Oral Health Survey

Oral Health Survey

The aims of O.H.S1.Which enable the present status & future needs of a population to be estimated on a sound basis .2.Supply reliable epidemiological data for developing national or regional oral health programmes & for providing effective oral health care .3.Useful in planning manpower development4.Establish or expanded preventive & restorative services

The rules in starting any survey are:

Objectives. Selection of the sample. Pilot study. Approval and scheduling . Calibrating the examiners. Organizing the survey .

Establishing the Objectives ( determination of objectives)

The objectives of a study is to determine the kind of data that will be needed and the form in which they should be collected , unless the objectives are clearly defined before a study begins , unnecessary data or data unusable form may be gathered at considerable cost , while data really needed may even be overlooked . Thus , the final objectives must be kept clearly in mind when oral health assessment are being selected for inclusion in a study to ensure that each piece of information is essential for planning , evaluation or research purposes

obtain data for the following purposes :

1- To estimate the prevalence of specific oral diseases and conditions , and Identifying variations in local regional or national groups. 2- Supply data to assist oral health administrators in determining priorities with respect to : A- Health education , preventive and treatment services . B- The groups in most need of oral health care . 3- Supplying base line data, for subsequent evaluation of oral health care programmes.

Selecting of sample

The experimental unit in dental epidemiology is normally the individual and the task of the epidemiologist is to obtain information on groups of individuals . The size of these groups may vary in number , depending on the aims and scope of the investigation . It is impossible to examine every individual in the population because of resources in terms of time , money and manpower available . The sample selected must be truly representative of the population in all relevant respects


major aim in selection of the sample must be to avoid bias
Bias in a sample normally arises in : Non random sampling : human choice is involved e.g rats The sampling frame ( the list of subjects in the population used to draw the sample e.g telephone ) Some members of the population can not be reached or may refuse to cooperate

Types of sampling :

Random sampling . Simple random sampling . Systemic sampling. Multistage sampling. Stratified Sampling Cluster sampling.

Path Finder Survey

This type of survey is intended to be economical and practical way of obtaining data by selecting a limited number of age and other groups, the age groups selected are 6 year old children , 12 y , 15 y , 35 – 44 y , 65 -74 y .

Random Sampling

Which is defined as that every element in the population has an equal and independent chance of being selected , or is one in which each member of the population has the same known probability of selection . In America random sampling is in fact called probability sampling .• Random sampling is the procedure of choice when ever possible .• It prevents the possibility of selection bias on part of the researcher .• One of the easiest ways of doing this is to use tables of random numbers , such as are found in books of statistical tables . ( simple random sampling )

System Sampling

Is not a true sample because every one may not have an independent chance of being selected , this type of sample is usually obtained by drawing a number and then selecting every nth individual ,this method is used when dealing with a large population numbering as several thousands , for example suppose we wish to select a random sample of 300 from a population of 30,000 in other words one for every hundred in the population , we would pick the first member of the sample using random numbers , then select every 100th individual from them.

Stratified Sampling

The population is divided in to subgroups or strata , and each of these strata is sampled randomly to produce a known sample size . The reason for this is usually a condition under investigation that is known to be related to various factors such as age, sex, socioeconomic level, educational level or area of residence e.g the age specific and dental caries , the population is stratified by age , weighting the strata to take in to account the proportion of each stratum in the population .

Multi – Stage Sampling ( Sampling by stage)

Cluster sampling

This is used when it is impractical to use any of the foregoing methods and also it is more convenient for administrative and economic purposes , e.g. if a dentists wants to examine 10 % of the 6 years old children in his area it may well prove best to sample the schools rather than the individual children . In this case each school forms the appropriate cluster and selected randomly until the total number of children in the school reaches the 10 % of the 6 year olds . Clearly such a sample would not perhaps be free from bias as a true random sample , but it would be an adequate substitute . Identifying the first subject , the researcher continues taking numbers vertically or horizontally , until the desired sample size is established , repeated numbers are omitted and subject selection is continued .

Pilot study

A pilot study gives all personnel associated the regular study experience in working together and provides the opportunity ( chance ) for resolving difficulties that may arise in the implementation of the study protocols ( procedures ) This type of study may be used for training records / and the interpretation of the diagnostic criteria , carry out the procedures , standardizing the examiners technique and procedure and calibrating their examination technique .

Questionnaire

After preparing of primary questionnaire forms , than a pilot study distributed to 20 individuals , the reason is to eliminate as much as possible limitations that could be faced during the study , then the primary questionnaire will be rearranged and new questions will be added and some omitted , so a modification was made so that the final form of the questionnaire was approved to be more easier and understood and easy to be answered by the individual .

Approval

To get a permission to examine population groups must be obtained from a local , regional and national authority e.g. if a school population are to be examined , the school authorities should be approached and the purpose of the study explained to them , their approval for the programme should be obtained to ensure full cooperation . Also in case of examination and then treatment of the children , a written permission from the parents must be obtained before the children can be examined .

Scheduling

In any study , the preparation of an orderly schedule for data collection or carrying out any procedure is very important to avoid wasting time . The researcher can estimate from a pilot study or from previous experience , how much time on average each examination or procedure will take , a daily and a weekly schedule can then be made for the researcher and school.