0 Caries DiagnosisThe following slides describe the radiographicdiagnosis of caries.In navigating through the slides, you should clickon the left mouse button when you see themouse holding an x-ray tubehead or you aredone reading a slide. Hitting “Enter” or “PageDown” will also work. To go back to the previousslide, hit “backspace” or “page up”.
CariesCaries is the breakdown of tooth structurecaused by acid-producing bacteria in the mouth.These bacteria are found in the white or paleyellow plaque that builds up on the teeth if theyare not cleaned properly on a regular basis. Thebacteria break down carbohydrates (sugars) toform the acid that demineralizes tooth structure,leading to caries.The diagnosis of caries is made through acombination of the clinical examination andradiographs.Unless fairly large, interproximal caries in theposterior region usually requires radiographs tomake a diagnosis.
RadiographsThe bitewing film is primarily used for cariesidentification, but the periapical film is also helpful.The difference in angulation between the two filmsgives two different perspectives and can be especiallyhelpful in diagnosing recurrent caries around existingrestorations.There is a lot of discussion on which film speed (D orF) should be used. Many dentists use D-speed filmbecause they feel it provides sharper images as aresult of the smaller grain size. Most educators, on theother hand, recommend the F-speed film (Insight)because of the significant reduction in x-ray exposureto the patient (approximately 60% less than when usingD-speed film).
0 Proximal caries susceptible zone cariesApproximately 40-50 % demineralization is requiredfor radiographic detection of a lesion. As seen in theocclusal view, above right, the thickness of the toothbuccolingually masks the carious lesion when it issmall.The actual depth of penetration of a carious lesionis actually deeper than it appears on the radiograph.
Factors affecting appearance of carieson radiographs:Buccolingual thickness of tooth. The thicker thetooth, the more difficult it is to see the extent ofthe caries.Limitations of two-dimensional film. The extent ofcarious involvement can not be seen in abuccolingual (cheek to tongue) direction.
Factors affecting appearance of carieson radiographs (continued):X-ray beam angle (horizontal or vertical). This isespecially important when trying to identifyrecurrent caries, since changes in angulation maycause the superimposition of the existingrestoration with the carious lesion. Overlap due toimproper horizontal angulation makes it verydifficult to diagnose early interproximal caries.Exposure factors. Caries detection is improvedwith a lower kVp setting, which provides a highercontrast. If the overall density of the film is toolight or too dark, the diagnostic potential of thefilm is limited.
Transillumination 0In the anterior region,interproximal caries canoften be diagnosed usingtransillumination, whichinvolves directing a brightlight through the contactareas. Combiningtransillumination withradiographs enhances thediagnostic information transilluminatorobtained.
Caries Classification I M A AI = Incipient (Stage I)M = Moderate (Stage II)A = Advanced (Stage III) SS = Severe (Stage IV)
Interproximal Caries (Incipient) IUp to half the thickness of enamelUsually not restored unless patienthas high level of caries activity (highrisk). Treat with fluoride.
The arrow points to incipient lesions on themesial of # 19 and the distal of # 20.
Occlusal CariesMust have penetrated into dentinDiagnosed from clinical examMay be seen as thin radiolucent line orcup-shaped zone underlying occlusalenamel, but difficult to see onradiographs unless lesion is large.Some feel that a sharp explorer used tooforcefully may contribute to spreadof caries by opening up pit or fissure
Buccal/Lingual CariesShould be identified from clinicalexam. Sometimes seen as well-defined circular area in middle oftooth, although it is not veryradiolucent. Depth can not bedetermined radiographically.
Lingual caries (Can’t tell whether it’s buccalor lingual from one radiograph
Buccal caries with severe interproximalcaries on # 12
Root CariesSaucer-like cratering on the roots of theteeth, involving the cementum. Usuallyfound on older individuals withprominent recession and/orperiodontitis. May have xerostomia dueto medications. May be confused withcervical burnout (discussed on laterslide).
Cervical BurnoutCervical burnout is an apparent radiolucencyfound just below the CE junction on the rootdue to anatomical variation (concave rootformation posteriorly) or a gap between theenamel and bone covering the root(anteriorly). Mimica root caries. Posteriorly,this radiolucency usually disappears whenanother film of the region is examined. Cariesdoes not occur on the root of the tooth unlessthere is loss of alveolar bone and gingivaltissue due to recession or periodontitis.
Posterior cervical burnout. The invaginationof the proximal root surfaces allow more x-rays to pass through this area, resulting in amore radiolucent appearance on theradiograph. X-rays directed at a differentangle usually pass through more toothstructure and the radiolucency disappears.
Radiolucency seen at left (arrow)disappears on periapical film ofsame tooth. This is cervical burnout.
Anterior cervical burnout. The space between the enamel and the bone overlying the tooth will appear more radiolucent than either the enamel or the bone-tooth combination.bone level
Cervical burnout in theanterior region due togap between enamel(red arrows) andalveolar bone over root(blue arrows).
Recurrent CariesFound around the margins of existingrestorations. May be due to unusualsusceptibility to caries, poor oralhygiene, failure to remove all of thecaries during cavity preparation, adefective restoration or a combinationof the above.
Mach BandOptical illusion giving appearance of increasedradiolucency at the junction of differing tissuedensities, such as enamel and dentin. If you blockoff the enamel with a fingernail, the radiolucencywill disappear if due to the mach band effect. If theradiolucency persists, it may be caries.
0This concludes the section on Caries.Additional self-study modules are availableat: http://dent.osu.edu/radiology/resources.htmIf you have any questions, you may e-mailme at: firstname.lastname@example.org.Robert M. Jaynes, DDS, MSDirector, Radiology GroupCollege of DentistryOhio State University