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1. GOOD MORNING

2. GUIDED BY,
 DR.LALIT MATHUR
 DR.BALAJI MANOHAR
 DR.RAJESH PILLAI
 DR.RAVIKIRAN N
 DR.NEEMA SHETTY
 DR.ADITI MATHUR
 DR MEETU JAIN
 DR. BARKHA MAKHIJANI

3. It doesn't matter how beautiful
your theory is,
what matters is how smart you are…

4. 1. Introduction
2. Definitions
3. History
4. Aims Of Epidemiology
5. Ultimate Aim
6. Objectives
7. Definitions
8. Bias - Definition
9. EPIDEMIOLOGY OF PERIODONTITIS (elaborated)
10. Sensitivity & Specificity
11. EPIDEMIOLOGICAL STUDY DESIGN
12. EPIDEMIOLOGICAL TRIAD
13. WHAT IS A PERIODONTAL DISEASE ?
14. RATE OF BONE LOSS
15. HOW IS PERIODONTITIS MEASURED ?
16. EPIDEMIOLOGICAL STUDIES
17. PREVALENCE OF PERIODONTAL DISEASES IN INDIA
18. Conclusion
19. references

5. Ever since the Beginning of this Universe, mankind
has struggled constantly against disease and the
struggle is never ending. Continuously, day by day,
new Diseases & health Problems come into
existence which needs discovery of basic facts
about the disease & the curative as well as
Preventive measures in pursuit of its eradication.
An aggressive approach towards all this achieved by
“Epidemiology”

6. That Branch of medical Science which treats epidemics.
(Thomas Parkin, 1873)
The science of the mass phenomena of infectious diseases.
(Frost, 1927)
The study of the distribution & determinants of disease
frequency in man.
(MacMohan, 1960)
The study of the distribution & determinants of health related
states or events in specified populations, and the
application of this study to the control of health problems
(John M. Last, 1988)

7. 1) THOMAS SYDENHAM (17th Century)
- Founder of Epidemiology
- History Of Disease
2) JOHN SNOW (1854)
-Father Of Epidemiology
3) WILLIAM BUDD (1811-1880)
-Physician & Epidemiologist
-Pioneer in The isolation of Infectious Diseases
4) W.H. FROST
First Professor of Epidemiology (U.S.)

8. 1) To describe the distribution & magnitude of
Health disease problems in Human
populations.
2) To Identify aetiological factors in the
pathogenesis of disease.
3) To provide the data essential to the
planning, implementation & evaluation of
Services for the prevention, control of
treatment of disease and to the setting up of
priorities among those services.

9. 1) To eliminate or reduce the health
problem or its consequences.
2) To promote Health & Well Being of
society as a whole.

10. 1) To identify the etiology or the cause of a disease
and the risk factors.
2) To determine the extent of disease found in the
community.
3) To study the natural history & prognosis of
disease.
4) To evaluate new preventive & therapeutic
measures and new modes of Health Care
delivery.
5) To provide the foundation for developing policy
& regulatory decisions relating to environmental
problems.

11.  Prevalence : Prevalence is the proportion of persons
in a population who have the disease of interest at a given point
in or period of time.
It is calculated by dividing the number of persons in the population
who have the disease, by the number of persons in the
population.
Information about Prevalence can be useful
for estimating the need for health care resources. For example,
Prevalence data on dental disease are used for estimating the
number of new general dentists and specialists that dental
school should train.
Carranza (10th Edition)

12.  Incidence :
(also referred as risk or cumulative incidence)
It is the average percentage of unaffected persons who will develop the
disease of interest during a given period of time.
Incidence can be viewed as the risk or probability that a person will
become a case.
It is calculated by dividing the number of new cases of disease by the
number of persons in the population who are at risk for the disease.
(Carranza, 10th Edition)

13.  Probing Pocket Depth :
Distance from the gingival margin to the location of the tip of a
periodontal probe inserted in the pocket with moderate probing
force
 Probing Attachment Level (PAL)
Or
Clinical Attachment Level (CAL) :
The distance from the Cemento – Enamel Junction (CEJ) to the
location of the inserted probe tip is known as Probing Attachment
Level (PAL) or Clinical Attachment Level (CAL).

14. Chronic periodontitis is the most common form
of destructive periodontal diseases and shows a
slow disease progression characterized by
bursts of disease activity separated by quiescent
periods of varying durations.
Aggressive periodontitis encompasses aggressive,
rapidly progressive forms of periodontitis,
which often commence during adolescence and
early adulthood.
Pre-pubertal periodontitis, juvenile periodontitis
& rapidly progressive periodontitis all are
considered forms of aggressive periodontitis.

15. When a diagnostic test for a disease or condition gives a Positive result,
the result can be correct (true positive) or incorrect (false positive).
When a test gives a negative result, the result can be true (true negative)
or false (false negative) (as shown in Table 1).
The ability of a test to give a correct answer is indicated by its Sensitivity
and Specificity.
(Carranza 10th Edition)

16. A
(True Positive)
B
(False Positive)
C
(False Negative)
D
(True Negative)
A ÷ (A+C)
D ÷ (B+D)
A ÷ (A+B)
D ÷ (C+D)

17. Sensitivity :
Sensitivity of a Test is the Proportion of subjects with the disease who test
positive.
A highly sensitive test is unlikely to be negative when someone has the
disease.
The clinician should choose a highly sensitive test when the consequences
of not identifying a person with a disease could be severe, such as
during testing for Human Immunodeficiency Virus (HIV).
Specificity :
The specificity of a test is the proportion of subjects without the disease
who is negative.
A highly specific test is unlikely to be positive when a person does not have
the disease.
Specific tests are especially indicated when the misdiagnosis of disease in
the absence of disease could harm a person emotionally, physically, or
financially.

18. STUDY DESIGN
EXPERIMENTAL
A.) COMMUNITY INTERVENTION
TRIALS
B.) RANDOMIZED CLINICAL TRIALS
C.) FIELD TRIALS
OBSERVATIONAL
ANALYTICAL
1.CASE CONTROL
2.COHORT
3.CROSS SECTIONAL
4. ECOLOGICAL
DESCRIPTIVE

19. 1. Usually the first phase of an epidemiological investigation.
2. Concerned with observing the distribution of disease or health
related characteristics in human population & identifying the
characteristics with which the disease in question seems to be
associated.
The various procedures involved are:
a) Defining the population to be studied
b) Defining the disease under study
c) Describing the disease by time, place and person
d) Measurements of disease
e) Comparing with known indices
f) Formulation of an etiological hypothesis

20. 1 EXPOSURE &
OUTCOME
HAVE
OCCURRED
BEFORE
START OF
STUDY
3. IT USES A
CONTROL OR
COMPARISSION
GROUP TO
SUPPORT OR
REFUTE AN
INFERENCE
2. THE
STUDY
PROCEEDS
BACKWARDS
FROM EFFECT
TO CAUSE

21. Major advantages & disadvantages of
case-control study
ADVANTAGES DISADVANTAGES
May study several exposures. Potential bias from sampling two
populations
Short duration Does not establish sequence of
events
Relatively inexpensive Potential bias in measuring
predictors
Relatively small Potential survivor bias
Yields odds ratio (measure of
association)
Does not yield incidence or true
relative risk (measure of
association)

22. Major advantages & disadvantages of cross-sectional study
ADVANTAGES DISADVANTAGES
May study several outcomes Not feasible for rare diseases
Short duration Does not establish
sequence of events
A good first step for a cohort
Potential survivor bias
study
Potential survivor bias
Yields prevalence Does not yield incidence or true
relative risk (measure of association)

24. Major advantages & disadvantages of
experimental study
ADVANTAGES DISADVANTAGES
Can produce the strongest evidence
for cause and effect
Costly in time and money
Only possible design for some
research question (new drug)
Many research questions are not
suitable: ethical barriers or
outcome too rare
Can sometimes be faster and
cheaper
Reduced generalizability
(standardized interventions may
be different than common
practice)
Tend to restrict the scope and
narrow the study question

25. • It is a prospective study.
• A group of people are observed over a period of time,
during which some of the group develops the disease
under study & some do not.
• “Cohort” is a group of persons who share a common
experience within a defined time period ; for example,
age ,occupation , pregnancy, etc.
• The association between exposure & disease outcome
can then be determined.

26. Major advantages & disadvantages of cohort
study
ADVANTAGES DISADVANTAGES
Establish sequence of events Often requires large sample sizes
Avoids bias in measuring predictors Not feasible for rare diseases
Avoids survivor bias Expensive
Can study several outcomes Long duration
More control over selection of
subjects
More control over measurements
Yields incidence, relative risk
(measure of association)

27. Strengths in Cohort vs. Case-control?
Cohort study Case-control study
Rare exposure Quick & inexpensive
Examine multiple effects of a
single exposure.
Well-suited to the evaluation of
diseases with long latency
Period.
Minimizes bias in the
exposure determination.
Rare diseases.
Direct measurements of
incidence of the disease.
Examine multiple etiologic
factors for a single disease.

28. Limitations in Cohort vs. Case-control?
Cohort study Case-control study
Not rare diseases Not rare exposure
Prospective: Expensive and
time consuming
• Incidence rates cannot be
estimated unless the study is
population based
Retrospective: inadequate
records
Selection Bias and recall bias
Validity can be affected by
losses to follow-up

30. Gingivitis
Periodontitis
PERIODONTAL
DISEASES

31. GINGIVITIS :
“Inflammation Of Gingiva”
It is the inflammation of the Gingiva in which the
junctional epithelium remains attached to the tooth
at its original level.
PERIODONTITIS :
It is the inflammatory process which involves the
Gingiva and the periodontium & loss of periodontal
attachment has occurred.
(Jan Lindhe 5th Edition)

32. comes from “Greek” word :
peri – ‘around’
odous – ‘tooth’
(genitive - odontos)
Suffix – itis
And in Medical Terminology : “Inflammation”
Periodontitis/Pyorrhoea :
It is a Set of inflammatory diseases affecting the
periodontium, i.e. Tissue that surrounds & support the
teeth.
Periodontitis involves progressive loss
of the alveolar Bone around the teeth, and if left untreated,
can lead to the loosening & subsequent loss of teeth.

33. ETIOLOGY
LOCAL
FACTORS
SYSTEMIC
FACTORS

34. A) LOCAL FACTORS :
1) Plaque
2) Calculus –
a) Supra-Gingival Calculus
b) Sub-Gingival Calculus
3) Materia Alba.
4) Faulty Dentistry.
5) Abnormal Habits.
6) Food Impactions.
7) Diet.
8) Improper Tooth Brushing.
9) Abnormal Anatomy.
10) Erupting teeth.
11) Factors of Occlusal Functions.

35. B) SYSTEMIC FACTORS :
1) Nutrition.
2) Vitamins.
3) Protein Deficiency.
4) Blood Dyscrasias.
5) Endocraniological Disorders.
6) Pituitary Disorders.
7) Allergies
8) Drug Idiosyncrasies.
9) Radiations.
10) Psychogenic Factors.

36. Loe and associates in 1986 did a study on Sri Lankan tea
labourers with no oral hygiene and no dental care and
found that the rates of bone loss on an average to be
about 0.2 mm a year for facial surfaces and about 0.3
mm a year for proximal surfaces, when periodontal
disease is allowed to progress untreated.

37. However, the rate of bone loss may vary, depending on the type of
disease present.
Löe et al identified the following three subgroups of patients with
periodontal disease based on interproximal loss of attachment
and tooth mortality:
1. Approx. 8% of persons had rapid progression of periodontal
disease, characterized by a yearly loss of attachment of 0.1 to
1.0 mm.
2. Approximately 81% of individuals had moderately progressive
periodontal disease, with a yearly loss of attachment of 0.05 to
0.5 mm.
3. The remaining 11% of persons had minimal or no progression of
destructive disease (0.05 to 0.09 mm yearly).

38. An Epidemiologic Survey performed during the 1950s in India, used
assessments of alveolar Bone height to distinguish between
gingivitis & destructive periodontal disease, in a sample involving
1187 dentate subjects.
(Marshall Day et al 1955)
1) A 100 % occurrence of destructive periodontitis after the age of
40 yrs has been seen.
2) A decrease in the percentage of studies with “Gingival disease
without any Bone involvement” with increasing age concomitant
with an increase in percentage of subjects with “Chronic
destructive periodontal disease”
(Jan Lindhe 4th & 5th Edition)
In a study of un-referred patients to ‘Glasgow Dental Hospital,
United Kingdom’, which included :
1. Number Of Subjects : 74
2. Age : 50 yrs (30) to 73 yrs (44)

39. 3. 54 % subjects : optimum Bone Height
4. 5 % Subjects : Generalized advanced Bone Loss (defined as
bone loss in 50 % or more remaining teeth)
5. 20 % subjects : Three Quarters of the teeth with advanced Bone
loss.
Also, Findings from other epidemiologic studies from the
same period, verified a high prevalence of destructive
periodontal disease in the adult population in general,
and a clear Increase in disease prevalence with ‘Age’
(Jan Lindhe 5th Edition)

40. The model of the pathogenesis of the periodontitis in the 1950s to
1970s was predicated on the following beliefs:
1. All individuals were equally susceptible to periodontitis.
2. Long standing gingivitis invariably progresses to periodontitis
with subsequent tooth loss.
3. Susceptibility to periodontal disease increases with increasing
age.
4. Risk for periodontal disease was determined by environmental
factors alone.

41. Periodontal Index :
1) Periodontal Index (by Russell A.L. in 1970)
2) Periodontal Disease Index(by Sigurd P. RamfJord in 1959)
3) Gingival Periodontal Index (O. Leary T.J., Gibson W.A., Shannon
I.L., Schuessler C.F. & Nabers C.L. In 1963)
4) Extent & Severity Index (J.P. Carlos, M.D. Wolfe & A. Kingman in 1986)
5) Community Periodontal Index (CPI)
6) Community Periodontal Index Of Treatment
Needs (CPITN) (“Joint working committee” of the ‘World Health
Organization’& ‘Federation Dentaire’)
By Jukka Ainamo, David Barmes, George Beagrie, Terry Cutress, Jean Martin & Jennifer
Sardo-Infirri in 1982

42. For the Assessment of Plaque :
1) Oral Hygiene Index (By Vermillion & Greene in 1960)
2) Oral Hygiene Index – Simplified (Vermillion & Greene in 1964)
3) Turesky – Gilmore – Glickman Modification Of the
Quigley Hein Plaque Index (Turesky & colleagues in 1970)
For the Assessment of Calculus :
1. Calculus Surface Index (By Ennever Sturzenberger C.P. & Radike A.W. in 1961)
2. Calculus Surface Severity Index (CSSI)
(By Enneverj et al 1961)

43. National Oral Health Survey And Fluoride
Mapping (2002-2003)
 First ever National level Epidemiological Survey done in India.
 Was Conducted by : “Dental Council of India”
 Subjects taken were : 210 (rural) & 110 (urban)
 Age Groups were : 12, 15, 35-44 , 65-74 years.
 Highest Prevalence of Periodontal Disease was in 35-44 yrs ( 89.6%)
and Lowest in of 12 yrs ( 57%) subjects.
 Calculus was more than bleeding in subjects aged 15yrs and above
 Prevalence was more in males.
 Comparatively, Higher prevalence was in rural subjects.

44. PREVALENCE OF PERIODONTAL DISEASES IN
INDIA
YEAR REFERENCE AREA AGE (in Years) SAMPLE SIZE CLINICAL
PARAMETERS
RESULTS/
FINDINGS
2009 Kumar TS, Dagli RJ
et al (7)
Bhill Adults in
Southern Rajasthan
15-54 years 1590 (male)
subjects
OHI-S & CPITN Debris, calculus &
OHI-S increased
with age
Shallow pockets
were prevalent
(40%) in
35-44 years age·
Deep pockets were
common (11%) in
older
Individuals.
2009 Parmar G, Sangwan
P et al. (8) -
Mean age 32
YEARS
365 subjects :
Areca nut &
Tobacco Chewers –
168 &
Non-chewers – 197
OHI-S & Clinical
examination for
ulcers and Burns
etc.
Periodontal pocket
are higher in Areca
nut & Tobacco
Chewers
2008 S Nagarajan,
Puspanjali K.
Bangalore 20-44 years 216 patients •Self administered
questionnaire
•Periodontal
examination
•Loe & Silness
CPITN
• Mobility
•Perceived
periodontal health
status was low.
•The awareness
increased with
increasing severity
of the disease
2008 Kumar S,
Dagli RJ et al (15)
Rajasthan 18-25 years
26-34 years
35-44 years
45 year and above
513 (male)
subjects
•WHO oral health
assessment form.
•Clinical
examination by
method by WHO
oral health survey
•Prevalence was
98.2%
•Prevalence
increased with
increasing age.
•Maximum disease
was present in
35-44 -45 years of
age.
•On an average 0.4%
sextant having deep

45. YEAR REFERENCE AREA AGE (in Years) SAMPLE SIZE CLINICAL
PARAMETERS
RESULTS/
FINDINGS
2007 Vandana KL,
Sesha Reddy
M (17)
Davanagere
distt.
15-74 years 1029 subjects •CPITN
•OHI-S
•Jackson’s
Fluorosis
index
1)With increasing
age gingivitis
reduce from
85% to 42.9%
and periodontitis
increased
18% to 57%.
2) With increased
severity of
Fluorosis.
3) Severity
of gingivitis
reduced 89.4% to
64% and
periodontitis
increased from
8.5% to 35.8%.
2007 Dhar V, Jan A
et al (18)
Udaipur distt. - 1587
Government
school
children
- Gingivitis
was found in
84.37% of
children,
Malocclusion
in 36.42%
and Fluorosis
in36.36%

46. YEAR REFERENCE AREA AGE (in years) SAMPLE SIZE CLINICAL
PARAMETERS
RESULTS/
FINDINGS
2005 Kumar M,
Chandu GN et al
(22)
- -
220 Psychiatric
Patients
CPITN
OHI-S
DMFT
Lower prevalence of caries
with poor oral hygiene &
extensive Needs for dental
Treatment
2005 GPI Singh,
J Bindra et al.
(23)
Ludhiana
- 1000 subjects
•500 : Rural
•500 : Urban
Assessment
according to
WHO
2005 Sood .M. (24) Ludhiana - 1000 subjects
•500 : Rural
•500 : Urban
•Assessment
according to
WHO
•Oral Health
assessment
Form
Periodontal disease
prevalence as well as
severity was more in
Smokers & Coronary
artery Disease
Patients.
RESULT URBAN RURAL
Bleeding 68.8% 69.2%
Calculus 96.8% 97.2%
Shallow
Pockets
42.3% 31.7%
Deep
Pockets
22.9% 11.0%

47. YEAR REFERENCES AREA AGE (in Years) SAMPLE SIZE CLINICAL
PARAMETERS
RESULTS/FINDINGS
1997 Alexandra S. et
al (33)
Mysore 7-17 years 817 (Tibetan
School Children)
•Bleeding
•Calculus
•Malocclusion
•Malocclusion &
Calculus were
more in Girls.
•Significantly,
Increase in
Bleeding among 8-
13 yrs & 17 yrs old
Girls than Boys
1993 Rao .S.,
Homagain .S.
(44)
Adult rural
Community
20-64 years 575 Subjects CPITN High Prevalence of
periodontal
diseases – 99.6%
Greater Treatment
Needs in Males
than in Females.
1990 Anil S., Hari S et
al (49)
Trivandrum distt.,
Kerala
•15-19 years
•25-29 years
•35-44 years
2756 (subjects)
Male : 1354
Female : 1402
CPITN •15-19 yrs age group
:Calculus &
Bleeding was
common (86%)
•25-29 yrs age group
: Calculus & shallow
pockets (80%)
•35-44 yrs :
Calculus & Deep
Pockets (33%)

48. • Periodontal diseases are one of the more prevalent oral diseases affecting more than
50% of Indian community.
• Untreated chronic periodontitis is responsible for tooth loss in majority of the cases.
• Constant presence of chronic inflammation and inflammatory mediators has also
been proved to be a significant risk factor of several systemic diseases e.g. preterm
low birth weight babies, coronary artery diseases, diabetes mellitus etc.
• Foreseeing the bad effects of periodontal diseases on oral as well as general health,
the prevention of these diseases should be included in national health programme
and national oral health survey should be conducted to get meaningful data for
different oral diseases and plan around preventive/curative measures.

49. • Fermin A. Carranza (10th Edition)
• Journals Of Periodontology, 1999
• Jan Lindhe (4th & 5th Edition)
• Journals Of Periodontology, 1998; Volume 16; Epidemiology of periodontal
disease among older adults
• Journals Of Periodontology; 2001, June 2001; Vol. 26 Issue 1.
• Soben - peter
• JOHCD Prevalence of Periodontal Diseases in India
• Journal of Indian Society Of Periodontology
• JOP (Journals Of Periodontology) 2005
• J Int. Acad Periodontol; PMC 2006 January 25
• Indian Journal of Community Medicine 2005-10-2005-12;30(4)
• Indian Journal of Community Medicine 2005-04-2005-06;30:2
• Indian J Dent Res 2003;14(4):289-297
• J Indian Soc Pedod. Prev. Dent 1997;15(4):114-117