PCD 8117 Study Guide - Final Guide: Microscope Slide, Net Present Value, Chlorhexidine
3 Jan 2020
School
Department
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assessment models that examine multiple variables.
alone does not predict caries risk as well as risk
SM/LB
Snyder test
Specificity
Sensitivity
Lecture #6 - Caries Activity Tests
1.
Understand the rationale for employing caries risk assessment.
o Dental preventative care is mostly non-specific.
o However, if you can predict caries risk, then you can tailor preventative treatment
to individual risk.
▪
Reinforce diet/hygiene recommendations and consider clinical measures.
2.
Understand the concepts behind sensitivity, specificity, and predictive values as they
apply to diagnostic tests.
o – detects disease, avoids false negatives
▪
# true positives / total number of those with disease
▪
▪
People are sensitive about having a disease
o – detects health, avoids false positives
▪
# true negatives / total number without disease
▪
o PPV = # true positives / total # of positive tests
o NPV = # true negatives / total # of negative tests
o In general, as sensitivity is increased, specificity will drop.
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If you want to ensure that you don’t miss anyone with a disease (avoid
false negatives), you’ll get more false positives.
▪
Even the best diagnostic tests will have sensitivity and specificity less than
1.0 (100%)
3.
Understand how the current caries activity tests work and develop and appreciation
for their utility and limitations.
o 1940’s –
o
slide.
for
– colorimetric assay to determine LB in saliva.
– culture method with selective medium on microscopic
▪
Used to estimate levels of SM or LB assuming salivary levels = plaque
levels/caries risk.
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Limitations – not all caries have high levels of SM/LB. MS/LB levels
aren’t high until shortly before caries develop. Pathology is also site-
specific, whereas the sampling is not.
▪
Summary: microbiology based tests may correlate with future caries risk,
but are better at predicting future health (than future caries).
o Using micro-tests alone provides limited accuracy. Moderate accuracy with multi-
variate models.
o Screening for microbiology
o Multi-variate models – combine measurements from multiple parameters to
evaluate risk.
Dip-slides
TN / TN + FP
TP / TP + FN
Document Summary
Tp / tp + fn: # true positives / total number of those with disease, people are sensitive about having a disease. Specificity: # true negatives / total number without disease. Tn / tn + fp: ppv = # true positives / total # of positive tests, npv = # true negatives / total # of negative tests, in general, as sensitivity is increased, specificity will drop. 1. 0 (100%) for their utility and limitations: 1940"s . Colorimetric assay to determine lb in saliva. Culture method with selective medium on microscopic: used to estimate levels of sm or lb assuming salivary levels = plaque, limitations not all caries have high levels of sm/lb. Ms/lb levels aren"t high until shortly before caries develop. Pathology is also site- specific, whereas the sampling is not: summary: microbiology based tests may correlate with future caries risk, but are better at predicting future health (than future caries). variate models, using micro-tests alone provides limited accuracy.
