MJDF Dental Public Health & Evidence-Based Dentistry 3 — Questions and Answers
Question 1: What is the Cochrane Collaboration and its relevance to dental practice?
- An independent non-profit organisation producing high-quality systematic reviews — Cochrane Oral Health publishes reviews directly relevant to clinical dentistry (Correct answer)
- A pharmaceutical regulatory body
- A UK government dental advisory group
- A professional dental organisation like the BDA
Correct answer: An independent non-profit organisation producing high-quality systematic reviews — Cochrane Oral Health publishes reviews directly relevant to clinical dentistry
Cochrane is the internationally recognised source of high-quality systematic reviews; Cochrane Oral Health group produces reviews on clinical questions directly applicable to dental practice, supporting evidence-based decision-making.
Question 2: What is the definition of 'sensitivity' of a diagnostic test?
- The proportion of those who truly have the disease who test positive — TP/(TP+FN) — the test's ability to detect true disease (Correct answer)
- Proportion of true negatives among disease-free people
- The accuracy of the test
- The percentage of correct diagnoses
Correct answer: The proportion of those who truly have the disease who test positive — TP/(TP+FN) — the test's ability to detect true disease
Sensitivity = TP/(TP+FN) — a highly sensitive test correctly identifies most true disease cases; a low-sensitivity test misses cases (false negatives). High sensitivity is important when missing disease would be harmful.
Question 3: What is 'specificity' of a diagnostic test?
- The proportion of disease-free people who correctly test negative — TN/(TN+FP) — the test's ability to exclude disease (Correct answer)
- Proportion of true positives among sick people
- Same as sensitivity
- The positive predictive value
Correct answer: The proportion of disease-free people who correctly test negative — TN/(TN+FP) — the test's ability to exclude disease
Specificity = TN/(TN+FP); a highly specific test correctly excludes disease in people who do not have it, minimising false positives. High specificity is important when a false positive would lead to harmful overtreatment.
Question 4: What is the Hawthorne effect in dental research?
- Participants modify their behaviour because they know they are being observed — potential source of bias in dental clinical trials (Correct answer)
- A method of randomisation
- A type of statistical error
- A blinding technique
Correct answer: Participants modify their behaviour because they know they are being observed — potential source of bias in dental clinical trials
The Hawthorne effect is a form of reactivity bias where study participants alter their behaviour (e.g., improving oral hygiene) simply because they know they are being studied, potentially inflating intervention effects.
Question 5: What is the purpose of randomisation in a clinical trial?
- Distribute known and unknown confounding variables equally between groups, reducing selection bias — allowing causality to be inferred (Correct answer)
- Ensure equal group sizes
- Blind participants to their treatment allocation
- Ensure the study recruits from the same population
Correct answer: Distribute known and unknown confounding variables equally between groups, reducing selection bias — allowing causality to be inferred
Random allocation ensures that both measured and unmeasured confounders are distributed between intervention and control groups by chance, making the groups comparable at baseline and allowing causal inference from the results.
Question 6: What is the GRADE system used for in evidence-based dentistry?
- Grading the quality (certainty) of evidence and strength of recommendations from systematic reviews and clinical guidelines (Correct answer)
- A scoring system for dental caries
- A measure of periodontitis severity
- A grading system for dental schools
Correct answer: Grading the quality (certainty) of evidence and strength of recommendations from systematic reviews and clinical guidelines
GRADE (Grading of Recommendations Assessment, Development and Evaluation) classifies evidence quality as high, moderate, low, or very low, and recommendation strength as strong or weak, guiding clinical guideline development.
MJDF Dental Public Health & Evidence-Based Dentistry 3
What is the Cochrane Collaboration and its relevance to dental practice?