A scanning electron microscope study of the three‐dimensional extent of Retzius lines in human dental enamel

Risnes, Steinar

doi:10.1111/j.1600-0722.1985.tb01323.x

Cited by 16 publications

(14 citation statements)

References 12 publications

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“…The SEM technique reveals fewer Retzius lines than light microscopy (Risnes, 1985). Kantorowicz (1904) and Cavanha (1965) reported that Retzius lines were a prominent feature in light-microscopic observations of pearl enamel.…”

Section: Discussionmentioning

confidence: 99%

Ectopic Tooth Enamel. An SEM Study of the Structure of Enamel in Enamel Pearls

Risnes

1989

Adv Dent Res.

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Eighteen human molars with enamel pearls ranging in diameter from 0.8 to 2.7 mm were sectioned, acid-etched, and processed for SEM observation. In addition to pearl enamel, the specimens contained crown enamel for comparison. All pearls were of the composite type. The enamel layer reached maximal thicknesses of between 0.3 and 0.7 mm opposite the tip of the dentinal cone. The enamel structure was normal, but more variable and irregular than crown enamel. The prism course was often irregular throughout the whole thickness of enamel. Distinct Hunter-Schreger bands were absent. Prisms and interprism were occasionally difficult to identify as separate entities. The packing of crystals seemed to be less tight in pearl enamel. The scarcity of Retzius lines was attributed to the method of preparation. Prism cross-striations with a periodicity ranging between 1.3 and 4.5 microns were frequently encountered. A superficial prism-free zone with a regular 1.7-2.5-microns striation was present in localized regions of many pearls. The formation time of a medium-sized pearl was calculated to be about 11.5 months. A variety of cross-cut prism configurations was observed. Occasional hypoplastic lesions and hypomineralized areas were encountered. In conclusion, pearl enamel possesses most of the structural attributes of crown enamel, but in general its organization seems to be less orderly. Enamel pearls represent developmental disturbances in position and timing more than in structure.

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Section: Discussionmentioning

confidence: 99%

Ectopic Tooth Enamel. An SEM Study of the Structure of Enamel in Enamel Pearls

Risnes

1989

Adv Dent Res.

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“…5). Andresen lines have been shown to be equivalent to Retzius lines (42), which are equivalent to perikymata (43), and therefore it is the case that internal and external crown and root long-period lines share the same periodicity.…”

Section: Methodsmentioning

confidence: 99%

Rapid dental development in a Middle Paleolithic Belgian Neanderthal

Smith

Toussaint

Reid

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

176

177

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The evolution of life history (pace of growth and reproduction) was crucial to ancient hominin adaptations. The study of dental development facilitates assessment of growth and development in fossil hominins with greater precision than other skeletal analyses. During tooth formation, biological rhythms manifest in enamel and dentine, creating a permanent record of growth rate and duration. Quantification of these internal and external incremental features yields developmental benchmarks, including ages at crown completion, tooth eruption, and root completion. Molar eruption is correlated with other aspects of life history. Recent evidence for developmental differences between modern humans and Neanderthals remains ambiguous. By measuring tooth formation in the entire dentition of a juvenile Neanderthal from Scladina, Belgium, we show that most teeth formed over a shorter time than in modern humans and that dental initiation and eruption were relatively advanced. By registering manifestations of stress across the dentition, we are able to present a precise chronology of Neanderthal dental development that differs from modern humans. At 8 years of age at death, this juvenile displays a degree of development comparable with modern human children who are several years older. We suggest that age at death in juvenile Neanderthals should not be assessed by comparison with modern human standards, particularly those derived from populations of European origin. Moreover, evidence from the Scladina juvenile and other similarly aged hominins suggests that a prolonged childhood and slow life history are unique to Homo sapiens.hominin ͉ human evolution ͉ life history ͉ ontogeny ͉ tooth growth

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“…There is no doubt that perikymata are continuous with underlying striae of Retzius [72,73] (fig. 3), but not all striae reach the surface.…”

Section: Perikymatamentioning

confidence: 99%

The Developing Dentition and Tooth Structure in Hominoids

Dean¹

1989

IJFP

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This review of hominoid dental development is presented in two parts. The first section reviews (1) the general relationship between dental development and life history in hominoids; (2) the methods used to document dental development, and (3) the nature of incremental growth markings in hominoid teeth. The second section builds on this and reviews the contributions to hominoid dental development that have been made by (1) studies of tooth emergence; (2) studies of tooth calcification stages, and (3) histological studies of incremental growth markings made either from sections of teeth or replicas of early hominid teeth prepared for scanning electron microscopy.

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A scanning electron microscope study of the three‐dimensional extent of Retzius lines in human dental enamel

Cited by 16 publications

References 12 publications

Ectopic Tooth Enamel. An SEM Study of the Structure of Enamel in Enamel Pearls

Ectopic Tooth Enamel. An SEM Study of the Structure of Enamel in Enamel Pearls

Rapid dental development in a Middle Paleolithic Belgian Neanderthal

The Developing Dentition and Tooth Structure in Hominoids

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