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Flashcards in Diagnosis & paralax Deck (21)
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1
Q

What is the health in a radiographic image?

A

-2mm space below CEJ to interdental crest

Bone changes are evaluated by the appearance of interdental septa and lamina dura.

2
Q

What should be included when reporting radiographs for periodontal findings?

A
  • Degree of bone loss
  • Pattern or type of bone loss
  • Furcation
  • Subginigval calculus
  • Other features include perio-endo lesions: widened periodontal
3
Q

Why can determining bone loss be missed on radiographs?

A

Buccal and lingual plates are superimposed and may mask eachother.

4
Q

Why would FM PA in a code 4 patient be useful?

A
  1. Identifies predisposing factors.
  2. Detects early to moderate bone changes where treatment can preserve dentition.
  3. Approximates the amount of bone loss and its location.
  4. Helps in evaluating the prognosis of affected teeth and the restorative needs of those teeth.
  5. Serves as baseline data and as a means of evaluating post treatment results.
  6. A record for medico-legal purposes.
5
Q

What is meant by triangulation of the periodontal membrane?

A

Break in the contiguity of the lamina dura and the mesial/distal aspect of the crest of the interdental septum.

Widening of the periodontal membrane space at the crest of the interproximal septum.

Earliest disease up to 1/3 bone loss

6
Q

What are the radiographic signs of moderate periodontal disease?

A

-Between 30-70% bone loss
-Bone loss shows up in both horizontal and vertical planes
Radiolucency’s can appear in the furcation of multirooted teeth indicating bone loss.

7
Q

What is horizontal bone loss?

A

Resorption that occurs in a plane parallel to a line drawn between the CEJ on adjoining.

8
Q

What is vertical bone loss?

A

Resorption of one tooth root sharing the septum is greater than the other, the infra-bony pocket.

9
Q

Can bone loss regenerate?

A

Horizontal cannot but vertical defects can infill and level out.

10
Q

What are the radiographic signs of advanced disease?

A
  • Bone loss greater than 70%
  • Furcation involvement
  • Thickened and widened periodontal membranes.
  • Indication of changes in tooth position.
11
Q

How much demineralisation is of the tooth is needed before the lesion is visible on a radiograph?

A

40%

Caries is always more advanced clinically than radiographically.

12
Q

What is meant by radiographic sensitivity?

A

Proportion of true positives that are correctly identified by a test.

13
Q

What is meant by radiographic specificity?

A

Proportion of correctly identified true negative results.

14
Q

What is the Mach Band effect?

A

Optical illusion - where the different radio-densities of of enamel and dentine detects a shadow between them which is not there.

Reduction in specificity - false positive result.

15
Q

What is cervical burnout?

A

Illusion of radiolucency at the neck of the tooth where there’s thinner dentine which appears very dark compared to adjacent enamel and alveolar bone.
Overexposed radiographs show more cervical burn out.

16
Q

What is condensing osteitis?

A

Perapical inflammatory disease as a reaction to dental infection causing more bone to be produced than destroyed.

17
Q

What are the FGDP guidlines for high risk patients?

A

6 monthly posterior bitewings taken until no new lesions apparent.

It is imperative to justify using this interval by assessing caries risk.

18
Q

What are the FGDP guidlines for moderate caries risk patients?

A

Annual posterior bitewings

19
Q

What are the FGDP guidlines for low caries risk patients?

A

12-18 month for primary dentiton

2 year intervals in permanent dentition. (More extended interval may be appropriate if continuing low caries risk.

20
Q

What is the principle of Parallax?

A

Two or more films taken to identify the exact location of structures.
-Second radiograph taken and x-ray tube moved distally (to right) by 0.1 FFD. Central is then directed through the original centering point.
If object moves in SAME= the ibject is lying LINGUALLY. If object moves in the OPPOSITE = BUCCALLY

21
Q

Why is parallax used?

A
  • Determine position of unerupted tooth
  • Localising foreign bodies
  • Assessing the relative position of structures within close proximity of each other.