The key to reliable Dental Age Estimation (DAE) is a robust system of the management of numerical data . In essence, the whole of the process of DAE is centred on adequate management of numbers. In practice, the main numbers used are the date of birth (dob) and date of radiograph (dor) which together define the Chronological Age (CA) of the Tooth Development Stages (TDSs) in the subjects comprising the Reference Data Set (RDS).
The formula for Calculating the CA is (dor – dob/365.25) The division by 365.25 is because computer software counts dates and ‘time difference between dates’ in years. For convenience and standardisation, the age is expressed as a numerical value to two decimal places e.g. 12.25 years. This applies to the Age at Attainment (AaA) for each of the 288 TDSs present in the human dentition. In this context it is helpful, to be aware that 1 month is equivalent to 0.08 years. One week is equivalent to 0.019 years. One day is equivalent to 0.0027 years, although this small unit (in DAE terms) is rarely used.
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