THE HISTORY AND SIGNIFICANCE OF THE SCHREGER PATTERN IN PROBOSCIDEAN IVORY CHARACTERIZATION
EDGARD O'NIEL ESPINOZA, & MARY-JACQUE MANN
Much of the current knowledge of proboscidean ivory morphology is based on observations published in the previous century. Two of the most respected names in 19th-century odontology, Bernhard Schreger and Richard Owen, are associated with the history and scientific analysis of ivory.
Schreger is credited with the description of Hunter-Schreger Bands in enamel. Schreger (1800) published observations on human and animal “Habitus der Knochensubstanz” (dentine) and “Schmelz” (enamel). Referring to dentine, he wrote “The differences of the direction of the stripes: namely it [the direction] depends on the form of the base of the inner cavity of the tooth … thus they [the stripes] tend to point in a simple arch with a concavity toward the hole” (p. 2). In contrast, with respect to enamel substructure, he referred to “distinguishable layers or bands” (p. 2).
Obermayer (1881) referred to Schreger's work. In the section on elephant ivory Obermayer stated, “First described by Schreger (1800) these lines characteristic of genuine ivory … carry the name ‘Schreger Lines’” (p. 106). Two subsequent German-language publications (Höhnel 1892;Hanausek 1907) use the term “Schreger Lines” as an accepted scientific term. After 1907, however, references to “Schreger Lines” seem to have disappeared from the literature.
Sir Richard Owen (1845, 1854, 1856) also published on the subject of proboscidean ivory pattern, and his work is cited in studies in English (Miller 1890; Penniman 1952; Miles and White 1960; Brown and Moule 1977) and German (Obermayer 1881; Höhnel 1892). Although Owen is clearly associated with the proboscidean ivory pattern, his name was given to a system of concentric dentine growth lines (Miles and White 1960) and not to the pattern itself. The term “Schreger Lines” was not used by English-language researchers, who chose Owen's descriptors for the proboscidean ivory pattern: “decussation,” “curvilinear,” “lozenge.”
Exclusive use of subjective and antiquted descriptors is inappropriate in a forensic or legal forum. Although utilization of the term “Schreger Lines” is limited to three authors, it appears to be the earliest known and accepted scientific appellation for the proboscidean ivory pattern. In deference to the historical precedent set by these early authors, and because of our need for consistency, we refer to the pattern of crossing lines in proboscidean ivory as the Schreger Pattern.