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Radiographs performs essential functions in three areas:
- 1.Diagnosis.
- –Identifying pathosis.
- –Determining root and pulpal anatomy.
- –Characterizing normal structures.
- 2.Treatment.
- –Determining working length.
- –Moving superimposed structures.
- –Locating canals.
- –Differentiating canals and PDL spaces.
- –Evaluating obturation.
- 3.Post operative evaluation or follow-up.
- –Identifying new pathosis.
- –Evaluating healing.
- –Evaluating final restoration.
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RADIOGRAPHIC SEQUENCE
- 1.Pre-op or diagnostic radiograph (s).
- 2.Working length radiograph (s).
- 3.Master cone radiograph (s).
- 4.Lateral condensation radiograph (s).
- 5.Final radiograph (s).
- Rubber dam isolation in place through 2-4.
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Pre-op or diagnostic radiograph (s).
- Primarily to detect pathosis and to provide general information on root and pulp anatomy.
- In most cases only a single PA is necessary, but the number of exposures depends on the situation.
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Paralleling technique:
- Less distortion and clearer images.
- Reproducibility.
- If can not be used, bisecting angle technique is the second choice (more dimensional distortion).
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Cone-image shift technique
- separates and identifies the facial and lingual structures
- SLOB rule: Same-Lingual, Opposite-Buccal
- Indications:
- –Separation and identification of superimposed canals : working length, presence of perforation, or external resorption, identification of undiscovered canals.
- –Movement and identification of superimposed structures
- Disadvantages:
- –Decreased clarity
- –Superimposition of structures
- Buccal rule: the root canal farthest from the x-ray film moves a greater distance on the film in a horizontal plane than the root or canal closer to the film.
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Working length radiograph (s).
- In general require only a single exposure.
- If a root contains two superimposed canals, either a mesial or distal angled projection is absolutely necessary.
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Master cone radiograph (s).
The same principles used with working length films apply.
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Lateral condensation radiograph (s).
If there is doubt about the accuracy of the lateral condensation. Errors in length or density can be corrected at this stage.
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Final radiograph (s).
- 1 PA with parallel projection.
- The endodontically treated tooth should be temporized and rubber dam isolation removed.
- Teeth with multiple canals need angle projections to visualize separate superimposed canals for separate evaluation of each.
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Post operative evaluation or follow-up.
- PA exposure with paralleling technique.
- If treatment is deemed to be questionable or a failure, additional angled exposures -> search for a previously undetected canal or other abnormality.
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Interpretation:
- radiographs can be termed the great pretenders; they often are misleading as they are helpful.
- Only hard tissues are visible: periapical bony changes, possible etiologic factors, possible internal or external resorption, and or root canal anatomy
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ENDODONTIC RADIOGRAPHIC ANATOMY - Limitations:
- Radiographic evidence of bony lesions happens after considerable bone resorption.
- Root location and thickness of the overlying cortical bone might influence the presence of radiolucent areas.
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DIFFERENTIAL DIAGNOSIS
- Endodontic pathosis:
- –Radiolucent lesions
- –Radiopaque lesions
- Non-endodontic pathosis
- –Radiolucent lesions
- –Radiopaque lesions
- Anatomic structures
- –Mandible
- –Maxilla
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differentiation/ Endodontic Dx. =
Clinical (pulp) evaluation + radiographic evaluation
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Endodontic pathosis:
- Radiolucent lesions: apical/radicular lamina dura is absent (resorbed).
- Circumferential (ish) apical radiolucency.
- The radiolucency “stays” at the apex, regardless the cone angulation.
- A cause of pulp necrosis is usually (but not always) present.
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Endodontic pathosis - Radiopaque lesions:
condensing osteitis: opaque, diffuse app, diffuse borders or roughly concentric to the apex
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Anatomic structures
- Mandible: mental foramen, may overlie the apex of a mandibular premolar.
- Maxilla: maxillary sinus, incisive canals, nasal fossa, zygomatic process, and anterior nasal spine.
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