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20 Radiographic Analysis of the Periodontium

Radiographic Analysis of the Periodontium

Introduction

  • Radiographic analysis of the periodontium is essential for understanding dental health and conditions relating to periodontitis and other periodontal diseases.

Radiographic Appearance of the Periodontium

  • Radiographs provide crucial information regarding various aspects of the periodontium:
    • Interdental Alveolar Bone Crests: The levels of these bone crests are vital indicators of periodontal health.
    • Tooth Roots: Radiographs help assess the size and shape of tooth roots.
    • Root Relationships: Assessing the relationship between adjacent tooth roots is essential for identifying potential issues.
    • Alveolar Bone Condition: Particularly in furcation areas, the condition of the alveolar bone can indicate disease.
    • Local Contributing Factors: Certain factors in the local environment can be identified through radiographic analysis.

Radiolucent Versus Radiopaque Structures

  • Radiolucent Structures:
    • Characteristics: Less dense and not as mineralized.
    • Appearance: Dark gray to black on radiographs.
    • Examples: Tooth pulp, periodontal ligament space.
  • Radiopaque Structures:
    • Characteristics: More dense and more mineralized.
    • Appearance: Light gray to white on radiographs.
    • Examples: Tooth enamel, dentin, pulp stones.

Challenges of Radiographic Interpretation

  • Many dental structures allow only limited penetration of x-rays, leading to various subtle shades of gray that can confuse clinicians.

Radiographic Features of the Periodontium

  • Cortical Bone:
    • Description: The outer surface of bone, composed of densely packed layers.
    • In Maxilla: Usually forms a thin shell covering.
    • In Mandible: Denser and thicker than in maxilla.
  • Cancellous Bone: Less radiopaque, displaying a lattice-like pattern that fills the alveolar process.

Radiographic Appearance of Cortical and Cancellous Bone

  • Cortical Bone:
    • Appears much more radiopaque with a thicker white border than surrounding cancellous bone.
  • Cancellous Bone:
    • Appears less radiopaque and shows a lattice pattern.

Evaluation of Alveolar Crest in Health

  • Normal Level:
    • Approximately 2 mm apical to the cementoenamel junction (CEJ).
    • Important to note the relationship between the alveolar crest level and the CEJ during analysis.
  • Contour of the Alveolar Crest:
    • Should be parallel to an imaginary line connecting the CEJs of adjacent teeth.
    • Horizontal Contour: When CEJs are at the same level.
    • Vertical (Angled) Contour: Occurs when adjacent teeth are tilted.

Shape and Character of Alveolar Crestal Bone in Health

  • Smooth surface covered with a thin layer of cortical bone.
  • Radiographically appears as a fine white line known as lamina dura.
  • The intercuspid bone crest is generally thin and pointed between incisors, while it tends to be flat or slightly rounded between posterior teeth.

Lamina Dura (Alveolar Bone Proper)

  • Description: A thin layer of dense bone lining the normal socket, observed as a continuous white line that runs along the entire socket wall.
  • Radiographic Considerations:
    • Its appearance may vary due to the complex contours of tooth roots and the changing angulation of the x-ray tube.

Periodontal Ligament Space (PDL)

  • Appears as a thin radiolucent black line surrounding the tooth root filled with periodontal ligament tissue.
  • Importance: Always evaluate for extremely widened PDL spaces, which might indicate periodontal issues.

Radiographic Techniques

  • Long-Cone Paralleling Technique:
    • Provides anatomically accurate radiographs compared to other techniques like bisecting-angle.
  • Vertical Bitewing Technique:
    • Increased visualization of alveolar bone when significant loss (≥5 mm) has occurred.
    • Film alignment: Long axis of film should be perpendicular to the occlusal plane.

Limitations of Dental Radiographs in Periodontal Evaluation

  • Two-dimensional Nature: Radiographs offer only 2D images of 3D structures, limiting the understanding of periodontal health.
  • Missing Information:
    • Radiographs do not show periodontal pockets or early alveolar bone loss.
    • Precise morphology of existing bone destruction cannot be determined.
    • Changes in the buccal or lingual cortical bony plate may be unobservable.
    • Alveolar bone loss in furcation areas is often obscured.
    • Information regarding tooth mobility and epithelial attachment levels is not visible and must be assessed through periodontal probing.

Benefits of Dental Radiographs during Periodontal Evaluation

  • Vital for supplementing clinical findings:
    • Can reveal bony changes related to periodontitis, widening of PDL spaces, and presence of local factors contributing to periodontal disease.

Assessment of Alveolar Bone Changes

  • Crestal Irregularities: Look for breaks or fuzziness at the interdental crest and widenings due to resorption.
  • Types of Bone Loss:
    • Horizontal Bone Loss: Parallel to an imaginary line beyond the normal 2mm distance between CEJs.
    • Vertical Bone Loss: Greater destruction on the interproximal aspect of one tooth more than the adjacent tooth, where the bone meets the tooth at an acute angle.

Assessment of Alveolar Bone Loss in Furcation Areas

  • Easier to detect on mandibular molars; however, maxillary molars present challenges due to their three-root structure, leading to potential superimpositions over furcation areas.

Special Considerations and Crown-to-Root Ratio Assessment

  • Radiographs reveal remaining bone rather than the amount of loss; must estimate bone loss based on the difference between remaining and expected bone heights.
  • The Crown-to-Root Ratio is important for evaluating the maintainability of teeth, ideally maintained at about 1:2.

Recognition of Local Contributing Risk Factors on Radiographs

  • Visible Risk Factors:
    • Calculus deposits and faults in restorations can often be detected radiographically in patients with periodontal disease.

Beyond Conventional Dental Radiography

  • Cone Beam Computed Tomography (CBCT):
    • Generates 3D images of the periodontium, increasingly indispensable for accurate treatment planning for surgical placements of dental implants.
    • Offers benefits in precise implant placement, enhancing mechanical stability, and preventing anatmic injuries.

Non-Dental Implant Treatment Planning Considerations

  • Conventional intraoral radiographs are often still used for detecting interproximal bone loss, although CBCT has not been confirmed to be superior and can expose patients to higher doses of radiation.
  • CBCT usage should be based on the assessment that the benefits outweigh the risks, alongside conventional radiography for optimal diagnosis.