Internship at D Y Patil Dental College, Navi Mumbai (New Mumbai)
May. 2, 2016

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  2. 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
  3. 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
  4. HISTORY • Hippocrates • CLAUDIUS GALEN (130-200A.D.) • THOMAS SYDENHAM ‘founder of epidemiology’. • JOHN SNOW ‘father of epidemiology’
  5. 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
  6. 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
  7. • 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
  8. PRINCIPLES OF EPIDEMIOLOGY • Exact observation • Correct interpretation • Rationale explanation • Scientific construction
  9. 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.
  10. COMPONENTS OF EPIDEMIOLOGY 1. Disease frequency: Rate or ratio 2. Distribution of disease : pattern of distribution 3. Determinants of disease : etiological hypothesis
  11. 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
  12. 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
  13. ENVIRONMENT Environment is the source or reservoir for the agents of disease • Physical • Biological • Social
  14. 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
  15. EPIDEMIOLOGICAL METHODS 1. Descriptive epidemiology 2. Analytical epidemiology 3. Experimental epidemiology • Experimental studies - efficacy of preventive interventions, treatments, and drugs.
  16. 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
  17. 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.
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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.
  24. 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)
  25. 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.
  26. 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
  27. 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
  28. 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
  29. Scientific method • Establishing the objective • Designing the investigation • Selecting the sample • Conducting the examinations • Analysing the data • Drawing the conclusions • Publishing the results
  30. • Most important but complex part of dental epidemiology • Special indices have been designed to provide objective measurement of identifiable features • Quantitative science PERIODONTAL EPIDEMOLOGY
  31. 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)
  32. 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)
  33. 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)
  34. Indices to measure degree of periodontal destruction • Periodontal disease index (Ramfjord SP , 1959) • Extent and Severity Index (ESI) (Carlos et al,1986)
  35. 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)
  37. 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 %
  38. 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%
  39. 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%
  40. 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%
  41. 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%
  42. 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%
  43. 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
  46. 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
  47. 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
  48. • 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)
  49. 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)
  50. • In Australian children (542) aged 5–12 years, 13.0% were found to display definite bone loss Darby et al. (2005)
  51. 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
  52. 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
  53. Risk determinants / background factors : • Genetic factors • Age • Gender • Race Risk indicators : • AIDS • Osteoporosis • Infrequent dental visits
  55. 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

Editor's Notes

  1. Derived from the term ‘epidemic’ oftenConcerned namely social, economic,microbiological genetic, environmental and behavioral factors importance
  2. This scientific method which was lost after death of Hippocrates was revived by in 17th century wrote the history of disease & became because of his findings on epidemic of cholera in London in 1854.
  3. based on clinical examination of individual.‘ 9-13 yrs
  4. Related to the basic principles of science (strict,vigrous,acurate ,precise) Free from error Intelligent sensible ,reasonable By expert knowledge and technical skill
  5. prevention
  6. Camparision of the rates of disease frequency between different population gives important clues on etiological factors and development of strategies for prevention of diseases. Lead to development of hypothesis for about causative factors Etiological hypothesis in identifying the risk factors of the disease
  7. The occurrence and manifestation of any disease are determined by interaction between 3 factors
  8. Host factors are
  9. Most epidemiologic studies are observational 1& 2 are observational studies. USEFUL IN studying the
  10. are measured at a point in time. Because these studies do not follow a population at risk of the disease over time, incidence cannot be determined.
  11. Events codition or characterstics or acombination of these factors which play an important role in in the production of disease. Before ensuring a factor as a cause several observation have to be made on so called exposure before it is prounced as a cause So ,beginning with exposure and searching for effects in prospective manner called as cohort and the other approach of beginning with the disease and searching for its causes in the past
  12. monitored for the development of the disease studies are that they can require and
  13. IN A DAY TO DAY LIFE THRER IS TENdency TO FIGURE OUT y an incident has occurred once it happened Primarily used to assess RiskS and study causes in general .
  14. can be visualized through experimental approach. Require strict protocol n ethical
  15. It is a measure of the burden of disease in a population.
  16. depending upon the time taken to examine the sample of population. Period prevalence are more useful when they are separated into their two components. Usually when the term ‘prevalence rate’ is used, it refers to ‘point prevalence’.
  17. Incidence related to occurance and duration depensd upon factors that influences course like assessing manpower needs in health services, delivery of health services etc.
  18. Better reporting of cases
  19. Decrease in incidence
  20. O to infinity,expressed as a ratE
  21. Increase incidence shows failure in preventive 0r control programme
  22. Logical scientific Clear ,describes what to be measured n can be in the form of hypothesis Cross sectional ,cohort case control or RCT DOES IT WORK AND IS IT BETTER THAN EXITING TREATMENT Indecies
  23. because pathologic changes in periodontal diseases involve both soft and hard tissues and there are so many subjective variation in objective measurement of periodontal FINDINGS like color change, pocket depth and swelling e a valid comparison of periodontal disease conditions in respect to different variables can be made
  24. Periodontal measurements Disease assessment
  25. incidence increases with age regardless oral hygiene method used Periodontal disease index ,periodontitis was due to ,debris calculus oral hygiene are In nagpur significantly associated with periodontitis Risk is 2.3 higher in person with age above 35 than below
  26. Smoking n age important reason for periodontitis Urban higher
  27. (3 mm or more)
  28. The rise of sex hormones during adolescence is suspected to be the cause of the increased prevalence
  29. a 100% occurrence of destructive periodontitis after the age of 40 years.
  30. never exposed to any preventive or therapeutic intervention related to oral diseases in annual rate of longitudinal attachment loss
  31. The likelihood that a person will get a disease in a specified time period is called risk The characteristics of individuals that place them at increased risk for getting a disease are called risk factors. The process of predicting an individual's probability of disease is called risk assessment
  32. Smoking- 5 times more likely to develop severe periodontitis, and the risk of the disease increases with the amount of cigarettes smoked." Systemic disease: Diabeteshe prevalence, severity, and extent of periodontitis are increased among poorly controlled diabetics. Genetic factors: associated with the aggressive forms Psychological factors/stress Alcohol consumption Factor :,………..May be environmental, behavioral or biologic factor that when present increase the likelihood that an individual will get the disease. —Carranm. Indicator’……………A probable or putative risk factor that has been associated with the disease through cross-sectional studies.
  33. THE PREVALENCE … world wide . FIRST DECADE to older age Early diagnosis treatment r essential Intercepted to prevent damage