Mineralization of the mandibular third molar: A study of American blacks and whites

Abstract

The tempo of tooth mineralization is under significant genetic control, and the orderly progression of morphological changes-in concert with the long span during growth in which teeth form-makes "dental age" a useful measure of a person's degree of biological maturity. The third molar is of particular interest because (1) it is the last and most variable tooth to form and (2) it is the only tooth to complete formation after puberty, which has made it attractive in forensic and legal circles as an estimator of adulthood. Age standards are described here for mandibular third molar formation stages in a cross-sectional sample of 4,010 persons (age range: 3-25 years), with proportionate sample sizes of American blacks and whites and males and females. Formation was scored against the 15-grade ordinal scheme of Moorrees, and descriptive statistics were computed using proportional hazards survival analysis. Blacks achieved each formation stage significantly ahead of whites, but not in a uniform manner. Instead, there was an enhanced advancement in blacks during crown formation and during late stages of root formation. In both races formation proceeded faster in males, which is unique for the third molar, as prior studies suggest. Sample variance increases with the stage of formation, such that 95% confidence limits span 8 or more years for root formation stages. Consequently, the third molar provides a rough gauge of an individual's chronological age, but the considerable variability precludes any precise estimate, particularly in late adolescence where most forensic interest has focused.

Forensic Age Estimation in Unaccompanied Minors and Young Living Adults

“…Perhaps due to the fact that a good part of the third molar formation process occurs once puberty is reached, sexual dimorphism contrary to the rest of the dental maturation processes can be observed, with males reaching the different development stages earlier than females, independently of their ethnic origin. Studies published to date agree in this respect (Arany et al, 2004;Garn et al, 1959;Gunst et al, 2003;Haavikko, 1974;Harris, 2007;Harris & Nortjé, 1984;Köhler et al, 1994;Levesque et al, 1981;Meinl et al, 2007;Orhan et al, 2007;Prieto et al, 2007;Solari & Abramovitch, 2002;Throson & Hägg, 1991;Willerhausen et al, 2001). Studies evaluating third molar development in the maxillary and mandibular arch appear to agree in the greater advance in maturation of maxillary molars versus mandibular ones (UNHCR, 2002;6), (14),(37), Meinl et al, 2007;Orhan et al, 2007;Solari & Abramovitch, 2002;Willerhausen et al, 2001).…”

“…From these 324 were up to 15 years old and 438 were aged 16 to 17. Most of them were detected at the airports and they came mainly from Iraq and Afghanistan during 2007. During 2003to 2006, the most usual nationalities were Turkish and Chinese, and other nationalities more unusual were Russian, Serbian, Vietnamese and Nigerian (Federal Office for Migration and Refugees, 2009).…”

Accuracy of Dental Age in Nonadults: A Comparison of Two Methods for Age Estimation Using Radiographs of Developing Teeth

“…More importantly the difference in means derived from Cameriere's versus the Americanspecific formula were statistically significant, indicating that while differences in the timing of tooth formation may not be between ethnic populations but may be geographically influenced. For example, these differences may be caused by differences in climate, nutrition, socioeconomic levels and urbanization (Al-Tuwiriqi et al 2011, Chaillet et al 2010, De Luca et al 2012, Harris 2007, Rai et al 2007. It is important to note, that the variation in timing of tooth formation between populations is not well understood and the existence of differences and their meaning has been debated by many researchers (Chaillet et al 2010, De Luca et al 2012, Harris 2007.…”

“…For example, these differences may be caused by differences in climate, nutrition, socioeconomic levels and urbanization (Al-Tuwiriqi et al 2011, Chaillet et al 2010, De Luca et al 2012, Harris 2007, Rai et al 2007. It is important to note, that the variation in timing of tooth formation between populations is not well understood and the existence of differences and their meaning has been debated by many researchers (Chaillet et al 2010, De Luca et al 2012, Harris 2007. While the data from this study lends support for the notion that such as difference exists, this data as well as research from others demonstrates that the impact of group differences on the accuracy of age estimation of an individual is small (Braga et al 2005;Thevissen et al 2010;Liversidge & Marsden 2010).…”

“…Previous research has demonstrated that there is variability in rate of tooth 6 maturation between populations (Al-Tuwiriqi et al 2011, Chaillet et al 2010, Rai et al 2007, Tompkins 1996, Ubelaker 1978. For example, Harris (2007) demonstrated that African Americans tend to achieve mineralization stages faster than their European…”