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The enamel on primary teeth has a more opaque crystalline form and thus appears whiter than on permanent teeth. The large amount of mineral in enamel accounts not only for its strength but also for its brittleness. [6] Tooth enamel ranks 5 on Mohs hardness scale (between steel and titanium) and has a Young's modulus of 83 GPa. [4]
The teeth of Arctodus pristinus transition between undulating to acute-angled Hunter-Schreger bands while Arctodus simus exhibited a transition between undulating to zigzag bands, demonstrating an evolution towards reinforced tooth enamel. This has been convergently evolved with giant pandas, agriotheriin bears, and Hemicyon. [9]
This process begins during tooth development after the initial formation of dentin (dentinogenesis), the layer beneath the enamel. [2] The inner enamel epithelium (IEE), a layer of cells within the developing tooth, plays a crucial role by signaling the differentiation of specialized cells called ameloblasts , [ 3 ] which then secrete the ...
An Encyclopedia of World History (5th ed. 1973), very detailed outline; 6th edition ed. by Peter Stearns (2001) has more detail on Third World; McAlister, Lyle N. Spain and Portugal in the New World, 1492–1700 (1984) Ness, Immanuel and Zak Cope, eds. The Palgrave Encyclopedia of Imperialism and Anti-Imperialism (2 vol 2015), 1456pp
The term "imperialism" is often conflated with "colonialism"; however, many scholars have argued that each has its own distinct definition. Imperialism and colonialism have been used in order to describe one's influence upon a person or group of people.
Imperialism is the maintaining and extending of power over foreign nations, particularly through expansionism, employing both hard power (military and economic power) and soft power (diplomatic power and cultural imperialism). Imperialism focuses on establishing or maintaining hegemony and a more or less formal empire.
The world's colonial population at the time of the First World War totaled about 560 million people, of whom 70.0% were in British domains, 10.0% in French, 8.6% in Dutch, 3.9% in Japanese, 2.2% in German, 2.1% in American, 1.6% in Portuguese, 1.2% in Belgian, and 0.5% in Italian possessions. The home domains of the colonial powers had a total ...
Enamel and dentin do not regenerate after they mineralize initially. Enamel hypoplasia is a condition in which the amount of enamel formed is inadequate. [59] This results either in pits and grooves in areas of the tooth or in widespread absence of enamel. Diffuse opacities of enamel does not affect the amount of enamel but changes its appearance.