Daily rates of dentine formation in macaque tooth roots

When tetracycline antibiotics are administered either orally or by injection they bind at the forming mineral front of the dentine and become incorporated into teeth as a permanent label. In this study, oxytetracycline was used as a label in order to investigate the growth of root dentine in macaques. There are no good data available in the literature for daily rates of root dentine formation over a prolonged period of time in either humans or macaques. Records of ten doses of oxytetracycline administered orally at irregular intervals (but at the same time of day) over a period of 10 months to a young rhesus macaque monkey (Macaca mulatta) were used to calculate the rate of dentine formation in tooth roots. Rates of dentine formation in the first portion of third permanent molar root formation, and in the apical portion of permanent canine and premolar root formation, were consistently between 3 μm and 4 μm per day. There was no evidence in this study of a gradual decrease in daily dentine formation rate from the crown to the root, or along the length of a dentine tubule through the bulk of the dentine, as has been implied previously. With the exception of faster rates recorded in cusps or slower rates recorded at the very beginning or very end of primary dentine secretion in other studies, the results of the present study suggest a consistent rate of dentine formation in permanent macaque teeth. What data there are for human dentine formation rates suggests that it is likely this finding can be extended to human dentine as well.     

Rates of dentine mineralization in permanent human teeth

Previous experimental studies have estimated linear rates of dentine formation in modern humans to be close to 4μm day⁻¹. In this study a method similar to that first adopted by Kawasaki, Tanaka and Ishikawa⁵ was used to estimate linear rates of dentine mineralization over a period of 1200 days in both the cusps and cervical regions of several permanent tooth types. All teeth were from the same individual. Rates in the cusps of teeth with the tallest crowns were estimated to be between 5 μm day⁻¹ and 6 μm day⁻¹. This is higher than previous estimates in permanent tooth crowns, although rates in the cusp of a first permanent molar, where cusps were less tall and cuspal dentine therefore less thick, were close to previous estimates of 4 μm day⁻¹. Despite this variation in cuspal rates, mineralization rates were linear in all cusps studied over a long period of time. Rates in the cervical region, either close to the enamel dentine junction or to the cement dentine junction, were estimated to be between 1.3 μm day⁻¹ and 1.5 μm day¹¹, much slower than reported previously. Rates in the mid-portion of the dentine, in both the lateral part of the crown and in the cervical one-third of the root, rose steadily to match rates in the cuspal region, but then slowed towards the pulp chamber. These data extend the findings of previous studies on permanent human dentine. They demonstrate a wide range of mineralization rates in permanent dentine and provide a more secure basis for judging different rates in different locations of different human tooth types.     

Problems and pitfalls in the diagnosis of linear enamel hypoplasia in cheek teeth of cattle

Prevalence and intensity of enamel hypoplasia have been used as markers of generalized physiological stress during dental development in a wide range of mammalian taxa. We studied cattle (Bos taurus) cheek teeth exhibiting morphological characteristics that are of relevance to the diagnosis of enamel hypoplasia in this and other bovid species. These characteristics were multiple, more or less horizontally arranged (waveform) lines or grooves in the cementum of the tooth crown and the adjacent root area, leading to an imbricated appearance of the cementum. On macroscopic examination of tooth surfaces, these lines resembled linear enamel hypoplasia (LEH). Microscopic analysis of tooth sections, however, revealed that the lines occurred in the cementum only, and that the underlying enamel did not exhibit morphological irregularities. In cheek teeth of older cattle, a thick cementum layer is regularly found in the cervical crown portion and the adjacent root area. Apposition of this cementum is related to the uplifting of the teeth from their alveoli, a process that compensates for the shortening of the tooth crowns due to occlusal wear. In the studied specimens, a pronounced periodic nature of tooth uplifting and the related deposition of cementum is the likely cause for the observed imbricated appearance of the cementum. While this phenomenon may be misinterpreted as representing a case of LEH, presence of enamel hypoplasia in bovid teeth may be overlooked when the defects become filled with coronal cementum and are therefore not apparent on external inspection. This was the case in one of the cattle teeth analyzed by us, in which the hypoplastic enamel defects were, however, clearly discernible in ground sections. Microscopic analysis of tooth sections is recommended for recording of LEH in bovid teeth in cases where macroscopic examination of tooth surfaces alone does not produce unequivocal results.     

Reconstructing dietary and environmental history from enamel isotopic analysis: time resolution of intra‐tooth sequential sampling

The carbon and oxygen isotopic composition of the mineral phase of tooth enamel is linked to diet and environment. Enamel is not remodelled once formed. Several studies of intra‐tooth isotopic variability in hypsodont mammal teeth have involved sequential sampling of enamel in order to detect changes in diet and environment during tooth formation. The possibility of exploring individual history opens the door to many applications, particularly in palaeoenvironment and herd management reconstruction. However, previous histological investigations have shown that enamel mineralization is a progressive and discontinuous process. The goal of the present study is to determine if this pattern significantly influences the time resolution of an intra‐tooth sequential sampling. Isotopic analyses (δ¹³C) were performed on tooth enamel from steers (Bos taurus) that had changed from a C₃ plant‐based diet to a C₄ plant‐based diet with very different carbon isotopic compositions. The change of diet was reflected in the mineral phase of enamel. The pattern of intra‐tooth isotopic variation suggests that completion of enamel mineralization required six to seven months. Such a lag in enamel mineralization will decrease the time resolution of enamel sequential sampling. The effects of prolonged mineralization of enamel have to be considered when interpreting patterns of intra‐tooth isotopic variations. Copyright © 2002 John Wiley & Sons, Ltd.     

Age at death estimates for the protohistoric Arikara using molar attrition rates: A new quantification method

Dental attrition is positively related to ageing and has often been used to determine age at death of animals and prehistoric/historic humans. A newly designed molar-attrition-scoring standard was applied to a protohistoric skeletal sample, the Arikara (N = 143) from the North American Plains. Several criteria are used in producing a molar tooth crown wear (MTCW) score. These include: (i) the size of enamel wear facets, (ii) the amount of dentine and secondary dentine exposure, (iii) the height of the tooth, (iv) the enamel rim thickness, and (v) the amount of pulp-cavity exposure in the advanced stages. Age-at-death estimates were generated from ordinary least-squares (OLS) analysis, with estimated age regressed independently on the total molar attrition score (TMAS), mean molar-1 tooth crown wear (ȲM1TCW), mean molar-2 tooth crown wear (ȲM2TCW), and mean molar-3 tooth crown wear (ȲM3TCW). In all analyses (with the exception of the third molar), the coefficient of determination (r²) revealed a strong relationship between molar attrition and age. Multiple-regression analysis revealed a significant sex difference in molar-attrition rates. Besides intercept and slope differences, the female scatter showed greater molar attrition variation than the male scatter. There was no statistical difference between mean upper molar attrition score (UMAS) and lower molar attrition score (LMAS). There was no significant difference in molar attrition rates by side, and side by molar tooth.     

Developmental defects and postmortem changes in archaeological pig teeth from Fais Island,Micronesia

The study investigated developmental defects of the dental hard tissues and postmortem changes in archaeological pig molars from Fais Island, Micronesia. The developmental defects of enamel were indicative of a disturbance of the secretory stage (accentuation of the incremental pattern, occurrence of Wilson bands and of hypoplastic defects) and the maturation stage of amelogenesis (hypomineralisation). Presence of coronal cementum in an M₃ indicated a partial premature breakdown of the reduced enamel epithelium or a partial demise of the enamel organ earlier during tooth development. Developmental defects of dentine presented as accentuated Andresen lines and areas of interglobular dentine. The pattern of developmental defects in the studied molars and the fact that deciduous premolars of the pigs from Fais did not exhibit developmental defects on macroscopic inspection are consistent with the hypothesis that the tooth defects were caused by periods of severe nutritional stress occurring after weaning. Postmortem changes caused by microbial infiltration were recorded in dentine and cementum. A presumed case of soft tissue preservation in the form of presence of odontoblast processes was observed in an M¹.     

The frequency and distribution of dental caries and tooth wear in a Byzantine population of Sa'ad,Jordan

The aim of this study was to determine the frequency, distribution and extent of dental caries and tooth wear in a Byzantine population in Sa'ad, to compare these with modern Jordanians, and to draw inferences about their lifestyle. Dental caries and tooth wear were examined in 1159 permanent teeth using direct vision and dental explorer. The location and extent of the lesions were recorded and evaluated according to defined criteria. The overall caries prevalence was 16.8% (n = 1159). Most of the carious lesions (13. 9%, n = 1159) were present in the tooth crown, on occlusal or proximal surfaces; 2.9% of teeth displayed root caries alone. The upper and lower central incisors exhibited the lowest coronal caries frequency, while molars showed the highest frequency. Attrition with moderate dentine exposure was evident in most teeth. Some teeth (9.8%) demonstrated oblique abrasion and 9 (0.78%) teeth exhibited cupped occlusal surfaces. The prevalence of caries was within the range reported for other Byzantine populations and lower than that of modern Jordanians. The attrition seen in most teeth and the cupped occlusal surfaces might be due to eating abrasive food, drinking wine or acidic beverages. Oblique abrasion on the facial and palatal surfaces reflects their business or craft, such as basket making and leather processing. Copyright © 2008 John Wiley & Sons, Ltd.     

Para-masticatory wear facets and their functional significance in hunter–gatherer maxillary molars

The mastication of tough and hard foods combined with the extensive use of teeth as tools, have been considered possible antemortem causes in determining enamel microfractures of the tooth crown. This phenomenon, known as dental chipping, has been found in different fossil hominins and in several pre-historic and historic human populations who adopted different subsistence strategies. However, little is understood of the mechanism, function and the formation of dental chipping.     

New techniques for the recovery of small amounts of mature enamel proteins

Currently there are no non-destructive techniques to obtain protein from the dental enamel, the most mineralized tissue in mammals and most resistant to diagenesis, which provides a window to the developing period by means of incremental markings containing proteins. To recover protein, dissolution of powdered enamel is required. Here we tested whether samples obtained by micro-etching of the enamel surface were adequate for protein analysis by MALDI-TOF/TOF mass spectrometry and identification in protein databases. The micro-etch techniques were effective in generating adequate samples for mass spectrometry (from 3 to 13.4 μm superficial enamel), being also highly conservative, since they rendered masses of enamel ranging from 0.1 to 0.4 mg. Using these techniques the separation of proteins by SDS-PAGE was not necessary, and the whole procedure was easier. Results showed successful identification of specific enamel proteins after whole crown superficial etching with 11% EDTA in the case of immature porcine samples, and with 10% HCl in the case of mature human enamel. X- and Y-isoforms of amelogenin, ameloblastin, and enamelin peptides were identified. The new techniques described here allowed the successful recovery of enamel proteins, opening new avenues for the use of enamel protein information in fossil/archeological material, where sometimes little protein is left.     

FLUORINE IN FOSSILIZED BONE AND TOOTH: DISTRIBUTION AMONG SKELETAL TISSUES

Because of differences in their physical properties, bone, tooth dentine and tooth enamel react very differently during the course of fossilization. This relationship is shown clearly in the case of diagenetic introduction of fluorine wherein bone and dentine with high permeability and small apatite crystallite size contain 2–3 times the amount of fluorine as coexisting enamel with its low permeability and large crystallites. Smaller differences in the same sense are found within bone types from the same species, and care must be used in applying fluorine content methods even among bones from the same deposit.     

Seasonality and season of birth of modern and late Neolithic sheep from south-eastern France using tooth enamel δO analysis

Stable oxygen isotopic analysis of tooth enamel was used to investigate seasonality and season of birth in sheep. Analyses were performed on the teeth of eight modern sheep bred at the Carmejane farm in south-eastern France and born in different periods of the year. This reference data set confirms that oxygen isotopic records in the second and third molars can be used to differentiate between sheep born in late winter and those born in early autumn. The results show that inter-individual variability in the timing of tooth formation is low for the second lower molar and more pronounced for the third lower molar in this population. The duration of the process of enamel mineralization has been estimated at approximately six months. The teeth of four sheep and two goats from the late Neolithic site of Collet-Redon in south-eastern France were analyzed using the same methodology. At this site, lambing occurred between the late winter and early spring. A slight difference appears in the seasonal sequence recorded in sheep and goat, although it cannot be determined, whether this is due to different timing of tooth development, or an actual shift in the birth period. From the distribution of slaughter ages and birth period, it is suggested that domestic caprines were killed throughout the year and that Collet-Redon was probably a permanent settlement.     

Refining the Quadratic Crown Height Method of age estimation: do elk teeth wear quadratically with age?

Teeth are the basis for the best methods for estimating the age-at-death of archaeological and paleontological faunal remains, because they change by eruption and wear throughout an individual's life and because they preserve well. However, age-at-death can be difficult to estimate when teeth are isolated or when no known-age reference sample is available. For these reasons, researchers developed the Quadratic Crown Height Method (QCHM), a set of quadratic formulae that can be used to predict age-at-death from tooth crown height, when unworn crown height and the ages when the tooth erupts and when its crown height should reach zero can be estimated. Previous tests of the QCHM suggest that modified equations could improve the method. Here, we use crown height measurements on a sample of 226 known-age Rocky Mountain elk (Cervus elaphus) to perform such modifications. We adjust the age at which each tooth type's crown height reaches zero from the species' potential ecological longevity or average maximum life span to an age that we empirically estimate for each tooth type. We also empirically assess whether for different elk teeth the exponent in the QCHM formula is actually equal to 2; it is for M1, but for P4 it is about 1, indicating a roughly linear relationship. The exponents for M2 and M3 are intermediate, being closer to 1.5. Because different teeth wear at different rates and wear completely away at different ages, we recommend that researchers use the modified equations provided here to estimate age-at-death for samples of Cervus elaphus.     

EXAMINING CHILDHOOD DIETS AT KAMINALJUYU,GUATEMALA, THROUGH STABLE ISOTOPIC ANALYSIS OF SEQUENTIAL ENAMEL MICROSAMPLES*

Stable carbon and oxygen isotope ratios of tooth enamel provide a means to examine nutritional changes during childhood. To date, such studies have used large enamel samples, often spanning the developmental period of the tooth. This paper reports the results of small samples drilled from first molars and premolars of human teeth from Kaminaljuyu, a Classic period city in highland Guatemala. Carbon isotopes show considerable increase between cuspal and cervical enamel for both teeth, indicating an increase in maize consumption during childhood. Oxygen isotope trends are more variable, and suggest some seasonal fluctuation. While the oxygen isotope data confirm the identification of foreign skeletons among the samples, they illustrate a need for caution when sampling teeth due to variable δ¹⁸O composition of enamel within a tooth.     

Measuring Root Dentine Translucency in Human Teeth of Varying Antiquity

Many workers have calibrated human root dentine transparency (RDT) as a linear regression on age. It is now regarded as a well-established means of estimating age at death in modern human material. Similar applications in archaeological material have not yet been developed. The aim of this study was to establish a standard protocol for measuring RDT which was derived from previous methods and which could be applied to teeth of unknown and varying antiquity. An initial study on two archaeological populations determined the choice of tooth to study and a second study, using expendable teeth (of unknown age and origin), evaluated various techniques of specimen preparation and examination. Findings from the pilot study indicated that the lower canine was the tooth of choice. From the second study it was observed that archaeological teeth could only be sectioned if they had first been infiltrated and embedded in methyl methacrylate. The optimal section thickness was found to be 150 μm and no benefit was gained by staining. Inter-observer reliability tests showed significant differences in repeated measures of RDT in intact teeth, which were not borne out when sectioned teeth were used. Intra-observer reliability was maintained for measurements in both intact and sectioned teeth. These findings have been used to establish a standard protocol for application to human teeth of any depositional phase to estimate the dental age at death of that individual.     

INVESTIGATING SEASONALITY AND SEASON OF BIRTH IN PAST HERDS: A REFERENCE SET OF SHEEP ENAMEL STABLE OXYGEN ISOTOPE RATIOS

Intra‐tooth sequential analysis of enamel δ¹⁸O is currently used to investigate birth seasonality in past animal populations, offering new insights into seasonal availability of animal resources, herd management and seasonality of site occupation. Reference data sets are still required to address two major difficulties: (1) that inter‐individual variability in the record of the seasonal cycle is affected by tooth size; and (2) that the season of birth cannot be directly estimated from the timing of tooth growth, because of a delay in enamel mineralization. We present a data set acquired on the lower second molar of 10 modern sheep from Rousay (Orkney) born within a few weeks of each other in April/May and submitted to the same environmental conditions until death. All sheep have recorded a sinusoidal pattern of δ¹⁸O variation spanning approximately a year. From the difference between the expected and the measured time sequence, the delay of enamel mineralization is estimated to be 5–6 months. The data set is then described using a model mainly based on a cosine function. The period, corresponding to the length of the M2 crown formed over a year, averaged 35.8 mm. A very slight variation of tooth growth rate with time and no attenuation of the isotopic signal towards the cervical margin of the crown could be detected in this data set. The lowest δ¹⁸O values, corresponding to the sheep's first winter, were tracked at a distance from the enamel/root junction that varied between 23.0 and 30.3 mm (x_min mean = 27.6 mm); the highest δ¹⁸O values, corresponding to the sheep's second summer, were between 6.3 and 11.6 mm (x_max mean = 9.9 mm). Most of the variability can be attributed to tooth size. When normalized on the period, x_min and x_max are 0.28 (± 0.05) and 0.78 (± 0.05) on average, meaning that the Rousay sheep have recorded the minimum and maximum δ¹⁸O values on average at 78% and 28%, respectively, of the end of the periodic cycle recorded in the second molar.     

Toothpick use among Epigravettian Humans from Grotta Paglicci (Italy)

This paper deals with two teeth (an upper right M1 and an upper right dM2) from the Epigravettian found in the site of Paglicci (Southern Italy) showing interproximal grooves that are situated below the crown, on the root walls just apical to the cementum–enamel junction. These grooves have been examined on a digital microscope which displays 3D images of the analysed surfaces. The images obtained made it possible to interpret these interproximal grooves as tooth picking activities that can be interpreted as an attempt to alleviate sore gums. The comparison with experimental images from available literature made it possible to form hypotheses concerning the nature of the probes that might have been used by the humans. Copyright © 2014 John Wiley & Sons, Ltd.     

Trace element concentrations in teeth – a modern Idaho baseline with implications for archeometry,forensics, and palaeontology

Concentrations of 69 minor and trace elements were measured in situ using laser ablation inductively-coupled plasma mass spectrometry in multiple teeth of modern herbivores (Cervus elaphus, Odocoileus hemionus, Odocoileus virginianus; n = 52), omnivores (Ursus americanus; n = 56), and carnivores (Felis concolor; n = 33; Canis lupus; n = 4) from Idaho, USA. On each tooth, two to five analyses were collected on enamel, primary dentine, and secondary dentine with spot diameters of 30–100 μm. Continuous 30-μm-wide line traverses were collected across deer, elk, and wolf teeth. Results confirm trace element concentrations below 1 ppm for many elements, including Li, Be, transition metals (excepting Mn, Fe and Zn), heavy metals (excepting Hg and Pb), the rare earths, and actinides. Strontium and Ba generally biopurify with increasing trophic level, but Ba shows decreasing discrimination with tissue type in the order secondary dentine – primary dentine – enamel. Most elements show strong zoning within tissues and variable trophic level behavior, so concentrations in omnivores rarely fall between herbivores and carnivores. Trace element mass balance suggests that soil and dust, not food, commonly deliver the largest trace element load in terrestrial carnivores and omnivores, even for elements that biopurify, like Ba. Use of trace elements for inferring past diets are likely compromised by unknown rates of dust and soil ingestion rather than indicating the degree of herbivory and carnivory. The low concentrations of many elements provide multiple sensitive markers of post-burial overprinting that can be used to discriminate altered vs. original biogenic compositions. REE and actinide trends do not directly follow bedrock compositions.     

Are Teeth Better? Histological Characterization of Diagenesis in Archaeological Bone–Tooth Pairs and a Discussion of the Consequences for Archaeometric Sample Selection and Analyses

Teeth are often the preferred source material for isotopic and genetic assay involving ancient biomolecules. The assumption is that dental tissue preserves better due to its anatomically protected location, the enamel cap, and lower porosity compared to bone. However, this assumption has not been widely tested. Some similarities in diagenetic processes are to be expected due to similarities in structure and chemical composition of dentine and bone. This has led to the suggestion that bone can be used as an indicator of dental preservation, as a pre‐screening technique in the selection of suitable samples for biomolecular studies. Thus, direct testing of the correlation between bone and tooth preservation and diagenesis is needed. This paper reports the results of the histological characterization of diagenetic alterations within 25 human femur–tooth pairs, from a Medieval to modern (AD 1850) cemetery in Eindhoven, the Netherlands. The results showed that teeth do indeed preserve better overall, but not always, and that this was dependent on the main diagenetic factor(s) at the burial location. Furthermore, good correlations are found between the microstructural preservation of bone and teeth; similar processes of decay were observed within bone and teeth of the same individual. Overall, the study demonstrated that histological analysis of bone is useful for the identification of degradation processes that affect biomolecular preservation in skeletal material. In this way, sample selection and analytical strategies can be optimized. Copyright © 2013 John Wiley & Sons, Ltd.     

Distribution of dental caries in an early 17th century swedish population with special reference to diet

The distribution of dental caries was determined in complete and partial human dentitions from a 17th century (1621–1640) city graveyard excavated in Gothenburg, Sweden. Sixty‐three adults and two children, divided into five different age groups, were studied. Altogether 949 teeth (943 permanent and six deciduous) were examined macroscopically using a dental probe and X‐rays. A high number of teeth had been lost post‐mortem. An increase in ante‐mortem tooth loss was found with increasing age. Sixty per cent of all individuals and 12% of all teeth showed signs of caries. The number of carious teeth per subject increased with increasing age. The highest prevalence of individuals with caries was found for the age group 26–35 (69%). Caries were most prevalent in the first, second and third lower molars (60%), while the incisors and canines in the upper and lower jaws were the least affected teeth (1%). The occlusal surface was the area most susceptible to caries (45%), followed by the buccal cemento–enamel junction (16%) and the approximal contact point (11%). This study shows that, although consuming a diet believed to have been lower in sugar content compared to modern populations, caries did affect a rather high number of individuals living in Sweden during the early 17th century. Copyright © 1999 John Wiley & Sons, Ltd.     

Sex assessment of medieval Norwegian skeletons based on permanent tooth crown size

The excavation of the Library site in Trondheim uncovered the medieval cemetry of St. Olav's church containing 388 skeletons, of which 248 had skulls with teeth. Sex assessment was based on osteological criteria, and for 145 skeletons sex classification was performed with a high degree of certainty. The remaining 103 were classified as uncertain male, uncertain female and sex undetermined. Mesio-distal and facio-lingual crown widths of permanent teeth in the group of reliably assessed males and females were used in sex-discriminant analyses. A combination of two or more teeth was less effective in discrimination than using one tooth alone. This was due to missing data in the combined variable sets and thereby loss of cases. Missing variables were due to post-mortem tooth loss, attrition or large deposits of calculus. The teeth were ranked according to their power in sex discrimination. The left maxillary first molar (26) represented by its facio-lingual dimension was the best sex discriminator (classified 85 per cent of the cases correctly), followed by the right maxillary first molar (16) also represented by its facio-lingual dimension (classified 77 per cent correctly). With only one variable in the discriminant function, a critical value could be calculated and tabulated for each tooth. This was used in sex assessment of the osteologically undetermined and uncertain groups. Only variables that could sex classify correctly at least 70 per cent of the cases with the Jack-knife procedure were used. Sex assessment could be made for 16 of 24 (66.7 per cent) of the osteologically sex-undetermined adult individuals and for 21 of 44 (47.7 per cent) of the children. Of 35 osteologically uncertainly sex-assessed skulls, only nine (six men and three women) corresponded with dental classification.