Century international institute of dental science & research center

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Century international institute of dental science & research center

Department Of Oral Medicine & Radiology





Shabhana . B

IV th BDS, Part 1.

  1. Introduction

  1. Indications

  1. Localization Technique

  1. Tube Shift Technique

  1. Right Angle Technique

  1. Stereoscopy

  1. Radiographic Technique for Localization of Impacted Teeth & Foreign Bodies

  1. Conclusion

  1. Bibliography


  • These are methods to locate the position of a tooth or an object in the jaws.

  • The dental radiograph is a two dimensional picture of a three dimensional object, it depicts the object in the superior – inferior and antero posterior relationship.

  • It fails to depict buccolingual relation or depth of the object.

  • Localization is used to overcome this lacune.


  • Foreign bodies

  • Impacted Teeth

  • Unerupted Teeth

  • Retained Roots

  • Salivary Stones

  • Jaw Fractures

  • Broken needles and instruments

  • Root positions

  • Filling Materials

Localization Techniques

  1. Tube shift technique [Buccal object rule or clarks rule]

  2. Right angle technique

  3. Stereoscopy

Tube shift technique

    • Buccal object rule or clarks rule

    • The basic principle is that relative position of the radiographic images of two separate objects changes when the projection angle at which the project was made is changed.

    • Different horizontal angle used when trying to locate vertically aligned images. Example: Root Canals.

    • Different vertical angle is used trying to locate a horizontally aligned images. Example: Mandibular Canal.


  • Two radiographs of the object taken.

  • First radiograph with proper technique and angulation as prescribed.

  • Second radiograph is with changing the direction of the central ray either with a different horizontal or vertical angulation and keeping all other parameter equivalent to the first radiograph.


  • If the dental structure seen in the second radiograph appears to have moved in same direction as the shift of PID, the object in question is said to be positioned lingually.

  • If the object appears to have moved in a direction opposite to the shift of PID, then object in question is said to be positioned buccally.


Right Angle Technique

  • Here two projections are taken at right angles to each other which helps to localize an object in the maxilla or mandible.


  • A periapical radiograph is taken to show the position of the object superior-inferiorly and anterio posteriorly.

  • Next occlusal radiograph is taken, which will show the object’s buccolingual and anterio posterior relationship.

  • Two radiographs when studied together, helps to localize the objects in all three dimension.


  • It is used to determine the location of small intracranial calcification and multiple foreign bodies in dense or thick section.

  • Also used in cases in which the interpretation of images produced at right angle might be difficult.

  • Evaluate the relationship of margins of bony fractures.

  • Stereoscopic imaging requires the exposure of two films, one for each eye and thus deliver twice amount of radiation to patient.

  • Between exposure, patient is maintained in position, film is changed, the tube is shifted from right eye to left eye position.

  • After processing, the film are viewed with a stereoscope that uses either mirrors or prisms to coordinate the accommodation and convergence of the viewers eye, so that brain can fuse the two images.

  • This technique is popular for the evaluation of bony pockets in patient with periodontal diseases.

  • For morphology of temperomandibular joint area.

  • Determination of root configuration of the teeth that require endodontic therapy.

  • Assessment of the relationship of the mandibular canal to the root of the unerupted mandibular third molars.

  • Assessment of bone shape when the placement of dental implant is considered.

Radiographic Techniques For Localization Of Impacted Teeth & Foreign Bodies

Maxillary Area

  1. Incisor Zone

  1. Cuspid Zone

    • Stereoscopic

    • Lateral profile

    • Occlusal

  2. Bicuspid & Molar Zone

    • Periapical

    • Occlusal

Mandibular Area

  1. Incisor Zone

    • Periapical

    • Lateral profile

    • Occlusal

  2. Posterior Zone

    • Occlusal

    • Periapical

  3. Third Molar Zone

    • Periapical

    • Lateral Oblique

    • Oblique Occlusal


  • In clinical practice, the dentist must often derive from a radiograph three dimensional information concerning patients.

  • This two methods, right angle technique and tooth shift technique are frequently used to obtain such three dimensional information.

  • The dentist may wish to use radiograph to determine the location of a foreign object or an impacted tooth within jaw.


  • Dental & Maxillo Facial Radiology (2nd Edition)

Chapter Number, Page Number.

By Freny R Karjodkar

  • Oral Radiology Principles & Intrepretation (6th Edition)

Chapter Number, Page Number

By Stuart C White, Michael J Pharoah

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