Incremental enamel development in modern human deciduous anterior teeth

Abstract

This study reconstructs incremental enamel development for a sample of modern human deciduous mandibular (n = 42) and maxillary (n = 42) anterior (incisors and canines) teeth. Results are compared between anterior teeth, and with previous research for deciduous molars (Mahoney: Am J Phys Anthropol 144 (2011) 204-214) to identify developmental differences along the tooth row. Two hypotheses are tested: Retzius line periodicity will remain constant in teeth from the same jaw and range from 6 to 12 days among individuals, as in human permanent teeth; daily enamel secretion rates (DSRs) will not vary between deciduous teeth, as in some human permanent tooth types. A further aim is to search for links between deciduous incremental enamel development and the previously reported eruptionsequence. Retzius line periodicity in anterior teeth ranged between 5 and 6 days, but did not differ between an incisor and molar of one individual. Intradian line periodicity was 12 h. Mean cuspal DSRs varied slightly between equivalent regions along the tooth row. Mandibular incisors initiated enamel formation first, had the fastest mean DSRs, the greatest prenatal formation time, and based upon prior studies are the first deciduous tooth to erupt. Relatively rapid development in mandibular incisors in advance of early eruption may explain some of the variation in DSRs along the tooth row that cannot be explained by birth. Links between DSRs, enamel initiation times, and the deciduous eruption sequence are proposed. Anterior crown formation times presented here can contribute toward human infant age-at-death estimates. Regression equations for reconstructing formation time in worn incisors are given.

Prenatal factors associated with the neonatal line thickness in human deciduous incisors

“…Determination of the position of NNL is the first step in all analyses regarding characteristics of the enamel formed in the prenatal and postnatal parts of ontogeny (Antoine et al, 2009;Beynon et al, 1998;Dean, 2009, 2014;Eli et al, 1989;Mahoney, 2011Mahoney, , 2012Sabel et al, 2008;Seow et al, 2005;Smith and Avishai, 2005;Żądzińska et al, 2013).…”

Nejsou čáry jako čáry: inkrementální linie v mikrostruktuře zubů a jejich využití při analýze kosterních nálezů

“…FitzGerald et al 2006;Thomas 2003;Mahoney 2011Mahoney , 2012Birch -Dean 2014), které však vyžadují přípravu histologického prepará-tu a tudíž destrukci zubu. Díky rozvíjejícímu se oboru virtuální histologie je v poslední době možná i nedestruktivní analýza mikrostruktury zubů v 3D zobrazení pomocí rentgenové mikrotomografie (µCT) se synchrotronem jakožto zdrojem rentgenového záření a s využitím fázo-vého kontrastu (Smith -Tafforeau 2008).…”

Difference in Striae Periodicity of Heilongjiang and Singaporean Chinese Teeth

“…Within an individual, periodicity values are also consistent regardless of the tooth type, or the jaw arch from which the tooth is taken (FitzGerald, 1998; Reid et al, 1998; Mahoney, 2012). Nevertheless, inter-individual variations in striae periodicities have been noted.…”

“…Extensive studies have shown no difference between striae periodicities in different parts of a single tooth (Fukuhara, 1959; Beynon, 1992; FitzGerald, 1998; Mahoney, 2008, 2012). Within an individual, periodicity values are also consistent regardless of the tooth type, or the jaw arch from which the tooth is taken (FitzGerald, 1998; Reid et al, 1998; Mahoney, 2012).…”