Microbiology for dentists theme 2b Flashcards
What is the DMFT index ?
Measure of the decayed, missing and filled tooth surfaces
cumulative caries and treatment experience
How do we measure the DMFT index ?
if a tooth is decayed, missing or filled it gets a score of 1
otherwise 0
score out of 32 if 8s present
What does the DMFT index exclude ?
teeth that are congenitally missing
teeth extracted for ortho/perio reasons
trauma
supernumerary teeth
If a tooth is decayed and filled which score would you give it ?
1
What are limitations of the DMFT index ?
gives equal weighting to missing, untreated and well restored teeth
only takes into account caries
fissure sealants given same weighting as restored teeth
rate not assessed nor risk
Which plaque index is most used ?
Plaque coverage index
What are some examples of plaque indices ?
Silness and Loe index
plaque coverage index
What does the plaque index measure ?
the number of surfaces with plaque as a percentage of total tooth surfaces
How do we carry out the plaque coverage index ?
divide tooth into 6
say yes or no
cross out missing teeth
dont measure occlusal surfaces
Which 6 surfaces would a mandibular tooth be divided into ?
MB Mid buccal DB ML Mid lingual DL
In what order should you measure the plaque ?
UB
UP
LB
LL
How would you calculate the plaque coverage index ?
total number of surfaces = number of teeth x 6
count all plaque surfaces
number of plaque surfaces/ total number of tooth surfaces x 100
What are disclosing tablets ?
veegtable dye used to stain plaque deposits
older tablets stain all plaque pink
new tablets stain new plaque pink and old plaque blue
What does the Silness and Loe index measure ?
the amount of plaque on surfaces
Which scores are used in the SL index ?
0- no plaque
1- film of plaque visibe only by removal
2- moderate accumulation visible by naked eye
3- Heavy accumulation
How would you calculate the SL index ?
Add up all scores
total number of surfaces
Total S and L score/ total surfaces x 100
What is epidemiology ?
the scientific method of studying diseases in populations
What are the 3 components of epidemiology ?
distribution
frequency
determinants
What is the process of finding a relationship ?
suspicion hypothesis tested with comparison group analyse data assess validity
What is the gold standard for measuring disease ?
is the method of measuring valid, simple, reliable and reproducible ?
What is the difference between DMFT and dmft ?
permanent and primary dentition
What do indices allow ?
standardisation universally
What does reliable mean ?
get the same result each time
What does reproducible mean ?
calibrated
What does sensitive mean ?
detect minute changes
Why do methods of maesuring disease have to be acceptable ?
they need to be done correctly to reduce chances of iatrogenic damage
What are case studies for ?
highlighting interesting cases
in recognition of a new disease
there is no control- so no comaprsion which can effect validity of the relationship
What is a case series ?
a report on a single patient or series of patients with an interest
no control group is required
What are the limitations of case studies ?
they might be standalone cases
cant compare and make links and prove
What is a cross sectional study ?
used for prevalence of disease
can find out potential risk factors
can establish an association and not a causality
observation of a population in a single point in time
What are cohort studies ?
2 groups side by side one with exposure and one without assess the results in time later use for common diseases blinding is difficult not good for rare diseases
What are randomised controlled trials ?
evaluate the effectiveness of something like a drug
2 groups- one receives treatment the other a placebo (current best)
very expensive
randomisation used for selection bias
high cost and ethical issues
What are systematic reviews ?
pool all studies and give an average result - uses exclusion and inclusion criteria asses the strength of the evidence end confusion highlight when not eniugh evidence save money by saying research is done
Epidemiology in dentistry operates in which 3 broad fields ?
- measurement of dental disease among groups to understand distribution
- identification of factors that cause conditions
- evaluation of effectiveness of new materials
What does reliable mean ?
measurements are taken on different occassions the same answer is obtained
What are descriptive studies ?
describe the pattern of disease
risk factors
dterminants
What are analytical observational studies ?
go back in time or forwards- retrospective or prospective
What are case control studies ?
people with the interest identified
matched with controls
questioned about what risk factors could have led to condition
What are analytical experinental studies ?
randomised clinical trials
What is prevalence ?
proportion of individuals in a population who have a disease at a specific instant
How do you work out prevalence ?
number of existing cases of disease/ total population
What does prevalence provide ?
an estimate of probability an individual will be ill at any time
What is incidence ?
number of new cases of disease during a given time period
What is cumulative incidence ?
number of new cases of a disease during a given time period/ total population at risk
How do you work out incident rate ?
number of new cases of disease during a given time period/total person time observation
How can you work out person time ?
addition of all the hours that everyone contributes
What is an index ?
measures the relative disease status of a population on a graudutsed scale with definite upper and lower limits
What do indices allow ?
allow comparison with other populations- universal
evaluate success of a treatment
compare health status
What are the characterisitics of an ideal index ?
equally sensitive
simple to apply
valid
reliable
What does valid mean ?
it measures what it says it measures
What is bias ?
a systematic error relating to the measurement of a variable
were the groups similar at the start, were they balanced and effectively masked ?
What is confounding ?
an error in the interpretation of a measurement
eg. saying things are linked when they are not
How can we manage confounding ?
randomisation
stratifying
matching
using statistical analysis
What is the dmft index ?
for the primary dentition
What is the DMFT index ?
for the permanent dentition
What is the IOTN ?
index of orthodontic treatment need
What is RCI ?
root caries index
What are problems with the DMFT ?
missing teeth could have been perio, developmental or trauma
filled teeth might be for prevention and not caries
score is irreversible- cant be used to show improvement
