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

Preventive dentistry (L)1 6 (L) （ 1 ） OHI-S ( DI-S )

Preventive dentistry （ 1 ） OHI-S (DI-S & CI-S)

Preventive dentistry  Ramfjord index teeth （ 2 ） Turesky Modification of the Quigley Hein Index

Preventive dentistry  Plaque discoloration （ 2 ） Turesky Modification of the Quigley Hein Index

Preventive dentistry 0=No plaque 1=Slight flecks at the cervical margin 2=thin continuous band (≤1 mm) at cervical margin （ 2 ） Turesky Modification of the Quigley Hein Index

Preventive dentistry 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 （ 2 ） Turesky Modification of the Quigley Hein Index

Preventive dentistry （ 3 ） GI Löe and Silness Index

Preventive dentistry （ 3 ） GI （ Löe and Silness ） 0No inflammation. Normal gingivae 1 Mild inflammation – slight change in colour, slight edema. No bleeding on probing. 2 Moderate inflammation – redness, edema and glazing. Bleeding on probing. 3 Severe inflammation – marked redness, edema. Ulceration. Tendency to spontaneous bleeding

Preventive dentistry CPI probe  Gingival bleeding  Subgingival calculus  PD （ 4 ） CPI

Preventive dentistry （ 4 ） CPI ≥20 years old 15 ～ 20 years old

Preventive dentistry 0 ＝ Healthy 1 ＝ Bleeding observed 2 ＝ Calculus detected, all the black band visible 3 ＝ Pocket 4-5 mm （ 4 ） CPI

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

Preventive dentistry （ 4 ） CPI

Preventive dentistry （ 4 ） CPI x

Preventive dentistry 15 years old Feature of distribition SextantGrade 0.0 ～ ～ ～ ～ ～ 6.0 Very low Low Middle High Very high

Preventive dentistry Feature of distribition 1 Area  Developing Vs Developed countries  Rural Vs Urban 2 time

Preventive dentistry Influential factors 3 population  age  gender male > female  race

Preventive dentistry  oral hygiene  smoking （ duration 、 frequency 、 type ）  nutrition  systemic diseases Related factors

Section 5 Epidemiology of Other Oral Diseases

Preventive dentistry Other oral diseases epidemiology  Oral cancer  Dental fluorosis  Cleft lip and palate  Dentofacial anomalies  Oral mucosal diseases

Preventive dentistry 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, age  Gender: male > female  Race

Preventive dentistry Oral cancer  District  Time, age  Gender: male > female  Race 口腔癌

Preventive dentistry 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)

Preventive dentistry Dental fluorosis 0Normal 0.5Questionable (few flecks, occasional spots) 1Very mild (opacities<1/4 of surface) 2Mild (opacities<1/2 of surface) 3Moderate (may have brown stain) 4Severe (pitting, hypoplasis and brown stain)

Preventive dentistry Dental fluorosis  Fci = ( n×W ) / N  Fci= 〔 (0.5× Questionable)+(1× Very mild )+…+(4× Severe )×100 ％〕 / N

Preventive dentistry Dental fluorosis  Public health significance 0-0.4Negative Borderline Slight 1-2Medium 2-3Marked 3-4Very marked

Preventive dentistry Dental fluorosis Feature of distribution  area  urban, rural  age  dentition

Preventive dentistry Cleft lip and palate  One Cleft lip or palate case per 500 ～ 700 infants  factors

Preventive dentistry Cleft lip and palate  area  urban, rural  gender

Section 6 Oral Health Survey & Evaluation

Preventive dentistry The survey and evaluation of oral health  Purpose  Item  Index  Method  Sample size  Error and prevention

Preventive dentistry Item  General item  Oral health assessment  Questionnaire

Preventive dentistry Questionnaire data collection  Collect information that cannot be observed. knowledge attitude practice belief

Preventive dentistry Index  Caries----  Periodontal diseases----  Dental fluorosis- ---

Preventive dentistry Methods Census （普查） ----a complete enumeration of the umits to be studied (mass examination) : no sampling error  : not practical, time consuming

Preventive dentistry Sampling -- measurements on part of the population --less resource demanding --quicker to complete --more cost-efficient --detail examination possible

Preventive dentistry 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

Preventive dentistry Simple random sampling sample population  Draw lots, throw a die  Random number table  Computer generated random number

Preventive dentistry Systematic sampling  In a list select every u unit in a list starting from a random number ( from 1 to uth) U+kU+2kU N1

Preventive dentistry Stratified sampling  Subdivide the population into strata and draw sample from each stratum independently  Common strata: age, gender, districts, etc sample population

Preventive dentistry Cluster sampling  Subdivide the population into several clusters (blocks of units)  All elements in these selected cluster are studied population cluster sample

Preventive dentistry Sampling Methods ？？？？？？

Preventive dentistry Multi-stage sampling  Sampling can take place in stages by repeating or combining the above sampling  More efficient for large scale surveys

Preventive dentistry Pilot survey  Include only one or two age groups to collect the minimum amount of data  12 years +one other age group

Preventive dentistry OH survey ----pathfinder  to include the most important population subgroups  A stratified cluster sampling technique  Variations in level, severity and need

Preventive dentistry Index age groups  5 yrs children ( primary teeth)  12 yrs children ( permanent )  15 yrs adolescents  yrs adults  yrs elders

Preventive dentistry Sample size  N=K×Q/P  N subjects, p proporation  Q=1 － P K Type II error 40010% 17815% 10020%

Preventive dentistry Error and bias  Selection bias （选择性偏倚）  Unresponse bias （无应答偏倚）  Information bias （信息偏倚）

Preventive dentistry Information bias

Preventive dentistry Information bias K (Kappa)reliability < 0.4poor 0.41~0.60medium 0.61~0.80good 0.81~1.0excellence Calibration ( 标准一致性试验）

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