DENTAL MORPHOLOGY PDF
Dental Morphology. Chapter (PDF Available) · August with 3, Reads. DOI: /ch9. In book: Biological. PDF | On Jan 1, , G. Richard Scott and others published Dental morphology. 1 4 Part 1 | Comparative Tooth Anatomy hen we enter into any new field of study, tooth morphology are the basic foundation for under- W it is initially necessary.
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International Symposia of Dental Morphology have been held eleven times over the Years Old and Still Not Organized: the International Dental Morphology. dentin is a calcified connective tissue penetrated by millions of tubules;. • their density varies from 40, to 70, tubules per square mm. • tubules are from 1 . Current Trends in Dental Morphology Research ABSTRACT. Tooth development is characterized by the rhythmic secretions of enamel- and dentine- forming.
The study of the hominin fossils recovered at Xujiayao and the new findings from the Xuchang site reveal that in the transition from the late Middle to the early Late Pleistocene North China was inhabited by some primitive populations with unclear taxonomic assignment 8 , 9 , The fossil discoveries and related studies of H.
In addition, the genetic analysis of the Denisovans and the individual from the Tianyuan Cave revealed possible interbreeding of these hominins with Neanderthals, early modern humans or even archaic populations in or around Oceania 14 , 15 , In the general context of a taxonomically more diverse scenario, the morphology and evolution of hominins in the late part of the Late Pleistocene, in particular, have been the subject of increasing attention. Recent analyses of both mitochondrial and Y chromosome DNA revealed high levels of genetic diversity in the populations of southern China, especially in Southwest China, with persistence of some novel basal haplogroups that directly emanate from the Eurasian founder nodes.
Subsequent analyses suggested that these newly identified basal lineages likely represent the genetic relics of modern humans initially peopling East Asia instead of being the results of gene flow from the neighboring regions. Southwest China was likely the genetic reservoir of modern humans after they entered East Asia 19 , According to some researchers, the morphology of the terminal Pleistocene human fossils from Maludong and Longlin, both in Southwest China could be indicative of complex demographic patterns, with several human migrations and possible survival of archaic populations 21 , 22 , 23 although their relationship with other Late Pleistocene-Holocene populations from mainland Southeast Asia remains unclear 24 , Despite these advances, the detailed morphological pattern, diversity and evolutionary implications of the terminal Pleistocene hominins in Southern China need further investigation.
The lack of a substantial number of well-described, reliably classified and accurately dated sites has seriously limited our understanding of human evolution in the Pleistocene-Holocene transition in southwest China. In the present study, we aim to contribute to this topic by reporting a recently discovered human dentition from Dushan Cave, southern China.
Excavation at Dushan Cave in unearthed some human remains, a rich assemblage of stone tools and some faunal remains see SI-1 for details. The human fossils found at Dushan Cave include a partial cranium, mandibular fragments, and complete upper and lower dentitions except for the left M3 Fig. All the fossils belong to the same individual Dushan 1.
In the present study, the metrics and both the external outer enamel surface, OES and internal enamel dentine junction, EDJ morphology of Dushan 1 are collected and compared to a large sample of fossil and contemporary Homo sapiens as well as some archaic Homo populations from East Asia. Figure 1 The maxillary and mandibular dentitions of Dushan 1.
A left maxillary dentition; B right maxillary dentition; C right mandibular dentition; D left mandibular dentition. From left to right: I1 to M3.
Left M3 was missing. Full size image Results The analysis and comparisons of the metric and non-metric traits of Dushan 1 teeth with those of various fossil hominins and recent modern humans in the present study indicate that both the maxillary and mandibular dentitions of Dushan 1 exhibit a mosaic morphological pattern combining primitive and derived traits.
Apart from the preliminary evaluation of the skull and the mandible, Dushan 1 teeth also present some derived features that are typically found in H.
Our study of the dental morphology of Dushan 1 suggests that it represents a Homo sapiens individual with an unusual retention of ancestral traits. Dental traits typical of H.
Table 1 The frequency and expressions of key dental traits in Dushan 1 and comparative samples. Full size table In general, both upper and lower anterior teeth of Dushan 1 are gracile and simple in their morphology Fig. Except the upper central incisors, all other incisors of Dushan 1 I2s, I1s and I2s exhibit weakly developed double shoveling which is usually regarded as autapomorphic of H.
All the upper and lower premolars of Dushan 1 exhibit well-developed mesial or distal accessory ridges Fig.
The frequencies of this trait in global RMH populations reported by Burnett and colleagues 29 are The frequencies they report for East Asian populations are even higher Considering both fossil hominins and recent modern humans have higher frequencies of the accessory ridge in premolars, we tentatively consider the occurrence of this trait in the premolars of Dushan 1 as resemblance to H. In addition, there are other traits in the postcanine dentition of Dushan 1 that are more frequently observed in H.
Crown size The crown sizes of Dushan 1 upper and lower teeth are very large compared to those of Middle Pleistocene archaic Homo, early modern humans and recent modern humans from East Asia. All the mesiodistal MD and buccolingual BL crown dimensions of Dushan 1 except for the BL dimensions of I1 and I2 exceed the diameters of Late Pleistocene early modern humans and Holocene modern humans and, in some dimensions, they are close to or even exceed the values of Asian Middle Pleistocene archaic Homo Fig.
Full size image Relative tooth size differences between Dushan 1 individual and comparative samples including Neanderthals, early and recent modern humans from China, the Levant, North Africa and the Canary Islands, are further confirmed by Principal Component Analysis PCA of crown dimensions across dental classes in both upper and lower dentition see SI-4 for details.
Additional analysis of both bivariate plots and PCA of the bucco-lingual widths of upper and lower I2, P3, and M1 of Dushan 1 and some specimens that preserve the three dental classes also reveal the same trend see SI-4 for details.
For East Asian Pleistocene hominins, the frequencies of the I1s labial convexity decreased from Bifurcated essential crest P3and P4 The bifurcated essential crests for P3 and P4 are more frequently observed in earlier hominins 30 , 35 , Bifurcated essential crests of upper premolars are also found in some Middle Pleistocene populations from Europe like Atapuerca SH and Neanderthals In our small sample of recent modern Chinese humans 52 and 47 for P3 and P4, respectively , bifurcated essential crest can be observed in Therefore, the presence of bifurcated essential crests in both P3 and P4 of Dushan 1 Fig.
Figure 3 Some morphological traits identified in Dushan 1 teeth.
A buccal view of right P4. Arrow indicates the buccal vertical groove. Conclusions: The sample studied presented a great affinity with ethnic groups belonging to the Mongoloid Dental Complex due to the frequency expression and variability gradation of the tooth crown traits, upper incisors, the Carabelli trait, the protostylid, cusp 6 and cusp 7.
The influence of the Caucasoide Dental Complex associated with ethno-historical processes cannot be ruled out.
Introduction Analysis of dental morphology in the context of dental anthropology seeks to understand the manner in which the frequency, sexual dimorphism and bilateral symmetry of Tooth Crown Morphological Traits TCMT present in deciduous and permanent teeth 1. The TCMT consist of phenotypic enamel forms expressed and regulated by the genome of an individual and population during odontogenesis.
Structures can be positive tubercular or negative inter-tuberculars and fosomorfos that have the potential to be present, or not, at a specific site frequency and in a different form variability in one or more members of a population group 2 - 6.
Based on the TCMT, dental morphology is studied from an interdisciplinary viewpoint biology, anthropology, dentistry, paleopathology, archeology, forensic science because teeth can be used in the estimation of biological relationships between populations.
This is accomplished by comparatively analyzing past and present human groups in an attempt to clarify the historical, cultural and biological macro and micro-evolutionary processes that lead to an understanding of the origin, formation, contacts, displacements, migrations pathways and isolates that have led to the populating of the planet and ethnic variation of humanity 1 , 3 , 7 - 8.
It similarly constitutes an accurate means of recognizing individuals whose death makes it difficult to distinguish them by other processes which are part of the individual reconstruction of osteobiography odontography or for that of the general population 1 , 8 - 9. This is an essential process in forensic dental identification to document the elements of the basic identification quatrain sex, age, ethnicity and height 9. The school children were from Colombian Nasa parents and grandparents and were between the ages of 5 to 18 years.
Students were selected from a survey and interview examination who met the inclusion criteria with clinically healthy teeth where the TCMT were taken into account and who were asked to sign an informed consent and had parents that authorized their participation via an informed consent agreement. Standardization of morphological analysis The six observers learned to manage the odontoscopic systems Asudas-Arizona State University Dental Anthropology System-, Dahlberg, Hanihara, Sciulli and Grine with a standardization protocol and double blind in nature to control bias and achieve a unified observational criteria, according to that described by Nichol and Turner II Table 1.The roots of teeth may be single in number single-rooted teeth or multiple.
Oral Surg Med Pathol The oblique ridges usually forms the distal boundary of the central fossa. Included in the app is a guide to the morphology and features of the teeth, with 3D demonstrations of how they relate to the tooth in question.
Canines and most premolars, except for maxillary first premolars, usually have one root. There are four classes of teeth: incisors , canines , premolars , and molars. Maxillary molars usually have three roots.