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Topic: Perikymata

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	::: Star Weekend Magazine ::: (Site not responding. Last check: 2007-10-14)
		Perikymata are even tinier horizontal lines on the teeth surface and each of them represents about eight days of enamel growth, so by counting their number, researchers can gauge the speed of tooth development.
		The perikymata showed that periods of up to three months of starvation for both the Neanderthals and the Inuit were not uncommon.
		An American researcher has revealed that students are more likely to drink, and smoke cigarettes and marijuana after obtaining a driving license and their drinking and driving behaviour become riskier as they gain further experience.
	www.thedailystar.net /magazine/2004/09/04/scitech.htm (986 words)

	4_04NotesForeWeek4
		The remainder terminate on the surface of the teeth.
		Brown striae terminate on the surface as perikymata.
		IF the perikymata are totaled and to that added an estimate of the hidden cuspal brown striae, THEN total time for enamel formation can be determined.
	www.uic.edu /classes/osci/osci590/4_04NotesForWeek4.htm (1243 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		They claim to have counted all the perikymata on the buccal surfaces of these teeth or to have estimated the number of perikymata on teeth with worn crowns.
		"Perikymata number in modern humans is significantly different to that in Neanderthals in all teeth from the sixth decile, except in I 1 and I 2, where significant differences are observed from the 7th decile.
		It is now clear that differences in perikymata spacing result from differences in periodicity of the long-period incremental markings, and since these diverge as they approach the surface, from differences in enamel thickness (Schwartz et al., 2001).
	www.jackcuozzo.com /pery.html (3313 words)

	Reply to "Surprising rapid growth in Neanderthals (Nature 428,936; 2004) (Site not responding. Last check: 2007-10-14)
		The authors claim to have counted all the perikymata on the buccal surfaces of the permanent anterior teeth from 146 H. neanderthalensis, 100 H. sapiens, 106 H. Heidelbergensis, and 8 H. antecessor, or to have estimated the number of perikymata on teeth with worn crowns.
		The buccal or labial surface of an incisor that is worn down to half or a quarter of its original height is not in such pristine condition so that counting this periodicity is "easily done".
		In addition, I have observed and photographed perikymata in Le Moustier 1, in Germany, and they are closely packed at the cervical margin, contrary to the author's claims.
	www.jackcuozzo.com /nature428.html (419 words)

	Abstracts
		Perikymata and striae of Retzius were counted on a total of 370 unworn (or minimally worn) anterior teeth of Neandertals and three comparative modern human groups.
		Perikymata are wave-like enamel surface manifestations of underlying striae of Retzius, incremental lines in enamel which are visible in transmitted light microscopy that have a modal periodicity of 8-10 days in hominins (Dean et al., 2001).
		Perikymata packing pattern (PPP) is considered to reflect variations of the extension rate of the enamel during crown formation.
	www.eva.mpg.de /evolution/confMay2005/files/abstracts.htm (9425 words)

	American Scientist Online - Growing up Neandertal (Site not responding. Last check: 2007-10-14)
		Their paper also examined the spacing of perikymata across the front surfaces of incisors and canines.
		In modern humans, the perikymata are widely spaced in the half of the tooth that formed first, indicating that lots of enamel was deposited during each nine-day increment.
		However, on the part of each Neandertal tooth that grew later, the perikymata are more spread out than in their human counterparts.
	www.americanscientist.org /template/AssetDetail/assetid/37226?&print=yes (1759 words)

	New Scientist Teenagers special: The original rebels - Features
		These perikymata are like rings in a tree trunk: the number of them tells you how long the crown of a tooth took to form.
		Across mammals, the speed of tooth development is closely related to how fast the brain grows, the age you mature and the age you die.
		A previous study of a remarkably well-preserved skeleton of a Neanderthal youth, known as Le Moustier 1, from south-west France had suggested that, with a dental age of 15 and the frame of an 11-year-old, the kid was about to undergo an adolescent growth spurt.
	www.newscientist.com /channel/being-human/teenagers/mg18524891.100 (2518 words)

	Changes in Perikymata and Their Significance to a Postmortem Dental Identification. Smith BC . 1991;36(1): 166-178. (Site not responding. Last check: 2007-10-14)
		Changes in Perikymata and Their Significance to a Postmortem Dental Identification.
		Abstract: Perikymata are wavelike features that are normally found in the surface enamel of teeth.
		The unusual pattern of perikymata change on two of the teeth suggests the antemortem existence of a removable partial denture.
	www.astm.org /jforensicsci/PAGES/1493.htm (117 words)

	[No title]
		They examined the perikymata -- small enamel ridges on the tooth surface -- of incisor and canine teeth from 55 Neandertals, 25 Homo antecessor and Homo heidelbergensis individuals (two species that some anthropologists group together) and 39 ancient but anatomically modern humans.
		The study also examined the spacing of perikymata across the front surfaces of incisors and canines.
		5) In modern humans, the perikymata are widely spaced in the half of the tooth that formed first, indicating that lots of enamel was deposited during each nine-day increment.
	saturniancosmology.org /files/neander/neander.txt (2086 words)

	2001 Abstracts
		Perikymata are spaced near the cusp tip becoming closer toward the cervix.
		Irrespective of total tooth height, the number of perikymata in each 10th percentile of total crown height was recorded.
		The variation of perikymata number through the 10th percentiles of the crown height enables us to establish the perikymata packing pattern.
	www.paleoanthro.org /abst2001.htm (10597 words)

	Newswise
		She microscopically examined teeth from the Neanderthal skulls for signs of linear enamel hypoplasia, as well as other normal growth increments in teeth called perikymata, and compared their prevalence with those from the Inuit skulls.
		Each one represents about eight days of enamel growth so by counting their number, researchers can gauge the speed of tooth development – more perikymata mean slower growth of the tooth surface.
		In fact, Guatelli-Steinberg found that Inuit teeth showed significantly more perikymata than did the Neanderthals, suggesting that the Inuit experienced stress episodes that lasted slightly longer than did those of the Neanderthals.
	www.newswise.com /articles/view/506904/?sc=wire (775 words)

	Daniel ANTOINE: Institute of Archaeology UCL
		Figure 2: Detail of the thin section from the tooth shown in figure 1 (polarised transmitted light microscopy; the surface, enamel and dentine are labelled as S, E and D).
		‘Growth layers’, known as perikymata, are visible on the surfaces of unworn teeth (figure 6).
		Simon Hillson and myself, new ways of using perikymata to estimate the formation of molar teeth are being tested.
	www.ucl.ac.uk /archaeology/staff/profiles/antoine.htm (1246 words)

	NSF Proposal Figures (Site not responding. Last check: 2007-10-14)
		These striae conform to the dimensions of the dentine horn in the cuspal enamel, producing appositional or cuspal enamel.
		In the lateral and cervical enamel, Retzius lines contact the enamel surface, forming circumferential rings known as perikymata.
		This region is referred to as imbricational or lateral enamel.
	www.sinc.sunysb.edu /Stu/tasmith/figure1.html (149 words)

	[No title]
		The (brown) striae of Retzius are incremental growth lines that on the sides of the crown run obliquely across the prisms to approach the enamel surface.
		At the surface they are often associated with a depressions called perikymata.
		Particularly in the outer regions of the enamel (as in this case) they may be very regularly spaced, approximating to seven days growth.
	www.dentistry.leeds.ac.uk /OROFACE/virtlab/histolab/data/txt51ov1.html (140 words)

	News in Science - Neanderthals sped through puberty - 29/04/2004 (Site not responding. Last check: 2007-10-14)
		Why they developed so quickly is a puzzle but Ramirez Rossi suspects Neanderthals had a high mortality rate because of the hostile conditions in which they lived and they adapted to this by maturing quickly.
		The researchers studied the series of minute horizontal ridges, called perikymata, on fossils of front teeth.
		The ridges are enamel that is routinely deposited on outer surface of the teeth as the creature proceeds through life.
	www.abc.net.au /cgi-bin/common/printfriendly.pl?/science/news/stories/s1097282.htm (508 words)

	BBC NEWS \| Science/Nature \| Neanderthals were 'adults by 15'
		Perikymata are disturbances in the deposition of crown enamel which are preserved on the tooth's surface as a series of horizontal ridges.
		More closely spaced perikymata indicate a slower rate of growth, while more widely spaced perikymata point to faster growth.
		They found that perikymata were generally more widely spaced in primitive humans such as Neanderthals, Homo heidelbergensis and Homo antecessor than in our own species.
	news.bbc.co.uk /1/hi/sci/tech/3663865.stm (631 words)

	2000-1 Lampl 51-62 (Site not responding. Last check: 2007-10-14)
		These individuals are assessed according to previously published methods for the ageing of incremental growth in crowns and roots of different teeth.
		Scanning electron micrographs were taken to count the perikymata on enamel surfaces and histological sections of teeth were prepared and analysed for counts of internal striae of Retzius and cross striations.
		The present data extend the descriptive data base on population variability in perikymata counts and striae of Retzius observations for comparative studies of dental development in modern humans.
	www.mzm.cz /Anthropologie/abstrakty/00-1abstrakty/00-1lampl51.htm (360 words)

	Neanderthal Life No Tougher Than That Of "Modern" Inuits (Site not responding. Last check: 2007-10-14)
		The small horizontal lines covering the surface of each tooth are perikymata, enamel growth increments representing approximately 8 days worth of growth.
		Image of an Inuit linear enamel hypoplasias with perikymata visible within the defect.
		Counting the number of perikymata within the linear enamel hypoplasias allows one to estimate the period of time during which enamel growth was disrupted.
	researchnews.osu.edu /archive/neanderpics.htm (114 words)

	Perikyma - Wikipedia, the free encyclopedia
		Over $75,000 has been donated since the drive began on 19 August!
		Perikymata (Greek plural of: perikyma) are the pits around the long microscopical prisms of tooth enamel.
		They indicate the places where enamel-producing cells used to make contact to neighbouring cells.
	en.wikipedia.org /wiki/Perikymata (77 words)

	Science News: Hominid headway: scientists have used modern technology to scour the inside of an ancient child's skull, ... (Site not responding. Last check: 2007-10-14)
		Conroy says that studies suggesting a weekly cycle of enamel formation are "60 to 70 percent convincing at this point,' although it is unclear why the periodicity occurs or what function perikymata serve.
		But Mann, as well as Frederick E. Grine of the State University of New York at Stony Brooks, regards the perikymata data as dubious and based on inadequate studies of enamel formation in modern populations.
		With dental anatomist David Beynon of the University of Newcastle, England, Dean has reviewed independent lines of evidence on the timing of perikymata formation in apes, humans and early hominids.
	www.findarticles.com /p/articles/mi_m1200/is_n25-26_v132/ai_6241783/pg_2 (349 words)

	Telegraph \| Connected \| How humans put the bite on Neanderthals
		Dr Rozzi could not say if our ancestors committed genocide but it seems clear that they did at least out-compete the Neanderthals: "We are still alive whereas there are no more living Neanderthals."
		The growth finding is based on a curious feature of dental development - ridges called perikymata that are deposited every nine days.
		The growth of modern human teeth was found to slow as the tooth develops, while Neanderthal tooth enamel grew at a constant rate.
	www.telegraph.co.uk /connected/main.jhtml?view=DETAILS&grid=P8&targetRule=10&xml=/connected/2004/05/05/ecneand29.xml (263 words)

	Dental Biomaterials - Dental Sciences - University of Newcastle
		There are both daily incremental markings within enamel and also longer period markings (about 8 or 9 days apart in humans and apes).
		The longer period markings can be seen on the surface of teeth, under a microscope, as fine ridges called perikymata.
		By making thin histological sections of modern and fossil teeth we were able to see and count daily incremental markings within the enamel of humans, apes and fossil hominins.
	www.ncl.ac.uk /dental/research/biomaterials/news_nature.htm (829 words)

	Neanderthals not as slow as once thought: study. 29/04/2004. ABC News Online (Site not responding. Last check: 2007-10-14)
		Dental growth records contain biological information and give an overall indication of the maturity of a species.
		Ramirez Rozzi and Bermudez de Castro studied the series of ridges, called perikymata, on teeth fossils.
		They compared teeth fossils from Neanderthals dating from 130,000 to 28,000 years ago, earlier samples dating between 800,000 and 400,000 years and teeth fossils of homo sapiens that were 20,000-8,000 years old.
	www.abc.net.au /news/newsitems/s1097156.htm (506 words)

	Book Of THoTH - News / Announcements - Neanderthals were 'adults by 15'
		Neanderthals formed their crowns 15% quicker than we do, reaching adulthood when modern humans of the same age were still floundering in adolescence.
		In modern humans (Homo sapiens) tooth growth slows dramatically after the formation of the top half of the crown.
		They found that perikymata were generally more widely spaced in primitive humans such as Neanderthals, Homo heidelbergensis and Homo antecessor than in our our own species.
	www.book-of-thoth.com /article623.html (803 words)

	Laborprogramm (Site not responding. Last check: 2007-10-14)
		HP Turbo Diamonds with diamond free spiral provide for a fast aggressive cutting of metals and acrylics.
		The Turbo 856 023 SC HP is the famous Perikymata Grinder by Brix.
		The Super-Max is an organically bonded HI-Power Diamond Grinder with exceptional features for all alloy types and ceramics.
	www.nti.de /englisch/produkte/labor/labor.htm (112 words)

	The prevalence and timing of enamel hypoplasia -- M.A. Thesis -- (Site not responding. Last check: 2007-10-14)
		Three methods are employed to determine the timing of linear enamel hypoplasia (LEH).
		(1) Imbricational enamel formation schedules are created for bonobo teeth (n=6) by counting the number of perikymata from the cemento-enamel junction to the occlusal surface.
		(3) Using scanning electron microscopy, tooth crown surfaces (n=22) are examined and perikymata counted within and between enamel defects.
	www.sfu.ca /archaeology/dept/gradstu/theses/masters/tsukamoto.htm (351 words)

	Research Notes (Site not responding. Last check: 2007-10-14)
		The number of perikymata on unworn teeth reflects the duration of enamel formation, while the spacing of perikymata reflects an important component of the enamel formation rate.
		It is often possible to discern perikymata within hypoplastic defects microscopically, and hence estimate the duration of disruption.
		Because the duration and rate of enamel formation is related to the length of the growth period in primates (including hominins), the answer to the first question will help clarify whether the life history pattern of Neanderthals differed from that of early modern humans.
	monkey.sbs.ohio-state.edu /Newsletter/AU03/research_notes.htm (1228 words)

	Nat' Academies Press, Health Effects of Ingested Fluoride (1993)
		Appendix 1711 TABLE A-3 Clinical Criteria and Scoring for Score Criteria Normal translucency of enamel remains after prolonged air-drying.
		Smooth surfaces: More pronounced lines of opacity that follow the perikymata.
		Smooth and Occlusal surfaces: Loss of main part of enamel with change in anatomic appearance of surface.
	www.nap.edu /books/030904975X/html/167.html (815 words)

	Prior to placement of a final enamel layer
		At the patients request, the definitive surface finish was compieted with minimal texture.
		In order to simulate perikymata, texture could have been placed with a medium-grit giamond in a low-speed handpiece.
		The occlusal finish line was a 0.7 mm to 1 mm
	www.oraltech.com.br /biblioteca/am0008/pag04.htm (555 words)

	A Topographical Approach to Dental Microwear (Site not responding. Last check: 2007-10-14)
		Using these techniques, it is possible to decompose the topographic relief of a tooth surface into components associated with features that occur at different spatial frequencies.
		For example, periodicities arising from enamel prisms and perikymata can be separated from those associated with overlying microwear by digital filtering.
		The filtered data provides information on microwear features ranging in size between 0.1 microns and 0.1 mm.
	www.anth.ucsb.edu /faculty/hagen/topo.html (343 words)

	Dental Fluorosis Classification Criteria
		Smooth surfaces: Merging and irregular cloudy areas of opacity.
		Accentuated drawing of perikymata often visible between opacities.
		Worn areas appear almost normal but usually circumscribed by a rim of opaque enamel.
	www.fluoridealert.org /health/teeth/fluorosis/criteria.html (725 words)

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