indications
•Interproximal Caries.
•Overhanging restorations.
•Crestal alveolar bone Involvement.
•Relation between deciduous & permanent teeth
•Pulp chamber.
3-Occlusal Film
Indications
•Identify large lesions
•bucco-lingual dimension.
•SG stones.
• fracture.
• trismus patients.
2- According to size
0: Children (PA & BW)
1: Adult anterior (PA)
2: Adult posterior (PA & BW);
also used for children occlusal (called standard
size)
3: Extra long (BW)
4: Occlusal
Pediatric occlusal
ANSI Classification:
American National Standard Institute
Classify intra-oral films according to type and size
By two digits separated by decimal point:
The 1st digit denotes the type.
The 2nd digit denotes the size.
1.2 : means Periapical size2
2.3 : means bite wing size 3
3.4 : means occlusal size 4
According to speed
What is the amount of radiation required to cause this latent
image and finally to give a radiographic image?
Radiographic Speed or
Sensitivity
Radiographic Speed is the amount of radiation
required to produce a radiographic image of
standard density.`
Radiographic speed is affected by:
•1-Crystal Size
-Br-Ag-Br
Ag+
-Br- Ag- Br- Ag- Br
Ag+
-Ag- Br- Ag- Br- Ag
Br-Ag-Br -Ag
Ag+
Radiographic speed is affected by:
1. Crystal Size
Large crystals require small amount of radiation, while smaller
ones require larger amount of radiation. Why?
Number of AgBr molecules which are responsible for the
density per unit area is greater with large crystals and so less
exposure is required. With small crystals, the number of AgBr
molecules responsible for the density per unit area is less and
has to be compensated by rising the exposure time.
In order to obtain Similar Densities on the final radiographs
using films with different crystal size, Exposure time should be
reduced with films made of large crystals & should be
increased with films made of small crytstals.
Radiographic speed is affected by:
Unfortunately,
As the Size of the crystals Increases the capability to record fine
Details and to give Sharp radiograph is Reduced.Why?
When the film is made of Small crystals, the Number of crystals
are increased, and so there are numerous numbers of crystals each
of which is responsible to record a single detail on the image =
Sharp Radiograph.
On the contrary, when the film is made of Large crystals, the
Number will be reduced, and so each crystal is responsible for
recording multiple details on the image = Less sharp Radiograph
Radiographic speed is affected by:
2. Emulsion Coat
Double –emulsion film, which is coated with an emulsion
on each side of the film base, are more sensitive to
radiation. Why?

With a double layer of emulsion, the number of Aghalide
molecules which are responsible for the density per unit
area is greater, and so less amount of radiation is
required to produce an image.
Radiographic speed is affected by:
Unfortunately,
Double coated films offer less image sharpness through
Parallax.

Because the x- ray beam is divergent and the film has
double emulsion coating, 2 images are recorded one on
each side of the film base with slightly greater
magnification on the side away from the x-ray source,
resulting in parallax unsharpness.

With single emulsion coating, more exposure is required
and more details are gained.
Parallax
Penumbra
4- Material of packet
• Plastic
• Cardboard
tight ,easily handled
leak saliva, easily cracked
5- Number of films in each packet
• Single
• Double (teaching, research purposes)
6- leaded or not
Films with lead backing: prevent back scattered
radiation so provide better sharpness
Films without lead backing: for speed processing
but image is usually fogged
7- Cassetted or not
• Films supplied in packets as IO films
• Occlusal films used with cassettes