Oral health information systemsOral health information systems
Section 3: Obtaining assistance from WHO
Section 3: Obtaining assistance
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3.1 Pre-survey assistance
WHO may assist with survey planning, including advice on the sampling plan, estimates of sample size and the appropriate use of standard assessment forms.
The aims of such assistance are to foster the use of uniform survey methods and to help investigators develop objectives and survey plans to meet their specifi c needs. Prior to seeking assistance from WHO, investigators might fi nd it helpful to discuss the survey and the proposed survey plan with experienced colleagues in the national health or education sector so that factors of impor- tance and interest are not neglected or overlooked. When seeking pre-survey assistance from WHO, investigators are requested to provide the following information:
•
name and address of the principal investigator;•
purpose and objectives of the planned survey;•
area(s) and region(s) to be surveyed;•
specifi cations of the target population, e.g. the number or percentage of the school-age population and the number or percentage of those who attend school;.•
age(s) of the population to be surveyed, e.g. children, adults, older people or all age groups;•
whether probability sampling is intended and, if so, the sampling frame from which the sample would be selected;•
whether a pathfi nder approach will be used;•
estimates of the levels of dental caries, periodontal disease or other oral conditions for the ages under consideration (copies of reports from previous surveys should be provided if available);•
important subgroups within the population, e.g. ethnic groups, poor and disadvantaged groups, including the population ratio of such groups; and•
whether a risk factor questionnaire survey is planned, either as a stand- alone survey or in conjunction with clinical examination.WHO attaches great importance to basic oral health surveys for planning, evaluation and surveillance of oral health programmes and, whenever possible, the Organization offers assistance directly or through one of its collaborating centres or consultants.
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Assistance in training and calibration of potential oral examiners may, under certain circumstances, be available from WHO. Subject to prior agreement, an experienced epidemiologist who has been trained in the recommended methods for basic oral health surveys may be appointed to attend the training and calibration sessions as a trainer and validating examiner.
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3.2 Post-survey assistance
Subject to prior agreement, WHO will assist, guide and facilitate use of a data entry programme in Epi Info or SPSS (Statistical Package for the Social Sci- ences) for analysis of data obtained through the procedures recommended in this manual, provided that the standardized format and coding have been used. The analysis may be carried out using a standard computer programme which will produce a standard set of tables (see Annex 9 and Annex 10). The summarized data will be systematically included in the WHO Global Oral Health Data Bank.
For investigators who do not have access to computer facilities, WHO may be able to arrange assistance, for example, through a WHO Collaborating Centre.
Generated variables
As regards dental caries, the prevalence and severity of disease should be reported in terms of the standard epidemiological indicators:
•
Age-specifi c proportion of persons with one or more untreated decayed lesions (D>0; d>0) and with caries experience (DMF>0; dmf>0). The DMF and dmf values of 0 are equivalent to a caries-free state. This is applicable to both the permanent and the primary dentitions.•
Age-specifi c means and measures of variation (e.g. standard deviation or standard error of means) for the following selected indicators of caries severity:dt (number of decayed teeth in the primary dentition) mt (number of teeth missing due to caries in the primary
dentition)
ft (number of fi lled teeth in the primary dentition)
dft (number of decayed and fi lled teeth in the primary dentition)
dmft (number of decayed, missing due to caries and fi lled teeth in the primary dentition)
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DT (number of Decayed Teeth in the permanent dentition) MT (number of Missing Teeth due to caries in the permanent
dentition)
FT (number of Filled Teeth in the permanent dentition) DFT (number of Decayed and Filled Teeth in the permanent
dentition)
DMFT (number of Decayed, Missing due to caries, and Filled Teeth in the permanent dentition)
The DFT index can also be calculated for tooth roots since these data are obtained from each individual tooth; this is of particular impor- tance in the age group of 65–74 years.
When the data have been collected by tooth surface (see Annex 3 and Annex 4), a second set of tables with the corresponding indicators should be prepared.
•
Age-specifi c contribution of each component to total caries index among individuals examined:Per cent D/DMFT or d/dmft (per cent of decayed teeth within total caries experience index).
Per cent M/DMFT or m/dmft (per cent of teeth missing due to caries within total caries experience index).
Per cent F/DMFT or f/dmft (per cent of fi lled teeth within total caries experience index).