Caries and Periapical Pathology - justification and interpretation

Question 1

What is justification?

Answer 1

• decision making process
• both ethical and legal requirement (IRMER17)
• selection of appropriate radiograph should be based on pt history and exam
• routine use of xrays based on generalised approach is unacceptable
• individual prescription required
• routine/screening radiograph prescriptions must be based on knowledge of prevalence of disease

Question 2

What is ALARP?

What is dose?

How is this reduced?

Answer 2

ALARP: As Low As Reasonably Practicable

Dose is amount of radiation absorbed by the patient

• difficult to quantify for each patient as they differ
• most appropriate way of reducing dose is to limit the amount of exposure to radiation
• fewer exposures, collimation, low dose techniques

Question 3

How can caries be diagnosed from radiographs?

Answer 3

• carious lesions can only be detected radiographically when there has been sufficient demineralisation
• must be distinguishable from enamel and dentine
• film must be well exposed and well processed
• optimum viewing conditions - low ambient light and a bright screen limited to area of image
• cannot tell whether lesion is active or arrested

Question 4

Which radiographic technique is recommended for diagnosing caries?

What can be mistaken for caries?

Answer 4

BWs - gold standard - usually horizontal

• paralleling periapicals

Mistaken for caries:

• cervical burnout or translucency
• visual perception - problem of contrast below dense metallic restoration
• air/lip shadow in premolar region
• dentine surrounding radio-opaque zone under amalgam
• radiolucent restorations

Question 5

What can bitewing radiographs display?

How often should they be taken?

Answer 5

• diagnosis of interproximal and occlusal caries
• caries risk assessment
• high risk child - 6 monthly
• moderate risk child - annually
• low risk child - 12-18 months deciduous
• 24 months of more for permanent teeth
• adults less evidence but much the same

Question 6

What are the three most important features on the peri-radicular region of a radiograph?

Why can these 3 areas be lost?

Answer 6

• radiolucent line representing the PDL space
• radiopaque line representing lamina dura
• trabecula pattern and density of surrounding bone

Lost due to personal variation and limitation due to:

• contrast
• resolution
• superimposition

Question 7

What does initial acute inflammation look like radiographically?

Initial spread of inflammation?

Further inflammatory spread?

Answer 7

Initial acute inflammation:

• no apparent changes or possible widening of PDL space

Initial spread of inflammation:

• loss of lamina dura at apex

Further inflammatory spread:

• periapical bone loss

Question 8

What doesinitial chronic inflammation look like radiographically?

Long standing chronic inflammation?

Answer 8

• no bone destruction seen or dense sclerotic bone periapically (sclerosing osteitis)

Chronic inflammation - long standing:

• circumscribed, well defined, radiolucent area periapically with sclerotic bone surrounding
• radiolucency sometimes described as rarefying osteitis