SP Lectures

• Caries detection is the most frequent reason for taking bitewing radiographs- guidelines from FGDP
• }Decreased tooth density caused by caries results in areas of radiolucency
• Diagnosing caries from rads?

  • 40% demineralisation of the tooth is needed before a lesion is visible on radiograph
  • Caries is always more advanced clinically than on the radiograph
  • Radiographs are an AID to the diagnosis and restoration of caries
• Interpreting Radiographs?

  • caries can be masked by the density of overlapping tooth structure
  • a carious lesion is 3 dimensional and a radiograph has only 2 dimensions
  • Caries overlapping pulp may mimic pulpal exposure
  • Interproximal caries shows more clearly than occlusal / buccal /lingual
• when might caries be missed?

  if contact points overlap
• Types of radiographs for caries diagnosis?

  • BWs best view
  • PAs if paralleling technique valuble, may increase exposure
  • OPGs less valuble, esp ants
• R1 - R4 interproximal caries:

  • not used clinically
  • description with respect to enamel/dentine lesion
  • R0 - sound on BW
  • R1 - radiolucency confined to enamel
  • R2 - radiolucency enamel to EDJ
  • R3 - radiolucency enamel to outer half dentine
  • R4 - radiolucency enaeml reaching inner half of dentine
• R Classification?

  R2

  
• R Classification?

  R3

  
• R Classication?

  R4

  
• sensitivity: the proportion of true positives that are

  correctly identified by a test i.e. caries is present and correctly identified
• specificity: proportion of correctly identified true negative results i.e. caries is not present and is correctly  identified as not being present
• a good diagnostic test has:

  • high sensitivity (high proportion of carious lesion)
  • high specificity (high proportion of correctly identified caries free areas)
• true positive result?

  • caries present and test correctly identifies this
  • good diagnostic test high percentage of true positive outcomes (high sensitivity)
• true negative result?

  • test correctly identifies an individual as caries free
  • shows high specificity
• false positive result?

  • diagnosis test incorrectly identifies caries when caries not present
  • test too sensitive and not specific enough to be accurate
• false negative result?

  • patient has caries but test says caries free
  • denotes low sensitivity and low specificity
• Mach Band Effect?

  • optical illusion between enamel and dentine on radiographs
  • eyes see 2 different radiolucencies detecting a shadow which isnt there
  • reduction in specificity - false positive result
• What diagnostic inaccuracy does the following show?

  Mach Band Effect

  
• Cervical Burnout?

  • illusion of radiolucency at the neck of the tooth
  • thinner dentine in this area appears very dark compared to the adjacent enamel and alveolar bone
  • overexposed radiographs show more cervical burnout
  • must not be confused with caries
• What does the below diagnostic inaccuracies show?

  Cervical burnout

  
• What caries is shown below?

  recurrent or secondary caries

  
• What other conditions may mimimic caries on a radiograph?

  • attrition
  • abrasion
  • radiolucent restorative material
• What does the image show?

  periapical radiolucency

  
• What does the following image show?

  perioapical radiolucency due to inadequate root filling

  
• why might bone appear radiopaque?

  • condensing osteitis: periapical inflammatory disease as a reaction to dental infection causing more bone production rather than destruction.
• What does the image show?

  condensing osteitis

  
• what does the image below show?

  residual periapical lesion

  
• what does the image show?

  internal root resoption

  
• what do the images show?

  external root resporption

  
• what guidelines do we follow for posterior bitewings?

  FGDP recommendation for posterior bitewings
• HIGH RISK ADULT GUIDANCE?

  • six monthly until no new or active lesions apparent and individual has entered another risk category
• moderate caries risk guidance:

  • annually until no new or active lesions are apparent and individual has entered another risk category
• low risk?

  • 12-18 month for primary dentition
  • 2 years for perm dentition
  • more extended intervals may be appropriate if continuing low caries risk
• what do we need to consider when studying radiographs?

  • normal anatomy
  • artefacts
  • pathology
• what does the image show?

  normal appearance of developing tooth follicle

  
• what does the image show?

  OPG of developing dentition

  
• what do the images show?

  erupting teeth

  
• what does the image show?

  impacted canines

  
• what does the image show?

  impacted third molar