Evidence based dentistry

Question 1

NNT

Answer 1

number needed to treat - in order to have an impact on one

numerically calculated by 1/ absolute risk

Question 2

risk ratio

Answer 2

risk in intervened group / risk in control group

Question 3

value of no difference

Answer 3

no difference in results between placebo and test subject
when analysing risk ratios (division sum) VND = 1
when analysing risk differences (subtraction sum) VND = 0

Question 4

confidence intervals

Answer 4

have an upper and lower limit and help to quantify the level of uncertainty
If confidence intervals overlap the VND it shows there is insufficient evidence for treatment , if it doesn’t overlap then there is sufficient evidence showing success of treatment

Question 5

case report / case series

Answer 5

report on single ptx or a series of ptx with an outcome of interest
no control group involved

Question 6

cross sectional study

Answer 6

observation of a defined population at a single point in time
used to measure prevalence of disease and potential risk factors

Question 7

case control study

Answer 7

study group of people with disease and a group of people without
looks for potential causes of disease
works backwards to investigate if cause of concern is present
e.g are teenagers with cross bite more likely to develop TMJ disorders , groups would be those with TMJ disorders and those without THEN identify who has cross bite occlusion

Question 8

cohort study

Answer 8

group of individuals followed over a period of time and exposures e.g smoking are measured and development of any diseases are monitored
used to study incidence of disease and cause of disease
very expensive and time consuming

Question 9

randomised control trials

Answer 9

ptx randomly allocated into placebo and intervention groups and monitored
gold standard of study
only difference between two groups in trial is treatments themselves
neither participant or assessor knows which group part of

Question 10

systematic review and meta analysis

Answer 10

all evidence from randomised controlled trials looking at a particular treatment are collected and analysed

Question 11

CONSORT guidelines

Answer 11

give guidelines for randomised controlled trials

Question 12

blinding

Answer 12

method to ensure neither clinician, ptx or analyser knows what group ptx are part of in RCTs