Brief communication: The timing of linear hypoplasias on human anterior teeth

Abstract

One hundred and fifteen unworn anterior teeth were sectioned longitudinally with a diamond saw and prepared for histological examination by polarized light microscopy. Incremental markings in the enamel of each tooth were used to estimate the average total crown formation times of each tooth type. The total time taken to form the crowns of each tooth type was apportioned by 1) cuspal enamel formation and 2) each tenth percentile of total tooth height. Based on these data, and on histological estimates for the time of initiation of mineralization in each anterior tooth, the following conclusions can be drawn. Little if any visible surface enamel is likely to form before the end of the first year after birth in any anterior tooth type. No relation exists between tooth crown height and the total time taken to form enamel. Anterior crown formation is nonlinear and slows towards the cervix in all teeth. The estimated mean chronological age at crown completion ranged in this study from between around 4 years for lower central incisors to around 6 years for lower canines. We suggest that these combined findings will be useful for devising more reliable ways to estimate the timing of linear enamel hypoplasias than some methods currently in use.

Stress physiologique et état de santé des plus anciens Hommes anatomiquement modernes du sud-est de l’Europe (données dentaires, couche 6-1, Buran-Kaya III, Crimée)

“…On peut noter cependant une tendance à une surestimation pour les populations nord européennes, qui pourrait sans doute être significative si la taille de l'échantillon était plus importante. Cependant de nombreux auteurs (Hillson et Bond, 1997 ;Reid et Dean, 2000 ;Cunha et al, 2004 ;King et al, 2005) considèrent que la méthode fondée sur le décompte des périkymaties est plus fiable que celle mesurant la hauteur de l'hypoplasie, du fait que le taux de croissance de l'émail dentaire ne soit pas constant entre le sommet de la cuspide et l'apex de la racine (Hillson et Bond, 1997).…”

Oral Health in Past Populations: Context, Concepts and Controversies

“…Nevertheless, linear enamel hypoplasias are especially useful in reconstructing the chronological timing of stress events during growth and development, because the age at which a defect formed can be estimated from its position on the labial surface of the tooth crown. The most reliable method of estimating the time of defect formation, and therefore the age at which a stress event occurred, remains controversial (Reid and Dean 2000;Martin et al 2008;Ritzman et al 2008). Nevertheless, bioarchaeological analysis of hypoplastic enamel is said to be an "untapped" source of valuable information that now provides tentative support for a concept known as the Barker Hypothesis, also more fully described as the Developmental Origins of Health and Disease Hypothesis (DOHaD) (Armelagos et al 2009).…”

Can premorbid episodes of diminished vagal tone be detected via histological markers in patients with PTSD?

“…The developing enamel matrix is one of very few tissues that cannot recover after being stressed (Dean et al, 2001;Reid et al, 1998;Reid and Dean, 2000b;Antoine et al, 1999;Dean, 2000;Hillson, 1996;White, 1991;Risnes, 1998;Risnes et al, 1996;Simpson, 1999;Dean, 1999;Reid and Dean, 2000b,a). Thus, the developing enamel has promise as an accessible repository of information on vagal tone chronology prior to age 10 when human third molars (the last developing teeth) complete crown formation (Goodman and Rose, 1990;Skinner and Anderson, 1991).…”