Endodontic

radiograph

BY

AHMED LABIB

Definition It is the shadow

features produced by x-ray on radiographic film

radiograph is a two dimensional shadow of a three dimensional object.

Terms and definitions

Radiolucent:Objects that can not

absorb x-ray and appear black on the film.Such as pulp canal, carious lesion, foramen, maxillary sinus…etc..

Radiopaque:Objects that absorb x-ray and appear white on radiograph Such as enamel of the tooth, bone, gutta-percha, metal filling materials, post, and some pathological conditions…etc

Functions of radiograph:-1-Diagnosis:a-Identifying pathosis.b-Determining root pulpal anatomy.c-Characterizing normal structure.

2-Treatmenta-Determining the working length.b-Moving the superimposed structure.c-Locating the canal.d-Evaluating the obturation. 

3-Recall:a-Evaluating the healing.b-Identifying the presence of new pathosis.

Types of x-ray films:Extra oral films: such as Cephalomatric films, Panoramic films..etc.Intra oral films: such as periapical films, bite wing films, and occlusal films.-The periapical x-ray films are the most frequently used in endodontic therapy.

General rules for X-ray exposure:

Explain to the patient about the procedures being undertaken and Place the lead apron on the patient

Examine the patient’s mouth for any deviation from the normal which may require some adjustment of the standard radiographic technique .

Remove any object from the patient’s mouth as removable PD. or orthodontic appliances.

Set the exposure factors.

Set the approximate the X-ray tube angel.

Adjust the patient head in correctly positioned.

Place the film into the patient mouth properly according to the X-ray technique used.

Re-Check the position of the patient’s head.

The operator must stand behind a lead screen.

Remove the film from patient’s mouth after exposure and to prevent leakage, dry the film before processing.

Techniques of

periapical x-ray

exposure

a- long cone technique

or parallel cone

technique.

b-Bisecting angle technique

a-Long cone technique:-The dental films must be placed parallel to the long axis of the tooth to be examined. -The central ray will be directed at a right angle to the tooth and to the film this reproduces the correct tooth length and gives great sharpness of the image.

-Intra oral long cone radiography requires supplemental equipments such as film holders, which hold the film in a parallel position to the long axis of the tooth.

A) Long cone technique: -The dental films must be placed

parallel to the long axis of the tooth to be examined.

-The central ray will be directed at a right angle to the tooth and to the film.

-It requires film holders, which hold the film in a parallel position to the long

axis of the tooth.

Advantages:1-It gives true lateral projection of the tooth2-It results in minimal enlargement and less distortion3-Sharp image4-Demonstrate the true relationship between the alveolar crest and the tooth5-Reduce the importance of the horizontal positioning planes,since the film and x-ray beam are at right angle

Disadvantages:1-Difficult to be used in small mouths or patient with shallow flattened palate2-Difficult to be used with a rubber dam in place3-Apices lie below zygomatic arch are usually not seen on radiograph4-Film holder is required

Bisecting angle

technique

-The film is placed against the tooth as straight as possible-There is an angle between the x-ray film and long axis of the tooth.-The central x-ray beam is directed perpendicular to an imaginary line which bisects the angle between the plane of the film and the long axis of the tooth-Elongation is produced by too flat (obtuse) angulations-While the foreshortening is produced by too acute angulation

Landmarks for the direction of the central

ray 

A)MAXILLA

1-Upper central incisors: the cone of the tube touching at the center of the tip of the nose2-Upper central and lateral incisors: the cone of the tube touching the corresponding side of the tip of the nose3-Upper cuspid and first bicuspid: the cone of the tube touching directly on the ala of the nose4-Upper bicuspids and first molar: the cone of the tube touching an imaginary line passing from the ala of the nose to the tragus of the ear at a point directly below the pupil of the eye5-Upper second and third molars: the cone of the tube touching an imaginary line passing from the ala of the nose to the tragus of the ear at a point directly below the outer canthus of the eye and underneath the zygomatic bone

B)MANDIBLE1-Lower central incisors: the cone of the tube touching about an inch above the border of the mandible at a point between the two centrals2-Lower central and lateral incisors: the cone of the tube touching a point between the central and lateral incisors on the line previously described3-Lower cuspid and first bicuspid: the cone of the tube touching a point opposite the cuspid on the line previously described4-Lower bicuspids and first molar: the cone of the tube touching a point opposite the second bicuspid on the line previously described5-Lower second and third molars: the cone of the tube touching a point opposite the second molar on the line previously described 

Buccal object rule(changing horizontal

angulation)

Buccal Objective Rule: (Changing Horizontal Angulations)

Two dimensions view for three dimensional objective only in .

3rd dimension does not appear in the

radiographic film.

superimposition of root canals over each other .

-In bi-canalled root, root canals are oriented buccolingually-So exposing a radiograph with a zero horizontal angulation will lead to superimposition of the buccal canal over the lingual canal on the film so only the buccal canal will appear-To avoid such problem and makes both the buccal and lingual canals appears in the same radiographic film, we applied the buccal objective rule, which stated that: When the x-ray cone is directed mesially, the canal farthest from the cone (lingual canal) comes mesially on the film, and the buccal (the nearest canal to the cone) directed distally on the same film (MLM role)

-By other meaning we can apply what is called SLOB (same lingual opposite buccal) this means that the lingual canal goes to the same direction of the x-ray cone and the buccal canal go to the opposite direction, i.e if the x-ray cone directed mesially, the lingual root canal would appear in the developed x-ray film dircted to the mesial side (same lingual) and the buccal root canal would be directed to the distal side(opposite buccal)

0 h ang.

M Shift

D Shift

B

L

S.L.O.B.

20⁰

20⁰

Hazards of x-rays:1-Dermatitis2-Alopecioa (loss of hair)3-Increased production of white blood cells(leukocytosis)4-Leukemia5-Anemia6-Feeling of loss of attitude7-Sterility8-Abortion

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