caries specificity and sensitivity

[Guest guest]

hi everyone... i found the following related to caries sensitivity and specificity on which there were a few questions in september 2010 part 1 exam. 

DiagnosisRelative Merits of Diagnostic Tests for CariesTests for caries display both Sensitivity and Specificity. These are important concepts to understand when you are trying to make sense of clinical findings. They tell you how much you can trust what you think you see.

What is Sensitivity ?  

 The percentage of Diseased sites correctly diagnosed.

Score yourself:

0

1What is Specificity?  

 The percentage of Healthy sites correctly diagnosed. 

Score yourself:

0

1 A test can have four outcomes. What are they ? 

 

a true negativeb false negativec false positived true positive. 

Score yourself:

0

1

2

3

4 How to calculate the values:

Sensitivity = True Positives / All Positives.

Specificity = True Negatives / All Negatives.

How does this affect you and your patient?If you did a test for caries which was positive, then prepared the tooth and found there was indeed caries, this is atrue positive. The patient has received the correct treatment, and you have served them well.

What would happen with a false positive ?  

 You would drill into your patient, and find no caries. They would have received an unnecessary filling.

Score yourself:

0

1 What would happen with a false negative ? 

 

 You would not restore the tooth, despite there being caries. The patient may return a couple of years later with gross caries, and need an extraction.

Score yourself:

0

1Which is worse - an unnecessary filling, or leaving untreated caries? 

 

 Neither are really a good idea. We need tests that are both Sensitive AND Specific.If you enforce an appropriate continuing care policy, caries you miss at one visit will be picked up later.

However, once you have placed an unnecessary filling, that tooth will need repeat treatments for the rest of the patient's life.

Score yourself:

0

1

2 Sensitivity & Specificity of current diagnostic tests for caries detection

Below is a table that illustrates the Sensitivity and Specificity for the various methods of detecting caries. It should be evident that more than one test is often needed to be sure of a correct diagnosis.

Also, there is no combination of tests that can make you 100% sure of your diagnosis.

Test Sensitivity 

SpecificityVisual 0.38 

0.99Transillumination0.67 

0.97Radiographs 0.59 

0.96Laser Fluorescence0.80

0.80Electrical Conductance0.90

0.75(figures are averages of many studies)The interesting thing about these figures is - there are times that you can be certain a tooth has caries (we all know that). But you can never be certain a tooth does NOT have caries. An electrical conductance meter is the best bet when trying to be sure that a tooth is caries free. However, very few dentists use them...

Take a few moments to go through this again, to be certain you understand the implications.Criteria for visual examination of fissure caries

Grade 0: No or slight change in enamel translucencyGrade 1: Opacity or discolouration hardly visible (wet) but distinctly so after drying surface

Grade 2: Opacity or discolouration distinctly visible without air dryingGrade 3: Localized enamel breakdown in opaque or discoloured enamel and / or grey discolouration from the underlying dentine

Grade 4: Cavitation in opaque or discoloured enamel exposing the dentineWhite spot lesions are more obvious on dry tooth surfaces. Why is this?  

It's to do with the refractive index (RI):The reduced RI of a white spot is what makes it appear different.Sound enamel has a RI of 1.62.

White Spot caries has a RI of 1.33.However, water also has a RI of 1.33, masking the appearance of the white spot.When dry, because air has a RI of 1.0, the difference between Sound and Carious enamel is easier to see.

regardsjasmine

[Guest guest]

THAT IS EXCELENT EXPLANATION JASMIN!

THANK YOU !

VERA

From: jasmine chopra <contactjasmine288@...> ; dentaljournalclub Sent: Sat, 8 January, 2011 17:09:54Subject: caries specificity and sensitivity

hi everyone... i found the following related to caries sensitivity and specificity on which there were a few questions in september 2010 part 1 exam.

DiagnosisRelative Merits of Diagnostic Tests for Caries

Tests for caries display both Sensitivity and Specificity. These are important concepts to understand when you are trying to make sense of clinical findings. They tell you how much you can trust what you think you see.What is Sensitivity ?

The percentage of Diseased sites correctly diagnosed.

Score yourself:

0

1

What is Specificity?

The percentage of Healthy sites correctly diagnosed.

Score yourself:

0

1

A test can have four outcomes. What are they ?

a true negativeb false negativec false positived true positive.

Score yourself:

0

1

2

3

4

How to calculate the values:

Sensitivity = True Positives / All Positives.

Specificity = True Negatives / All Negatives.

How does this affect you and your patient?

If you did a test for caries which was positive, then prepared the tooth and found there was indeed caries, this is atrue positive. The patient has received the correct treatment, and you have served them well.

What would happen with a false positive ?

You would drill into your patient, and find no caries. They would have received an unnecessary filling.

Score yourself:

0

1

What would happen with a false negative ?

You would not restore the tooth, despite there being caries. The patient may return a couple of years later with gross caries, and need an extraction.

Score yourself:

0

1

Which is worse - an unnecessary filling, or leaving untreated caries?

Neither are really a good idea. We need tests that are both Sensitive AND Specific.If you enforce an appropriate continuing care policy, caries you miss at one visit will be picked up later.However, once you have placed an unnecessary filling, that tooth will need repeat treatments for the rest of the patient's life.

Score yourself:

0

1

2

Sensitivity & Specificity of current diagnostic tests for caries detectionBelow is a table that illustrates the Sensitivity and Specificity for the various methods of detecting caries. It should be evident that more than one test is often needed to be sure of a correct diagnosis.Also, there is no combination of tests that can make you 100% sure of your diagnosis.

Test

Sensitivity

Specificity

Visual

0.38

0.99

Transillumination

0.67

0.97

Radiographs

0.59

0.96

Laser Fluorescence

0.80

0.80

Electrical Conductance

0.90

0.75(figures are averages of many studies) The interesting thing about these figures is - there are times that you can be certain a tooth has caries (we all know that). But you can never be certain a tooth does NOT have caries. An electrical conductance meter is the best bet when trying to be sure that a tooth is caries free. However, very few dentists use them...Take a few moments to go through this again, to be certain you understand the implications.

Criteria for visual examination of fissure caries

Grade 0: No or slight change in enamel translucencyGrade 1: Opacity or discolouration hardly visible (wet) but distinctly so after drying surfaceGrade 2: Opacity or discolouration distinctly visible without air dryingGrade 3: Localized enamel breakdown in opaque or discoloured enamel and / or grey discolouration from the underlying dentineGrade 4: Cavitation in opaque or discoloured enamel exposing the dentineWhite spot lesions are more obvious on dry tooth surfaces. Why is this?

It's to do with the refractive index (RI):The reduced RI of a white spot is what makes it appear different.Sound enamel has a RI of 1.62.White Spot caries has a RI of 1.33.However, water also has a RI of 1.33, masking the appearance of the white spot.When dry, because air has a RI of 1.0, the difference between Sound and Carious enamel is easier to see.

regards

jasmine