General Considerations
Tooth development as a means of estimating age has been used for several centuries. In the early part of the Industrial Revolution in Great Britain children were required to work in underground coal mines on attaining six years of age. Evidence of the attainment of six years was adduced from the presence in the mouth of any of the permanent first molars (Saunders 1837). In general terms this was accepted but was harsh on those children whose first permanent molars erupted at under 6 years, sometimes as early as 5 years and 3 months (Ekstrand, Christiansen, & Christiansen 2003). This highlights an important principle, which is the essential biological variability of growth of teeth, a factor inappropriately considered in many studies of Dental Age Assessment (DAA).
Methods of age assessment are used on subjects whose date of birth is unknown either because records are lost or have never existed. The possible techniques are psychological development, height, weight (Demirjian, Buschang, Tenguay, & Patterson, 1985), hand-wrist skeletal development (Tanner, Healy, Goldstein, & Cameron, 2001), sterno-clavicular joint maturation (Kreitner, Schweden, Reipert, Nafe, & Thelen,1998), tooth development (Bolanos, Manrique, Bolanos, & Briones, 2000; Liversidge, Lyons, & Hector, 2003), dental root canal width (Kvaal, Kolltveit, Thomsen, & Solheim, 1995), and/or tooth apical foramen width (Cameriere, Ferrante, & Cingolani, 2006). Occasionally dental age assessment is needed to assist in the identification process of cadaveric remains (Clark, 2008). Studies where different methods of age assessment are compared all indicate that tooth development correlates more closely with chronological age than any of the other techniques (Garn, Lewis, & Kerewsky, 1965; Lewis & Garn, 1960; Demirjian, et al., 1985).
The development of high quality radiographic images, especially the Dental Panoramic Tomograph (DPT), with which the whole of the dentition is viewed on a single image, has provided clinical investigators with a uniquely effective way of assessing dental maturation. This has led to the use of a number of different systems for generating quantitative data from defined stages of tooth development (Liversidge, Chaillet, Mornstad, Nystrom, Rowlings, & Taylor, 2006). The DPT (often referred to as an OPG or OrthoPantomoGraph) is widely used in clinical practice to assess dental disease in otherwise healthy children. This means that very large numbers of DPTs are available which are deemed to be representative of the general population. Occasionally, other radiographic projections which have a limited number of teeth, for example the upper standard occlusal, are used to generate reference data. Thus many studies have been carried out accurately defining the age of attainment of tooth development using clearly defined stages (Demirjian & Goldstein, 1976; Olze, Bilang, Schmidt, Wemecke, Geserick, & Schmeling, 2005).
Careful scrutiny of the literature shows that none of the publications cited explains the detailed method of exactly how an individual of unknown date of birth is assessed to establish her/his likely age.
A variety of methods have been used to estimate dental age (see Section 6e). The purpose of the present document is to describe the method used at the Dental Paediatric Unit of King’s College London Dental Institute and the UCL Eastman Dental Institute to carry out Dental Age Assessment (DAA). This is to inform colleagues, lawyers, immigration workers, social workers and subjects of unknown date of birth of the way in which DAA is conducted.