Relationships between attrition and lingual tilting in human teeth

Associations between occlusal dental attrition and the lingual tilting of human teeth were investigated in two aboriginal California populations. A literature survey suggests lingual tilting is related geographically and temporally to the helicoidal occlusal plane in humans; if true, lingual tilting should be expected throughout the Homo osteological record. Buccal alveolar abscesses, exposed pulp chambers, extent of tooth attrition, angle of lingual tilt, and amount of overjet were observed for lingually tilted teeth. These attributes were analyzed statistically, leading to a conclusion that lingual tilting is slight and infrequent unless tooth attrition is pronounced. It is suggested that lingual tilting is due in part to masticatory stress. A feedback model considers lingual tilting as one conspicuous manifestation of a more complex “severe attrition syndrome,” the initial stimulus for which may derive from heavy occlusal tooth wear. Untested possibilities should be examined–e.g., age-related changes, the impact of the helicoidal occlusal plane, and the role of masticatory forces.     

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.     

The depth of the lingual fossa in permanent maxillary incisors of Norwegian Lapps

The depth of the lingual fossa in permanent maxillary incisors of three groups of Norwegian Lapps was measured. No statistically significant sex differences or group differences were found. The assembled weighted estimates for lingual fossa depth of three groups of Norwegian Lapps were for I₁ sup: 0.44 mm and I₂ sup: 0.30 mm. Mean lingual fossae depths in Norwegian Lapps clearly fall within the Caucasoid range.     

Increase of tooth size in prehistoric coastal Peru, 10,000 B.P.-1,000 B.P.

Teeth increase in size during a 9,000-year period in an archaeologically derived, radiocarbon dated sample of skeletons from a geographically restricted area of coastal Peru. Although cultural change is extensive, including the transition to food production and pottery making, teeth do not reduce as predicted under these conditions by Brace's Probable Mutation Effect. Since most of the dental literature dealing with size change of teeth focuses upon dental reduction, hypotheses explaining why teeth increase through time are not well developed. No obvious selective forces explaining size increase are apparent in the present data. Attrition decreases through time. The increase in tooth size in this collection may be a function of overall cranialfacial size increase, which (pending further data) may be related to a general body size increase.     

The role of lead and cadmium in deciduous teeth and saliva on dental caries in children residing in Tehran,Iran

BackgroundLead (Pb) and Cadmium (Cd) are important environmental contaminants. There is no biological monitoring of exposure to these heavy metals and their potential effect on dental caries in children in Tehran, Iran, a polluted megacity. Therefore, the present study investigated the potential association between Pb and Cd levels in primary teeth and saliva and dental caries.MethodsIn a cross-sectional design, 211 children aged 6–11 years referred to Tehran University of Medical Sciences, School of Dentistry and residing in Tehran were examined. Pb and Cd levels of exfoliated primary teeth and stimulated saliva were determined by atomic absorption spectrophotometry (AAS). Dental caries prevalence was evaluated according to WHO criteria. Socioeconomic status, oral hygiene behavior, snacking frequency and salivary pH data were acquired as confounding factors. Frequency and percentages were reported for categorical variables, mean and standard deviation (SD) for continuous variables, and geometric mean for skewed continuous variables. A simple linear regression and Pearson correlation tests were used for statistical analyses. P-values < 0.05 were considered as significant.ResultThe mean (95 % confidence interval) Pb and Cd levels in teeth were 213.26 ppb (164.29–274.84) and 23.75 ppb (20.86–27.05), respectively. The mean Pb and Cd levels in saliva were 11.83 ppb (10.71–13.06) and 3.18 ppb (2.69–3.75), respectively. Furthermore, Pb and Cd in primary teeth and saliva were not associated (p > 0.05) with socioeconomic status, oral hygiene behavior and snacking frequencyConclusionThis study showed no association between Pb and Cd concentrations in primary teeth and in saliva with dental caries prevalence.     

东胡林4号人牙齿形态特征观察

北京门头沟区斋堂镇东胡林遗址是重要的新石器时代早期遗址。本文描述了东胡林4号人(14C年龄约为8540aBP., 树轮校正年龄约为7500aBC.) 的上颌牙、下颌牙21枚。多数牙齿重度磨耗, 意味着当时人类处于狩猎—采集经济时代, 食物结构可能主要以坚硬食物(如朴树果核) 或高纤维食物为主。上第三臼齿退化缩小, X光透视检查为东胡林人下第三臼齿阻生提供了确凿无疑的证据。在4枚牙齿上发现龋洞, 其中左上第一臼齿、第二臼齿的龋蚀已破坏牙本质全层。严重的龋齿病揭示了东胡林4号人的口腔状态, 在一定程度上可能与经常性地摄取富含碳水化合物的食物有关。     

The dentition of the Queckchi Indians. Anthropological aspects

The incidence of nine minor dental traits, in 540 Queckchi Indians from Guatemala is reported. A combination of frequencies of neither Caucasoid nor Mongoloid groups was observed. The apparently Caucasoid elements of their tooth morphology might well be the result of admixture with Spanish genes during the conquest.     

广西敢造遗址史前居民口腔的健康状况

广西扶绥敢造遗址是华南新石器时代一处典型的河岸贝丘遗址,其人骨测年结果的上限为8488 BC,下限为6492 BC。本文对敢造遗址2014年出土的108例个体的999枚恒齿进行观察统计,结果显示居民的饮食结构应是以肉食为主并辅以富含淀粉的块茎类植物。该遗址居民的龋齿率高于部分农业人群,但远低于同为华南渔猎—采集经济的鲤鱼墩、甑皮岩和顶蛳山遗址,其原因应与食用块茎类植物的多寡有关。较高的牙结石罹患率(89.86%)可能与鱼类、贝类等高蛋白饮食有关。相比农业、游牧或狩猎人群,该遗址居民偏重的牙齿磨耗可能与食用含沙量较大的螺类、贝类等有关;肉类食物的食用导致该遗址居民上颌前部牙齿磨耗重于后部牙齿,而“上颌前部牙齿舌侧过度磨耗”现象的出现则与食用块茎类植物有关。     

Brief Communication: An enigmatic enamel alteration on the anterior maxillary teeth in a prehistoric North Italian population

In this paper we describe a hitherto undocumented modification of the dental enamel surface observed in an Early Bronze Age population from northern Italy. The defect, which can be described as a curvilinear groove, is located on the lingual surface of incisors and canines in the upper jaw. This groove, documented both in the permanent and deciduous dentition, is located at approximately 1 mm from the cervix and extends from the mesiolingual to the distolingual surface. The occurrence of the groove is not related to the sex of the affected individuals, but its degree of expression is related to age at death. Because of its morphology, the groove cannot be considered as a result of disruptions in the process of enamel deposition. At the present stage of research we suggest that the groove might have been the result of some kind of dental erosion caused by as yet unidentified chemical factors. Am J Phys Anthropol 154:609–614, 2014. © 2014 Wiley Periodicals, Inc.     

Homologies of the anterior teeth in indriidae

Schwartz ('74) proposed revised homologies of the deciduous and permanent anterior teeth in living lemuriform primates of the family Indriidae. Gingerich ('77) described a juvenile specimen of Avahi and emphasized the importance of functional integrity in controlling the pattern of dental reduction in primates, neither of which supports Schwartz's interpretation. Schwartz ('78) recently reiterated his position without adequately discussing the Avahi evidence and the functional basis that probably controls dental reduction. Avahi has a deciduous dentition intermediate in morphology between that of Lemuridae and Indriidae, and similar to both. Thus the lower deciduous dental formula of Indriidae is probably 2.1.3, which is the typical and maximum deciduous complement known in living and fossil lemuriform primates. The formula of the lower permanent dentition in Indriidae is thus 2.0.2.3.     

Shape components of the maxillary molars in Australian aboriginals

Principal components analysis was used to quantify the variability in crown outlines of maxillary molars in Australian Aboriginals. The outlines were measured by 36 radii from the central pit to the crown periphery. The first component, responsible for over half of the total variance, was concerned with general crown size. Four remaining components were retained to indicate sources of variability resulting from contrasting degrees of development or reduction of different crown components. Shape changes from the first to third molars were identified with components representing overall size reduction, diminution of the hypocone, and metacone elements and mesiodistal compression. An anteroposterior gradient along the molar series in average scores and variances for all components resulted from the progressive reduction of distal crown elements, increasing mesiodistal compression, and greater morphological variation.     

Deciduous dental morphology of the prehistoric Jomon people of Japan: Comparison of nonmetric characters

Morphological variations of the deciduous dentition are as useful as those of the permanent dentition for determining the biological affinities of human populations. This paper provides material on morphological variations of deciduous teeth of the prehistoric Japanese population from the Late and the Latest Jomon Period (ca. 2000–ca. 300 B.C.). The expression of nonmetric traits of the deciduous teeth in the Jomon sample shows a closer affinity with modern Japanese and Native American samples than with American White, Asiatic Indian, and African samples. However, the frequency of shoveling in deciduous upper incisors in the Jomon sample is lower than those in modern Japanese and Native American samples. The Jomon sample also expresses a much higher frequency of cusp 6 in deciduous lower second molars than seen in modern Japanese, Ainu, and Native American samples. The frequency in the Jomon sample is equal to that in the Australian Aboriginal sample, which shows cusp 6 most frequently among the samples compared. A somewhat low incidence of incisor shoveling in the Jomon sample was also reported in the permanent dentition (Turner [1976] Science 193:911–913, [1979] Am. J. Phys. Anthropol. 51:619–635, [1987] Am. J. Phys. Anthropol. 73:305–321, [1990] Am. J. Phys. Anthropol. 82:295–317; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:163–182, 88:183–196). However, the frequency of cusp 6 in the Jomon sample shows no significant difference from those of Northeast Asian or Native American samples in the permanent dentition (Turner [1987] Am. J. Phys. Anthropol. 73:305–321; T. Hanihara [1992] Am. J. Phys. Anthropol. 88:1–182, 88:183–196). Evidently, some nonmetric traits express an inter-group difference only in the deciduous dentition. © 1995 Wiley-Liss, Inc.     

Patterns of dental wear in the Lengua Indians of Paraguay

Wear patterns were examined on dental casts of 202 living Lengua Indians from the Chaco area of Paraguay. Consideration was given to the development of the molar helicoidal plane, age-related changes in occlusal attrition, coalescence of dentine exposures, interproximal attrition, and erupted crown height. This study lends support to Osborn's theory of the helicoidal plane development by showing that attrition enhances rather than modifies posteruption molar occlusal planes. The rate of interproximal attrition was found to slow down with the eruption and functional initiation of the third molars. Sinuous and cavo-convex interproximal contact areas that are generated with age, however, appeared to be less abrasion resistant than straight surfaces, hence leading to an increase in interproximal attrition rates with advanced age. Maximum crown height reduction occurred between the ages of 20 and 40 years in central incisors, canines, and first molars. Kruskal-Wallis tests and log linera models failed to demonstrate significant sexually dimorphic or antimeric differences in wear patterns of Lengua teeth.     

Crown diameters of the deciduous teeth in Australian Aboriginals

Mesiodistal and buccolingual crown diameters were measured from dental casts representing the deciduous dentitions of 197 Aboriginal children from the Northern Territory of Australia. Double determination analysis indicated that the semi-automatic recording procedure used was reliable leading to observer errors of no practical significance. Tooth-size was greater in the male subjects but the sexual dimorphism was less marked than in the permanent teeth of the same subjects. The mandibular teeth were more uniform than maxillary with respect to buccolingual size relative to mesiodistal. Extremes of general tooth-size were more marked in the deciduous dentition than in the permanent as a consequence of the relatively large deciduous second molar which in Aboriginals approximates in size the permanent first molar of many other ethnic groups.     

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.     

Enamel microstructure and molar wear in the greater galago,Otolemur crassicaudatus (mammalia,primates)

This study describes the molar enamel microstructure of the greater galago, based on SEM study of four individuals. Galago molar enamel consists primarily of radially oriented Pattern 1 prisms. However, the most superficial enamel is characterized by regions of poorly developed prisms or nonprismatic enamel, and Pattern 3 prisms can be found at depths intermediate and deep to the enamel surface. Orientations of prism long axes relative to wear surfaces differ among functionally distinct regions (cuspal facets, Phase I/II facets, and crushing basins). Consequently, orientations of enamel crystallites relative to these surfaces also differ. Because crystallites are the structural unit involved in enamel abrasion, these differences in orientation may have important effects on molar wear patterns. Crystallite orientations differ most between cuspal facets and Phase I/II facet surfaces. Cuspal facets are characterized by near surface-parallel interprismatic and surface-oblique prismatic crystallites. Previous experimental studies suggest that this arrangement is most resistant to wear when surface-normal (compressive) loads predominate. In contrast, prismatic and interprismatic crystallites intercept Phase I/II facet surfaces obliquely, an arrangement expected to resist abrasion when surface-parallel (shearing) loads predominate. Superficial enamel is preserved at most basin surfaces, indicating that these regions are subject to comparatively little abrasive wear. These results support the hypothesis that galago occlusal enamel is organized so as to resist abrasion of different functional regions, a property that may prove important in maintaining functional efficiency. However, this largely reflects constraints of occlusal topography on a microstructure typical of many mammals and thus does not appear to represent a structural innovation. © 1993 Wiley-Liss, Inc.     

Artificial interproximal grooving of the teeth in American Indians

Artificial grooves about 2 mm in width have been observed on the cervical region of teeth of American Indian populations which come from widespread localities and which extend through considerable time depth. The grooves appear to have been made ante-mortem and to show a close relationship with interproximal caries and peridontal bone resorption. It is conjectured that the grooves represent efforts of a therapeutic or, at least, palliative nature.     

Subvertical grooves of interproximal facets in neandertal posterior teeth

Subvertical grooves, located on the interproximal facets of most Neandertal posterior teeth, are less frequently noted on the teeth of other hominids, including modern humans. These grooves, 0.1–0.5 mm in width, are strictly localized within the facet area. Scanning electron microscopic (SEM) examination of grooves present on Neandertal teeth from Caverna delle Fate (Liguria, Italy) and Genay (Côte d'Or, France) demonstrated that they were produced during the life of these individuals. Characteristics of the groove surface suggest an erosion-abrasion mechanism of formation. These grooves, which developed in parts of the dentition exposed to marked stress, originated in areas characterized by changes in the orientation of enamel prism bundles (i.e., Hunter-Schreger bands). Observations carried out on modern human molars showed a subvertical disposition of these bands near interproximal ridges facilitating subvertical microfractures. Possible correlations between enamel structure, masticatory stress, and interproximal groove formation in Neandertals are discussed. © 1995 Wiley-Liss, Inc.     

Differences in interproximal and occlusal tooth wear among prehistoric Tennessee Indians: implications for masticatory function

Breadth of the interproximal wear facet between lower P2 and M1 and between lower M1 and M2 was measured in human skeletal samples representing the Archaic, Woodland, and Mississippian periods of Tennessee River Valley prehistory, with the aim of assessing relative magnitudes of applied masticatory forces. When stratified by level of occlusal wear, mean interproximal facet breadth was consistently larger in the Archaic sample than in the Mississippi sample, with the Woodland sample intermediate. An analysis of covariance demonstrated that there was significant (p less than or equal to 0.01) differences in facet size among the three groups even when differencs in crown breadth were taken into account. Similar results were obtained in regressions of facet size on chronological age (Archaic larger than Mississippian at P less than or equal to 0.01). Since rate of occlusal wear appears to be somewhat greater in the Archaic sample than in the later samples, the differences in interproximal wear are probably underestimated. It is suggested that the high levels of interproximal wear in the Archaic are indicative of the large occlusal forces and repetitive chewing required to masticate a diet of seeds, wild plant foods, and small animals, for which prior preparation (e.g., grinding, cooking) was minimal or nonexistent (as indicated by paleofecal samples). The lower amounts of interproximal wear observed in the Woodland and Mississippian samples imply considerable reductions in strenous mastication, perhaps due to the widespread adoption during these period of pottery and the earth oven, together with ethnographically-documented techniques of food preparation that transformed most foods to a soft consistency.