Patterns of dental wear and the role of the canine in Cercopithecinae.

The importance of dental wear patterns in understanding masticatory functions in primates has long been appreciated. However, studies of wear patterns among populations of nonhuman primates are few. The purpose of this investigation is to establish the developmental aspects of dental wear in the Cercopithecinae and to describe certain relevant morphological traits. Studies were made of dental casts from 200 primate specimens of Macaca nemestrina, Macaca mulatta, and Papio cynocephalus. These casts were taken at four-month intervals, beginning at two years of age and continuing over a period of six to seven years. The wear pattern starts with the rounding and eventual flattening of the protoconid and protocone of the erupted first molars. Once this stage is reached, the hypoconid and metaconid of the mandibular, and the hypocone and paracone of the maxillary molars are rounded and eventually flattened. This pattern is maintained until the cusp tips are removed and the dentin exposed, however, the entoconid and metacone are not subjected to significant wear at this stage. Analysis of these dental casts and museum specimens has provided data on the development of dental wear during the maturation of these primates. The distribution of forces acting upon the teeth produce diagnostic patterns of wear, which provide evidence of the force location and magnitude. In examining the data, the hypothesis of canine guidance and its limitation of mandibular motion was evaluated. Specimens whose canines were removed demonstrate that the canines play no significant role in the development or maintenance of dental wear planes.     

当代水族男性的牙齿磨耗特点及其成因

一直以来,有关人类牙齿磨耗的研究主要集中在年龄判定和生业方式比较方面。然而,很多研究因样本人群来源复杂、忽视个体牙齿磨耗的特殊性及缺乏足够的个人信息,很难进一步解释其牙齿磨耗特点的成因。本文基于对当代水族男性牙齿磨耗的记录和相关信息,通过梳理该人群牙齿磨耗的一般特点和特殊磨耗形式,探讨了有关影响该人群牙齿磨耗的可能因素。笔者发现,总体来说,该人群的牙齿磨耗较轻,牙齿磨耗水平与其年龄分布呈正相关关系,符合人类牙齿面随年龄增长而发生退行性生理磨耗的规律。牙齿磨耗等级在不同年龄中呈镶嵌式分布,某些个体存在越位磨耗现象。从本文的结果看,这些现象的产生除了退行性生理磨耗的原因外,还可能与口腔健康状况、饮食结构和少餐习惯等因素密切相关。     

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.     

Development of the helicoidal plane

In this study of thebelicoidal occlusal plane the relationships between tooth wear, the transverse slopes of mandibular molars and dental arch breadths were examined in 74 pre-contemporary Australian Aboriginal skulls. With increasing age and tooth wear the orientation of the mandibular occlusal surfaces increased towards the buccal. The differential occlusal orientation from first to third molars, present at eruption, tended to increase progressively with tooth wear. These functionally induced changes, together with regional differences in relative breadths of the maxillary and mandibular dental arches, are important in the development of abelicoidal occlusal plane.     

济南大辛庄遗址商代居民的牙齿疾病

大辛庄遗址位于济南市历城区大辛庄村,是山东省内已知面积最大的一处商代遗址,甲骨文及其他丰富遗存的出土对于鲁北及整个山东地区商文化研究具有重要意义。本文主要从人骨的牙齿健康状况入手,对济南大辛庄商代遗址2003、2010年出土的45例人骨标本的牙病情况,尤其是龋病、牙周病、牙结石以及牙齿磨耗情况进行统计与分析,得知大辛遗址商代人群牙齿疾病的基本情况:1)牙结石的出现率男女之间存在明显的性别差异,除此之外其他牙病在罹患率的性别分组上的差异不显著,但均为女性的罹患率要高于男性;2)牙病的罹患率在年龄分组上存在显著差异,随年龄的增长罹患牙病的风险增高;3)龋病、牙周病及牙结石多好发于臼齿;4)重度磨耗牙齿患牙病的风险增加,牙周病表现尤为明显;5)牙病的罹患率不仅受到性别、年龄、牙位以及齿冠磨耗程度的影响,而且与大辛庄商代人群农业经济发展的食物结构有关。     

Mineralization and wear of mandibular first molars in red deer (Cervus elaphus) of known age

The degree of dental wear was measured in 41 mandibular first molars from red deer of known age (range 2–18 years). The calculated wear indices were positively correlated with age ( r = 0.780, P < 0.001). In the same sample, significant ( P < 0.001) differences in hardness (determined by microhardness testing) were observed between enamel and coronal dentine as well as between outer and inner enamel and dentine, respectively. In animals belonging to the same age group (three-year-olds, n = 11), a negative correlation ( r = -0.830, P = 0.0016) was found between wear index and maximum mean enamel hardness. In a sample of five specimens from this age group, a negative correlation ( r = -0.918, P = 0.028) between maximum calcium concentration of enamel (measured by electron microprobing) and wear index was also recorded. We concluded that the intensity of enamel mineralization had a decisive effect on the degree of dental wear. Measuring of enamel hardness and subsequent modification of wear scores or indices is therefore recommended for future studies on the relationship between age and the degree of dental attrition in deer.     

Canine role in dental wear patterns: Macaca nemestrina

A study of variables and patterns in dental wear among 30 individuals in a colony of Macaca nemestrina shows that consideration of age and sex are crucial for understanding differential wear degrees on molar occlusal planes. With advanced age, this species of non-human primate undergoes obliteration of initial morphological characteristics through the gradual erosion of enamel. Wear gradients are differential from PM1-M3 in both sexes. It appears that there is a functional relationship between degrees of occlusal plane wear and the degree of wear on the canines, and that females show a greater degree of wear changes relative to males of equivalent age because of initial differences in canine length and robusticity due to sexual dimorphism. It appears that there is a direct relationship between occlusal wear plane changes and the degree of wear on the canines, with advanced differential wear showing up in individuals in whom years of maxillary canine honing, canine damage, and the normal wear of mastication has reduced dimensions of unworn permanent canines. Other considerations included in this study are the honing functions of the deciduous first mandibular molars and molar cusp height relative to canine function.     

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.     

Palaeoecology of cave bears as evidenced by dental wear analysis: a review of methods and recent findings

Abstract

The study of dental wear was first used years ago to infer the palaeoecology of fossil mammals and in particular their diet. Results depend predominantly on the scale of the analysis used. Analyses of dental macrowear, mesowear or microwear do not provide the same type of dietary information, be it about the seasonal, annual or lifetime diet. This contribution focuses on emblematic species, cave bears (Ursidae), in particular Ursus spelaeus spelaeus. Methods used by previous researchers to infer their dietary preferences and thus their palaeoecology are reviewed and compared. This review is complemented by an analysis of several specimens of cave bears from the Goyet cave in Belgium, using dental microwear texture analysis (DMTA), a methodology widely applied for reconstructing palaeodiets. Three main conclusions are drawn here: (1) DMTA is the method that provides the most precise palaeobiological inferences; (2) during the pre-dormancy period, cave bears show dietary flexibility; (3) dental wear alone might be not sufficient to provide a complete reconstruction of the cave bear palaeodiet.     

Dental wear,wear rate,and dental disease in the African apes

The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin‐enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin–enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin–enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample. Am. J. Primatol. 72:481–491, 2010. © 2010 Wiley‐Liss, Inc.     

Feeding‐related characters in basal pterosaurs: implications for jaw mechanism,dental function and diet

?si, A. 2011: Feeding‐related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet. Lethaia, Vol. 44, pp. 136–152. A comparative study of various feeding‐related features in basal pterosaurs reveals a significant change in feeding strategies during the early evolutionary history of the group. These features are related to the skull architecture (e.g. quadrate morphology and orientation, jaw joint), dentition (e.g. crown morphology, wear patterns), reconstructed adductor musculature and post‐cranium. The most basal pterosaurs (Preondactylus, dimorphodontids and anurognathids) were small‐bodied animals with a wingspan no greater than 1.5 m, a relatively short, lightly constructed skull, straight mandibles with a large gape, sharply pointed teeth and well‐developed external adductors. The absence of extended tooth wear excludes complex oral food processing and indicates that jaw closure was simply orthal. Features of these basal‐most forms indicate a predominantly insectivorous diet. Among stratigraphically older but more derived forms (Eudimorphodon, Carniadactylus, Caviramus) complex, multicuspid teeth allowed the consumption of a wider variety of prey via a more effective form of food processing. This is supported by heavy dental wear in all forms with multicuspid teeth. Typical piscivorous forms occurred no earlier than the Early Jurassic, and are characterized by widely spaced, enlarged procumbent teeth forming a fish grab and an anteriorly inclined quadrate that permitted only a relatively small gape. In addition, the skull became more elongate and body size increased. Besides the dominance of piscivory, dental morphology and the scarcity of tooth wear reflect accidental dental occlusion that could have been caused by the capturing or seasonal consumption of harder food items. □Basal pterosaurs, heterodonty, dental wear, insectivory, piscivory.     

The caries-attrition competition

Contradictory reports on the interreation of caries and attrition concerning their destructive activity at the occlusal surface of teeth required more investigation. Some suggested that the abrasive action of attrition worked against the progress of decay. Others proposed that attrition facilitated the development of caries in dentine exposed due to the dental wear. A comparison of the condition of teeth in western societies from an intermediate stage, with the preceding period characterized by excessive attrition, and with the following period of ongoing reduction of dental wear, might elucidate the mutual relationship. For this reason the almost complete dental assemblage of fifty men, whalers buried during their short sojourn in the Arctic in the 17th and 18th centuries at a Dutch whaling station, and the data of their contemporaries, were evaluated. The results confirmed the proposition that the rise in caries incidence from (pre-) medieval times on, was associated with an ongoing fall of dental attrition. Within this sample of an intermediate phase, one sees that the percentage of carious molars decreases considerably when the degree of dental wear increases. Besides, at the occlusal surface the decay was almost exclusively located in the natural fissures and pits of teeth, not in the exposed dentine due to wear. These findings strongly suggest a competitive relationship between progress of caries and attrition. The best impression of the attrition rate is gained by linkage of degree of dental attrition (i.e. functional age) to age at death. The wide age ranges fitting to the degrees of molar wear make it hazardous to use attrition for age determination.     

Dental wear and oral pathology: possible evidence and consequences of habitual use of teeth in a Swedish Neolithic sample

Atypical wear and oral lesions were studied in the dental remains from the Middle Neolithic Pitted Ware Culture site Ajvide on the island of Gotland in the Baltic Sea. Teeth (n = 764) from 17 males and 11 females were examined microscopically to document unusual wear, assess wear patterns and oral lesions as evidence of habitual behavior, and determine their effect on the oral health of this population. Five atypical wear types were observed: occlusal facets, occlusal excessive load, labial vertical striae, labial horizontal striae, and interproximal striae. Three oral lesions were recorded: chipping, periapical lesions, and dental tilting. Results indicate that teeth were used in a habitual manner at Ajvide, based on the morphology and regularity of the patterns of atypical wear. Differences were observed between the sexes, indicating gender-related differences in the habitual use of teeth. Some wear categories showed a significant correlation with age, signifying increased or accumulated wear with age. Statistically significant positive correlations were found in the molars between occlusal excessive load wear and periapical lesions as well as tilting. Other apparent links were also observed between chipping and vertical striae as well as excessive load, although these were not significant. This suggests a relationship between dental wear and dental pathologies at this site, suggesting that habitual use of teeth indirectly affected the general oral health at the site. Wear patterns, furthermore, seem to mirror both frequent activities as well as single events.     

Maximum realised lifetime parasitism and occurrence of time limitation in Gonatocerus ashmeadi (Hymenoptera: Mymaridae) foraging in citrus orchards

The relationship between body size (hind tibia length), <12 h egg load, wing wear and parasitoid age was used to estimate realised lifetime parasitism of recently dead Gonatocerus ashmeadi collected in a citrus orchard. Under prevailing field conditions and methodology assumptions, it was estimated that female G. ashmeadi lived on average for 183 ± 17 degree-days, parasitised a total of 87 ± 9 Homalodisca vitripennis eggs, and died with 34 ± 5 eggs remaining in the ovaries. Only 17% of dead G. ashmeadi died with no mature eggs suggesting that 83% of G. ashmeadi were not egg limited at time of death. Estimates of realised lifetime parasitism for female G. ashmeadi under prevailing field conditions in July and August in a southern California citrus orchard indicated that time of year had a significant effect on reproductive output. Additionally, live G. ashmeadi captured daily during June through August 2006 had body size, egg load and wing wear recorded to detect possible monthly changes in parasitoid age and egg load. Foraging G. ashmeadi captured alive in June were older and oviposited more eggs in the field compared with August. Only 0.5% of live G. ashmeadi were captured with no mature eggs in their ovaries indicating that the vast majority of live G. ashmeadi were not egg limited.     

Feeding mechanisms of the sauropod dinosaurs Brachiosaurus,Camarasaurus, Diplodocus and Dicraeosaurus

Skull morphologies and dental wear patterns have been examined in four sauropod genera to evaluate their probable feeding mechanisms. Wear facets on teeth are generally confined to their apices in Brachiosaurus and Dicraeosaurus and they are sometimes also present on the mesial and distal carinae. Skull morphology and dental wear patterns in Diplodocus and Dicraeosaurus are consistent with a raking motion of the jaws during feeding. Diplodocus became mechanically adapted to feed in this way by evolving anteriorly directed teeth in the premaxilla and mesial parts of the maxilla, and by changing the direction of jaw adduction relative to the long axis of the skull. Similar features are present in the few known skulls of Apatosaurus and they may also have been present in Dicraeosaurus. In Brachiosaurus dental wear patterns also imply a raking motion of the jaws, although the more robust skull and teeth and the more vertically directed action of the jaw adductor muscles have led some to suggest the possibility of isognathous occlusion. Camarasaurus employed a powerful bite in its feeding, possibly with slight propaliny of the lower jaw, and its skull was modified to cope with increased stresses arising from mastication. Archaic sauropods appear largely to have employed isognathic occlusion in chopping off vegetation. The raking motion employed by diplodocids and dicraeosaurids was an advanced mode of cropping and stripping, linked evolutionarily to their highly apomorphic cranial morphology.     

Lemur habitat and dental senescence in Ranomafana National Park, Madagascar

Not only can teeth provide clues about diet, but they also can be indicators of habitat quality. Conspecific groups living in different habitats with different kinds of foods may exhibit different rates of dental attrition because their teeth are less well adapted to some foods than to others. Ecological disequilibrium describes the situation in which animals live in habitats to which they are relatively poorly adapted. We test whether dental senescence, the wear-related decrease in dental functionality that is associated with decreased survival of infants born to older Propithecus edwardsi females, can be explained by ecological disequilibrium. Specifically, we compare the rates of dental wear in sifaka groups living in nearby habitats that differ in the degree of anthropogenically induced disturbance. We hypothesize that sifakas living in disturbed areas have an unusual rate of tooth wear compared to those living in a more pristine area, and that dental senescence is a consequence of an atypically high wear rate in a degraded habitat. To test whether habitat quality affects tooth wear more generally, we compare rates of use-wear in two subsets of Microcebus rufus living in either relatively undisturbed or disturbed habitats. Contrary to our predictions, we did not detect different rates of tooth wear in disturbed versus undisturbed habitats for either species and consider that reproductively detrimental dental senescence in P. edwardsi females is unlikely to be a pathological consequence of ecological disequilibrium.     

Knowledge and attitude of elderly persons towards dental implants

doi: 10.1111/j.1741‐2358.2011.00586.x Knowledge and attitude of elderly persons towards dental implants Background: Despite their unrivalled place in restorative treatment, dental implants are still scarcely used in elderly patients. Introduction: The aim of this survey was therefore to identify potential barriers for accepting an implant treatment. Materials and methods: Participants were recruited from a geriatric hospital, two long‐term‐care facilities and a private clinic. The final study sample comprised 92 persons, 61 women and 31 men with an average age of 81.2 ± 8.0 years. In a semi‐structured interview, the participants’ knowledge of implants and attitude towards a hypothetical treatment with dental implants were evaluated. Results: Twenty‐seven participants had never heard of dental implants, and another 13 participants could not describe them. The strongest apprehensions against implants were cost, lack of perceived necessity and old age. Univariate and multiple linear regression analysis identified being women, type and quality of denture, having little knowledge on implants and being hospitalised as the risk factors for refusing implants. However, old age as such was not associated with a negative attitude. Conclusion: The acceptance of dental implants in the elderly population might be increased by providing further information and promoting oral health in general. Regardless of the age, dental implants should be placed when patients are still in good health and live independently.     

Estimating age of immobilized elephants from teeth impressions using dental silicon

High precision condensation dental silicon, Zetalabor^TM, was used to create moulds of the lower jaw molars from 22 immobilized African elephants (Loxodonta africana Blumenback) during radio collaring operations. These moulds were used to determine the elephant's age using Laws and Jachmann's molar aging criteria. The technique proved easy and fast and produced useful imprints in 90% of the cases. We found our age estimates, based on physical appearance, made prior to immobilizations were relatively accurate, with 75% within ±3 years and 95% within ±5 years from the age indicated from molar evaluation. When re‐collaring the same individuals in 2–3 years, new moulds will be made to compare a known time period with the degree of tooth wear. This will provide verification of Laws age estimates from free‐ranging elephants.     

Biocultural implications of oral pathology in an ancient Central California population

Bioarchaeologists have long noted two unusual trends in the dentitions of prehistoric Native Californian populations: high rates of wear and low prevalence of caries. The Central California site of CA‐CCO‐548 offers a unique opportunity to examine the relationship between oral pathology and extreme dental wear in a large (n = 480), ancient (4,300–3,100 BP), and temporally well‐defined population sample. This study specifically examines three interrelated processes of the oral cavity in this population: dental wear, dental caries, and periodontal disease. The results show high levels of dental wear (average of 6.1, Smith system), low frequencies of carious lesions (2.5%), low frequencies of periodontal disease (17.8%), and high frequencies of periapical abscesses (10.7%). The pathological processes examined here have complicated multifactorial etiologies. However, they all share the common primary etiological agents of facultative pathogenic bacteria proliferation in the oral biofilm. Integration of the current etiological explanations for infections of the oral cavity, information from the ethnographic record pertaining to subsistence and activity patterns in Native Californian populations, and statistical analysis of specific disease and wear patterns leads to a novel explanation for the observed pattern of oral pathology in this population sample. Specifically, the introduction of antibacterial compounds through dietary items and non‐alimentary tooth use is suggested as the most likely explanation for the unusually low prevalence of dental caries and periodontal disease. Am J Phys Anthropol 154:171–188, 2014. © 2014 Wiley Periodicals, Inc.