Hanuman Langur: Monkey of India

An apparently new type of dental wear pattern, lingual surface attrition of the maxillary anterior teeth (LSAMAT), has been found in 85% of 46 adult crania from a 3000–4200 BP Archaic site called Corondó near the Atlantic Ocean coast of Brazil. LSAMAT is associated with a high caries rate (60% of 77 adults; 11% of 1,219 permanent teeth) in what on archeologica grounds alone would be considered a mainly meat-eating population. It is suggested that both LSAMAT and caries resulted from eating some starchy plant like manioc.     

More lingual surface attrition of the maxillary anterior teeth in American Indians: prehistoric Panamanians

Lingual surface attrition of the maxillary anterior teeth (LSA-MAT) has been found in additional prehistoric Latin American Indian skeletons. LSAMAT was first observed in crania from an Archaic Brazilian site. This second finding occurs in teeth from Venado Beach, a late prehistoric site in Panama. LSAMAT is also present in some fragmentary specimens from the Archaic Cerro Mangote site in Panama. LSAMAT at Venado Beach is present in 57% of 28 adult crania. As in the Brazilian study, LSAMAT is associated with a high caries rate (82% of 50 adults; 11.7% of 852 permanent teeth). As first suggested, eating and processing of some type of abrasive carbohydrate food, such as manioc, is the possible cause of LSAMAT. However, other possible causes relating to habitation on or near marine coasts cannot be totally ruled out.     

Intrapopulation variation in macro tooth wear patterns—a case study from Igloolik,Canada

The pattern of human tooth wear—the way it varies between teeth in the mouth—is crucial to our understanding of important questions in archeology and paleoanthropology, such as the contrasts in diet and behavior between Neanderthals and early modern humans in Europe and Asia, or with the adoption of agriculture in the Americas. Little is known, however, about the way in which wear patterns develop with increasing age or the way in which they differ between males and females. One explanation is that few living people show the high rates of tooth wear seen worldwide throughout the preindustrial archaeological record. The study described here investigates the macroscopic pattern of tooth wear in a unique group of known age and sex dental casts from living Canadian Inuit from Igloolik. The results show that the Igloolik people possessed a pattern of extremely heavy anterior tooth wear, relative to the first molar and the other posterior teeth, which is attributed to the use of the anterior teeth in cultural practices as well as the extreme and marginal environments in which they lived. Heavy anterior tooth wear was established at an early age and maintained throughout life; statistically significant differences were found between the wear patterns of males and females and are explained in terms of sexual division of labor within the community. This study highlights the need to understand both intra‐ and interpopulation variation in tooth wear patterns when interpreting patterns in past human groups. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.     

Modular Wear Facet Nomenclature for mammalian post-canine dentitions

Abstract

Dental wear facets on the occlusal surface of premolars and molars are traces of their main function, the mastication and therefore reflect masticatory movements and also paramasticatory (i.e. non-dietary use of teeth) behavior. Here we present the Modular Wear Facet Nomenclature applicable to most mammalian dentitions. Topographic positions of wear facets in relation to the major cusps and crests of the teeth are used to designate the areas of the occlusal surface the facets occupy (e.g. their mesial, distal, lingual, or buccal position). Previous published systems for labeling wear facets have been inconsistent with each other. Therefore, we provide a synoptic review of the most widely-used terminologies, and introduce the alternative Modular Wear Facet Nomenclature. This nomenclature aims to overcome the difficulties caused by the existing inconsistent wear facet terminologies. Our new approach is applicable to dentitions where the occlusal morphology does not change significantly for most of the lifetime of the animal. In those dentitions, the primary occlusal surfaces are not significantly modified as wear facets become more extensive with wearing. This appears to be a common pattern in pre-tribosphenic, tribosphenic molars, and the teeth derived from tribosphenic precursors (e.g. bunodont molar morphologies). In teeth where the secondary occlusal surface is functionally intensely modified (i.e. high-crowned and evergrowing teeth with large areas of dentine exposed) any facet labeling system appears to be challenging, since the identification of individual facets is blurred and their spatial position may be indeterminable.     

Variation in dental wear and tooth loss among known‐aged,older ring‐tailed lemurs (Lemur catta): a comparison between wild and captive individuals

Tooth wear is generally an age‐related phenomenon, often assumed to occur at similar rates within populations of primates and other mammals, and has been suggested as a correlate of reduced offspring survival among wild lemurs. Few long‐term wild studies have combined detailed study of primate behavior and ecology with dental analyses. Here, we present data on dental wear and tooth loss in older (>10 years old) wild and captive ring‐tailed lemurs (Lemur catta). Among older ring‐tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar (n=6), the percentage of severe dental wear and tooth loss ranges from 6 to 50%. Among these six individuals, the oldest (19 years old) exhibits the second lowest frequency of tooth loss (14%). The majority of captive lemurs at the Indianapolis Zoo (n=7) are older than the oldest BMSR lemur, yet display significantly less overall tooth wear for 19 of 36 tooth positions, with only two individuals exhibiting antemortem tooth loss. Among the captive lemurs, only one lemur (a nearly 29 year old male) has lost more than one tooth. This individual is only missing anterior teeth, in contrast to lemurs at BMSR, where the majority of lost teeth are postcanine teeth associated with processing specific fallback foods. Postcanine teeth also show significantly more overall wear at BMSR than in the captive sample. At BMSR, degree of severe wear and tooth loss varies in same aged, older individuals, likely reflecting differences in microhabitat, and thus the availability and use of different foods. This pattern becomes apparent before “old age,” as seen in individuals as young as 7 years. Among the four “older” female lemurs at BMSR, severe wear and/or tooth loss do not predict offspring survival. Am. J. Primatol. 72:1026–1037, 2010. © 2010 Wiley‐Liss, Inc.     

Changes in the pattern of tooth wear from prehistoric to recent periods in Japan

Although a number of studies have been performed on interpopulational variation of tooth wear patterns in recent humans, the major interest in the study of tooth wear so far has been in reconstructing the subsistence and behavior of prehistoric populations, and hence research on wear pattern changes in historic times has been superficial. The present study investigated temporal change in the pattern of wear on the permanent dentition of the Japanese through comparison of the following five groups: prehistoric hunter-gatherers, prehistoric agriculturists, medieval, premodern, and recent populations. The pattern of reduction of occlusal wear severity across thesechronological groups was not similar between the anterior and posterior portions of the dentition. Occlusal wear on the anterior teeth was noticeably lighter in the prehistoric agriculturists and later populations than in the prehistoric hunter-gatherers, while clear reduction of occlusal wear on the posterior teeth occurred after medieval times. The temporal variations in the degree of mesiodistal crown diameter loss due to wear and its anterior-posterior gradient within the dentition are generally consistent with those observed in the occlusal wear pattern. Possible causative factors of these temporal changes in the wear pattern are discussed. Am J Phys Anthropol 109:501–508, 1999. © 1999 Wiley-Liss, Inc.     

新疆吐鲁番加依墓地青铜—早期铁器时代居民牙齿的磨耗

本文对新疆吐鲁番市加依墓地青铜—早期铁器时代居民的牙齿磨耗、口腔疾病和骨质隆起等特征进行了观察与研究,结果显示,加依墓地居民的牙齿磨耗较重,但前后部牙齿的磨耗程度差异不大,臼齿偏斜式磨耗现象显著,龋齿罹患率偏低。生前脱落、牙结石等口腔疾病在该人群中普遍流行,部分个体的下颌存在发育显著的骨质隆起现象。本文还通过臼齿磨耗方向指数(Wear Orientation)对加依墓地居民的偏斜式磨耗进行了量化研究,并参考相关民族学调查、考古发现以及现代医学研究成果对加依墓地居民复杂的牙齿磨耗形态和口腔疾病的成因进行了初步探讨。推测加依墓地居民的食物结构应以肉类为主,谷类亦占有一定地位;此外可能是受到恶劣生活环境及特殊谷物加工技术的影响,日常食物较为坚硬。     

True grit: A microwear experiment

Recently we noted the effects of experimental diets on microscopic dental wear in the American opossum and concluded that it might prove difficult to distinguish the microwear produced by an insectivorous diet from that produced by some kinds of herbivorous ones. We also noted that wear caused by gritty diets and those containing plant opal, although they might be confused with one another, are easily distinguished from other sorts of dietary wear. Our conclusions have been challenged on the basis that possibly we did not allow sufficient time in the experiments for diagnostic wear patterns to emerge. Additional data reported here show that this is not so. Even in our n “control” animals, fed a relatively soft unabrasive diet, enough time elapsed to produce significant dental wear. A new technique is described which for the first time allows the study of changing patterns of microscopic wear in a living animal over a period of time, thus allowing each animal to serve as its own control. A solution containing a broad-spectrum proteolytic enzyme when applied to the teeth of an anesthetized animal removes the proteinaceous coat (pellicle) which will otherwise obscure wear scratches. Precision dental impressions can then be made which reveal the details of the pattern of microwear on the teeth.     

Interproximal grooving in the Atapuerca-SH hominid dentitions

The dental sample recovered from the Sima de los Huesos (SH) Middle Pleistocene cave site of the Sierra de Atapuerca (Spain) includes 296 specimens. Interproximal wear grooves have been observed in 20 maxillary and mandibular posterior teeth belonging to at least five of the 32 individuals identified so far in the SH hypodigm. Interproximal grooving affected only the adults, and at an age between 25 and 40 years. The appearance, morphology, and location pattern of the SH wear grooves are similar to those reported in other fossil hominids and in more recent human populations. Two alternative proposals, the toothpicking and the fiber or sinew processing hypotheses, compete for explaining the formation of this anomalous wear. The characteristics observed in the wear grooves of the SH teeth are compatible only with the habitual probing of interdental spaces by means of hard and inflexible objects. Dietary grit may also have contributed to the abrasion of the root walls during the motion of the dental probes. Am. J. Phys. Anthropol. 102:369–376, 1997. © 1997 Wiley-Liss, Inc.     

Tooth wear and compensatory modification of the anterior dentoalveolar complex in humans

In populations living in environments where teeth wear severely, some compensatory modification of the dentoalveolar complex is thought to occur during life whereby functional occlusion is maintained as tooth substance is lost by wear. This study investigates one aspect of this modification process: Changes in the anterior dentoalveolar complex that are accompanied with wear were examined in a series of Japanese skeletal samples. In the prehistoric Japanese hunter-gatherer population heavy wear occurs over the entire dentition. The following changes were demonstrated to have occurred in the anterior segment of the dentition accompanied by wear on the anterior teeth: The anterior teeth tip lingually with wear up to a nearly upright position to fill in interproximal spaces that would have been generated by wear, and to maintain contact relations between adjacent teeth. At the same time, the anterior surface of the maxillary alveolar process also inclines lingually to a certain extent. The amount of lingual tipping is greater in the maxillary anterior teeth than in their mandibular antagonists. It is because of this discrepancy that, with age, the horizontal component of the overlap between maxillary and mandibular anterior teeth decreases, and their bite form changes from scissor bite to edge-to-edge bite. Lesser degrees of lingual tipping of the anterior teeth were also detected in the prehistoric agriculturists and historic Japanese populations. The variation in the degree of lingual tipping observed among the samples is explained by inter-population variation in severity and pattern of tooth wear. This and other evidence suggests that mechanisms that compensate for wear in the anterior dentition may be characteristic of all living human populations, independently of the degree of wear severity endured in their environments.     

Mechanical wear of the gastropod radula: a scanning electron microscope study

The wear sustained by the teeth of the highly mineralized radula of Patella vulgata and the unmineralized radula of Agriolomax reticulatus has been studied with the scanning electron microscope. The unworn teeth of P. vulgata have tall pointed cusps and wear is first seen as a chipping of the tips then as abrasion. There is a well defined abraded surface giving the worn teeth a chisel shape. In cleaved teeth fibres ˜ 800 Å in diameter are observed parallel to the axis of the tooth. Evidence is presented for chemical etching and for the existence of a surface coat on the tooth. A. reticulatus teeth show wear over their whole surface. With the aid of the grooves in the jaw caused by the teeth the role of the jaw in flattening the radula and protracting and retracting the odontophore is confirmed. From the arrangement of the abraded surfaces on the teeth of P. vulgata it was deduced that the teeth rows are abraded one at a time while on a convex surface at or near the bending plane.     

Geratodontology and horn growth of the impala (Aepyceros melampus)

Examination of the jaws of an impala population showed advanced wear on mandibular M1 compared with other ungulates which have been examined. This could lead to an erroneous interpretation of age if based upon mandibular tooth wear alone. Explanations are offered for this pattern in terms of the apparent pattern of wear of the impala molar teeth. Suggestions are also put forward for a method of determining specific age, from a conceptual wear model, when only extreme parameters are known. Horn growth in the male is also described.     

Measurements of tooth wear among Australian Aborigines: I. Serial loss of the enamel crown

The dental casts made from Aboriginal children during the course of a longitudinal growth study in Central Australia provided material for analyzing tooth wear under known environmental conditions. The wear facets produced on the occlusal surfaces were clearly preserved on the dental stone casts and recorded the progress of enamel attrition from ages 6 to 18. These casts were photographed and traced by electronic planimetric methods that automatically recorded the location and size of wear facets on the first and second permanent molars. These areas of worn tooth surface were compared to the total tooth surface. The worn surface was regressed on age to calculate wear rates of each tooth. Discriminant analyses were also performed to determine the significance of dental attrition differences between the sexes at each age group. The total wear on each tooth was highly correlated with age as expected but females wore their teeth at a significantly higher rate than males. The mandibular molars wore more rapidly than maxillary teeth in both sexes. The discriminant analysis successfully grouped 91% of the cases according to age and sex. Pattern of wear, the location, and size of wear facets also differed between age groups and sex. The questions of why there is a difference between male and female wear or why there is greater wear on one arch or arch region have no ready answers. The differing rates and pattern of dental wear do suggest that arch shape and growth rates may be the answer though it has yet to be tested. However, the occlusal surface wear is useful for age estimation in a population and provides a record of shifting masticatory forces during growth.     

Alternative dental measurements: proposals and relationships with other measurements

Most archaeological and fossil teeth are heavily worn, and this greatly limits the usefulness of tooth crown diameter measurements, as they are usually defined at the widest points of the crown. There are alternatives, particularly measurements at the cervix of the tooth, where the crown joints the root, and measurements along a diagonal axis in molars, that are much less affected by wear. These would allow a wider range of specimens to be included, e.g., in the study of dental reduction in Upper Palaeolithic and Mesolithic Homo sapiens. In addition, they would allow the little-worn teeth of children to be compared directly with well-worn teeth in adults. These alternatives, however, have been little used, and as yet there have not been any studies of the repeatability with which they can be measured, or of the extent to which they are related to the more usual crown diameters. The present study is based on a group of unworn teeth, where direct comparisons could be made between the alternative measurements, which are not much affected by wear, with the usual crown diameters, which are very much affected. In an interobserver-error study of this material, cervical and diagonal measurements could be recorded as reliably as the usual crown diameters. The buccolingual cervical measurement was strongly correlated with the normal bucclingual crown diameter in all teeth, whereas the mesiodistal cervical measurement was highly correlated with the normal mesiodistal crown diameter in incisors and canines, but less so in premolars and molars. The molar diagonal measurements showed high correlations with all other measurements. Crown areas (robustness index) calculated from the usual diameters were strongly correlated with crown areas calculated from cervical measurements, and crown areas calculated from molar diagonals were strongly correlated with both other areas. Despite the long usage of the more usual maximum crown diameters, the alternative dental measurements could be measured just as reliably, could record similar information about tooth crown size, and would be better measures for the worn dentitions seen in archaeological and fossil material.     

Tool use in animals: Cognition and ecology. Edited by Crickette M. Sanz,Josep Call,and Christophe Boesch. New York,NJ: Cambridge University Press. 2013. 313 pp. ISBN 978‐1‐107–01119‐9. $110 (hardcover).

Enamel thickness has been linked to functional aspects of masticatory biomechanics and has been demonstrated to be an evolutionary plastic trait, selectively responsive to dietary changes, wear and tooth fracture. European Late Paleolithic and Mesolithic hunter‐gatherers mainly show a flat wear pattern, while oblique molar wear has been reported as characteristic of Neolithic agriculturalists. We investigate the relationships between enamel thickness distribution and molar wear pattern in two Neolithic and medieval populations. Under the assumption that dietary and/or non‐dietary constraints result in directional selective pressure leading to variations in enamel thickness, we test the hypothesis that these two populations will exhibit significant differences in wear and enamel thickness patterns. Occlusal wear patterns were scored in upper permanent second molars (UM2) of 64 Neolithic and 311 medieval subadult and adult individuals. Enamel thickness was evaluated by microtomography in subsamples of 17 Neolithic and 25 medieval individuals. Eight variables describing enamel thickness were assessed. The results show that oblique molar wear is dominant in the Neolithic sample (87%), while oblique wear affects only a minority (42%) of the medieval sample. Moreover, in the Neolithic molars, where buccolingually directed oblique wear is dominant and greatest enamel lost occurs in the distolingual quadrant, thickest enamel is found where occlusal stresses are the most important—on the distolingual cusp. These results reveal a correlation between molar wear pattern and enamel thickness that has been associated to dietary changes. In particular, relatively thicker molar enamel may have evolved as a plastic response to resist wear. Am J Phys Anthropol 155:162–172, 2014. © 2014 Wiley Periodicals, Inc.     

Tooth wear and dental pathology at the advent of agriculture: new evidence from the Levant

Differences in patterns of diet and subsistence through the analysis of dental pathology and tooth wear were studied in skeletal populations of Natufian hunter-gatherers (10,500-8300 BC) and Neolithic populations (8300-5500 BC, noncalibrated) from the southern Levant. 1,160 Natufians and 804 Neolithic teeth were examined for rate of attrition, caries, antemortem tooth loss, calculus, periapical lesions, and periodontal processes. While the Natufian people manifest a higher rate of dental attrition and periodontal disease (36.4% vs. 19%), Neolithic people show a higher rate of calculus. Both populations manifested low and similar rates of caries (6.4% in the Natufian vs. 6.7% in the Neolithic), periapical lesions (not over 1.5%), and antemortem tooth loss (3.7% vs. 4.5%, respectively). Molar wear pattern in the Neolithic is different than in the Natufian. The current study shows that the dental picture obtained from the two populations is multifactorial in nature, and not exclusively of dietary origin, i.e., the higher rate and unique pattern of attrition seen in the Natufian could result from a greater consumption of fibrous plants, the use of pestles and mortars (which introduce large quantities of stone-dust to the food), and/or the use of teeth as a "third hand." The two major conclusions of this study are: 1) The transition from hunting and gathering to a food-producing economy in the Levant did not promote changes in dental health, as previously believed. This generally indicates that the Natufians and Neolithic people of the Levant may have differed in their ecosystem management (i.e., gathering vs. growing grains), but not in the type of food consumed. 2) Changes in food-preparation techniques and nondietary usage of the teeth explain much of the variation in tooth condition in populations before and after the agricultural revolution.     

Gross enamel hypoplasia in molars from subadults in a 16th-18th century London graveyard

Dental Enamel Hypoplasia has long been used as a common nonspecific stress indicator in teeth from archaeological samples. Most researchers report relatively minor linear and pitted hypoplastic defects on tooth crown surfaces. In this work we report a high prevalence and early age of onset of extensive enamel defects in deciduous and permanent molars in the subadults from the post-medieval cemetery of Broadgate, east central London. Analysis of the dentition of all 45 subadults from the cemetery, using both macroscopic and microscopic methods, reveals disturbed cusp patterns and pitted, abnormal and arrested enamel formation. Forty-one individuals from this group (93.2%) showed some evidence of enamel hypoplasia, 28 of them showing moderate or extensive lesions of molars, deciduous or permanent (63.6% of the sample). Scanning Electron Microscope images reveal many molars with grossly deformed cuspal architecture, multiple extra cusps and large areas of exposed Tomes' process pits, where the ameloblasts have abruptly ceased matrix production, well before normal completion. This indented, rough and poorly mineralized surface facilitates both bacterial adhesion and tooth wear, and when such teeth erupt fully into the mouth they are likely to wear and decay rapidly. We suggest that this complex combination of pitted and plane-form lesions, combined with disruption of cusp pattern and the formation of multiple small cusps, should henceforth be identified as "Cuspal Enamel Hypoplasia."     

Deciduous dentition and eruption pattern in late Miocene Pachyrukhinae (Hegetotheriidae,Notoungulata) from La Pampa Province,Argentina

The study of juvenile remains of Paedotherium Burmeister from Cerro Azul Formation (La Pampa Province, Argentina; late Miocene) is presented. Upper and lower deciduous dentition (or permanent molars supposed to be associated with non-preserved deciduous teeth) are recognised. Several ontogenetic stages are distinguished among juveniles, according to the degree of wear and the replaced deciduous teeth. Besides, some morphological and metrical differences are observed along the crown height. Deciduous cheek teeth are high-crowned and placed covering the apex of the corresponding permanent tooth. The height of the crown and the degree of wear allow establishing the pattern of dental replacement of deciduous and permanent premolars in a posterior–anterior direction (DP/dp4–2 and P/p4–2), as well as the eruption of M/m3 before DP/dp4 is replaced. Some of the studied remains are recognised as young individuals of Tremacyllus Ameghino, but with complete permanent dentition, which leads to propose a different timing in the dental replacement with respect to Paedotherium; they also allow the establishment of an opposite premolar eruption pattern, from P/p2 to P/p4. This knowledge of the deciduous dentition of Paedotherium suggests the need of revising the morphological and metrical characters previously used for defining species within this taxon.