High-resolution isotopic evidence of specialised cattle herding in the European Neolithic.

Reconstructing stock herding strategies and land use is key to comprehending past human social organization and economy. We present laser-ablation strontium and carbon isotope data from 25 cattle (Bos taurus) to reconstruct mobility and infer herding management at the Swiss lakeside settlement of Arbon Bleiche 3, occupied for only 15 years (3384-3370 BC). Our results reveal three distinct isotopic patterns that likely reflect different herding strategies: 1) localized cattle herding, 2) seasonal movement, and 3) herding away from the site year-round. Different strategies of herding are not uniformly represented in various areas of the settlement, which indicates specialist modes of cattle management. The pressure on local fodder capacities and the need for alternative herding regimes must have involved diverse access to grazing resources. Consequently, the increasing importance of cattle in the local landscape was likely to have contributed to the progress of socio-economic differentiation in early agricultural societies in Europe.

An in vitro assessment of fluoride uptake by tooth enamel from four different fluoride dentifrices.

AIM: The aim of this study was to evaluate fluoride uptake by tooth enamel with four different fluoride dentifrices. STUDY DESIGN: Sixty human premolars extracted for orthodontic purpose were selected for the study. The teeth were covered with nail varnish leaving a window of 4 × 4 mm on the enamel surface of the buccal and lingual sides. The teeth were demineralised and were divided into four groups with 15 teeth in each group. The buccal window served as experimental and the lingual as control. The teeth were immersed in toothpaste slurry containing: sodium fluoride (Group A); sodium monofluorophosphate (Group B); stannous fluoride (Group C) and amine fluoride (Group D). The fluoride content in the etched superficial enamel layer in the windows was analysed using a fluoride ion-specific electrode. RESULTS: Within the parameters of this study, the uptake of fluoride was statistically significant in Group D (p < 0.05). The uptake of fluoride by tooth enamel in an increasing order was Group A < Group B < Group C < Group D. CONCLUSION: The study showed that enamel treated with amine fluoride had the highest fluoride uptake.

In vitro assessment of a toothpaste range specifically designed for children.

OBJECTIVE: To evaluate the ability of a range of low abrasivity experimental toothpastes designed for use by children at different stages of their development (typically ages 0-2 years, 3-5 years and 6+ years) to promote fluoride uptake and remineralisation of artificial caries lesions. METHODS: pH cycling study: demineralised human permanent enamel specimens were subjected to a daily pH cycling regime consisting of four 1-minute treatments with toothpaste slurries, a 4-hour acid challenge and remineralisation in pooled whole human saliva. Surface microhardness (SMH) was measured at baseline, 10 days and 20 days, and the fluoride content determined at 20 days. Enamel Fluoride Uptake (EFU): these studies were based on Method #40 described in the US Food and Drug Administration (FDA) testing procedures. Abrasivity: relative enamel abrasivity (REA) and relative dentine abrasivity (RDA) were measured using the Hefferren abrasivity test. Bioavailable fluoride: the bioavailable fluoride was determined for all experimental toothpastes from slurries of one part toothpaste plus 10 parts deionised water. RESULTS: Enamel remineralisation measured by changes in SMH correlated with enamel fluoride content. A statistically significant fluoride dose response was observed for all toothpastes tested across all age groups (P < 0.05). The fluoride content of specimens in the pH cycling model correlated with the EFU testing results. The enamel and dentine abrasivities were low and the level of bioavailable fluoride was high for all experimental toothpastes. CONCLUSION: A series of low abrasivity experimental toothpastes were developed which were effective at promoting fluoride uptake and remineralisation of artificial caries lesions.

Laboratory assessment of the anticaries potential of a new dentifrice.

OBJECTIVE: The aim of the present study was to investigate the anticaries potential of a new sodium fluoride dentifrice in comparison to two commercial dentifrices containing different fluoride compounds by determining enamel fluoride uptake (EFU) and early caries lesion remineralization (REM) in an established in vitro caries remineralization/demineralization pH cycling model. METHODS: Test products were: new dentifrice formulation in a fluoride dose-response (0; 675; 1426 ppm F as sodium fluoride [NaF-0; NaF-675; NaF]); Elmex Kariesschutz (1400 ppm F as amine fluoride [AmF]); and Oral-B Pro-Expert (1450 ppm F-1100 ppm F as stannous fluoride and 350 ppm F as sodium fluoride [SnNaF]). Artificial caries-like lesions were formed in human enamel specimens by immersion in lactic acid buffer (LA). Specimens were then subjected to a daily cycling regime for 20 days comprising four one-minute dentifrice slurry treatments (prepared in pooled human saliva), and one four-hour LA challenge and remineralization in pooled human saliva. After 20 days, REM was evaluated as the change in surface Vickers microhardness from lesion baseline and EFU using the microdrill technique. The data were analyzed using ANOVA. RESULTS: A good fluoride dose-response was established for EFU and REM, with NaF delivering greater EFU and REM than NaF-675, which was superior to NaF-0 (p < 0.05). The new dentifrice NaF also showed greater EFU and REM than AmF and SnNaF (p < 0.05). In EFU, AmF and SnNaF were as efficacious as NaF-675 and superior to NaF-0 (p < 0.05). AmF and NaF-675 were also comparable in REM, whereas both products exhibited superior REM vs. SnNaF (p < 0.05), which was superior to NaF-0 (p < 0.05). CONCLUSION: The present study has demonstrated that fluoride dentifrices vary in their capability of enhancing anticaries potential as determined using an established in vitro caries cycling model. The new dentifrice NaF showed superior predicted anticaries potential compared to the two commercial dentifrices AmF and SnNaF in this model, which demonstrates the importance of fluoride compound and formulation excipients on driving anticaries potential in vitro.

Assessment of 90Sr concentration in dental tissue using thin-layer beta-particle detectors and verification with numerical calculations.

Electron paramagnetic resonance (EPR) measurements of tooth enamel can be used as an individual biological dosimeter for external dose assessment. However, the presence of 90Sr in the tooth tissues makes the task of interpreting EPR tooth dosimetry more complicated. The determination of the dose contribution of incorporated 90Sr in calcified tissue to the total dose measured by EPR is one of the main aspects of correct interpretation of EPR tooth dosimetry. In this work, experimental and numerical calculations were performed to convert the measured beta-particle dose rate to 90Sr concentration in calcified tissue. The cumulative beta-particle dose was measured by exposing artificially contaminated dentin and enamel to thin-layer alpha-Al2O3:C detectors in two different exposure geometries. Numerical calculations were performed for experimental exposure conditions using calculations of electron transport and secondary photons [Monte Carlo n-Particle Transport code version 4C2 (MCNP)]. Numerical calculations were performed to optimize the sample size and exposure geometry. The applicability of two different exposure conditions to be used in routine analysis was tested. Comparison of the computational and experimental results demonstrated very good agreement.

Assessment of enamelysin (MMP-20) selectivity to three peptide bonds on amelogenin sequence.

Recent studies have highlighted the potential role of the metalloproteinase enamelysin (MMP-20) in controlling some of the most critical stages during enamel development. This study was aimed to assess the selectivity of enamelysin to the three most abundant cleavage sites on the amelogenin sequence, and to gain insight into the factors that control the pattern of amelogenin processing during enamel mineralization. Three deca-peptides with sequences based on pig amelogenin and including the proteolytic cleavage sites W/L, S/M, and P/A were synthesized as substrates. Statistical analysis revealed no significant differences in the rates of cleavage among the three peptides, indicating comparable selectivity of enamelysin for these peptide bonds. Considering the selective appearance of amelogenin proteolytic products, we suggest that amelogenin folding and assembly are the primary factors in controlling the pattern of its proteolysis during the secretory stage of enamel development.

Reversal of primary root caries using a dentifrice with a high fluoride content.

Root caries is a widespread problem and can be quite serious in older populations. The restoration of root carious lesions is often difficult. Compared to enamel caries, there has been limited research into the pharmaceutical management of primary root caries lesions (PRCLs), and many of these studies have been carried out in vitro, with limited numbers of clinical trials. Fluoride is presently a cornerstone in dentifrice formulations for cost-effective and anticaries therapy. It is generally accepted that fluoride ions promote remineralization of tooth substances and reduce the rate of demineralization. The use of a dentifrice with a high fluoride content may be considered to reverse PRCLs, since more fluoride is required for the remineralization of roots than for enamel. This paper reviews the effects of dentifrices with high fluoride contents on the management of root caries.

Enamel lead biomarker for prenatal exposure assessment.

The development of the enamel biomarker for heavy metal exposure assessment is designed to improve studies of dose-effect relationships to embryonic anomalies, particularly neurotoxic dysfunction. This report documents initial demonstrations of ambient lead (Pb) relative to calcium (Ca) in histological cross sections of deciduous tooth enamel of three human subjects, by use of ion mass spectrometry. The goal of this research was to measure Pb and Ca in tooth enamel for use as a temporal biomarker in assessing prenatal and postnatal exposure. This involves measurement of these heavy metals in enamel at high spatial resolution along histological transects following the temporal pattern of enamel growth. The technique may be applied when completely developed to cross-sectional and longitudinal research.

Strontium metabolism in teeth and enamel dose assessment: analysis of the Techa river data.

People living on the banks of the Techa river were exposed to 90Sr in the early 1950s. Data obtained by radiochemical measurements of extracted permanent teeth, 90Sr autopsy measurements in bone and tooth samples, in vivo measurements of surface beta activity of the anterior teeth and whole-body counter (WBC) measurements of 90Sr in the skeleton have been analyzed. Surface beta activity measurements indicate a biological half-life of 90Sr of about 35 years in enamel. The WBC measurements have been performed since 1974 and a model for the age-dependent strontium retention in human bone has been used to extrapolate to previous time periods when the other measurement results were obtained. For the first decade after the intake, the ratio of the 90Sr concentrations in teeth and bones were found to decrease with age at the time of major intake, from about 10 for 1-year-old children to about 0.3 for adults. There was a considerable variability of individual data within each age group. For adults, the correlation between 90Sr in skeleton and teeth was not high at 0.47 according to radiochemical data for posterior teeth (molars and premolars) and 0.43 according to measurements of surface beta activity for anterior teeth. For children and adolescents there was no correlation between individual measurements in the skeleton and teeth. The absorbed dose in enamel due to 90Sr in dentine has been calculated by Monte Carlo simulations of the electron transport. The results are in agreement with EPR measurements of the absorbed dose in the enamel of persons exposed, mainly due to 90Sr ingestion.

An in vitro assessment and a pilot clinical study of electrical resistance of demineralized enamel.

Electrical resistance measurement was evaluated in vitro and in vivo as a method for comparing the remineralizing performance of toothpastes. In the in vitro study, areas of sound enamel on 12 unrestored, mature, extracted human molars and bicuspids, with electrical resistance readings greater than 99.99 M omega, were demineralized to an electrical resistance of 1 to 4 M omega. The teeth were divided into three groups. The change in electrical resistance was measured following a 15 cycle regimen of treatment, demineralization and salivary soaking. Treatments were five-minute exposures to either a 1:2 slurry in saliva of Enamelon (E), a remineralizing fluoride-toothpaste also containing soluble calcium and phosphate ions, a 1:2 slurry in saliva of Crest (C), a conventional fluoride toothpaste (P), or to saliva alone. Demineralization was performed with a 30-minute exposure to 0.1 M lactic acid 50% saturated with calcium hydroxyapatite. The salivary soaking was 1 hour in duration. The mean electrical resistance of the E, C and the saliva treated sites was 63.9 +/- 4.3, 37.6 +/- 9.5 and 2.1 +/- 0.7 M omega, respectively. The final resistance was statistically different for each group (p < 0.05). A pilot clinical study was then conducted to assess the electrical resistance technology in vivo. Eighteen adult subjects with at least one site of early enamel caries with an electrical resistance between 1.0 M omega and 20.00 M omega were randomly assigned to either Enamelon, Crest, or a non-fluoride placebo toothpaste and asked to brush twice daily. After three months, the mean resistance of the test sites was 23.57 M omega for E, 9.61 M omega for C and 13.24 M omega for P. However, the mean resistance changes did not proceed consistently over time. At the end of the study, the electrical resistance measurements on four sites out of twelve in Group E were suggestive of remineralization, whereas measurements on one site out of ten were suggestive of remineralization in Group C and two or three sites out of twelve were suggestive of remineralization in Group P. Progression of demineralization was possibly indicated in only one site, which was in Group C. There were insufficient subjects for statistical significance in the pilot clinical study. There were apparent problems with the variability of some measurements between visits in the in vivo study. Overall, however, the results of both studies indicate that with modifications to the equipment, electrical resistance measurements may be a means of comparing the remineralization performance of toothpastes.

Proton microprobe assessment of the distribution of fluoride in the enamel and dentine of developing central incisors of sheep and changes induced by daily fluoride supplements.

Ten sheep were given 0.5 mg fluoride (F) and 10 sheep 0.2 mg F/kg body wt orally for periods of 1-6 months while 8 sheep received no additional F. One incisor from each sheep was sectioned longitudinally in the midline and, using the proton microprobe, multiple scans for calcium and F were made across the enamel and dentine. F was determined by proton-induced gamma-ray emission and calcium by X-ray emission. Tooth length and hence the stage of ameloblast activity for each of the 28 teeth at the start of the experiment was determined using a tetracycline marker. In addition, the stage of enamel development of the eight control teeth (no dietary F) at the time of their extraction was assessed from their macroscopic appearance. Continuous changes in F levels occurred in both enamel and dentine throughout tooth development and also in the mature enamel and associated dentine after ameloblast regression. All scans for all stages of tooth development and all F treatments showed a high F concentration at the enamel surface. Early in the secretory phase, a wide-based F peak occupied the entire width of the enamel with a similar F peak in the dentine. In the control teeth, no consistent increase in F concentration occurred at the enamel surface during later development. When F supplements were started early in the maturation phase an increase in F concentration only at the enamel surface was recorded. When F supplements were also given during the secretory phase, higher F concentrations were recorded not only at the enamel surface but also for the inner enamel and dentine plateau. These findings, based on a small number of sheep, indicate that further research is needed to clarify the method and control of F uptake and to determine the changes in these processes during the different stages of tooth development.

Formation of phosphate-containing calcium fluoride at the expense of enamel, hydroxyapatite and fluorapatite.

During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were investigated under well-defined conditions. pH and pF were monitored; calcium and phosphate concentrations were measured at selected times; the solid phases were examined by infra-red, X-ray diffraction and transmission electron microscopy. Precipitation of phosphate-containing calcium fluoride crystals, CaF2(P), can cause severe reduction in the calcium ion concentration and release of hydrogen ions from the precipitated phosphate. These reactions result in considerable dissolution of enamel, HAP and even of FAP. More of the added mineral dissolves with 50 mmol/l fluoride than with 10 mmol/l fluoride, mainly due to the greater reduction in calcium ion concentration. This work shows that phosphate-containing calcium fluoride is most likely an important compound to be considered in the caries process.

Assessment of loosely-bound and firmly-bound fluoride uptake by tooth enamel from topically applied fluoride treatments.

The amounts of loosely-bound fluoride (F) deposited on human enamel by two topical F treatments were measured with use of a constant-composition F washing method. Enamel biopsies conducted before treatment and after the washing were used for determination of the firmly-bound F uptake. The results showed that (1) the washing system did not remove F from untreated enamel surface, (2) a four-minute application of an acidulated phosphate fluoride (APF) gel deposited 27.2 (2.4) (mean, S.E.) micrograms of loosely-bound F per cm2 of enamel surface and 186 (111) ppm of firmly-bound F in the outer 10 microns of enamel, and (3) a four-minute application of a pH-2.1 dicalcium phosphate dihydrate (DCPD)-forming solution followed by APF produced 44.9 (3.1) micrograms/cm2 of loosely-bound F and 1280 (354) ppm of firmly-bound F in the outer 10 microns of enamel. The results showed that the DCPD pre-treatment effectively enhanced the enamel reactivity with F, so that the DCPD-APF treated enamel acquired greater amounts of both loosely-bound F and firmly-bound F than did samples treated with APF alone.