Chemical Composition Of Dentin Research Articles

In vitro study on how cold plasma affects dentin surface characteristics

PurposeStudies evaluating different features of cold plasma action on dentin surface characteristics are lacking. Thus, this in vitro study aimed to determine the effect of cold plasma under different protocols of exposure time, distance to plasma source, and the association of argon gas with distinct concentrations of oxygen on the wettability, surface energy, total free interaction energy, surface roughness, morphology and chemical composition of dentin. Material and methodsOne hundred and twenty-five bovine dentin samples were used and divided into twenty-five groups according to the exposure time to plasma (15, 30, or 60 s); distance between plasma source and dentin surface (3 or 6 mm); argon gas without plasma generation; and plasma generated by argon gas and association of argon gas with distinct concentrations of oxygen (2 % or 3 %) (n = 5). Contact angle (θ), surface energy (γs) and total free interaction energy (ΔG) were measured using a goniometer (Krüss), while surface roughness (Ra) was evaluated by a profilometer (Mitutoyo). Representative samples were submitted to scanning electron microscopy (JEOL) to ilustrate the morphology and chemical composition of dentin. Data comparing control group with all experimental groups were submitted to ANOVA followed by Tukey's test (α = .05). Data comparing oxygen gas action at different concentrations and argon gas on dentin characteristics were submitted to non-parametric Kruskal–Wallis test, followed by Dunn test for comparison between the groups and methods (α = 0.05). ResultsIn general, argon gas without plasma generation promoted no significant difference on dentin surface characteristics compared to control group (P > .05), differently for the cold plasma that significantly reduced contact angle values and increased total free interaction energy of dentin surface (P < .05). Overall, feeding of oxygen at distinct concentrations promoted significant difference on dentin surface characteristics compared to control group (P < .05). Exposure time and distance protocols interfered with contact angle, surface energy and total free interaction energy analyses for each gas. There was no significant difference on surface roughness (P > .05), morphology and chemical composition of dentin submitted to argon gas, cold plasma, and distinct concentrations of oxygen. ConclusionIn conclusion, plasma generated by argon gas and its feeding with 2 % and 3 % oxygen gas improved the dentin surface characteristics about wettability, surface energy and total free interaction energy. Such treatments preserved the surface roughness, morphology and chemical composition of dentin. The protocols of groups Ar-6mm-15sec, ArO2-3mm-30sec and ArO3-3mm-15sec are recommended for improvement of dentin surface characteristics.

Effect of a Modified Irrigation Protocol on the Cleanliness of Moderately Curved Canals.

Objectives This study tested the hypothesis that modifying the sequence of sodium hypochlorite (NaOCl)/ethylene diamine tetra-acetic acid (EDTA) irrigation during root canal shaping would improve apical cleanliness in moderately curved canals. Materials and Methods Forty-five root canals were prepared using Protaper Gold with three irrigation protocols. Standard irrigation (SI) used 0.5 mL 3% NaOCl between each instrument, followed by 5 mL 17% EDTA manually agitated for 30 seconds. Reverse irrigation (RI) used 0.5 mL of 17% EDTA between each instrument, then 5 mL of 3% NaOCl, manually agitated for 30 seconds. Reverse irrigation plus (RI+) was similar to RI, except NaOCl (5 mL), used as a final rinse, was allowed to interact for 3 minutes with dentin before manual agitation (30 seconds). Root canal cleanliness was evaluated under the scanning electron microscope (SEM) (Hulsmann score); the chemical composition of dentin after irrigation was analyzed by energy dispersive X-ray (EDX). Statistical Analysis Results were compared using Kruskal–Wallis ANOVA by ranks and Wilcoxon matched paired posthoc tests. A Chi-square test assessed whether the best cleanliness would demonstrate a significant association with one irrigation protocol; odds ratio calculation was performed using score “1” versus score “2 or more” (2+) ( p < 0.05). Results In the apical region, cleanliness was better in RI+ than SI and both significantly better than RI. Odd ratios indicate that the cleanliness in RI+ was significantly better than RI and SI groups ( p < 0.000 and 0.003, respectively). Independently of the irrigation protocol, EDX analyses showed no chemical alteration of root dentin. Conclusions Using 17% EDTA during shaping, followed by 3% NaOCl rinse for 3 minutes, improved apical cleanliness without inducing erosion of dentin.

Physiochemical characteristics: A robust tool to overcome teeth heterogeneity on predicting laser ablation profile.

To avoid excessive tissue removal and collateral damage, the high-power density laser is apt for dental surgery also need to have high precision. For high-precision dental surgery with minimal tissue damage, the present work frames a method to predict laser ablation profile based on surface morphology and chemical composition of dentin. The surface morphology and chemical composition were studied on different dentin samples using scanning electron microscope (SEM) and Energy Dispersive X-ray Analysis (EDAX), respectively. The key laser ablation parameters (ω0 , Deff , and Fth ) were determined by laser irradiation study using 800 nm, Ti:Sapphire femtosecond laser at processing condition of 100 fs, 10 kHz and 10 mm/s. The dentin samples show a strong linear correlation between physiochemical characteristics and laser ablation parameters. The surface morphology exhibits a negative linear correlation with threshold fluence, whereas the converse is true for chemical composition. The laser ablation parameters of a random dentin sample are derived from the knowledge of linearity data. From the obtained laser ablation parameters, the complete theoretical ablation profile is constructed and validated with experimental ablation profile. Even though the surface morphology of dentin shows high linearity, the concentration of Ca and P can be used as the most feasible probe in clinical settings. Furthermore, the laser ablation rate and ablation efficiency are predicted by the method to optimize the laser processing condition for any specific teeth. The versatility of the method overcomes the problem of heterogeneity on various teeth and simplifies the method of finding optimal laser processing condition for immaculate laser surgery.

Ultrastructural and Chemical Composition of Dentin and Enamel in Lab Animals.

Statement of the Problem:Human tooth is clinically the most appropriate material that can be used for in-vitro dental research. However, there are limitations and drawbacks for using human teeth. Therefore, alternatives to samples of human teeth for dental studies are necessary. Purpose: This study purposed to evaluate and compare the microstructure and chemical composition of enamel and dentin of teeth in some lab animals. Materials and Method: In this experimental study, teeth of mouse, rabbit, guinea pig, dog, cat, and sheep were used. Scanning electron microscope observations and X-ray diffraction analysis were performed on samples. Results: This study revealed resemblance in general structure of dentin and enamel between mentioned animals and human. The minimum mean of dentinal tubules diameter is found in guinea pig (0.5µ), while the highest is in cat (1.5µ). Also the lowest and the highest mean intertubular distance was measured respectively in guinea pig (3µ) and sheep (4.8µ) and the maximum and minimum mean diameter of rods was measured in rabbit (6.6µ) and guinea pig (1.5µ), respectively. Conclusion:The recorded details and the measured values indicate great resemblance between dog and human dentin and enamel. Cat is in the second place for dentinal studies; sheep and guinea pig have the least resemblance to human within the scope of the reviewed criteria.

Effect of different irrigating solutions with surfactants on the microhardness and smear layer removal of root canal dentin: An in vitro study.

Aim:The present in vitro study was undertaken to check the effect of the different irrigating solutions with surfactants, i.e., sodium hypochlorite-(Naocl)-Extra, chlorhexidine (CHX)-Ultra, ethylenediaminetetraacetic acid (EDTA), QMix, and BioPure MTAD on the microhardness and smear layer removal of root canal dentin.Materials and Methods:A total of 120 straight rooted lower premolars were collected and were randomly divided into 2 equal groups of 60 each (n = 60). The microhardness of the samples was evaluated by Vickers hardness tester and the removal of smear layer by scanning electron microscope after irrigation of the samples with the tested solutions.Results:CHX-Ultra showed the least microhardness reduction, and EDTA showed the maximum microhardness reduction in all the tested groups. BioPure MTAD showed the maximum removal of smear layer in the apical third, and CHX-Ultra showed the minimal smear layer removal in the apical third.Conclusion:During smear layer removal, irrigating solutions cause alterations in the chemical composition of dentin, which may decrease the microhardness of the root dentin causing erosion and affecting the clinical performance of the endodontically treated teeth. Irrigating solution with maximum smear layer removal with minimum changes in microhardness should be used.

Does the Photon-Induced Photoacoustic Streaming Activation of Irrigation Solutions Alter the Dentin Microhardness?

Objective: The aim of this in vitro study was to evaluate the efficacy of photon-induced photoacoustic streaming (PIPS) activation of sodium hypochlorite (NaOCl), chlorhexidine (CHX) or ethylenediaminetetraacetic acid (EDTA) on the dentin microhardness and to assess the compositional changes of root dentin. Background data: It is still unclear whether PIPS activation of irrigants alters the dentin microhardness and mineral content of dentin. Materials and methods: Root canals of 72 extracted single-rooted teeth were prepared and teeth were fixed in microcentrifuge tubes with silicone impression material. After setting of the silicone, teeth were removed and split longitudinally in buccolingual direction. One half was used as control (pretreatment) while the other was placed into the tube (posttreatment). Then specimens were divided into six test groups (three with and three without PIPS activation). The irrigants tested were 2.5% NaOCl, 17% EDTA, and 2% CHX. Experimental tooth specimens were irrigated with 6 mL of test solution, with additional PIPS activation applied to the PIPS groups. Then specimens were subjected to Vickers microhardness testing. Percentage change of microhardness was calculated. Energy dispersive X-ray spectroscopy (SEM-EDX) was performed to measure element content. Results: Among the irrigant-alone groups, NaOCl and CHX did not alter the dentin microhardness, whereas statistically lower microhardness values were obtained in EDTA group. Chemical composition of dentin was affected from all irrigants used. PIPS activation led to no additional alteration in dentin microhardness. PIPS significantly increased the phosphorus level in NaOCl group. Conclusions: Dentin microhardness was significantly affected by the irrigation solution, not by the PIPS activation.

Сравнительный рентгеноспектральный анализ химического состава дентина зубов с клиновидным дефектом при различной глубине микротрещин эмали

Сравнительный рентгеноспектральный анализ химического состава дентина зубов с клиновидным дефектом при различной глубине микротрещин эмали

Effect of Er:YAG laser energy densities on thermally affected dentin layer: Morphological study.

Physical and chemical composition of dentin is subject to modification when irradiated with Er:YAG laser. Temperature rise causes water evaporation and micro-mechanical ablation of dentin. The misuse of laser parameters could affect negatively dentin collagen fibers leading to failure in bonded composite restorations. The aim of this in vitro study was to evaluate the effect of Er:YAG laser radiation at different levels of energy on the morphology of thermally affected dentin layer. Forty-eight freshly extracted human third molars were randomly divided into six groups (n = 8). In all groups, except for the control groups, dentin was subject to irradiation with H02 handpiece Er:YAG laser in non-contact mode (SSP mode = 50 µs; 10 Hz; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min) with the following levels of energy (40, 60, 80, 100, and 120 mJ) respectively. Teeth were sliced longitudinally. Photo-ablated cavities were observed. The cavity depth and dentin fiber collagen deterioration were measured. Laser irradiation increased the depth of dentinal crater from 46.57 µm to 178.2 µm, when energy level increased from 40 mJ to 120 mJ. A superficial black layer, representing dentinal affected collagen fibers, was present in all groups except for control group. When comparing the thickness of the black layer, there was no significant difference between groups. It increased at 40 mJ to 28.17 µm then decreased to 15.19 µm at 60 mJ and then increased again for 80 mJ to 19.93 µm, 100 mJ to 22.87 µm and 120 mJ to 28.53 µm. Only one group (60 mJ) showed low values and significant difference as compared to the other irradiated groups, when multiple comparisons tests (ANOVA) were made using Newman-Keuls test. Dentin organic matrix presented the minimum alteration when Er:YAG laser is used specifically at an appropriate level of energy (60 mJ).

Effect of a Papain-based Chemomechanical Agent on Structure of Dentin and Bond Strength: An in vitro Study.

AimTo evaluate the microtensile bond strength of teeth restored with packable composite after removing caries with three chemomechanical caries removal agents (Carisolv, Papacarie and Carie-care) and also to analyze its effect on chemical composition of dentin using energy-dispersive X-ray (EDX) analysis.DesignA total of 40 carious molars with 1 to 1.5 mm of remaining dentin were selected and divided into four groups of 20 each. Group I (control)—bur, group II—Carisolv, group III—Papacarie, group IV—Carie-care. A total of 15 samples from each group were restored with composite; 1 mm thick sections were made and were debonded under tensile load. Remaining five samples from each group were subjected to EDX for elemental analysis of dentin surface.ResultsNo statistically significant difference in the bond strength values and Ca/P ratio was observed between control group and three chemomechanical agents tested in the study.ConclusionNone of the chemomechanical agents tested in the study adversely affected the bond strength of composite resin to caries-affected dentin. Therefore, newer papain-based chemomechanical agent Carie-care can be considered as an equally effective economical alternative to commonly used agents Carisolv and Papacarie.How to cite this article: Nair S, Nadig RR, Pai VS, Gowda Y. Effect of a Papain-based Chemomechanical Agent on Structure of Dentin and Bond Strength: An in vitro Study. Int J Clin Pediatr Dent 2018;11(3):161-166.

Analysis of the effects of several decalcifying agents alone and in combination with sodium hypochlorite on the chemical composition of dentine.

To investigate the effects of several decalcifying agents alone and in combination with sodium hypochlorite (NaOCl) on the organic and inorganic components of dentine using attenuated total reflectance in Fourier transform infrared spectroscopy (ATR-FTIR). Dentine slices from bovine teeth were submitted to (n=5) the following: 0.9% saline, 9% and 18% etidronic acid (HEDP), 5% and 10% tetrasodium EDTA (EDTANa4 ), 17% trisodium EDTA (EDTAHNa3 ), and 0.5% and 2.0% peracetic acid (PAA) for 0.5-10min; and to the combinations: G1 - mixture 5% NaOCl+18% HEDP (5 and 10min); G2 - mixture 5% NaOCl+10% EDTANa4 (5 and 10min); G2 - 2.5% NaOCl (5min)+17% EDTAHNa3 (1min); G3 - 2.5% NaOCl (5min)+0.5% PAA (1min); G4 - 2.5% NaOCl (5min)+9% HEDP (5min). Specimens of G2, G3 and G4 received final flushes with 2.5% NaOCl for 0.5-10min. Amide III/phosphate and carbonate/phosphate ratios of the spectra collected from the dentine specimens before and after immersion in the solutions were determined. Data were submitted to one-way repeated measures and one-way anova. For the same decalcifying agent, the higher the concentration and immersion time the greater the removal of phosphate, exposure of collagen matrix and consequently the increases in amide III/phosphate ratio. However, significant differences were found only between the two concentrations of PAA (P<0.05). PAA caused greater increases in this ratio, followed by EDTAHNa3 , EDTANa4 and HEDP, and this order was retained in the combinations with NaOCl. This ratio was significantly reduced in G1 (P<0.05) and not altered in G2 (P>0.05). Due to collagen degradation, the amide III/phosphate ratio reduced significantly after the use of NaOCl in G3, G4 and G5 (P<0.05). NaOCl required approximately 0.5s to deproteinate the collagen matrix exposed after phosphate removal by EDTAHNa3 and PAA. The carbonate of dentine was removed more rapidly than phosphate by all decalcifying agents alone and in G3, G4 and G5. In the combinations with NaOCl, the last irrigant used defined the dentine amide III/phosphate and carbonate/phosphate ratios. HEDP and EDTANa4 caused minor whilst EDTAHNa3 and PAA caused greater demineralization of dentine; both effects were time and concentration dependent. NaOCl degraded the dentine organic matrix more rapidly when it was exposed. Combinations of NaOCl and decalcifying agents can be used to create dentine surfaces with varying compositions for interaction with endodontic sealers.

EVALUATION OF AUTOGENOUS FRESH DEMINERALIZED TOOTH GRAFT PREPARED AT CHAIRSIDE FOR DENTAL IMPLANT (CLINICAL AND HISTOLOGICAL STUDY)

INTRODUCTION: Although, the chemical composition of dentin is similar to bone, extracted teeth are still considered a clinical waste and therefore being discarded. With successful extraction of growth factors and bone morphogenic proteins (BMPs) from mammalian teeth, many researchers have supported development of a bone substitute using tooth-derived substances. OBJECTIVES: To evaluate clinical, radiological and histological efficiency of autogenous fresh demineralized tooth (AFDT) graft prepared at the chairside for alveolar bone grafting in fresh extracted sockets for dental implant surgery MATERIALS AND METHODS: Ten patients requiring tooth extraction and alveolar bone regeneration for dental implant placement were included in the study. Within 45 minutes the extracted teeth were mechanicaly prepared, grinded, sieved, defatted, demineralized and sterilized. In the same setting, the graft material was used to reconstruct defects at the extraction. After 3 months of uninterrupted healing at time of implant placement bone samples were collected for histological analysis. CBCT were taken preoperative, 3months after grafting and 3 and 6 months after implant placement. RESULTS: Histologically the osteoconductive, Osteoinductive and Biodegradation of (AFDT) graft was evident. Clinically 100 % success rate of implants was achieved, with no adverse tissue reaction. CBCT have shown increase of bone density at the graft site and stability of marginal bone level around implants. CONCLUSIONS: (AFDT) graft should be considered as an option given its autogenous origin and favorable clinical, radiographical and histological outcomes when teeth extraction is necessary.

Reinforcing Effects of Calcium Silicate-based Cement and Dual Cure Composite Resin in Simulated Immature Teeth with an Open Apex: An in vitro Study.

AimTo evaluate the fracture resistance of simulated immature teeth with an apical plug of biodentine followed by composite resin vs total obturation with biodentine tested immediately and after 3 months of aging and also to find out the chemical composition of dentin in contact with these materials.Materials and methodsExtracted human maxillary central incisors with simulated immature apex with radicular dentin thickness (RDT) of 1 to 1.5 mm selected and divided into three groups of 20 each. Group I (control)—4 mm biodentine apically and thermoplasticized gutta-percha. Group II—4 mm biodentine apically and composite resin. Group III—complete obturation with biodentine. About 10 samples from each group were tested immediately and remaining 10 stored in phosphate buffered solution (PBS) and tested after 3 months for fracture resistance and chemical analysis of dentin.ResultsNo significant difference in fracture resistance between the groups was observed when tested immediately. After 3 months of aging, only biodentine group showed a significant reduction in fracture resistance with increased Ca/P ratio of root dentine.ConclusionBiodentine group has shown drastic reduction in fracture resistance after 3 months of aging, and hence, cannot be recommended as a reinforcement material in immature teeth with thin dentin walls.How to cite this article: Zhabuawala MS, Nadig RR, Pai VS, Gowda Y, Aswathanarayana RM. Reinforcing Effects of Calcium Silicate-based Cement and Dual Cure Composite Resin in Simulated Immature Teeth with an Open Apex: An in vitro Study. Int J Clin Pediatr Dent 2017;10(4):351-357.

Effect of gamma irradiation on the wear behavior of human tooth dentin.

The objective of this study was to evaluate the effect of gamma irradiation on the wear behavior of human tooth dentin in terms of possible alterations in crystallinity, grain size, and composition. Human premolars (n=19) were collected to obtain the perpendicular or parallel to the direction of the dentin tubule specimens. Each specimen was subjected to 60Gy of gamma irradiation, in daily increments of 2Gy. The nanoscratch tests were conducted. The scratch traces were observed via scanning electron microscope (SEM) and surface profilometer. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the alteration of crystallography and chemical composition of dentin after irradiation. The change of surface microhardness (SMH) was also evaluated. The nanoscratch results showed that the friction coefficient of dentin after irradiation became higher, and the depths and widths of scratch were greater than that of dentin before irradiation. Additionally, irradiation decreased the crystallinity of dentin and induced the formation of bigger crystals. The carbonate/mineral ratio was increased. Furthermore, a significant reduction in microhardness after irradiation was observed. The main damage mechanisms consisted of the formation of delamination and crack in both the specimens cut perpendicular and parallel to tubule dentin after irradiation. Irradiation affected directly the wear behavior of tooth dentin, accompanied by the alterations in crystallography, chemical composition, and surface microhardness of dentin. This would help extend understanding the influence of irradiation on dentin and provide suggestions for selecting more suitable materials for irradiated tooth.

Effect of aging on the microstructure, hardness and chemical composition of dentin

ObjectiveUnderstanding the effects of biological aging on human tissues has been a topic of extensive research. With the increase in healthy seniors and quality of life that topic is becoming increasingly important. In this investigation the effects of aging on the microstructure, chemical composition and hardness of human coronal dentin was studied from a comparison of teeth within “young” and “old” age groups. MethodsThe microstructure of dentin within three regions (i.e., inner, middle and outer) was analyzed using electron and optical microscopy. The mineral-to-collagen ratio in these three regions was estimated using Raman spectroscopy and the hardness was evaluated using microindentation. ResultsResults showed that there were significant differences in tubule density, tubule diameter and peritubular cuff diameter with depth. Although there was no difference in tubule density and diameter of the tubules between the age groups, there was a significant difference in the occlusion ratio. A significant increase in hardness between young and old patients was found for middle and outer dentin. An increase in mineral-to-collagen ratio from inner to outer dentin was also found for both groups. In old patients, an increase in mineral content was found in outer coronal dentin as a consequence of tubule occlusion. ConclusionsAn increase in occlusion ratio, hardness, and mineral content was found in the dentin of adult patients with age. This increase is most evident in the outer coronal dentin.

Chemical and morphological changes in human dentin after Er:YAGlaser irradiation: EDS and SEM analysis.

Sixty samples of human dentin were divided into six groups (n = 10) and were irradiated with Er:YAG laser at 100 mJ-19.9 J/cm(2), 150 mJ-29.8 J/cm(2), 100 mJ-35.3 J/cm(2), 150 mJ-53.0 J/cm(2), 200 mJ-70.7 J/cm(2), and 250 mJ-88.5 J/cm(2), respectively, at 7 Hz under a water spray. The atomic percentages of carbon, oxygen, magnesium, calcium, and phosphorus and the Ca-to-P molar ratio on the dentin were determined by energy dispersive X-ray spectroscopy. The morphological changes were observed using scanning electron microscopy. A paired t-test was used in statistical analysis before and after irradiation, and a one-way ANOVA was performed (P ≤ 0.05). The atomic percent of C tended to decrease in all of the groups after irradiation with statistically significant differences, O and Mg increased with significant differences in all of the groups, and the Ca-to-P molar ratio increased in groups IV, V, and VI, with statistically significant differences between groups II and VI. All the irradiated samples showed morphological changes. Major changes in the chemical composition of dentin were observed in trace elements. A significant increase in the Ca-to-P ratio was observed in the higher energy density groups. Morphological changes included loss of smear layer with exposed dentinal tubules. The changes produced by the different energy densities employed could have clinical implications, additional studies are required to clarify them.

A Novel Procedure to Process Extracted Teeth for Immediate Grafting of Autogenous Dentin

Background: Extracted teeth are still considered a clinical waste and therefore being discarded. It is evident that chemical composition of dentin is similar to bone. Following tooth replantation the tooth is replaced by bone then followed by root resorption and ankyloses and finally integrated into the surrounding alveolar bone. Aims: Here we present a novel procedure in a clinical setting that employs freshly extracted teeth that are processed into a bacteria-free particulate dentin, and then grafted immediately into extraction sites or bone deficiencies. Methods: The procedure consists of reducing any restorations, caries or debris. The clean and dry tooth, mostly dentin, is immediately grinded using a specially designed 'Smart Dentin Grinder'. The dentin particulate of 300-1200 um is sieved through a special sorting system. The sorted particulate dentin is immersed in basic alcohol cleanser in a sterile container to dissolve all organic debris and bacteria. Then, the particulate is washed by sterile saline. The bacteria-free particulate dentin is ready for immediate grafting into extraction sites or into bone defect sites. Results: During the period of two years, more than 100 procedures were performed, most of which for the purpose of preservation of alveolar bone. In those patients, implant insertion was possible as soon as 2-3 month after grafting of autogenous dentin. On x-rays and biopsy of grafting sites a dense dentin-bone composite was found. No wound healing complications were observed. Conclusion: Autogenous mineralized dentin particulate grafted immediately after extractions should be considered as the gold standard for socket preservation, bone augmentation in sinuses and bone defects.

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.

The influence of sodium hypochlorite and EDTA on the chemical composition of dentine

Aim To characterise changes in the chemical composition of dentine after exposure to sodium hypochlorite and ethylenediaminetetracetic acid (EDTA) using ATR‐FTIR and Raman spectroscopy.Methodology Crown dentine was acquired from recently extracted molars stored in formal‐saline (group A) or saline and frozen at −2oC (group B); it was then ground and sieved into a range of particle sizes. Samples from both groups (n = 5 each) were analysed with FTIR to investigate the influence of storage medium and to assign FTIR spectral peaks for collagen, carbonate, phosphate. As no differences were found, the samples were pooled for subsequent experiments. Ten samples of particle size range 38–75 μm were used to study the effect of mass ratio of NaOCl (2.5%): dentine over 5–10 min. Thirty samples of all sizes were reacted with 2.5% sodium hypochlorite at 1:0.5 (dentine:NaOCl) mass ratio for 2–10 min; EDTA (n = 90) for 5–1440 min; NaOCl for 10 min followed by EDTA for 10 mins (n = 30); the latter samples were further exposed to NaOCl for 10 min after obtaining FTIR spectra.Results FTIR spectra from the surface of the particles (~1.5 μm depth) were obtained for all the samples and Raman spectra (40 μm depth) were obtained for one sample each reacted either with NaOCl or EDTA. Spectral peak assignment was confirmed by previous data. Storage media had no effect on outcome measures used. The dentine:NaOCl ratio influenced collagen depletion. NaOCl affected the collagen FTIR peaks, mostly in the first 2–4 min, but only influenced the phosphate and carbonate peaks slightly. EDTA affected the phosphate:collagen peaks, which reduced over time, whilst the collagen peak values showed an increase. The two solutions (NaOCl and EDTA) used alternately, respectively increased collagen or phosphate peaks depending on the final solution used.Conclusions These series of investigations confirmed that sodium hypochlorite depletes the organic content of dentine and EDTA depletes the inorganic content. Used alternately, they have the ability to progressively degrade dentine structure.

The chemical compositions of dentine and enamel from recent reptile and mammal teeth—variability in the diagenetic changes of fossil teeth

Principal component analyses, based on microprobe data and coupled with microstructural observations, have been applied to investigate the differences between teeth of recent and fossil mammals and reptiles, and their fossil counterparts. In recent samples, enamel is compositionally distinct from dentine, and differences also exist between mammal and reptile teeth. During fossilization, both the physical structure and chemical composition of enamel and dentine can be altered, the degree and extent of which varies from site to site, depending on the nature of the burial environment. The higher porosity of the dentine structure allows for a more open pathway for fluids within the burial environment to permeate more efficiently. Subsequently, dentine is often considered to be more susceptible to diagenesis than enamel. However, enamel from one fossil site has undergone significant diagenetic alteration. Because of the variable and unpredictable effects of diagenesis, the chemical composition of fossil teeth is not a reliable indicator of the lifetime (i.e.in vivo) composition. Thus, interpretation of the lifestyle or environment of individuals that is based on compositional parameters, such as palaeodiet, needs to take into account the degree and extent of diagenetic alteration associated with individual fossil sites. Additional factors that can affect post-mortem alteration of teeth, are the mechanical and chemical modifications that result from predation and digestion.