1. Radiographic Interpretation of Dental Disease

2. Dental Caries Interpretation
Detection of Dental Caries:
Both careful clinical examination & a radiographic examination are necessary. Radiographic examination helps the dentist to:
1-Identify the carious lesions that are not visible clinically.
2-Allow evaluating the extent & severity of carious lesions.

3. Clinical Examination
The probe used as a tactile device to detect the presence of any changes in consistency (catches or tug-back) in the pits, groves, fissures of the teeth.
Some teeth with dental caries exhibit a discolored area or a cavitation, whereas the others have no visible changes.
Caries that occur between the teeth may be difficult or impossible to be detected clinically, in such cases the radiographs play an important role.

5. Radiographic Examination:
The bitewing radiograph is the radiograph of choice for evaluation of caries because it provides the dental professional with diagnostic information that cannot be obtained from any other source.
A periapical radiograph using the paralleling technique can be used for evaluation of dental caries.

6. Factors Affecting the Caries Interpretation
Technical errors results in non diagnostic radiograph, e.g. incorrect horizontal angulation lead to overlapping & obscured the proximal caries.
Incorrect exposure factors, like incorrect exposure time, kVp & mA resulted in films that too light or too dark thus its useless in dental caries detection.

7. Radiographic Classification of Caries
Interproximal caries.
Occlusal caries.
Buccal caries.
Lingual caries.
Root caries.
Recurrent caries.
Rampant caries.
Radiation caries

8. It follows the path of dentinal tubules
Interproximal Caries
It is found between two adjacent teeth, its seen at or just below (apical to) the contact point. This area is difficult if not impossible to examine clinically.
It follows the path of dentinal tubules
Interproximal Caries

10. Interproximal caries classified according to its severity
Incipient caries, extends less than half way through the thickness of enamel (seen in the enamel only).
Moderate caries, extends more than halfway through the thickness of the enamel but dose not involve the DEJ (seen in the enamel only).
Advance caries, extends to or through the DEJ & into dentin but dose not extend through the dentin more than half the distance toward the pulp (affects both enamel & dentin).
Severe caries, extends through enamel & through the dentin more than half the distance toward the pulp (involve both enamel & dentin) and may clinically appear as cavitation(or hole) in the tooth.

12. Occlusal Caries
A thorough clinically examination is the method of choice for the detection of occlusal caries. Because of superimposition of dense buccal & lingual enamel cups, early occlusal caries is difficult to detect on a dental radiograph
The first radiographic sign is a dark line between enamel and dentin. It follows the enamel rods.

14. Classification of Occlusal caries
Incipient caries, cannot be seen on a dental radiograph & must be detected clinically with dental probe.
Moderate caries, extends into dentin & appears as a very thin radiolucent line located under the enamel of the occlusal surface.
Severe caries, extends into dentin & appears as a large radiolucency under the enamel of the occlusal surface of the tooth, clinically appears as a cavitation in a tooth.

16. Buccal & Lingual Caries
*Buccal caries involve the buccal tooth surface.
*Lingual caries involve the lingual tooth surface.
Because of superimposition of the densities of normal tooth structure, they are difficult to be detected by the dental radiograph & are best detected clinically.
Radiographically these carious lesions appear as a small circular radiolucent area.

18. Root Surface Caries
Clinically: It is easily detected on exposed root surface.
Radiographically: It appears as a cupped-out or crater-shaped radiolucency just below the CEJ. It doesn't occur in areas covered by a well attached gingival.
It may be confused with cervical burnout.

20. Recurrent Caries
Secondary or recurrent caries occurs adjacent to a pre-existing restoration due to:
Inadequate cavity preparation.
Defective margins.
Incomplete removal of caries prior to the placement of restoration.
Radiographically: appears as a radiolucent area just beneath a restoration, occurs most often beneath the interproximal margins of a restoration.

21. Recurrent Caries

22. Rampant Caries The term rampant means growing or spreading.
It is an advanced & severe caries that affects numerous teeth.
It is seen in children with poor dietary habits or in adults with a decreased salivary flow.

24. Radiation caries
Resulting from Xerostomia caused by head and neck radiation therapy.

25. Radiographic interpretation of dental caries is not always straightforward, it is often complicated by two additional radiographic shadows:
Radiolucent cervical burn-out.
Radiopaque zone beneath amalgam restoration.

26. Radiolucent Cervical Burn-Out

27. Radiopaque Zone beneath Amalgam Restorations
It has been shown with time, tin & zinc ions are released into the underlying demineralized dentine producing radiopaque zone which follow the s-shape of the dentinal tubules. The normal dentin on either sides appear more `radiolucent by contrast, this more radiolucent normal dentin may simulate the shadow of caries & lead to difficult diagnosis.

28. Limitations of Radiographic Diagnosis of Caries
1. Carious lesions are usually larger clinically than they appear radiographically & very early lesions are not evident at all. 2. Technique variations in film & x-ray beam position can affect the image of the carious lesion (incorrect horizontal angulation make carious lesion confirm in the enamel to be progressed into dentin). 3. Exposure factors can affect the overall radiographic contrast & thus affect the appearance or size of carious lesions on the radiograph.

31. 4. Superimposition & two dimensional image
mean that the following features cannot always be determined:
The exact site of a carious lesion, e.g. buccal or lingual
The bucco-lingual extent of a lesion.
The distance between the carious lesion & pulp horns (two shadows can appear to be close together or even in contact but they may not be in the same plane).
The presence of an enamel lesion (density of the overlying enamel may obscure the zone of decalcification).
The presence of recurrent caries (existing restorations may completely overlie the carious lesion).

35. Radiographic Assessment of Restorations
The important features to note include,
the type & radiodensity of the restorative material,
Amalgam.
Cast metal.
Composite or classionomer material.
Over contouring.
Overhanging ledges.
Under contouring.
Negative or reverse ledges.
Presence of contact points.
Adaptation of the restorative material to the base of the cavity.
Marginal fit of cast restorations.
Presence or absence of lining material.
Radiodensity of lining material.

37. Assessment of the Underlying Tooth
These include:
Recurrent caries.
Residual caries.
Radiopaque shadow of released tin & zinc ions.
Size of the pulp chamber.
Internal & external resorption.
Presence of root filling material in the pulp chamber.
Presence & position of pins or posts.