This document provides an overview of epidemiology and periodontal disease. It defines epidemiology and describes its aims, principles, approaches, tools of measurement, and study designs. Descriptive epidemiology is discussed, including defining a population, disease, and describing disease distribution. Analytical epidemiology studies like case-control and cohort studies are also summarized. Key points covered include the epidemiologic triad of agent, host, and environment, and prevalence and incidence rates.

1. EPIDEMIOLOGYOF PERIODONTAL
DISEASE
DR.AYUSHI SINGH
MDS IIND YEAR

2. CONTENTS
1. Introduction
2. Definition of Epidemiology
3. Aims of Epidemiology
4. Principles of epidemiology
5. Epidemiological approach
6. Tools of measurement in epidemiology
7. Epidemiological triad
8. Epidemiological study design
9. Risk versus prognosis
10. Prevalence of gingival disease
11. Prevalence of periodontal disease
12. References.

3. INTRODUCTION
• Epidemiology is derived from the word epidemic
epi = among;
demos = people;
logos = study .
• Epidemiology = the science which deals with what falls upon people
• The Greek physician Hippocrates has been called the ‘Father of
Epidemiology.

4. DEFINITION OFEPIDEMIOLOGY
• The World Health Organization (WHO) defines epidemiology as “the study
of the distribution and determinants of health-related states or events
(including disease) in specified populations, and the application of this study
to the control of diseases and other health problems.”
(John Last-1988)

5. AIMS OFEPIDEMIOLOGY
The International Epidemiological Association has listed three main aims of
epidemiology, which was put forward by Lowe & kostrzewski in 1973 as
follows -
1. To describe the size and distribution of the disease problems in human
populations
2. To provide the data essential for the planning, implementation &
evaluation of health services for the prevention, control & treatment of
diseases and for the setting up of priorities among those services.
3. To identify etiological factors in the pathogenesis of disease.

6. PRINCIPLES OFEPIDEMIOLOGY
The principles of epidemiology as a scientific field of science are related to
the basic principles of science. The four important principles are -
1. Exact observation (strict, vigorous, accurate, precise)
2. Correct interpretation (free from error)
3. Rational explanation (intelligent, sensible, reasonable)
4. Scientific construction (by expert knowledge & technical skill).

7. EPIDEMIOLOGICALAPPROACH
Asking questions 1-
• Related to health events—what is the event, what is its magnitude, where did
it occur, when did it occur, who are affected, why did it happen?
• Related to health action—what can be done to reduce this problem, to
prevent it, what action has to be taken by the community, health services,
other sectors, where and for whom, what resources are required, how are the
activities to be organized, what difficulties will arise and how to overcome
them?

8. EPIDEMIOLOGICALAPPROACH
Making comparison1 –
• The basic approach in epidemiology is to make comparisons and draw
inferences.
• This may be comparison of exposed and not exposed, or those having and
not having the disease.

9. TOOLS OFMEASUREMENT IN
EPIDEMIOLOGY
The most commonly used tools are1 –
• Rate
• Ratio
• Proportion

10. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
RATE –
A rate is the frequency of a disease or characteristic expressed per
unit size of the population or group in which it is observed.
A rate measures the occurrence of some particular event
(development of disease or the occurrence of death) in a population
during a given time period1.
Rate = number of events ( deaths or disease ) in a specified period X 10n
Population at risk of experiencing the event or disease .

11. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
RATIO –
• Ratio denotes the relation in size between two random quantities. In a ratio,
the numerator is not a part of the denominator.
• In simpler terms, the ratio can be expressed as the result of one quantity
divided by the other & is usually represented by the formula A:B or A/B1.
• Eg. The ratio of dentist to population in a state in India is 1:10,000 or
1/10,000 , which means that for every 10,000 people there is one dentist.

12. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
PROPORTION –
• A proportion is a ratio which expresses the relation in magnitude of a part of
the whole. In a proportion, the numerator is always a part of the denominator.
It is usually expressed in a percentage1.
Eg. The number of college students with periodontitis at a certain time X 100
The total number of students in the college at the same time

13. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
INCIDENCE -
• The number of new cases of a specific disease occurring in a defined
population during a specified period of time1.
Incidence = New cases X 1000
Population at risk
Uses of incidence rate:
• To control disease
• For research into etiology & pathogenesis, distribution of disease & efficacy
of preventive & therapeutic measures1.

14. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
PREVALENCE -
• Indicates all current cases (old & new) of a particular disease existing in a
given population at a given point in time, or over a period of time1.
• Point prevalence:
Total no. of cases at a given point in time X 100
Estimated total population
• Period prevalence:
Total no of cases during a given time interval X100
Estimated mid-interval population at risk.

15. TOOLSOFMEASUREMENTINEPIDEMIOLOGY
RELATION BETWEEN INCIDENCE & PREVALENCE
USES OF PREVALENCE
• To estimate the magnitude of health/disease problems in the community &
identify potential high risk populations
• For administrative & planning purposes eg. manpower needs, rehabilitation
facilities etc1.
Prevalence = Incidence X Duration

16. EPIDEMIOLOGIC TRIAD
• The epidemiologic triangle is a model that scientists have developed for
studying health problems. It can help us understand infectious diseases and
how they spread. The triangle has three corners2 (called vertices):
Host
Agent
Environment
Time
The epidemiologic triangle

17. EPIDEMIOLOGICTRIAD
Parts of the Epidemiologic Triangle
Vertex 1. The agent—“what”
• The agent is the cause of the disease. When studying the epidemiology of
most infectious diseases, the agent is a microbe —an organism too small to
be seen with the naked eye2.
• Disease-causing microbes are bacteria, virus, fungi, and protozoa (a type of
parasite). They are what most people call “germs.

18. EPIDEMIOLOGICTRIAD
Vertex 2. The host—“who”
• Hosts are organisms, usually humans or animals, which are exposed to and
harbor a disease. The host can be the organism that gets sick, as well as any
animal carrier (including insects and worms) that may or may not get sick.
• Although the host may or may not know it has the disease or have any
outward signs of illness, the disease does take lodging from the host. The
“host” heading also includes symptoms of the disease.
• Different people may have different reactions to the same agent. For
example, adults infected with the virus varicella (chickenpox) are more likely
than children to develop serious complications2.

19. EPIDEMIOLOGICTRIAD
Vertex 3. The environment—“where”
• The environment is the favorable surroundings and conditions external to
the host that cause or allow the disease to be transmitted.
• Some diseases live best in dirty water. Others survive in human blood. Still
others, like E. coli, thrive in warm temperatures but are killed by high heat2.
• Other environment factors include the season of the year (in the US, the peak
of the flu season is between November and March, for example).

20. EPIDEMIOLOGICTRIAD
Time -
• In the center of the triangle is time.
• Most infectious diseases have an incubation period—the time between when
the host is infected and when disease symptoms occur. Or, time may describe
the duration of the illness or the amount of time a person can be sick before
death or recovery occurs2.
• Time also describes the period from an infection to the threshold of an
epidemic for a population.

21. EPIDEMIOLOGICALMETHODS
EPIDEMIOLOGICAL
METHODS
OBSERVATIONAL
STUDIES
EXPERIMENTAL STUDIES /
INTERVENTION STUDIES
DESCRIPTIVE
STUDIES
ANALYTICAL
STUDIES RANDOMIZED CONTROL
TRIALS
CASE CONTROL
STUDIES
COHORT
STUDIES

22. EPIDEMIOLOGICALMETHODS
DESCRIPTIVE EPIDEMIOLOGY1 –
• Descriptive studies are usually the 1st phase of epidemiological
investigation.
• These studies are concerned with the distribution of diseases or health-
related characteristics in human populations and identifying the
characteristics with which the disease in question seems to be associated.
• The study describes the disease in terms of time, place and person.

23. DESCRIPTIVEEPIDEMIOLOGY
Procedures in descriptive studies are1:
1. Defining the population
2. Defining the disease
3. Describing disease in terms of - Time, Place, Person
4. Measurement of disease
5. Comparing with known indices
6. Formulating of etiological hypothesis

24. DESCRIPTIVEEPIDEMIOLOGY
1. Defining the Population to be studied –
• First step is to define the population base not only in terms of the total
number but also in terms of age, sex, occupation, cultural characters and
similar information needed for the study.
• “Defined population” can be the whole population in a geographic area, or
specifically selected group such as age and sex group, occupational groups,
school children wherever a group of people can be fairly accurately counted
and should be stable without migration.
• The defined population provides a denominator for calculating rates.

25. DESCRIPTIVEEPIDEMIOLOGY
2. Defining the disease under study Epidemiologist –
• It needs a definition that is both precise and valid to enable the
epidemiologist to identify those who have the disease from those who do not.
• He looks out for an “operational definition” that is a definition by which the
disease condition can be identified and measured in the defined population.

26. DESCRIPTIVEEPIDEMIOLOGY
3. Describing the Disease - Describing the disease by: Time, Place, Person
• Time distribution - Patterns of disease may be described by the time of its
occurrence that is by week, month, year, day of the week, etc.
Epidemiologist has identified 3 kinds of time trends in disease occurrence.
They are: Short-term fluctuations, e.g. epidemic, Periodic fluctuations,
Long-term or secular trends which imply changes in the occurrence of
disease (progressive increase or decrease) over a long period of time,
generally several years or decades.

27. DESCRIPTIVEEPIDEMIOLOGY
Place Distribution – these can be International variations, National
variations, Rural-urban differences & due to Local distributions.
Person Distribution - In descriptive studies, the disease is further
characterized by defining the persons who developed the disease by: age,
sex, ethnicity, marital status, occupation , social class, behavior, stress&
migration.

28. DESCRIPTIVEEPIDEMIOLOGY
4. Measurement of Disease - This information should be available in terms
of mortality, morbidity, disability and so on; and should preferably be
available for different subgroups of the population.
5. Comparing with Known Indices - By making comparisons between
different populations, and subgroups of same population, it is possible to
arrive at clues to disease etiology and also identify groups who are at
increased risk for certain diseases.

29. DESCRIPTIVEEPIDEMIOLOGY
6. Formulation of a Hypothesis - By studying the distribution of disease and
utilizing the techniques of descriptive epidemiology, it is possible to
formulate hypothesis relating to disease etiology. A hypothesis can be
accepted or rejected, using the techniques of analytical epidemiology. An
epidemiological hypothesis should specify—the population, specific
cause, expected outcome, dose-response relationship, and time-response
relationship. For example, the smoking of 30–40 cigarettes/day causes
lung cancer in 10% of smokers after 20 years of exposure.

30. EPIDEMIOLOGICALMETHODS
ANALYTICAL EPIDEMIOLOGY2
• Subject of interest- individual
• Object- to test the hypothesis
• Two types :
• Case control study
• Cohort study
• From each of these study one can determine :
• Whether or not a statistical association exists between a disease and a
suspected factor
• If one exists the strength of the Association.

31. EPIDEMIOLOGICALMETHODS
CASE CONTROL STUDY1
• Retrospective study
• First approach to test causal hypothesis
• Has three distinct features :
• Both exposure and outcome (disease) have occurred before the start of the
study.
• The study proceeds backwards from effect to cause
• It uses a control or comparison group to support or refute an inference

32. CASECONTROLSTUDY
Involves two populations
• Cases
• Controls
DESIGN OF CASE CONTROL STUDY
Time
Direction of enquiry

33. Cases
(those with condition)
Eg. Cases with oral cancer
Controls
(those without condition)
Eg. Those free of oral cancer
Exposed
(with characteristic or risk factor)
eg. Tobacco chewers
Unexposed
(without characteristic or risk factor)
eg. non chewers
Exposed
(with characteristic or risk factor)
eg. Tobacco chewers
Unexposed
(without characteristic or risk factor)
eg. non chewers

34. CASECONTROLSTUDY
POPULATION EXPOSED NON-EXPOSED
CASE A C
CONTROL B D
Analysis :
Exposure rates
Cases = a / a+c
Controls = b / b+d
Estimation of disease risk associated with exposure
Relative risk (rr) = Incidence among exposed × 100
Incidence among non-exposed

35. CASECONTROLSTUDY
Precautions to be taken –
• Confounding factors should be standardized by matching
• Confounding Factors: Factor which is associated with exposure & disease, &
is distributed equally in study & control groups
• Matching : Process by which we select controls in such a way that they are
similar to cases with regard to certain pertinent selected variables which are
known to influence the outcome of disease and which, if not adequately
matched for comparability, could distort the result.

36. CASECONTROLSTUDY
ODDS RATIO
• Used to calculate an association of an exposure and disease.
• Ratio of exposure among cases to controls.
• ODDS RATIO= AD / BC
RISK FACTORS CASES CONTROLS
PRESENT A B
ABSENT C D

37. CASECONTROLSTUDY
ADVANTAGES
1. Relatively easy to carry out
2. Rapid and inexpensive
3. Require comparatively few subjects
4. Particularly suitable to investigate rare diseases or diseases about which
little is known.
5. No risk to subjects
6. Allows the study of several different etiological factors
7. Risk factors can be identified. Rational prevention and control programs
can be established
8. No attrition problems, because case control studies do not require follow-
up of individuals in the future.
9. Ethical problems minimal.

38. CASECONTROLSTUDY
DISADVANTAGES
1. Problems of bias
2. Selection of an appropriate control group may be difficult
3. We cannot measure incidence, and can only estimate the relative risk rr
4. Do not distinguish between causes and associated factors
5. Not suited to the evaluation of therapy or prophylaxis of disease
6. Another major concern is the representativeness of cases and controls.

39. EPIDEMIOLOGICALMETHODS
COHORT STUDY1 -
• Also called as Prospective study /Longitudinal study /Incidence study and
Forward-looking study
Distinguishing features:
• Cohorts are identified prior to the appearance of the disease under
investigation.
• Study groups are observed over a period of time to determine the frequency
of disease among them.
• Study proceeds forward from cause to effect.

40. COHORTSTUDY
Indications
1. When there is good evidence of an association between exposure and
disease.
2. When exposure is rare, but the incidence of disease is high among
exposed.
3. When attrition of study population can be minimized.
4. When ample funds are available.

41. COHORTSTUDY
Considerations for cohort studies -
• Cohort must be free from disease under study
• Both cohort & control groups should be equally susceptible to the disease
under study
• Diagnostic & eligibility criteria of the disease must be defined beforehand
Time
Direction of enquiry

42. COHORTSTUDY
Types of Cohort studies
• Prospective cohort studies In which the disease has not yet occurred at the
time the investigation begins
• Retrospective cohort studies In which the outcome have all occurred before
the start of the investigation
• Combination of retrospective and prospective cohort studies Cohort is
identified from past records & is followed up for future assessment of
outcome

43. DESIGN OF COHORT STUDY
Population
People without the disease
Exposed Non-exposed
Disease Disease
No disease No disease

44. COHORTSTUDY
Analysis -
• Estimation of risk -
• Relative Risk (rr) = Incidence of disease among exposed / Incidence of
disease (or death) among non-exposed
• Attributable Risk = (Incidence of disease rate among exposed minus–
incidence of disease rate among non-exposed / Incidence rate among
exposed) × 100

45. COHORTSTUDY
Advantages -
• Incidence can be calculated.
• Several possible outcomes related to exposure can be studied simultaneously.
• Provide a direct estimate of relative risk.
• Dose-response ratio can also be calculated.
• Since comparison groups are formed before disease develops, certain forms of
bias can be minimized like misclassification of individuals into exposed &
unexposed.

46. COHORTSTUDY
Disadvantages
• Involve a large number of people.
• Takes a long time to complete the study and obtain results
• It is not unusual to lose a substantial proportion of the original cohort. They may
migrate, lose interest in the study or simply refuse to provide any required
information.
• There may be changes in the standard methods or diagnostic criteria of the
disease over prolonged follow-up.
• Expensive.

47. EPIDEMIOLOGICALMETHODS
EXPERIMENTAL EPIDEMIOLOGY1
AIMS:
• To provide scientific proof of etiological or risk factors which may permit
the modification or control of those diseases
• To provide a method of measuring the effectiveness & efficiency of health
services for the prevention, control & treatment of disease & improve the
health of the community
2 types
• Randomized control trials
• Non randomized or non-experimental trials

48. EPIDEMIOLOGICALMETHODS
Randomized control trials1
• Following are the steps in Randomized Controlled Trial -
• Drawing up a protocol
• Selecting reference and experimental populations
• Randomization
• Manipulation or intervention
• Follow-up
• Assessment of outcome

49. Design of randomized control trial
Select suitable population (Reference or target population)
Select suitable sample (Experimental or study population)
Make necessary exclusions
Randomize
Experimental Group Control Group
Manipulation & follow up
Assessment
Not eligible
Do not give consent

50. BASED ON RANDOMIZATION:
1. Randomized controlled trials: where randomization is used
for allocation of products and / or subjects.
2. Non-randomized or “non-experiment” or quasi-
experiment: those departing from strict randomization for
practical purposes in such a manner that non-randomization
does not seriously affect the theoretical basis of conclusions
e.g. natural experiments, water fluoridation studies.
TYPES OF RANDOMIZED CONTROLLED TRIALS

51. BASED ON STUDY DESIGNS:
• Concurrent parallel study design: In this design, comparisons are
made between two randomly assigned groups, one group exposed
to specific treatment, and the other group not exposed. Patients
remain in the study group or the control group for the duration of
the investigation.
• Factorial Design: Factorial design study may be more efficient than
a parallel design if there is an interest in studying more than one
intervention at a time. In addition to efficiency, an advantage to this
design is that one might derive suggestions of differential effect of
treatment in the presence or absence of the other treatment.

52. • Cross-over type of study designs: With this type of study design, each
patient serves as his own control. As before, the patients are randomly
assigned to a study group and control group. The study group receives
the treatment under consideration. The control group receives some
alternate form of active treatment or placebo. The two groups are
observed over time. Then the patients in each group are taken off their
medication or placebo to allow for the elimination of the medication
from the body and for the possibility of any "carry over" effect. After
this period of medication (the length of this interval is determined by
the pharmacologic properties of the drug being tested), the two groups
are switched. Those who received the treatment under study are
changed to the control group therapy or placebo, and vice versa.

53. • Split mouth design: Dental arches, quadrants, sextants, or
individual teeth within patients are randomized for treatment. Not
applicable for systemic therapies, only to evaluate site- specific
therapies. It is often seen in trials that evaluate dental filling
materials; subjects would require two similar cavities on the
opposite side before entering the trial. The test material can then be
compared in the same environment as the control material.

54. BASED ON USES:
• Clinical trials
• Preventive trials
• Risk factor trials
• Cessation experiment
• Trial of etiological agents
• Evaluation of health services
• Community intervention trials

56. EPIDEMIOLOGICALMETHODS
DIAGNOSIS - Practitioners use diagnostic tests to increase the probability of
making correct diagnosis.
SENSITIVITY2
• The sensitivity of a test is the proportion of subjects with the disease who test
positive
• Sensitivity = No. of subjects who test positive
No. of subjects with disease

57. SENSITIVITY
• Highly sensitive test - unlikely to be negative when someone has the disease
(false negative).
• Choose a highly sensitive test when the consequences of not identifying a
person with a disease could be severe e.g HIV infection

58. EPIDEMIOLOGICALMETHODS
SPECIFICITY2
• The specificity of a test is the proportion of subjects without the disease who
test negative.
• Specificity = No. of subjects who test negative
No. of subjects without disease
• Highly specific test - unlikely to be positive when a person does not have the
disease (false positive).
• Indicated when the misdiagnosis of disease in the absence of disease could
harm a person either emotionally, physically, or financially

59. RISK VERSUS PROGNOSIS
• RISK- likelihood that a person will get a disease in a specified time period.
• RISK FACTORS- characteristics of individuals that place them at increased
risk for getting a disease
RISK ASSESSMENT- process of predicting an individual's probability of
disease
• Clinicians use risk assessment
• To predict which patients are at risk for disease.
• To aid in the diagnosis of disease.
• To prevent disease by identifying and modifying risk factors

60. RISKVERSUSPROGNOSIS
• PROGNOSIS- Is the prediction of the course or outcome of the disease.
• PROGNOSTIC FACTORS- Characteristics or factors that predict the
outcome of a disease once disease is present
• PROGNOSIS ASSESSMENT- Process of using prognostic factors to predict
the course of a disease

61. PERIODONTAL EPIDEMOLOGY
Indices used to assess gingival inflammation -
• Papillary-marginal-attachment index (PMA) - (Schour & Massler, 1948).
• Gingival index (GI) - (Loe & Silness, 1963).
• Modified Gingival Index (MGI)- (Lobene et al., 1986)
• Periodontal index (PI)- (Russell, 1956)
• Gingivitis component of periodontal disease index (PDI) (Ramfjord SP ,
1959)

62. Indices used to assess gingival bleeding -
• Gingival index used by the National Institute of Dental Research
(NIDR) (Miller et al., 1987)
• National Institute of Dental & Craniofacial Research (NICDR)
(NHANES III, 1997)
• Sulcus Bleeding Index (Mϋhlemann & Major, 1958)
• Bleeding Point Index (Lenox & Kopczyk, 1973)
• Ainamo’s Gingival Bleeding Index (Ainamo & Bay, 1975)
• Carter’s Gingival Bleeding Index (Carter & Barnes, 1974)
• Eastman Interdental Bleeding Index (Caton & Polson, 1985)
PERIODONTAL EPIDEMOLOGY

63. Indices used to assess plaque & calculus -
• Plaque Index (PI) (Silness & Loe, 1964)
• Plaque component of PDI (Ramfjord, 1959)
• Turesky modification of Quigley Hein Index (Quigley & Hein 1962,
Turesky 1970)
• Shick and Ash Modification of Plaque Criteria ( Shick & Ash 1961)
• Oral Hygiene Index-Simplified (OHI -S) (Greene & Vermillion ,1964)
• Calculus component of PDI (Ramfjord, 1959)
• Calculus severity index (Ennever &Radike 1961)
PERIODONTAL EPIDEMOLOGY

64. Indices to measure degree of periodontal destruction -
• Periodontal disease index (Ramfjord SP , 1959)
• Extent and Severity Index (ESI) (Carlos et al,1986)
Indices used to assess treatment needs -
• Gingival plaque index (O'Leary et al., 1963)
• Periodontal Treatment Need System (PTNS) (Bellini & Gjermo, 1973)
• CPITN- Community Periodontal Index Of Treatment Needs (Ainamo
et al., 1982)
PERIODONTAL EPIDEMOLOGY

65. National survey in India National oral health survey and
fluoride mapping DCI,2004
• First ever national wide survey
• WHO probe & CPI index used
• M- F
• Rural >Urban
PERIODONTAL DISEASES IN INDIA
Age group( yrs) Periodontitis
12 57%
15 67.7%
35-44 89.6%
65-74 79.9%

66. Oral health in India, Govt. of india & WHO, 2004
• 22,400 subjects
• M>F, Geriatric F>M,
• Rural>urban
• 65-74>>35-44 yrs
States 35-44yr 65-74yr
Maharashtra 78% 96%
Orissa 68% 90%
Delhi 46% 85.5%
Rajasthan 33% 75%
Uttar Pradesh 30% 68%
Pondicherry 20% 55%
Arunachal
Pradesh
15% 20%
PERIODONTAL DISEASES IN INDIA

67. PREVALENCE OF GINGIVITIS ACCORDING TO THE
GEOGRAPHIC LOCATION -
NAME YEAR AREA PREVALENCE
Marshal & Day 1940 North India 59.6%
Marshal, Day &
Shourie
1944 Kangra, HP 81%
Mehta &
Sanjana
1956 Bombay 93.7%
Greene 1960 India 96.9%
S P Ramford 1961 Bombay 100%
Dutta 1965 Calcutta 89.8%
PERIODONTAL DISEASES IN INDIA

68. PREVALENCE OF PERIODONTAL DISEASE ACCORDING
TO THE GEOGRAPHIC LOCATION –
In adult population
PERIODONTAL DISEASES IN INDIA
Name Year Area Prevalence
Marshal & Day 1940 North India 60%
Greene J.C. 1960 Bombay 90.3%
Gupta O.P. 1962 Trivandrum 96.9%
Chawla T.N. 1963 Lucknow 100%
Miglani D.C. 1965 Madras 94.9%
Ramachandra 1973 Chennai 95.5%
Anil S & Hari
S
1990 Trivandrum 80%

69. PREVALENCE OF PERIODONTAL DISEASE ACCORDING
TO THE GEOGRAPHIC LOCATION –
In child population
PERIODONTAL DISEASES IN INDIA
Name Year Area Prevalence
Marshal & Day 1940 North India 60%
Marshal ,Day
& Shourie
1947 Lahore 73.3%
Dutta A.N. 1965 Calcutta 89%
Miglani D.C. 1965 Madras 83%
Tewari 1979 Chandigarh 92.4%
Pandit K 1985 Delhi 41.7%
Srivastava R P 1989 Jhansi 94%

70. PREVALENCE OF GINGIVALDISEASE
• 3rd National Health and Nutrition Examination Survey (NHANES III) (1988
to 1994)
• 54% of the civilian U.S. population aged 13 years and older had gingival
bleeding in at least one gingival site.
• Gingival bleeding- most prevalent in the 13-17 year old age group (63%) and
declined gradually through the 35-44 year old age group
• Prevalence increased again at the 45-54 year old age group but remained
fairly constant in older age groups.
• The extent of gingival bleeding was higher in the younger and older age
groups than in the middle age groups

71. PREV
ALENCEOFGINGIV
ALDISEASE
Is More or less Gingivitis Present Now than Previously?
• It is generally believed that the prevalence of gingivitis is declining in the
U.S., the epidemiologic data needed to make that claim do not exist .
Why Do Patients Have Gingivitis, And What Puts Them at Risk?
• Microbial plaque is the direct cause of gingivitis
Linde (1973); Loe et al. (1965); Page (1986); Payne et al. (1975)
• Factors that influence the oral hygiene status of individuals- influence the
prevalence of gingivitis.

72. PREV
ALENCEOFGINGIV
ALDISEASE
• The generally poorer oral hygiene status of males - higher prevalence and
extent among males. ( Addy et al. 1994)
• Higher prevalence of gingivitis among adolescents.
• Poor oral hygiene
• Increased levels of circulating sex hormones → affects the composition of
the subgingival micro flora (Nakagawa et al. (1994)
• Role of smoking in gingivitis is unclear.
• Several studies have indicated that gingival bleeding is reduced among
smokers. (Bregstrom 1990; Preber 1985)

73. PREVALENCE OF PERIODONTAL DISEASE
How Much Chronic Periodontitis Is Present?
NHANES III (1988-94)
• Data for adults aged 30 years and older
• The prevalence of periodontal attachment loss is greatly dependent on the
threshold chosen, ranging from a high of 99% for a threshold of > 1 mm to a
low of 7% for a threshold of >7 mm.
• The prevalence of attachment loss increased steadily with age, from a low of
35.7% for the 30-39 year old age group to a high of 89.2% for the 80- 90
year old age group.

74. PREV
ALENCEOFPERIODONTALDISEASE
• The mean percentage of teeth affected also increased with age.
• Maxillary molars and mandibular incisors were more likely than other
teeth to have attachment loss of >3 mm, whereas maxillary central
incisors were the least likely.
• The prevalence of periodontal pockets is also greatly dependent on
the threshold chosen.
• Generally, pockets >3 mm are considered to reflect disease.
• The increase in the prevalence of attachment loss with increasing age
is not seen with pocket depth.

75. PREV
ALENCEOFPERIODONTALDISEASE
Is More or Less Chronic Periodontitis Present Now than Previously?
Prevalence of periodontal disease has decreased in the U.S. over the past 30
years. However, because of methodological differences in the national
surveys conducted over the years, making any conclusions about changes in
the prevalence of periodontal disease is difficult.
How Much New or Progressing Chronic Periodontitis Is Present?
A 10-year follow-up study among Chinese individuals aged 20-80 years -
79.8% of all sites measured experienced attachment loss.
Approximately 48% of the sites measured lost >2 mm, 21.8% of the sites lost
>3 mm, and 9% of the sites lost >4 mm.

76. PREV
ALENCEOFPERIODONTALDISEASE
• The average attachment level change per person was between 1.45-1.86 mm
during the follow-up period, corresponding with 0.15 to 0.19 mm per year.
• Because very little difference in mean attachment loss by age groups existed-
influence of age on the rate of periodontal disease progression might be
minimal. (Baelum et al. 1987)
• The prevalence of attachment loss and periodontal pockets are higher in
males than females
• Males are more likely than females to have more teeth with attachment loss
and more teeth with pockets.

77. PREV
ALENCEOFPERIODONTALDISEASE
• The prevalence and extent of periodontal attachment loss increases with age.
• The increase in attachment loss with age without a corresponding increase in
pocket depth may result from the increasing prevalence of gingival recession
with age.
Why Do Patients Have Chronic Periodontitis, & What Puts Them at
Risk?
• Periodontitis is an infectious disease associated with a group of mainly gram-
negative bacteria. ( Zambon 1996)

78. PREV
ALENCEOFPERIODONTALDISEASE
• In response to periodontal pathogens and their endotoxins, immune cells in
the periodontium, particularly monocytes, secrete pro-inflammatory
mediators such as prostaglandin E, interleukin I & TNF.
• The body's inflammatory response is an attempt to protect itself from the
pathogens, but at the same time the inflammation can lead to periodontal
connective tissue destruction and bone degeneration as the body attempts to
rid itself of the infectious tooth.

79. REFERENCES
1. Essentials of public health dentistry ( community dentistry ) – Soben
Peter 6th Edition.
2. Textbook of preventive and community dentistry – Joseph John – 3rd
Edition.
3. Newman and Carranza’s clinical periodontology – 13th Edition.
4. Clinical periodontology and implant dentistry – Jan lindhe 6th Edition.
5. Sanjana MK, Mehta FS, Docto RH, Baretto MA. Mouth hygiene habits
and their relation to periodontal disease. J Dent Res 1956;35:645-7.
6. Greene JC. Periodontal Disease in India: Report of an epidemiological
study. J Dent Res 1960;39:302-12
7. Ramfjord SP, Emslie RD, Greene JC, Held AJ, Waerhaug J.
Epidemiological studies of periodontal diseases. Am J Public Health
Nations Health1968;58:17-22.
8. Gupta, O.P. Epidemiological study of dental diseases in the state of
Kerala. JIDA, 34: 45-8; 1962.

80. REFERENCING
9. Miglani, DC, Sharma, O.P., Incidence of acute necrotizing gingivitis
and periodontitis among the cases seen at the government hospital,
10. Madras. JIDA; 1965: 37; 183.
11. Ramachandran, K., Rajan, B.P., & Shanmugam, S. (1973).
Epidemiological studies of dental disorders in Tamil Nadu populations.
Journal of the Indian Dental Association, 45(4), 65-70.
12. Anil, S., Hari, S. and Vijayakumar, T., Periodontal conditions of a
selected population in Trivandrum District, Kerala, India. Community
Dentistry and Oral Epidemiology, 1990; 18: 325.
13. Basu MK, Dutta AN. Report on prevalence of periodontal disease in adult
population at Calcutta--Russel's technique. J All India Dent Assoc. 1965
Jul;37(7):230-3 passim. PMID: 5213150.