EPIDEMIOLOGY OF

PERIODONTAL DISEASES

(CH 5 CARARANZA/11TH EDITION)

OBJECTIVES To describe the destribution and

magnitude of periodontal diseases To identify etiological factors and

pathogenesis of disease To study prognosis of the disease To provide data essential for prevention

and treatment of disease

PREVALANCE Prevalance is the proportion of persons

in a population who have the disease at a given point in a period of time

PREVALANCE=NO OF PERSON WITH DISEASE TOTAL NO OF PERSON IN POPULATION

INCIDENCE It is average percentage of unaffected

person who will develop the disease of interest during a given period of time

Incidence = no of new cases no of person at risk in

population

PERIODONTAL CONDITION TYPICALLY MEASURED CLINICALY Probing depth Bleeding on probing Gingival recession Mobility of teeth Presence of furcation involvement Clinical attachment levels Microbiological measures Gingival crevicular fluid

TRANSLATING PERIODONTAL CONDITIONS INTO TRADITIONAL EPIDEMIOLOGIC MEASURES OF DISEASE OCCURANCE 188 sites in patient that may or may not

bleed1 bleeding site or 5 bleeding site

regardless of no of teeth

ESI (extent and severity index) Consider the site where attachment loss

is more than 1mm E.g ESI(20,5.0) 20% site examined has disease Attachment loss 5mm

TRUE AND SURROGATE MEASURES True endpoint:Tangible outcomes that directly measure

how patient feel,function,or survivee.g painful periodontal abcess Surrogate endpoint: changes that are intangible to patiente.g anatomic measures…probing depth measure of inflammationMicrobiological measuresImmunological measures

CHALLENGES IN OBTAINING EPIDEMIOLOGICAL MEASUES Continuous changes in type of surrogate

data collected Diversity of measurement Paucity of information e.g probing depth from no of teeth

present leads to bias

EPIDEMIOLOGY STUDY DESIGN

STUDY DESIGN

EXPERIMENTAL OBSERVATION

ANALYTICAL

ANALTICAL DESCR

IPTIVE• COMMUNITY

INTERVENTION TRIALS• RANDOMIZED CLINICAL TRIALS• FIELD TRIALS

• CASE CONTROL• COHORT

• CROSSSECTIONAL• ECOLOGICAL

DESCRIBITIVE STUDIES..observing the destribution of disease

ANALYTICAL STUDIES… to determine etiology

Establish casual relationship between factor and disease

RANDOMIZED CONTROLLED TRIALS

Provide a probabilistic basis for making causal inference between intervention and outcome

Scaling and rootplaning in

preganent womenBiphasic calicum

phosphate cermics

Infant low birth weight

Clinical attachment

level

823

137

treatment outcome Sample size

COHORT STUDY Exposure based study design Subjects are classifed with respect to

exposure i.e smoking,diabetes

Exposure ……outcomePeriodontal disease+tooth loss …coronary heart

diseaseGingivitis…. Tooth loss

CASE CONTROL STUDY Outcome based study design Compare between case(person with condition

of interest) and control(person without condition of interest)

Case:Person in population or study group having

particular disease,health disorder and condition

Incident cases(date of diagnosis is after date of study initiation)

Prevalent cases(date of diagnosis preceed)Decedent cases(who died before date of study)

WHO IS AT RISK ? Case control

ETIOLOGY Sufficient cause: set of causes that

initiate a chronic disease smoking,delay neutrophils apoptosis,IL-1

gene defect Component cause:The element of sufficent cause are

component cause Necessary cause:A component cause which is an element

of all sufficient causes for a given disease

Fermentable carbohydrates necessary cause of dental caries

Smoking is not necessary cause of lung cancer