JUSTIFICATION & INTERPRETATION Flashcards
What must be considered to justify taking a radiograph?
- Decision making process
- Both ethical and a legal requirement (IRMER 2017)
- Selection of appropriate radiograph should be based on patient’s history & clinical examination
- Routine use of x-rays based on generalised approach is unacceptable
- Individual prescription required.
- Routine/screening radiograph prescriptions must be based on knowledge of the prevalence of disease
What does Interpretation of intra oral radiograph depend on?
- Knowledge of how image is acquired
- Knowledge of anatomy
- Knowledge of disease process
Understand the effects of :-
- Positioning
- Exposure
- Processing
- For digital imaging, the programme algorithms & computer factors
What does ALARP stand for?
As
Low
As
Reasonably
Practicable
What does ALARP refer to?
- ALARP refers to dose
- Dose is the amount of radiation absorbed by the patient
- It is 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 etc
What are some points when Diagnosing caries using radiographs?
- 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.
- Correct view/projection must be requested
- knowledge of normal variants
- cannot tell whether lesion is active or arrested
- superimposition - a 2D image
- sensitivity of technique and observer skills
- Importance of clinical examination
What is Sensitivity & Specificity of radiographs?
- One study has shown that the sensitivity of diagnosing the presence or absence of occlusal caries is 0.96 and the specificity of the detection of dentine radiolucencies is 0.58. The teeth examined were clinically sound.
- Other studies have shown for approximal caries a sensitivity of 44% and a specificity of 94%
The results are therefore confusing! But bitewings radiographs are still considered the “gold standard”
What are Recommended techniques for diagnosing caries?
Bitewings - usually horizontal
Paralleling periapicals
What should we be able to see in radiographs?
- Crowns of the teeth and the coronal portion of roots
- Contact points with no or very little overlap
- The alveolar bone crest
- Distinguish enamel from dentine
- The pulp chamber
- If restorations present, to be able to check for any overhangs or deficiencies at the margins
What can be 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
What are some Limitations of caries diagnosis?
- Overlap
- technique
- anatomy
- Exposure factors
- 2D image
What are the similarities between Bitewings and paralleling periapicals?
- Similar techniques
- film is parallel to long axis of tooth
- x-ray beam at 90º to film & tooth
- long cone should be used - a near parallel beam
When would you use Bitewing Radiograph?
- Diagnosis of interproximal & occlusal caries
- Caries risk assessment
- “routine” radiographs based soley on time intervals is unsupportable
- High risk child – 6 monthly
- Moderate risk child – annually
- Low risk child – 12 -18 months deciduous,
- 24 months or more for permanent teeth
- Adults, less evidence but much the same
What are the 3 most important features in Radiology & peri-radicular disease?
- radiolucent line representing the periodontal ligament space
- radiopaque line representing lamina dura
- trabecula pattern & density of surrounding bone
These 3 are key to interpretation of radiographs BUT can be lost due to personal variation & Limitation due to:
- contrast
- resolution
- superimposition etc
What is Radiographic appearance of periapical pathology such as Initial acute inflammation?
Initial acute inflammation
- no apparent changes
- or
- possible widening of periodontal ligament space
What can you see at the Initial spread of inflammation?
Loss of lamina dura at apex
What can you see in Further inflammatory spread?
Periapical bone loss
What can you see in Initial chronic inflammation?
- No bone destruction seen
- or
- dense sclerotic bone periapically (sclerosing osteitis)
Multiple radiolucencies enhance appearance of IDC
Multiple radiolucencies enhance appearance of IDC
Chronic root resorbtion
Chronic root resorbtion
Radicular cyst
Radicular cyst
