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At least 1,279 records · Page 71Linked to original sources
PubMed1990

Canine "honing" in Australopithecus afarensis.

The maxillary canines of Australopithecus afarensis show a distal wear facet that extends from the apex of the crown to a point near the distal cingulum. Although these facets bear a superficial resemblance to the honing facets found on the projecting portions of the canines of other anthropoids, a more detailed examination provided in this paper shows that they are not homologous or functionally equivalent. The facets are not related to the use of the maxillary canine as a weapon or as an additional masticatory surface. Instead, their presence in A. afarensis represented a blunting or dulling of the posterior edge of C so that its occlusion with P3 would be consistent with cheek tooth occlusion.

Animals↗
PubMed1990

Tooth wear and temporomandibular joint change in Australian aboriginal populations.

The masticatory system consists of teeth, temporomandibular joints, and the supporting craniofacial skeleton. The form and function of each of these components of the system can be understood only within the overall context of the system. In a series of studies, the complex relationships between tooth wear and temporomandibular joint morphology and pathology were considered in samples consisting of a total of 58 male and 54 female crania from two Australian Aboriginal populations. The extent and buccolingual direction of tooth wear were assessed using established techniques. Both metric and nonmetric descriptions of temporomandibular joint morphology and pathology were developed. Significant differences in patterns of tooth wear and in the frequencies of various temporomandibular joint changes were evident between sexes and between populations. Furthermore, significant correlations between a number of tooth and joint variables were also evident. In addition, there was clear evidence of relationships between both tooth wear and temporomandibular joint changes and craniofacial morphology. The results of this study provide additional evidence of the complex relationships between the form and function of the masticatory system.

Adult↗
PubMed1991

Relationships between age and dental attrition in Australian aboriginals.

Tooth wear scores (ratios of exposed dentin to total crown area) were calculated from dental casts of Australian Aboriginal subjects of known age from three populations. Linear regression equations relating attrition scores to age were derived. The slope of the regression line reflects the rate of tooth wear, and the intercept is related to the timing of first exposure of dentin. Differences in morphology between anterior and posterior teeth are reflected in a linear relationship between attrition scores and age for anterior teeth but a logarithmic relationship for posterior teeth. Correlations between age and attrition range from less than 0.40 for third molars (where differences in the eruption and occlusion of the teeth resulted in different patterns of wear) to greater than 0.80 for the premolars and first molars. Because of the generally high correlations between age and attrition, it is possible to estimate age from the extent of tooth wear with confidence limits of the order of +/- 10 years.

Adolescent↗
PubMed1991

On the etiology of interproximal grooves.

The recent suggestion by Brown and Molnar (1990) that the common etiology of sinew processing is responsible for the production of interproximal tooth grooves is contested. Based on a review of the Australian evidence and presentation of a previously undescribed dentition from Central Europe, it is argued toothpicks are a likely cause of many artificial grooves in human teeth.

Fossils↗
PubMed1991

Dental microwear in live, wild-trapped Alouatta palliata from Costa Rica.

One problem with dental microwear analyses of museum material is that investigators can never be sure of the diets of the animals in question. An obvious solution to this problem is to work with live animals. Recent work with laboratory primates has shown that high resolution dental impressions can be obtained from live animals. The purpose of this study was to use similar methods to begin to document rates and patterns of dental microwear for primates in the wild. Thirty-three Alouatta palliata were captured during the wet season at Hacienda La Pacifica near Canas, Costa Rica. Dental impressions were taken and epoxy casts of the teeth were prepared using the methods of Teaford and Oyen (1989a). Scanning electron micrographs were taken of the left mandibular second molars at magnifications of 200x and 500x. Lower magnification images were used to calculate rates of wear, and higher magnification images were used to measure the size and shape of microwear features. Results indicate that, while basic patterns of dental microwear are similar in museum samples and samples of live, wild-trapped animals of the same species, ecological differences between collection locales may lead to significant intraspecific differences in dental microwear. More importantly, rates of microwear provide the first direct evidence of differences in molar use between monkeys and humans.

Alouatta↗
PubMed1992

Brief communication: interproximal tooth wear: a new observation.

Microscopic observations were made of wear on the proximal surfaces of tooth crowns of Australian Aboriginals and whites. Typical wear facets displayed well-defined borders within which vertical or near vertical furrows, ranging from about 0.1 to 0.5 mm in width, were noted. Furrows on the interproximal surface of one tooth seemed to "interdigitate" with those on the proximal surface of the adjacent tooth. These observations are not consistent with the commonly-held view that interproximal tooth wear results from a buccolingual movement of adjacent teeth that maintain contact through mesial migration. Vertical or near vertical movement of teeth, possibly including a tipping action, must be an important factor, although the precise nature of the movement requires further investigation.

Humans↗
PubMed1992

Diet and dental caries among later stone age inhabitants of the Cape Province, South Africa.

Stable carbon isotope measurements and incidences of dental caries are presented for three groups of prehistoric human skeletons from different regions of the Cape Province, South Africa. The isotopic analyses of bone collagen demonstrate the importance of marine foods in the diet and vary through time, across space, and according to sex. The incidence of dental caries ranges from 0% among heavily marine-dependent individuals from the south-western Cape coast, to 17.7% among skeletons from an archaeological site on the south coast. The extremely high incidence of caries in a hunter-gatherer population may be related to lack of fluoride in the water.

Dental Caries↗
PubMed1992

Dental microwear and diet in Venezuelan primates.

Recent microwear analyses have demonstrated that wear patterns can be correlated with dietary differences. However, much of this work has been based on analyses of museum material where dates and locations of collection are not well known. In view of these difficulties, it would be desirable to compare microwear patterns for different genera collected from the same area at the same time. The opportunity to do this was provided by the collections of the Smithsonian Venezuelan Project (Handley, 1976), in which multiple primate genera were collected from the same humid tropical forest sites within the same month. The monkeys represent a wide range of dietary preferences, and include Saimiri, Cebus, Chiropotes, Ateles, Aotus, Pithecia, and Alouatta. As in previous microwear analyses, epoxy replicas were prepared from dental impressions, as described by Rose (1983) and Teaford and Oyen (1989). Two micrographs were taken of facet 9 on an upper second molar of each specimen. Computations and analyses were the same as described by Teaford and Robinson (1989). Results reaffirm previously documented differences in dental microwear between primates that feed on hard objects versus those that do not--with Pithecia and Alouatta at the extremes of a range of microwear patterns including more subtle differences between species with intermediate diets. The subtle microwear differences are by no means easy to document in museum samples. However, additional results suggest that 1) the width of microscopic scratches may be a poor indicator of dietary differences, 2) large and small pits may be formed differently, and 3) there are very few seasonal differences in dental microwear in the primates at these humid tropical forest sites.

Analysis of Variance↗
PubMed1993

Molar microwear in extant small-bodied faunivorous mammals: an analysis of feature density and pit frequency.

This study quantitatively examined molar microwear in nine species of extant small-bodied faunivorous primates and microchiropterans. Comparative analyses were performed within the food category faunivory, both between hard- and soft-object feeding faunivores and between primarily insectivorous and carnivorous taxa. Additionally, microwear in faunivores was compared to that reported in the literature for frugivorous and folivorous primates. The results indicated that although insectivores and carnivores could not be distinguished by microwear analyses, hard-object faunivores (i.e., those that primarily consume beetles or actively comminute bone) can be readily distinguished from soft-object faunivores (i.e., moth, caterpillar, or vertebrate flesh specialists). The hard-object faunivores consistently exhibited greater pit frequencies (in excess of 40%). Furthermore, comparisons of these microwear data on faunivorous mammals to previous work on frugivorous and folivorous primates (Teaford, 1988, pers. comm.; Teaford and Runestad, 1992, pers. comm.; Teaford and Walker: American Journal of Physical Anthropology 64:191-200, 1984) permitted three observations to be made. 1) Faunivores tend to have higher mean feature densities than either frugivores or folivores, although these differences are not consistently statistically distinct. 2) Faunifores and frugivores that feed on hard-objects have comparable mean pit frequencies. 3) Although it is impossible to distinguish faunivores and folivores on the basis of metric analysis of gross molar morphology, this distinction can be made on microwear criteria. Both hard- and soft-object faunivores exhibit much higher mean pit frequencies than primarily folivorous species.

Analysis of Variance↗
PubMed2005

Effect of prism orientation and loading direction on contact stresses in prismatic enamel of primates: implications for interpreting wear patterns.

The ability of prisms to effectively dissipate contact stress at the surface will influence wear rates in teeth. The aim of this investigation was to begin to quantify the effect of prism orientation on surface stresses. Seven finite element models of enamel microstructure were created, each model differing in the angulation of prism orientation with regard to the wear surface. For validation purposes, the mechanical behavior of the model was compared with published experimental data. In order to test the enamel under lateral loads, a compressed food particle was dragged across the surface from the dentino-enamel junction (DEJ) towards the outer enamel surface (OES). Under these conditions, tensile stresses in the enamel model increased with increases in the coefficient of friction. More importantly, stresses were found to be lowest in models in which the prisms approach the surface at lower angles (i.e., more obliquely cut prisms), and highest when the prisms approached the surface at 60 degrees (i.e., less obliquely cut). Finally, the direction of travel of the simulated food particle was reversed, allowing comparison of the difference in behavior between trailing and leading edge enamels (i.e., when the food particle was dragged either towards or away from the DEJ). Stresses at the trailing edge were usually lower than stresses at the leading edge. Taken together with what is known about prism orientation in primate teeth, such findings imply greater wear resistance at the intercuspal region and less wear resistance at the lateral enamel at midcrown. Such findings appear to be supported by archeological evidence.

Animals↗
PubMed2006

Brief communication: intertooth and intrafacet dental microwear variation in an archaeological sample of modern humans from the Jordan Valley.

Dental microwear was recorded in a Bronze-Iron Age (3570-3000 BP) sample of modern humans recovered from Tell es-Sa'idiyeh in the Jordan Valley. Microwear patterns were compared between mandibular molars, and between the upper and lower part of facet 9. The comparison revealed a greater frequency of pits and shorter scratches on the second and third molars, compared to the first. Pit frequency also increased on the lower part of the facet on the first molar, compared to the upper part. These results support previous calls for standardization when selecting a molar type for a diet-microwear study. Otherwise the microwear variations along the tooth row could mask any diet-microwear correlations. The results also suggest that there may be a need to choose a consistent location on a facet in order to enhance comparability among studies.

Adolescent↗
PubMed2007

Continuity or discontinuity of the life-style in central Italy during the Roman Imperial Age-Early Middle Ages transition: diet, health, and behavior.

Dento-alveolar pathologies and alterations (dental wear, caries, abscesses, ante mortem tooth loss (AMTL), calculus, hypoplastic defects, and chipping) and skeletal markers of health (cribra orbitalia and periostitis) were analyzed in two skeletal samples from the necropolises of Quadrella (I-IV c. AD) and Vicenne-Campochiaro (VII c. AD) in the Molise region of central Italy. The aim was to determine if the Roman Imperial Age-Early Middle Ages transition characterized by political, socioeconomic, and cultural transformations affected the biology of these populations, particularly their alimentation and health status. The frequencies of caries and AMTL, similar in the two samples, suggest a high consumption of carbohydrates. The higher levels of heavy wear, calculus, and interproximal chipping in the Vicenne population indicate a greater use of fibrous foods (both meat and others), in line with the dietary model of Germanic peoples. Health conditions do not appear to have been good in either period, as shown by the high frequencies of linear hypoplasia and the presence of cribra orbitalia and periostitis. The diet of the individuals buried with horses of the Vicenne population did not differ from that of the rest of the population, whereas there were evident differences in the use of the teeth for nonmasticatory activities among these individuals. Therefore, from the point of view of alimentation and health status, the profound socioeconomic and cultural transformations during the Late Antiquity-Early Middle Ages transition do not seem to have been translated into a true discontinuity of the two Molisan populations.

Diet↗
PubMed1979

The effect of wear on the cheek teeth and associated dental tissues of the lizard Uromastix aegyptius (Agamidae).

Serial coronal sections of the teeth and their surrounding tissues in the agamid lizard, Uromastix aegyptius, were examined with the light microscope in order to determine how these structures change as the teeth wear. Because new teeth are added only at the posterior end of the tooth row and older teeth are not replaced, the series of sections included the youngest as well as the oldest teeth. Two types of changes occur as the teeth become older: bone under the teeth changes from cancellous to compact, and the pulp chamber of the tooth is obliterated. Although the labial surface of the dentary lacks a periosteal covering and some of the bone lacks any covering at all, it remains functional throughout the life of the animal.

Animals↗
PubMedDate not supplied

A semiautomated image analysis procedure for the quantification of dental microwear II.

Paleontologists often examine microscopic scratches and pits that form on teeth for indications of the diets of past animals. Most researchers count and measure scratches and pits from photomicrographs to identify microwear patterns for comparison among samples. This paper describes an affordable, available semiautomated image analysis procedure for microwear quantification. An image is downloaded from a scanning electron microscope frame buffer to a microcomputer, and the user identifies microwear features with a mouse-driven pointer. Microwear feature density, dimensions, and orientations are then computed and stored as ASCII files for subsequent data analysis.

Animals↗
PubMedDate not supplied

Error rates in dental microwear quantification using scanning electron microscopy.

There is a degree of correlation between dietary habits and dental microwear in extant primates, and this has enabled inferences to be made about prehistoric diets. Several techniques have been used to quantify microwear, but the comparability of results derived from each has not been demonstrated. Moreover, neither intra- nor interobserver error rates in microwear quantification have been documented to date. We here assess intra- and interobserver error using Microware 4.0, and evaluate intertechnique comparability using the three methods that have been most widely employed in the field. This study documents an overall intraobserver error rate of about 7%, and an overall interobserver error rate of some 9%. Both intra- and interobserver error appears to be influenced substantially by the nature of the micrograph being measured. In no instance did the results obtained by different observers using Microware 4.0 differ significantly, and there was a reasonable degree of interobserver consistency in the rank ordering of micrographs in relation to any given parameter. The results obtained through the use of different quantitative techniques differed significantly, with an overall intertechnique error rate of approximately 19%. Several variables, including differences in magnification factor, scanning electron microscope kV settings, and specimen-detector relationships undoubtedly contribute to the differences among the three methods, but we were not able to assess their relative importance. Microwear quantification permits distinctions between broad dietary categories, but the margin of intra- and interobserver error should be taken into account when defining pattern differences between populations (or species) or when documenting seasonally mitigated differences within a taxon. In view of the error introduced by the use of different methods, we suggest that a consistent technique, such as offered by the Microware software package, be adopted by current researchers to establish a common microwear database.

Animals↗
PubMedDate not supplied

Quantification of dental microwear by tandem scanning confocal microscopy and scale-sensitive fractal analyses.

Dental microwear analysis is among the most commonly used approaches to reconstructing the diets of extinct animal species and past peoples. The usual procedure involves imaging tooth wear surfaces by scanning electron microscopy (SEM). Surfaces are characterized quantitatively by measurement of individual wear features (pits and scratches) on photomicrographs. Recent studies of living animals have shown associations between diets on one hand and patterns of dental microwear on the other. Furthermore, patterns on fossil teeth have been used to reconstruct diets in extinct forms. However, conventional methods for microwear analysis are limited. Scanning electron microscopy does not provide a true representation of these surfaces in three dimensions, and identification and measurement of individual features is time consuming, subjective, and subject to high interobserver error. This paper describes a new approach to the analysis of dental microwear using tandem scanning confocal microscopy and scale-sensitive fractal analyses. The instrument used in this study provides three-dimensional coordinates representing surfaces at a resolution equivalent to that employed by most SEM microwear studies. Fractal analyses offer objective, repeatable, quantitative characterization of surfaces. This approach eliminates major sources of error and increases power to resolve differences between species. Moreover, rapid surface characterization will allow examination of large samples to assess within species variation and to make finer distinctions between species.

Animals↗