EPIDEMIOLOGY OF
PERIODONTAL DISEASES

Contents
• Introduction
• History
• Definition
• Principles & Purpose of epidemiology
• Components of epidemiology
• Epidemiological triad
• Epidemiological methods
• Epidemiologic measures of disease
• Periodontal epidemiology
• Periodontal disease in India
• Periodontal disease – Global overview
• Conclusion
• References

INTRODUCTION
• Epi - among, demos- people, logos- study
• Epidemiology - well being of society as a whole rather than
individuals
• Multifactorial etiology of periodontal diseases
• Measures prevalence, extent and severity of periodontal
diseases

HISTORY
• Hippocrates
• CLAUDIUS GALEN (130-200A.D.)
• THOMAS SYDENHAM ‘founder of epidemiology’.
• JOHN SNOW ‘father of epidemiology’

History of Dental Epidemiology
Descriptive studies........Hippocrates
Health habits & dental status of 96 old men, all over 80 years
Sir John Linchour ; Britain 1803
First dental epidemiology, studied eruption of teeth
Edwin Saunders; Britain 1837
Tooth mortality study
John Tomes; 1848
Dental status of school children
Fisher ; Britain 1885
Nation wide survey of school children
Ainsworth & Young; Britain 1925

DEFINITION
• The study of the distribution of disease or a physiological
condition in human populations and of the factors that
influence this distribution
Lilienfeld 1978
• Epidemiology is essentially an inductive science, concerned
not merely with describing the distribution of disease, but
equally or more with fitting it into a consistent philosophy
Frost 1941

• The study of the distribution and determinants of health-
related states or events in specified populations, and the
application of this study to control health problems
Last JM,1995

PRINCIPLES OF EPIDEMIOLOGY
• Exact observation
• Correct interpretation
• Rationale explanation
• Scientific construction

PURPOSE OF EPIDEMIOLOGICAL STUDY
1. To determine the amount and distribution of a disease in a
population
2. To investigate causes for the disease.
3. To apply this knowledge to control & prevent the disease.

COMPONENTS OF EPIDEMIOLOGY
1. Disease frequency: Rate or ratio
2. Distribution of disease : pattern of distribution
3. Determinants of disease : etiological hypothesis

EPIDEMIOLOGICAL TRIAD
• Agent,Host,Environment
• AGENT: “An organism, a substance or a force, the presence or
lack of which may initiate a disease process or may cause it to
continue”
Living - Bacteria,viruses etc
Nonliving - carbohydrate ,protein
Chemical Agents
Physical Agents

HOST
“A person or an animal that afford subsistence lodgement to a
infectious agent under natural conditions”
• Demographic characteristics: Age, Gender, Race
• Biological characteristics: Genetic, Immune, Nutritional
• Socio-economic characteristics : Social class, Religion,
Education, Marital status
• Life style : living habits, food habits

ENVIRONMENT
Environment is the source or reservoir for the agents of disease
• Physical
• Biological
• Social

Tools of measurement
• Rate = No. of disease in a specified period X 1000
Population at risk of expressing the disease
• Ratio
• Proportion= No. of school children with gingivitis X 100
Total No. of children in the school

EPIDEMIOLOGICAL METHODS
1. Descriptive epidemiology
2. Analytical epidemiology
3. Experimental epidemiology
• Experimental studies - efficacy of preventive interventions,
treatments, and drugs.

Descriptive epidemiology
Describes the pattern of occurrence of disease/condition
relative to other characteristics of population.
Any departure, subjective or objective from a state of physical
well being
morbidity: prevalence-cross sectional study
incidence-longitudinal study

Cross-Sectional Studies
• Disease frequency surveys or prevalence studies.
• Presence or absence of disease and characteristics of subjects
• Generates hypothesis regarding the etiology of a disease.
Limitation :
• Only identify prevalent cases of disease.
• Determining whether the characteristic preceded the disease is
not always possible
Advantages
• Generally less expensive than longitudinal studies
• Quicker to conduct.

Analytical epidemiology
It deals with discovering the causes of disease
2 approaches:
Cohort study- from exposure to effects
case control study- from disease to cause

Cohort Studies
• Strong support for an association
• Exposed & unexposed groups and followed over time
• Incidence in exposed group >> unexposed
Limitations
• long periods of follow up & can be expensive to conduct.
• Rare diseases- large numbers of subjects will need to be
followed

Case-Control Studies
• In day to day…
• Cases and controls
• Primarily used to assess risk
Limitation
• The temporal relationship between the exposure & disease may
be obscured
• Historical information often cannot be validated.
Advantage
• Require fewer resources and conducted quickly than cohort
studies
• Rapid evaluation of chronic diseases

Experimental epidemiology
The results obtained from observational studies about
association & causation/benefit of a particular intervention
1.Randomised controlled trials
2.Field trials
3.Community trials

EPIDEMIOLOGIC MEASURES OF DISEASE
PREVALENCE:
• Prevalence is the proportion of persons in a population
who have the disease of interest at a given point or period
of time.
• Prevalence = No of persons with the disease X 100
No of persons in the population

Types of prevalence:
• Point prevalence - ’the no of all current cases (both old &
new) of a specific disease at one point in time in relation to a
defined population’.
• ‘A point in time’ can be either a day, few days or even few
weeks
• Period prevalence- ‘the total no of existing cases (old &new)
of a specific disease during a defined period of time in
relation to a defined population’
• It is the sum of the point prevalence & the incidence.

USES
1. To estimate the magnitude of disease or health problems in
community
2. To identify the potential high risk population
3. Useful in administrative & planning purposes
Limitations of prevalence rates:
• It is not the ideal measure for studying etiology of disease.(I x
D)

Factors influencing prevalence
Prevalence rate increases by:
1. Longer duration of the disease.
2. Prolongation of life of the patient
3. Prolongation of life of patient without care e.g. periodontitis
4. In-migration of cases
5. Improved diagnostic facilities.

Prevalence rate decreases by:
1. Shorter duration of disease
2. High case fatality from disease
3. Decrease in new cases
4. Improved cure rate of disease

Incidence
• ‘ The number of new cases of a specific disease occurring in a
defined population during a specified period of time’
• Incidence =no of new case during a given period of time x 1000
no of persons at risk

Uses of incidence rates:
• It helps with the study of distribution of disease.
• It is useful in evaluating the efficacy of preventive &
therapeutic measures.
• It gives clues to research into the etiology & pathogenesis of
disease.
• It helps in taking action to control the disease

Scientific method
• Establishing the objective
• Designing the investigation
• Selecting the sample
• Conducting the examinations
• Analysing the data
• Drawing the conclusions
• Publishing the results

• Most important but complex part of dental epidemiology
• Special indices have been designed to provide objective
measurement of identifiable features
• Quantitative science
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)

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)

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)

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 DISEASES IN INDIA

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
Age
group(yrs)
Periodontitis
12 57 %
15 67.7 %
35-44 89.6 %
65-74 79.9 %

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 35-44 yr 65-74yr
Maharashtra 78% 96%
Orissa 68% 90%
Delhi 46% 85.5%
Rajasthan 33% 75%
Uttar pradesh 30% 68%
Puducherry 20% 55%
Arunachal
Pradesh
15% 20%

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%

PREVALENCE OF PERIODONTAL DISEASE ACCORDING TO THE
GEOGRAPHIC LOCATION
In adult population
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%

PREVALENCE OF PERIODONTAL DISEASE ACCORDING TO THE
GEOGRAPHIC LOCATION
In child population
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%

Name Year Area Prevalence
Samant Asha 1976 Chandigarh Increased in
2nd trimester
Dixit J 1980 Lucknow Increased in
2nd trimester
In Pregnant women
In Handicapped children
Name Year Prevalence
Mehrotra AK 1982 88.5%
Shobha tendon 1986 97.3%

Recent studies
• Gingivitis : 80-85%
Bhayya,2010
• Males > females (84% vs 78%)
Mehta ,2010
• Periodontitis :
• 35% for 35-40 yrs
• 85% for 80-90 yrs
• Aggressive periodontitis < 1%
• Loss of attachment - 45-77% in 35-44
55-96% in 65-74
Jacob, 2010

PERIODONTAL DISEASES – GLOBAL OVERVIEW

ASIAN OVERVIEW

Gingivitis
• Increased tooth brushing frequency & better oral hygiene score
were associated with lower PI scores
NHANES I, 1971-74
• Younger and older age groups > middle age
NHANES III, 1988-1994
• Most prevalent in 13-17 yrs (63%) > 45-54 yrs > 35-44 yrs
NIDR,1986

Periodontitis in adults
(1) periodontal disease - major, global public health problem in
35–40 years
(2) gingivitis in youth- lead to periodontitis
(3) age and oral hygiene
Scherp 1964
• Extent & severity
Loe etal, Baelum et al. 1986
• Probing assessments at six sites per tooth around all teeth -the
highest prevalence
Susin et al. 2004

• In 480 Sri Lankan, Male tea-plantation labourers, aged 14–31
years
RP (8%) - 0.1 and 1.0 mm,
MP (81%) -0.05 and 0.5 mm
NP (11%) - 0.09 mm
• Prevalence of gingival recession (> 1 mm) increases with age
38% - 30-39 yr
90% - 80-90 yr
• Attachment loss of moderate magnitude was frequent in
elderly subjects
( Beck et al. 1990; Mack et al. 2004)

Periodontal disease in children and
adolescents
• In Michigan, USA
27% for 5–7-year-old children,
25% for 8–10-year-olds and
Jamison, (1963)
• Presence of subgingival calculus at baseline was significantly
linked to disease progression.
Clerehugh et al. (1990)
• In US ,14 013 adolescents from baseline
62% - localized periodontitis lesions 6 years later,
35% - generalized disease pattern.
Brown et al. (1996)

• In Australian children (542) aged 5–12 years, 13.0% were
found to display definite bone loss
Darby et al. (2005)

Prevalence of juvenile periodontitis
• 0.53% LJP
• O.13% GJP
NIDR ,1989
• Severely affected teeth : 1st molars > 2nd molars >
incisors
• African Americans > Whites
(M> F) (F> M)
• South Indian : (females> males)
• Incidence: 1.5 cases per 1000 person per year at risk.
Loe & Brown,1991

RISK FACTORS
• Helps in predicting ,who will get the disease
• Risk factor
• Risk assessment : to prevent disease by identifying and
modifying risk factors
• Tobacco smoking
• Systemic diseases such as Diabetes mellitus
• Pathogenic bacteria and microbial tooth deposits

Risk determinants / background factors :
• Genetic factors
• Age
• Gender
• Race
Risk indicators :
• AIDS
• Osteoporosis
• Infrequent dental visits

CONCLUSION

REFERENCES
• Newman MG, Takei HH, Klokevold PR, Carranza FA. Carranza’s
Clinical Periodontology. Saunders Elsevier;10th Edition.
• Soben Peter ; Essentials of Preventive and Community dentistry , 2nd
edition
• Niklaus P. Lang, Jan Lindhe . Clinical Periodontology and Implant
Dentistry. 5th ed.
• Agarwal V. Prevalence of Periodontal Diseases in India J Oral Health
Comm Dent 2010;4(Spl)7-16
• Shaju JP, Zade RM, Das M . Prevalence of periodontitis in the Indian
population :a literature review. J Indian Soc Periodontol, 2011,15,29-
34
• Esmonde F. Corbet, K.-Y. Zee & Edward C. M. Lo . Periodontal
diseases in Asia and Oceania : Periodontology 2000, Vol. 29, 2002,
122–152

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