Role of Radiographs in the Diagnosis of Periodontal Disease

Content • Introduction• Radiographic Techniques in Assessing Periodontal

Disease• Radiographic Features of Healthy Periodontium• Radiographic Examinations• Radiographic Changes in various Periodontal Diseases• Advanced Radiographic Aids• Limitations of Radiographs• Conclusion

INTRODUCTION

• Most periodontal diseases are diagnosed by- - case history and- clinical signs and symptoms

• Radiographs is an adjunct to clinical examination; • It reveals only the alterations in the calcified tissue

instead of current cellular activity.

Radiographic Techniques in Assessing Periodontal Disease

a. Periapical radiograph (Intra-oral)i. Long cone or Paralleling technique ii. Bisecting angle techniqueb. Bitewing radiograph (Intra-oral)c. Panoramic radiograph (Extra-oral)

Long cone or Paralleling Technique for IOPA View X-ray

• Prichard (1972) established the following four criteria to determine adequate angulation of periapical radiographs:

1. The radiograph should show the tips of molar cusps with little or none of the occlusal surface showing.

2. Enamel caps and pulp chambers should be distinct.3. Interproximal spaces should be open.4. Proximal contacts should not overlap unless teeth

are out of line anatomically.

IOPA view X-ray taken at different angle

• A Full Mouth Series of radiographs is generally composed of 20 films-

- 4 Bitewing radiographs and - 16 Periapical radiographs.

Radiographic Features of Healthy Periodontium

1. Alveolar Bone: - Normally lamina dura forms the wall

of the socket.- The alveolar crest in young individual

is as close as to the CEJ (1.5 - 2 mm).- Alveolar crest is continuous with the

lamina dura of the adjacent tooth. - Trabecular pattern of interdental

bone is distinct and fills the interradicular area.

2. Interdental Septa:- Located between the two adjacent tooth.- The shape of the interdental septum depends on

the morphology of the contiguous teeth. - The crest of the interdental septum is parallel to

the line between the CEJs of the approximating teeth.

3. PDL Space:- It is the space between the

lamina dura and the tooth root (lamina lucida).

- It is a fine, black, radiolucent line next to root surface.

- Width of this space vary from patient to patient, tooth to tooth in the same individual and from location to location around one tooth.

Radiographic Examination

• Height of alveolar crest • Lamina dura• Bone Density • Distribution of Bone Loss • Pattern of Osseous Defects

Osseous Defects:a. Horizontal bone lossb. Vertical bone lossc. Furcation defectsd. Interdental craters

a. Horizontal bone loss:- It appears as decreased alveolar

marginal bone around adjacent teeth.

- Both buccal and lingual plates as well as interdental bone resorbs.

- The remaining bone margin is roughly perpendicular (90⁰) to the long axis of tooth.

b. Vertical bone loss:- Vertical defects are generally “V” shaped and are

sharply outlined.

c. Furcation defects:

The following diagnostic criteria are suggested:- The slightest radiographic change in the furcation

area should be investigated clinically, especially if there is bone loss on adjacent roots.

- Diminished radiodensity in the furcation area in which outlines of bony trabeculae are visible suggests furcation involvement.

- Whenever there is marked bone loss in relation to a single molar root, it may be assumed that the furcation is also involved.

d. Osseous Interdental Craters:- Osseous craters are concavities in the crest of the

interdental bone confined within the facial and lingual walls.

- These craters are seen as irregular areas of reduced radiopacity on the alveolar bone crests

- Radiographs do not accurately depict the morphology or depth of interdental craters, which sometimes appear as vertical defects.

Radiographic Changes in Various Periodontal Diseases

A, Normal appearance of interdental septa.

B, Fuzziness and a break in the continuity of the lamina dura at the crest of the bone distal to the central incisor (left). There are wedge-shaped radiolucent areas at the crests of the other interdental septa.

C, Radiolucent projections from the crest into the interdental septum indicate extension of destructive processes.

D, Severe bone loss.

1. Radiographic Changes in Periodontitis

2. Radiographic Appearance of the Periodontal Abscess• The typical radiographic appearance is that of a

discrete area of radiolucency along the lateral aspect of the root. However, the radiographic picture is often not typical because-

i. The stage of the lesion ii. The extent of bone

destruction and the morphologic changes of the bone

iii. The location of the abscess.

3. Radiographic Changes in Aggressive Periodontitis

• Combination of the following radiographic features:1. Bone loss may occur initially in the maxillary and

mandibular incisor and/or first molar areas, usually bilaterally, and results in vertical, arclike destructive patterns.

2. Loss of alveolar bone may become generalized as the disease progresses but remains less pronounced in the premolar areas.

4. Radiographic Changes in Trauma from Occlusion (TFO)• In TFO the tissue injury is more on faciolingual

aspects of the affected tooth.• TFO can produce radiographically detectable changes

in the- - lamina dura, - morphology of the alveolar

crest, - width of the periodontal space,

and - density of the surrounding

cancellous bone

• These radiographic changes are not pathognomonic of TFO. It has to be interpreted in combination with clinical findings, particularly tooth mobility, presence of wear facets, pocket depth, and analysis of occlusal contacts and habits.

• The injury phase- a loss of the lamina dura may be noted in apices, furcations, and/or marginal areas, which results in widening of the PDL space.

• The repair phase of TFO results- a widening of the PDL space, which may be generalized or localized.

• More advanced traumatic lesions may result in deep angular bone loss and may extend around the root apex in terminal stages, producing a wide radiolucent periapical image (cavernous lesions).

• Root resorption may also occur as a result of excessive forces on the periodontium, particularly those caused by orthodontic appliances.

5. Additional Radiographic Criteria in theDiagnosis of Periodontal Disease

• Radiopaque horizontal line across the roots.• Vessel canals in the alveolar bone.• Differentiation between treated and untreated

periodontal disease.

6. Skeletal Disturbances Manifested in the jaws

i. Osteitis fibrosa cystica (Recklinghausen's disease of bone) develops in advanced primary or secondary hyperparathyroidism causing osteoclastic resorption results in a scattered "cystlike“ radiolucent areas throughout the jaws, and a generalized disappearance of the lamina dura.

ii. Paget's disease, the normal trabecular pattern is replaced by a hazy, diffuse meshwork of closely knit, fine trabecular markings, with the lamina dura absent or scattered radiolucent areas may contain irregularly shaped radiopaque zones.

iii. Fibrous dysplasia- a small radiolucent area at a root apex or as an extensive radiolucent area with irregularly arranged trabecular markings. There may be enlargement of the cancellous spaces, with distortion of the normal trabecular pattern and obliteration of the lamina dura.

iv. Langerhans' cell histiocytosis (disturbances in immunoregulation)- appear as single or multiple radiolucent areas.

v. Numerous radiolucent areas occur when the jaws are involved by multiple myeloma.

vi. In osteopetrosis (marble-bone disease, Albers-Schonberg disease) the outlines of the roots may be obscured by diffuse radiopacity of the jaws.

vii. In scleroderma, the PDL is uniformly widened at the expense of the surrounding alveolar bone.

Advanced Radiographic AidsDigital Radiography (1987): • The diagnostic accuracy in the detection of subtle alveolar

bone changes was increased by the introduction of digital subtraction in dental radiography

• They rely on a sensor of two systemi. Direct method- charged coupled device (CCD) sensor is

linked with a fiber optic or other wire to the computer system.

ii. Indirect method- a phosphor luminescence plate (flexible filmlike radiation energy sensor) is placed intraorally and exposed to conventional X-ray tube. A laser scanner reads the exposed plates offline and reveals digital image data.

Imaging Receptors:

Rigid CCD Digital Sensor: Sirona Dental

Systems, LLC

Digital Phosphor PlateAir Technique, Inc.

F-Speed Dental FilmKodak Dental Systems

Advantages:1. Enables the use of computerized images that can

be stored, manipulated, and corrected for under and over exposures.

2. The radiation dose can be minimized 1/3rd to half over conventional radiograph.

Types of Digital Radiographya. Digital Subtraction Radiography (DSR).b. Computer Assisted Densitometric Image Analysis

(CADIA) System.

a. Digital Subtraction Radiography (DSR):- A series of radiographs are obtained and converted

into digital images which are superimposed and the resultant composite viewed on a video screen.

- Changes in the bone density and/or volume can be detected as lighter areas (bone gain) or dark areas (bone loss).

- A second image is taken at the same point and they are compared after normalization and image alignments.

- The elements that remain unchanged are subtracted from two images and the remaining image information is displayed. Using pseudocolorization techniques, only the areas that changes are visible to the dentist.

Digital subtraction radiography

The automatic registration method. (a) The original baseline radiograph. (b) The radiograph to be registered. (c, d) The cropped images of (a) and (b), respectively. (e) The registered radiograph after the application of the automatic geometric registration and contrast correction methods. (f) Superposition of the edges of the registered radiograph (e) on the baseline image (c). (g) The subtraction image. (h) The fused image.

b. Computer Assisted Densitometric Image Analysis (CADIA) System:

• A video camera measures the light transmitted through a radiograph, and the signals from the camera are converted into gray-scale images.

• The camera is interfaced with an image processor and a computer that allow the storage and mathematical manipulation of the images.

Limitations of Radiographs

• The condition of gingiva cannot be predicted.• It provides two-dimensional views of three-

dimensional situation; often fail to disclose osseous destruction particularly of buccal and lingual surfaces.

• Radiographs typically show less severe bone destruction than is actually present.

• Measuring bone level from CEJ is not valid when there is over eruption or severe attrition with passive eruption.

• Radiograph do not demonstrate the soft tissue hard tissue relationship and thus provide no information about the depth of soft tissue pockets. However, if a radiopaque material, such as GP is inserted into the pocket, the depth of the pocket can usually be recorded on radiograph.

• Widening of PL space on radiograph does not necessarily indicate tooth mobility.

• They do not specifically distinguish between the successfully treated and untreated cases.

• Radiographs do not play a major role in periodontal diagnosis but are useful in treatment planning.

• The possible therapeutic profit of any radiograph in affected patients must be considered before exposing to radiation.

• Conventional radiographs provide a two dimensional image of complex of the three dimensional anatomy.

• Due to superimposition, the details of the bony architecture may be lost.

Conclusion

• Radiographs do not demonstrate incipient disease, as a minimum of 30% demineralization must occur before radiographic changes are apparent.

• Radiographs do not reliably demonstrate soft tissue contours, and do not record changes in the soft tissues of the periodontium.

• Therefore, only a careful clinical examination, combined with a proper radiographic diagnosing technique should be prescribed.

• Panoramic oral radiographs, supplemented by selected intra-oral views, can reach the ‘‘gold standard’’ with reduced radiation exposure.

• Digital panoramic oral radiographs, viewed through computers are advantages over conventional film panoramic radiographs.

• Digital subtraction radiography will likely remain a research tool. The application of cone-beam CT in informing periodontal treatment decisions is only beginning to be investigated, and its application and utility remain to be elucidated/clarified.

ThankQ

Radiographic Techniques in Assessing Periodontal Disease

I. Conventional Radiographs:a. Periapical radiograph (Intra-oral)i. Long cone or Paralleling technique ii. Bisecting angle techniqueb. Bitewing radiograph (Intra-oral)c. Panoramic radiograph (Extra-oral)

II. Advanced Radiographic AIDS:a. CCDs or CMOSb. PSP

Intraoral Radiography

• Principle One: X-rays should be emitted from the smallest source of radiation as possible.

• Principle Two: The x-ray source-to-object distance should be as long as possible. Position indicating device (PID or cone)

Position indicating device (PID or cone)

Principles Intraoral Radiography

• Principle Three: The object-to-receptor distance should be as short as possible.

• Principle Four: The receptor and long axis of the tooth should be parallel to each other.

• Principle Five: The x-ray beam should be directed perpendicular to the receptor.

a. Periapical Radiography:

i. Long cone or Paralleling techniques (Gordon)ii. Bisecting angle techniques

i. Paralleling Technique:• Place the receptor parallel to the long axis of the tooth. • The central ray is directed perpendicular to both the

tooth and receptor.

The advantages of the paralleling technique:

The paralleling technique meets four of the five shadow-casting principles.

- Better dimensional accuracy: the paralleling technique results in less distortion of the image of the teeth. (The shape of the teeth and the relationship of the teeth to surrounding structures are more accurate).

- When using the paralleling instrument with the aiming ring, the alignment of the x-ray beam is simplified.

- It is easier to standardize films. By using the positioning instrument, it is easier to position the film in approximately the same position at different appointments.

- Head position is not as critical. Because of the paralleling instrument, with its aiming ring, it is easy to properly align the x-ray beam no matter how the head is positioned.

- When the long axis of the film is parallel with the long axis of the tooth; the image of the tooth on the film looks the same as the tooth itself (no distortion). The image will be slightly larger than the actual tooth (magnification), but the shape is the same.

Disadvantages of Paralleling Technique:

- Less comfortable. Because the film is usually more upright when using the paralleling technique, it impinges more on the palate or floor of the mouth, thus making it more uncomfortable.

- More limited by the anatomy of the patient’s mouth. A shallow palate or floor of the mouth makes it harder to position the film using the paralleling technique.

ii. Bisecting Angle Technique:

• Place the receptor as close to the tooth as possible.• The central ray of the x-ray beam should be directed

perpendicular to an imaginary line that bisects the angle formed by the long axis of the tooth and the plane of the receptor.

b. Bitewing Radiograph Technique (Raper, 1925): - The receptor is placed into the mouth parallel to the

crowns of the maxillary and mandibular posterior teeth.

- The patient stabilizes the receptor by biting on a tab or bitewing holder.

- The horizontal angle of the x-ray beam is then directed through the contacts of the posterior teeth and at a +5º to +10º vertical angle.

i. Panoramic Radiography (OPG)

c. Panoramic radiograph (Extra-oral):

• Panoramic radiographs provide a general view of the oral structures, and are useful for screening bone loss patterns in general.

• They are not suitable for accurate assessment of the degree of bone loss associated with individual teeth, as there is severe distortion and the outline of the bone margin is often unclear due to superimposition of intervening structures.

Advanced Radiographic AidsDigital Radiography (1987): • The diagnostic accuracy in the detection of subtle alveolar

bone changes was increased by the introduction of digital subtraction in dental radiography

• They rely on a sensor of two systemi. Direct method- charged coupled device (CCD) sensor is

linked with a fiber optic or other wire to the computer system.

ii. Indirect method- a phosphor luminescence plate (flexible filmlike radiation energy sensor) is placed intraorally and exposed to conventional X-ray tube. A laser scanner reads the exposed plates offline and reveals digital image data.

Imaging Receptors:

Rigid CCD Digital Sensor: Sirona Dental

Systems, LLC

Digital Phosphor PlateAir Technique, Inc.

F-Speed Dental FilmKodak Dental Systems

Advantages:1. Enables the use of computerized images that can

be stored, manipulated, and corrected for under and over exposures.

2. The radiation dose can be minimized 1/3rd to half over conventional radiograph.

Types of Digital Radiographya. Digital subtraction radiography (DSR).b. Computer Assisted Densitometric Image Analysis

(CADIA) System.

a. Digital subtraction radiography (DSR):- A series of radiographs are obtained and converted

into digital images which are superimposed and the resultant composite viewed on a video screen.

- Changes in the bone density and/or volume can be detected as lighter areas (bone gain) or dark areas (bone loss).

- A second image is taken at the same point and they are compared after normalization and image alignments.

- The elements that remain unchanged are subtracted from two images and the remaining image information is displayed. Using pseudocolorization techniques, only the areas that changes are visible to the dentist.

Digital subtraction radiography

The automatic registration method. (a) The original baseline radiograph. (b) The radiograph to be registered. (c, d) The cropped images of (a) and (b), respectively. (e) The registered radiograph after the application of the automatic geometric registration and contrast correction methods. (f) Superposition of the edges of the registered radiograph (e) on the baseline image (c). (g) The subtraction image. (h) The fused image.

b. Computer Assisted Densitometric Image Analysis (CADIA) System:

• A video camera measures the light transmitted through a radiograph, and the signals from the camera are converted into gray-scale images.

• The camera is interfaced with an image processor and a computer that allow the storage and mathematical manipulation of the images.

Conclusion • Radiographs do not play a major role in periodontal

diagnosis but are useful in treatment planning. • The possible therapeutic profit of any radiograph in

affected patients must be considered before exposing to radiation.

• Radiographs should be prescribed only on the basis of a clinical assessment.

• Panoramic oral radiographs, supplemented by selected intra-oral views, can reach the ‘‘gold standard’’ with reduced radiation exposure.

• Digital panoramic oral radiographs, viewed through computers are advantages over conventional film panoramic radiographs.

• Digital subtraction radiography will likely remain a research tool. The application of cone-beam CT in informing periodontal treatment decisions is only beginning to be investigated, and its application and utility remain to be elucidated/clarified.

ThankQ

Distortions Produced by Variations in Radiographic Technique

• Variations in technique produce distortion on-- bone level, - pattern of bone destruction, - width of the PDL space, - radiodensity, - trabecular pattern, and - marginal contour of the interdental septum.

• These are modified by altering the exposure and development time, type of film, and x-ray angulation.

• Standardized, reproducible techniques are required to obtain reliable radiographs for pretreatment and posttreatment comparisons.

• A grid calibrated in millimeters, superimposed on the finished film, is helpful for comparing bone levels in radiographs taken under similar conditions.

• The effects of angulation- • The long cone paralleling technique (projects the

most realistic image). • The bisection-of-the angle technique (facial bone

margin distort more than the lingual margin). • Shifting the cone mesially or distally without changing

the horizontal plane projects the x-rays obliquely and changes the

- shape of the interdental bone, - width of the periodontal ligament space, and - the appearance of the lamina dura. • It may also distort the furcation involvement.