Dentary tooth shape in Sphenodon and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia).
CONCLUSION: These three categories correspond to food processing as inferred from tooth wear (puncturing+crushing, grinding+shredding and tearing+cutting, respectively). A phylogenetic signal is also present as the teeth of basal taxa generally conform to the first category. The larger tooth bases of derived taxa provide stronger attachment and contribute to a stouter tooth shape more resistant to loading and torsional forces. This in turn corresponds to skull architecture because the skulls of derived taxa could accommodate larger jaw muscles with a greater leverage relative to basal taxa.
PMID: 19828962 [PubMed -...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Molar crown and root size relationship in anthropoid primates.
This study assesses the relationship between the volume and surface area of molar crowns and roots by examining two main hypotheses: (1) crown size correlates significantly with root size, and (2) the proportion of root-to-crown surface area is related to dietary proclivity. Permanent M2s (n=58) representing 19 anthropoid species were CT scanned and the volume and surface area of the crown and root were measured. Interspecific correlation and regression analyses reveal significant isometric relationships between crown and root volume and a positive allometric relationship between root and crown surface area (i.e. as crown ...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
How many landmarks? Assessing the classification accuracy of Pan lower molars using a geometric morphometric analysis of the occlusal basin as seen at the enamel-dentine junction.
Authors: Skinner MM, Gunz P, Wood BA, Hublin JJ
Abstract
Previous research has demonstrated that species and subspecies of extant chimpanzees and bonobos can be distinguished on the basis of the shape of enamel-dentine junction of lower molar crowns. Thus, there is potential for fossil taxa, particularly fossil hominins, to be distinguished at similar taxonomic levels using lower molar crown morphology. New imaging techniques allow for the collection of large amounts of shape data, but it is not clear whether taxonomic distinctiveness increases with the inclusion of more and more finely detailed aspects of...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Preserved microstructure and mineral distribution in tooth and periodontal tissues in early fossil hominin material from Koobi Fora, Kenya.
Authors: Klinge RF, Dean MC, Risnes S, Erambert M, Gunnaes AE
Abstract
The aim of this study was to explore further the preservation of tissues and the mineral distribution in 1.6 million-year-old fossil hominin material from Koobi Fora, Kenya attributed to Paranthropus boisei (KNM-ER 1817). Bone, dentine and cementum microstructure were well preserved. Electron microprobe analysis of dentine and bone revealed an F-bearing apatite. Calcite now filled the original soft tissue spaces. The average Ca/P atomic ratio was 1.93, as compared to 1.67 in biological hydroxyapatite, indicating that the Ca-content had ...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Dental morphology: an introduction.
Authors: Teaford MF
PMID: 19828966 [PubMed - indexed for MEDLINE] (Source: Frontiers of Oral Biology)
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Tooth form and function: insights into adaptation through the analysis of dental microwear.
Authors: Ungar PS
Abstract
Mammalian molar form is clearly adapted to fracture foods with specific material properties. Studies of dental functional morphology can therefore offer important clues about the diets of fossil taxa. That said, analyses of tooth form provide insights into ability to fracture resistant foods rather than the food preferences of individuals. Recent work suggests that specialized occlusal morphology can relate to either preferred foods, or to occasionally eaten fallback items critical for survival. This paper reviews dental microwear texture analysis, a new approach that can be used...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Primate dental enamel: what it says about diet.
This study involved the mechanical loading of extracted human and sea otter teeth using hard and soft indenters to simulate hard and soft diets. The tests were accompanied by real-time imaging. At least three types of fracture were seen in the enamel--median, radial and margin cracks. Each kind of fracture appears to have a different cause, although the distinction between median and radial cracks blurs as they propagate. Only margin cracks appear to form under soft indenters. Several aspects of tooth form can be described as devices to limit damage to a tooth crown against the onslaught of hard or soft foods. The damage m...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Testing the utility of dental morphological traits commonly used in the forensic identification of ancestry.
Authors: Edgar HJ
Abstract
Few human variants are truly population specific, with 100% frequency in one group and 0% in others. However, for traits to be of use in forensic identification they must be as specific to a population as possible. Forensically, several dental morphological traits have been described as useful for determining an unknown individual's ancestry. For these traits to be of value, they should occur in their associated group in proportions statistically different from all other groups. Furthermore, ancestral groups not associated with the trait should have no significant frequency diffe...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Meaning of the canine sexual dimorphism in fossil owl monkey, Aotus dindensis from the middle Miocene of La Venta, Colombia.
Authors: Takai M, Nishimura T, Shigehara N, Setoguchi T
Abstract
The owl monkey, Aotus, is the only modern nocturnal anthropoid with monogamous social structure. It has been demonstrated by the fossil species, Aotus dindensis, discovered from La Venta, Colombia, that the Aotus lineage had emerged as early as the middle Miocene (12-15 Ma). The type specimen of A. dindensis, which was discovered in 1986, preserves extremely large orbits, indicating a nocturnal habit. However, a few anatomical traits in living Aotus, such as the lack of a tapetum lucidum, indicates that nocturnality is a secondary adaptation ...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Observation of lateral mandibular protuberance in Taiwan macaque (Macaca cyclopis) using computed tomography imaging.
Authors: Kondo S, Naitoh M, Futagami C, Hanamura H, Goto K, Ariji E, Takai M
Abstract
Morphological characteristics of the protuberance on the external surface of the mandible in Taiwan macaque (Macaca cyclopis) was investigated using cone-beam computed tomography. We observed 49 skulls of M. cyclopis. Of 7 skulls with deciduous and mixed dentitions in which M2s did not erupt, the protuberance was not found. Of the 13 skulls with mixed and permanent dentitions in which M2s had erupted, a palpable protuberance was found in one specimen. Of the 29 samples in which M3s had erupted completely, a perceptible pr...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Dental tissues: an introduction.
Authors: Dean MC
PMID: 19828972 [PubMed - indexed for MEDLINE] (Source: Frontiers of Oral Biology)
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Extension rates and growth in tooth height of modern human and fossil hominin canines and molars.
Authors: Dean MC
Abstract
The aim of this study was to describe similarities and differences in the way modern and fossil hominin teeth grow in height. Measurements from longitudinal ground sections of 7 modern human canines and 19 first permanent molars were used to calculate extension rates in the crowns and roots and to plot distance curves for growth in tooth height. These were compared with identical data for 3 fossil hominin teeth attributed respectively to Paranthropus robustus, Homo erectus and Homo neanderthalensis. Enamel extension rates in each of the three fossil taxa fell within the range of m...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Amelogenin evolution and tetrapod enamel structure.
Authors: Diekwisch TG, Jin T, Wang X, Ito Y, Schmidt M, Druzinsky R, Yamane A, Luan X
Abstract
Amelogenins are the major proteins involved in tooth enamel formation. In the present study, we have cloned and sequenced four novel amelogenins from three amphibian species in order to analyze similarities and differences between mammalian and non-mammalian amelogenins. The newly sequenced amphibian amelogenin sequences were from a red-eyed tree frog (Litoria chloris) and a Mexican axolotl (Ambystoma mexicanum). We identified two amelogenin isoforms in the Eastern red-backed salamander (Plethodon cinereus). Sequ...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Microstructure of dental hard tissues and bone in the Tuatara dentary, Sphenodon punctatus (Diapsida: Lepidosauria: Rhynchocephalia).
Authors: Kieser JA, Tkatchenko T, Dean MC, Jones ME, Duncan W, Nelson NJ
Abstract
The Tuatara, Sphenodon, is a small reptile currently restricted to islands off the coast of New Zealand where it feeds mainly on arthropods. A widely held misconception is that 'Sphenodon does not have real teeth' and instead possesses 'serrations on the jaw bone'. One hatchling and one adult dentary were examined under SEM. Two longitudinal ground sections 100-microm thick were prepared through a lower canine tooth and its supporting tissues. There was clear evidence of aprismatic enamel (primless enamel) containing dentine ...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
Temporal nature of periradicular bands ('Striae periradicales') on mammalian tooth roots.
Authors: Smith TM, Reid DJ
Abstract
Periradicular bands, or fine circumferential lines on tooth roots, have received attention recently due to their prominence on hominin fossils and their potential utility for informing studies of root formation. In 1938, Komai and Miyauti [Dtsch Zahn Mund Kieferheilkd 1938;5:791-795] demonstrated that periradicular bands are related to dentine growth rather than cementum, suggesting that they were equal to accentuated lines in dentine ('dentine lamellae' or 'contour lines'). More recent indirect evidence from band spacing on primate roots suggests that they are temporall...
Source: Frontiers of Oral Biology - November 25, 2014 Category: ENT & OMF Tags: Front Oral Biol Source Type: research
