preventive dentistry

Preventive Dentistry

Teaching & Research Section of Preventive Dentistry

Section 4

Epidemiology of Periodontal Disease

Preventive dentistry

Index for periodontal condition OHI-S PLI GI CPI

Periodontal disease


6 1 6

6 (L)

1 6 (L)

（ 1 ） OHI-S ( DI-S )


（ 1 ） OHI-S (DI-S & CI-S)


6 1 4

4 1

6

Ramfjord index teeth

（ 2 ） Turesky Modification of the Quigley Hein Index


Plaque discoloration



0=No plaque

1=Slight flecks at the cervical margin

2=thin continuous band (≤1 mm) at cervical margin



3 ＝ A band of plaque >1 mm but < 1/3 of the area

4 ＝ covering 1/3 - 2/3 of the area

5 ＝ covering ≥ 2/3 of the area



（ 3 ） GI

Löe and Silness Index


（ 3 ） GI （ Löe and Silness ）

0 No inflammation. Normal gingivae

1Mild inflammation – slight change in colour, slight edema. No bleeding on probing.

2Moderate inflammation – redness, edema and glazing. Bleeding on probing.

3Severe inflammation – marked redness, edema. Ulceration. Tendency to spontaneous bleeding


CPI probeGingival bleedingSubgingival calculusPD

（ 4 ） CPI


（ 4 ） CPI

17 16 11 26 27

47 46 31 36 37

16 11 26

46 31 36

≥20 years old 15 ～ 20 years old


0 ＝ Healthy1 ＝ Bleeding observed2 ＝ Calculus detected, all the black band

visible3 ＝ Pocket 4-5 mm

（ 4 ） CPI


4 ＝ Pocket ≥6 mm (black band not visible)X ＝ Excluded sextant （ <two teeth ）9 ＝ not recorded

（ 4 ） CPI


（ 4 ） CPI


（ 4 ） CPI

4 0 2

2 2 x


15 years old

Feature of distribition

Sextant Grade

0.0 ～ 1.5

1.6 ～ 2.5

2.6 ～ 3.5

3.6 ～ 4.5

4.6 ～ 6.0

Very low

Low

Middle

High

Very high


Feature of distribition

1 Area

Developing Vs Developed countriesRural Vs Urban

2 time


Influential factors

3 population

age

gender male > female race


oral hygiene smoking （ duration 、 frequency 、 typ

e ）nutrition systemic diseases

Related factors

Section 5

Epidemiology of Other

Oral Diseases


Other oral diseases epidemiology

Oral cancerDental fluorosisCleft lip and palateDentofacial anomaliesOral mucosal diseases


Oral cancer

China 0.7 ， Thailand 4.6 ， India 12.6 /100,000

District: one of the most common tumor in east south Asia

Time, ageGender: male > femaleRace


Oral cancer

DistrictTime, ageGender: male > femaleRace

口腔癌

http://miharasi.truku.hohayan.net.tw/picture/blank2/02377886.GIF


Dental fluorosis

Dean’s index

Based on the 2 most severely affected teeth (record the status if they are the same and record the less severe if they are not)


Dental fluorosis

0 Normal

0.5 Questionable (few flecks, occasional spots)

1 Very mild (opacities<1/4 of surface)

2 Mild (opacities<1/2 of surface)

3 Moderate (may have brown stain)

4Severe (pitting, hypoplasis and brown stain)


Dental fluorosis

Fci = ( n×W ) / N

Fci= 〔 (0.5× Questionable)+(1× Very mild )+…+(4× Severe )×100 ％〕 / N


Dental fluorosis

Public health significance

0-0.4 Negative

0.4-0.6 Borderline

0.6-1.0 Slight

1-2 Medium

2-3 Marked

3-4 Very marked


Dental fluorosis

Feature of distribution

area urban, ruralage dentition


Cleft lip and palate

One Cleft lip or palate case per 500 ～ 700 infants

factors


Cleft lip and palate

area urban, ruralgender

Section 6

Oral Health Survey & Evaluation


The survey and evaluation of oral health

Purpose Item IndexMethodSample sizeError and prevention


Item

General item

Oral health assessment

Questionnaire


Questionnaire data collection

Collect information that cannot be observed.

knowledge

attitude practice

belief


Index

Caries----

Periodontal diseases----

Dental fluorosis----


Methods

Census （普查） ----a complete enumeration of the umits to be studied (mass examination)

: no sampling error

: not practical, time consuming


Sampling

--measurements on part of the population

--less resource demanding

--quicker to complete

--more cost-efficient

--detail examination possible


Sampling Methods

Most important issue is whether the sample can adequately represent the bigger population

Simple random sampling 单纯随机抽样 Systematic sampling 系统抽样 Stratified sampling 分层抽样 Cluster sampling 整群抽样


Simple random sampling

sample

population

Draw lots, throw a die Random number table Computer generated random number


Systematic sampling

In a list select every u unit in a list starting from a random number ( from 1 to uth)

U+k U+2kU

N1


Stratified sampling

Subdivide the population into strata and draw sample from each stratum independently

Common strata: age, gender, districts, etc

sample sample

population


Cluster sampling

Subdivide the population into several clusters (blocks of units)

All elements in these selected cluster are studied

population

cluster cluster cluster

sample


Sampling Methods

？？？


Multi-stage sampling

Sampling can take place in stages by repeating or combining the above sampling

More efficient for large scale surveys


Pilot survey

Include only one or two age groups to collect the minimum amount of data

12 years +one other age group


OH survey ----pathfinder

to include the most important population subgroups

A stratified cluster sampling techniqueVariations in level, severity and need


Index age groups

5 yrs children ( primary teeth)12 yrs children ( permanent ) 15 yrs adolescents35-44 yrs adults65-74 yrs elders


Sample size

N=K×Q/PN subjects, p proporationQ=1 － P

KType II error

400 10%

178 15%

100 20%


Error and bias

Selection bias （选择性偏倚）

Unresponse bias （无应答偏倚）

Information bias （信息偏倚）


Information bias


Information bias

K (Kappa)

reliability

< 0.4 poor

0.41~0.60 medium

0.61~0.80 good

0.81~1.0 excellence

Calibration ( 标准一致性试验）

Thankst

preventive dentistry

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