Dentin Collagen Research Articles

A Novel Chemical Binding Primer to Improve Dentin Bonding Durability

The dentin collagen matrix that is not completely enveloped by resin adhesive is vulnerable to degradation by intrinsic collagenases during the etch-and-rinse process, which contributes to the deterioration of the bonding interface. Current commercial adhesives have no functional components that can form covalent bonds to the dentin collagen matrix. In this study, a photocurable aldehyde, 4-formylphenyl acrylate (FA), was synthesized and for the first time applied as a primer in adhesive dentistry to covalently bind to collagen. Experimental groups with different concentrations of FA (1%, 3%, 5%, 7%, 9%) were prepared as primers. The cytotoxicity was evaluated by live/dead-cell staining and thiazolyl blue tetrazolium bromide assay. The interaction of FA with collagen was examined by attenuated total reflection Fourier transform infrared spectroscopy, hydroxyproline release under the degradation of type I collagenase, and thermogravimetric analysis. An optimal group was selected based on the degree of conversion of 2 universal adhesives and further divided depending on the treatment time (20 s, 30 s, 1 min, 2 min). The bonding performances were evaluated by microtensile strength before and after aging. Finally, the bonding interface was observed under confocal laser scanning microscopy and scanning electron microscope. The results indicated that FA demonstrated good biocompatibility, dentin modification capability, and infiltration. It not only effectively cross-linked dentin collagen to improve its stability against enzymatic hydrolysis and modify the adhesive interface but also potentially acted as a diluting monomer to induce deep penetration of adhesive resin monomers into the dentin. The bonding strength after aging was improved without jeopardizing the degree of conversion of 2 commercial adhesives. Such prominent advantages of using FA to improve the bonding performance promotes its further application in adhesive dentistry.

Dentin conditioned with a metal salt-based conditioner

ObjectivesUniversal adhesives (UAs) can optionally be applied in either an etch-and-rinse (E&R) or self-etch (SE) bonding mode. As the preferred bonding mode differs for enamel versus dentin, a universal conditioner for both enamel and dentin in replacement of the relatively aggressive phosphoric-acid etchant remains desirable. This study aimed to test if a metal salt-based etchant (ZrO(NO3)2) provides as durable bonding to dentin as a classic E&R or SE bonding mode MethodsBefore applying the UA Adhese Universal (‘AdU’; Ivoclar Vivadent) to bur-cut dentin of 24 teeth (n = 8), dentin was conditioned with either (1) an experimental metal salt-based conditioner (‘ZON’; Ivoclar Vivadent) or (2) 37% phosphoric acid (Total Etch gel, Ivoclar Vivadent), representing a classic ‘E&R′ mode; (3) a third experimental group involved AdU applied in SE mode. Bonding effectiveness was determined in terms of immediate (‘1w’) and aged (‘50k’ TC) micro-tensile bond strength (μTBS) to bur-cut dentin. Adhesive-conditioned dentin interfacial interactions were characterized by S/TEM. ResultsLinear mixed-effects modeling revealed significantly higher immediate μTBS to dentin of ZON_AdU than E&R_AdU, while ZON_AdU performed not significantly different from SE_AdU. No significant differences were found between the three experimental groups after 50k TC (aged μTBS). S/TEM disclosed less exposure of dentinal collagen fibrils when AdU was bonded upon ZON etching than when applied in E&R mode. Moreover, ZON resulted in more hydroxyapatite (HAp) crystals remaining at the bottom of the hybrid layer, while dentinal tubule orifices remained nearly fully closed, by which hardly any resin tags were formed. SignificanceThe alternative metal salt-based conditioner revealed at dentin a more HAp-protected hybrid layer with less exposure of collagen fibrils, while a comparable bond strength was obtained to that with a phosphoric-acid E&R as well as with an SE (no conditioner) bonding mode. These findings confirm that the metal salt-based conditioner can be considered as a suitable alternative (enamel/)dentin conditioner to classic phosphoric acid employed in an E&R bonding mode.

Chemical and morphological analysis of dentin collagen degradation after Nd:YAG laser irradiation

Chemical and morphological analysis of dentin collagen degradation after Nd:YAG laser irradiation

Level of knowledge about metalloproteinases in dental students close to graduate from three universities in Peruvian capital city.

Metalloproteinases are proteolytic enzymes that degrade dentin and periodontal collagen; therefore, it is of special interest that dental students know its mechanism of action and how its effects can be inhibited. Therefore, the aim of this research was to evaluate the level of knowledge about metalloproteinases in dental students close to graduate from three universities in Peruvian capital city. In this analytical, observational, cross-sectional and prospective study, 223 dental students close to graduate in three Peruvian universities were evaluated from September to November 2020. A questionnaire of 20 closed questions with three answers was validated and used to measure the level of general and dental knowledge about metalloproteinases. A logit model was used to evaluate the influence of the following variables: "gender" (X1), "type of university" (X2), "marital status" (X3) and "age group" (X4), in the knowledge levels of the students, considering a p-value <.05. Of the 223 dentistry students, it was obtained that the level of knowledge about metalloproteinases was predominantly low with 82.1%, (95% confidence interval (CI): 77.1%-87.1%) of the total. According to multivariate logistic regression analysis, "type of university" was the only variable that proved to have a significant influence (p=.022) on the level of knowledge about metalloproteinases with an odds ratio of (OR=0.44; CI: 0.21-0.89), whilst the other variables "age group" (p>.05), "gender" (p=.058) and "marital status" (p=.114) were not considered influential factors. The majority of final year dental students in three Peruvian universities presented a low level of overall knowledge about metalloproteinases. In addition, private university students were 56% less likely to pass the subject knowledge test. On contrary, gender, age group and marital status did not significantly influence the level of knowledge of the students.

Effect of 30% Grape Seed Extract on the Shearbond Strength of Orthodontic Adhesive Resin: An In-vitro Study

Introduction: Grape Seed Extract (GSE) contains Proanthocyanidins (PA) which have been shown to cross-link and strengthen demineralised dentin collagen. There is paucity of research to evaluate if grape seed extract increases the shear bond strength of orthodontic resin when bonding to enamel. Aim: To evaluate the shearbond strength and Adhesive Remnant Index (ARI) scores of enamel surface bonded with orthodontic resin after immersing in 30% of grape seed extract and compare the same with that of control group. Materials and Methods: In this in-vitro study, 72 extracted teeth samples were divided into two groups. The two groups, each with 36 specimens, included Group I (Control), Group II (Test). Teeth in the test group were soaked in 30% grape seed extract for 10 minutes before bonding and teeth in the control group were bonded directly without soaking in grape seed extract. Shearbond strength were measured using a Universal testing machine. To evaluate the amount of resin left on the enamel surfaces after debonding, ARI scores were used. The samples were subsequently evaluated using Scanning Electron Microscope (SEM) to study the surface characteristics of enamel after immersion in grape seed extract. Student t test was used to assess the difference between two groups in shear bond strength and Chi-square test was used for ARI scores. Results: Total of 72 teeth were analysed, 36 extracted teeth in each group. The mean shearbond strength in Group I was 78.9 Newton (N), 59.03 N in Group II. There was a stastistically significant differences in the mean scores of shearbond strength between the groups (p-value=0.0024). The shearbond strength of control group was significantly higher than the Test group. Significant difference(p-value=0.016) found in ARI scores between the two groups. In SEM analysis after grape seed extract conditioning followed by acid etching, pronounced cobble stone appearance was noticed indicating a type II etching pattern. Conclusion: Adhesive failure occurred at the resin and bracket interface indicating that shear bond strength reduces when teeth were immersed in Grape Seed Extract.

Stable isotope analysis and differences in diet and social status in northern Medieval Christian Spain (9th–13th centuries CE)

The Iberian Peninsula was at the forefront of the religious, economic, and political changes that swept across Europe during the Medieval Period, including the expansion of Christianity following the disintegration of the Umayyad Caliphate. Between the 9th and the 13th centuries CE, northern Iberia, in particular, witnessed a marked demographic and economic expansion that accompanied the emergence and development of different Christian Kingdoms. A growth in religious infrastructure driven by territorial expansion at the expense of Al-Andalus, and the emerging importance of the Camino de Santiago (the Way of St. James) from the 11th century CE, represented vital processes in changing urban networks and social stratification. However, shifting diets and social structures brought about by these changes require direct study beyond historical texts or localised osteoarchaeological and biomolecular studies in order to determine their wider impacts on peoples’ lived experience. Here, we apply radiocarbon dating (n = 6) and stable carbon and nitrogen isotope analysis to bone and dentine collagen from various locations (n = 10) across the north and north-eastern areas of modern Spain, where three prominent Medieval Christian Kingdoms (Aragon, Castille and Navarre) developed. We sampled 40 human and 32 faunal remains dating to between the 9th and 13th centuries CE, including historical personages such as Sancho Ramirez, Count of Ribagorza and an illegitimate son of King Ramiro I of Aragon; Saint Raymond William or San Ramón de Roda; Pedro de Librana, the first bishop of the city of Zaragoza after its conquest by the Christians in the 12th century CE; an unknown princess from the royal house of Aragon; and individuals from the urban and rural nuclei of Pamplona, Logroño, Lobera de Onsella (Zaragoza), and San Roque de las Quintanillas (Burgos). We compared our results to existing data from the same area demonstrating clear differences in access to animal protein and marine/freshwater resources between rural, urban, and high social status populations on a regional scale. Our data show significant differences in δ15N values between the different groups, with the highest values seen among the ‘elite’, followed by urban populations who benefited from trade and socio-economic diversity. This dataset acts as an important reference point for future studies focusing on changes in the diet and health among different sectors of Medieval society and, in particular, the development of social inequality in the Christian Kingdoms of Iberia as they formed at the centre of novel cultural and religious exchanges across Europe.

A Comparative Evaluation of Root Surface Biomodification with Erbium-Doped Yttrium Aluminum Garnet Laser, Ethylenediaminetetraacetic Acid Gel, and Titanium Nitride Curette: In Vitro Scanning Electron Microscope and Profilometry Analyses.

Objective: This study aims to evaluate the in vitro effects of different biomodification treatment methods on extracted tooth/root surfaces in terms of biologically acceptable changes favoring better periodontal healing. Background data: The use of various agents for root surface biomodification (RSB), during periodontal procedures is of critical importance to increase the success of the treatments through healing. Ethylenediaminetetraacetic acid (EDTA) is the most frequently used chemical RSB agent in periodontal clinical practice. Erbium-doped yttrium aluminum garnet (Er:YAG) lasers have well-known advantages on blood cell adhesion and fibrin network formation on root surfaces. Recently, novel titanium nitride (TIN) curettes are of great interest due to smoother surface changes obtained after their application. Materials and methods: Forty-four dentine specimens from extracted single-rooted teeth were randomly divided into four groups: Group 1: No treatment; Group 2: Er:YAG laser irradiation; Group 3: EDTA gel application; Group 4: TIN curette instrumentation. All specimen surfaces were wet polished before treatments. Before and after root surface roughness parameters of all specimens were assessed with a profilometer. Further, all scanning electron microscopy micrographs were analyzed and scored for root surface and smear layer morphology characteristics by two different blinded researchers. Results: There were no statistical differences between the initial roughness of all groups (p = 0.687). After treatments, EDTA gel group revealed an intact intertubular area, some smear debris on dentine surfaces, and partially occluded dentine tubules. Er:YAG laser created the highest roughness (p < 0.05) among all treatment groups with no smear layer and exhibited fully exposed dentine tubules and collagen fibrils. Surfaces instrumented with TIN curette were the smoothest (p < 0.05) and covered with a compact and thick smear layer. Conclusions: Within the limits of this study, Er:YAG laser-irradiated surfaces exhibited exposed collagen fibrils, and Er:YAG laser irradiation was found as the only method yielding the desired surface characteristics for better periodontal healing, where the fibrils are exposed in the absence of smear layer.

Applications of Silver Diamine Fluoride in Dentistry

Various studies published in the literature around the world indicate a significant prevalence of early childhood caries (ECC). Treatment of early childhood caries (ECC) using silver diamine fluoride (SDF) has become a viable alternative, particularly for young and anxious children, because traditional restorative treatments is unlikely to combat this prevalent condition. Arrested caries is identified by the hardening of teeth and it changes its color from dark brown to black. More restorative treatments can be performed if necessary. Traditional ECC restorative treatments are not always inexpensive or feasible, as they involve patient cooperation to achieve a satisfactory result. Japan was the first country to promote silver diamine fluoride in 1960. SDF has been used to prevent the spread of caries in various Asian nations, including Japan and China. It was enacted as a fluoride to treat sensitive teeth in the United States by Food and Drug Administration ( FDA). For young children or individuals with specific needs, it is painless and simple to use .The fluoride in SDF stimulates remineralization while the silver ions act as an antimicrobial agent when applied to carious lesions and stop cariogenic biofilms from growing. SDF also prevents future degradation of the dentin's collagen. With a 38 percent use rate, SDF has been utilized in a number of nations. According to a review, SDF is a harmless, economical caries control agent with a wide utilisation in dentistry, and it may meet the WHO Millennium Development Goal (MDG) as well as the United States Institute of Medicine's criteria. The applications of SDF in dental treatment are discussed in this article.

Effect of Cavity Cleanser With Long-Term Antibacterial and Anti-Proteolytic Activities on Resin-Dentin Bond Stability.

ObjectiveSecondary caries caused by oral microbiome dysbiosis and hybrid layer degradation are two important contributors to the poor resin–dentin bond durability. Cavity cleansers with long-term antimicrobial and anti-proteolytic activities are in demand for eliminating bacteria-induced secondary caries and preventing hybrid layers from degradation. The objectives of the present study were to examine the long-term antimicrobial effect and anti-proteolytic potential of poly(amidoamine) dendrimers with amino terminal groups (PAMAM-NH2) cavity cleanser.MethodsAdsorption tests by attenuated total reflectance–infrared (ATR-IR) spectroscopy and confocal laser scanning microscopy (CLSM) were first performed to evaluate whether the PAMAM-NH2 cavity cleanser had binding capacity to dentin surface to fulfill its relatively long-term antimicrobial and anti-proteolytic effects. For antibacterial testing, Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis were grown on dentin surfaces, prior to the application of cavity cleanser. Colony-forming unit (CFU) counts and live/dead bacterial staining were performed to assess antibacterial effects. Gelatinolytic activity within the hybrid layers was directly detected by in situ zymography. Adhesive permeability of bonded interface and microtensile bond strength were employed to assess whether the PAMAM-NH2 cavity cleanser adversely affected resin–dentin bonding. Finally, the cytotoxicity of PAMAM-NH2 was evaluated by the Cell Counting Kit-8 (CCK-8) assay.ResultsAdsorption tests demonstrated that the binding capacity of PAMAM-NH2 on dentin surface was much stronger than that of 2% chlorhexidine (CHX) because its binding was strong enough to resist phosphate-buffered saline (PBS) washing. Antibacterial testing indicated that PAMAM-NH2 significantly inhibited bacteria grown on the dentin discs as compared with the control group (p < 0.05), which was comparable with the antibacterial activity of 2% CHX (p > 0.05). Hybrid layers conditioned with PAMAM-NH2 showed significant decrease in gelatin activity as compared with the control group. Furthermore, PAMAM-NH2 pretreatment did not adversely affect resin–dentin bonding because it did not decrease adhesive permeability and microtensile strength. CCK-8 assay showed that PAMAM-NH2 had low cytotoxicity on human dental pulp cells (HDPCs) and L929.ConclusionsPAMAM-NH2 cavity cleanser developed in this study could provide simultaneous long-term antimicrobial and anti-proteolytic activities for eliminating secondary caries that result from a dysbiosis in the oral microbiome and for preventing hybrid layers from degradation due to its good binding capacity to dentin collagen matrix, which are crucial for the maintenance of resin–dentin bond durability.

The Roles of 10-Methacryloyloxydecyl Dihydrogen Phosphate and Its Calcium Salt in Preserving the Adhesive–Dentin Hybrid Layer

10-Methacryloyloxydecyl dihydrogen phosphate (MDP) has been regarded as the most effective dentin-bonding monomer for more than 20 years. Although the dentin-bonding promoting effect of MDP has been well demonstrated, the mechanisms by which it benefits the stably of collagen within the adhesive–dentin hybrid layer are not currently fully understood. In the present study, we found that MDP preserves the hybrid layer through multiple modes of action. MDP forms a stable collagen-phosphate complex through strong hydrogen bonding with the collagen in dentin. Furthermore, it generates MDP-Ca salts that are deposited on the dentin collagen scaffold, protecting it from degradation. Moreover, both free MDP and the MDP-Ca salt inhibit matrix metallopeptidase directly, with the inhibitory effect of the calcium salt being significantly stronger than that of the free form. Based on the findings of this study, MDP-based adhesives preserve the collagen components within the hybrid layer by simultaneously improving the enzymatic resistance of collagen and inhibiting MMP activity, both of which contribute to the longevity of dentin–resin bonding.

Strategies for demineralized dentin matrix protection and its research progress in dentin-resin bonding restoration

Both pathological injuries and clinical iatrogenic operations can lead to dentin demineralization, forming demineralized dentin matrix (DDM). Dentin demineralization activates endogenous matrix metalloproteinase (MMP) and cysteine cathepsin (CC), and the mechanical properties of DDM decrease, so DDM is prone to lose its structural integrity under the action of enzymatic degradation and mechanical destruction, which in turn results in the reduction of clinical functional value of DDM in dentin-resin bonding restoration. The administrations of dentin collagen cross-linking reagents and MMP/CC inhibitors are effective strategies to protect DDM structural integrity and achieve its clinical functional value. A variety of chemically synthesized reagents and plant-derived extracts are capable of significantly improving the mechanical properties of DDM and enhancing its enzymatic tolerance. However, the cytotoxicity caused by chemically synthesized reagents and the tooth staining aroused by plant extracts have considerably affected their clinical applicability. Protecting dentin collagen while exerting antibacterial properties is a new direction for future DDM protective agent research. Accordingly, from the perspectives of cross-linking reagents, enzyme inhibitors and compounds which possess the dual proper ties, this review discusses the latest research progress in DDM protection, and looks into its application prospects in dentin-resin bonding, in an attempt to provide reference for the clinical promotion of DDM protection strategy.

A mussel glue-inspired monomer-etchant cocktail for improving dentine bonding

ObjectivesThe humid oral environment adversely affects the interaction between a functionalised primer and dentine collagen after acid-etching. Robust adhesion of marine mussels to their wet substrates instigates the quest for a strategy that improves the longevity of resin-dentine bonds. In the present study, an etching strategy based on the incorporation of biomimetic dopamine methacrylamide (DMA) as a functionalised primer into phosphoric acid etchant was developed. The mechanism and effect of this DMA-containing acid-etching strategy on bond durability were examined. MethodsEtchants with different concentrations of DMA (1, 3 or 5 mM) were formulated and tested for their demineralisation efficacy. The interaction between DMA and dentine collagen, the effect of DMA on collagen stability and the collagenase inhibition capacity of the DMA-containing etchants were evaluated. The effectiveness of this new etching strategy on resin-dentine bond durability was investigated. ResultsAll etchants were capable of demineralising dentine and exposing the collagen matrix. The latter strongly integrated with DMA via covalent bond, hydrogen bond and Van der Waals’ forces. These interactions significantly improve collagen stability and inhibited collagenase activity. Application of the etchant containing 5 mM DMA achieved the most durable bonding interface. ConclusionDopamine methacrylamide interacts with dentine collagen in a humid environment and improves collagen stability. The monomer effectively inactivates collagenase activity. Acid-etching with 5 mM DMA-containing phosphoric acid has the potential to prolong the longevity of bonded dental restorations without compromising clinical operation time. Clinical SignificanceThe use of 5 mM dopamine methacrylamide-containing phosphoric acid for etching dentine does not require an additional clinical step and has potential to improve the adhesive performance of bonded dental restorations.

Reconstructing the childhood diet of the individuals from the Middle Late Bronze Age Bezdanjača Cave, Croatia (ca. 1430 1290 BCE) using stable C and N isotope analysis of dentin collagen

This paper investigates the childhood diet of 16 individuals from the Middle Late Bronze Age (1430 1290 BCE) Bezdanjača Cave (Lika region, Croatia) using stable isotope analysis of dentin collagen from permanent first molars. Results from the analysis reveal that the individuals from Bezdanjača consumed notable quantities of C4 plants during their childhood. The most common C4 plant is millet, whose spread throughout Southern Europe was recently dated to the second half of the 2nd millennium BCE, which agrees with the results obtained in this research. Comparisons between the data collected for the individuals from Bezdanjača and other Middle and Late Bronze Age sites in Croatia suggest that only the individuals from the site of Veliki Vital (Middle Bronze Age, inland Croatia) exhibit similar isotopic values to those from Bezdanjača. Human isotopic values from coastal sites, however, reveal that during the Middle and Late Bronze Age people from the coast had diet that still predominantly contained C3 plant-based foods, which appears to suggest that the dispersion of this crop in Croatia during the Bronze Age followed an east-west trajectory, appearing earlier (Middle and Late Bronze Age) in inland settlements such as Veliki Vital and Bezdanjača and only later (Late Bronze Age and mostly Iron Age) in coastal sites.

Dentin interaction with universal adhesive containing isopropanol solvent studied by solid-state NMR spectroscopy

ObjectiveThis study investigated the chemical and structural changes in the mineral phase and collagen of dentin during application of a mild universal adhesive. Particular attention was paid to the role of isopropanol and changes in water molecules. MethodsIn vitro application of the mild universal adhesive on dentin with two established etching modes (self-etch and etch-and-rinse) was studied using solid state nuclear magnetic resonance spectroscopy. ResultsIt was evidenced that the etch-and-rinse mode leads to a decrease of the inorganic apatite and a reorganization of the residual mineral phase with a low amount of adhesive phosphate monoesters calcium salt formed, compared to the self-etch mode. In contrast, the adhesive interacts very similarly to the level of dentin collagen in both protocols, with a strong decrease in the amount of the free water molecules induced by the presence of isopropanol as the adhesive solvent, but without significant changes in the initial collagen structure. For both modes, the adhesive acrylates monomers remain mobile and can infiltrate the collagen. SignificanceUnderstanding the molecular interactions between dentin and adhesive solutions is a major challenge for designing products that lead to the formation of ideal dentin resin hybrid layer. Notably, one point considered essential is the presence of unbound water which, over time, is associated with a hydrolytic degradation of the organic matrix. Isopropanol, as an adhesive solvent, leads to a decrease in the amount of the less stable water molecules while the water molecules strongly attached to the collagen are retained, thus preserving the collagen structure.

Effects of Remineralizing Agents Based on Calcium Phosphate, Sodium Phosphate, or Sodium Fluoride on Eroded Cervical Dentin.

To evaluate the effect of remineralizing agents on collagen matrix pattern, precipitate formation, and dentinal tubule obliteration in eroded cervical dentin. One hundred bovine cervical dentin specimens were previously eroded (0.6% hydrochloric acid, pH 2.3, 5 minutes) and then randomized into five groups (n=20): G1, control (without treatment); G2, Desensibilize Nano P (FGM); G3, MI Paste Plus (Recaldent); G4, Regenerate (NR-5); and G5, Desensibilize KF 2% (FGM). These treatments were applied in four sessions with 7-day intervals. During this period, the samples were subjected to an erosive challenge with orange juice (pH 3.8, 5 minutes). The specimens were analyzed by polarized light microscopy with picrosirius red staining, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The G3 showed a higher concentration of type I collagen than G2 and G5 (p<0.05). The G3 showed greater formation of surface precipitates than that of G1 and G5 (p<0.05). In addition, G4 and G5 showed a greater number of open dentinal tubules than that of G3 (p<0.05). Calcium phosphate-based remineralizing agents have shown to be a promising alternative treatment for preventing deleterious effects on the eroded dentin collagen matrix. In addition, they promoted precipitate formation and dentinal tubule obliteration on the eroded dentin.

Children of the abyss: Investigating the association between isotopic physiological stress and skeletal pathology in London during the Industrial Revolution

ObjectiveThis project sought to investigate whether an association may be observed between isotopic stress indicators and skeletal evidence of pathological conditions. MaterialsDeciduous and permanent teeth of 15 non-adults from two contemporaneous mid-19th century London burial grounds (City Bunhill, Lukin Street). Methodsδ13C and δ15N was measured in the incrementally sectioned dentine collagen. Isotopic profiles for each individual included death during tooth development. ResultsIndividuals with skeletal evidence of chronic pathological conditions (e.g., rickets, tuberculosis) exhibited raised δ15N values of 0.5–1.7‰ in the months prior to death. Isotopic change consistent with chronic physiological stress prior to death was also recorded in two individuals with no skeletal evidence of disease. An offset was observed between co-forming bone and dentine δ15N values in both populations, indicating that bone and dentine are not recording the same isotopic changes. ConclusionsIsotopic change consistent with chronic physiological stress was observed in both those with and without skeletal evidence of disease, suggesting that adaptation to chronic stress in childhood was not uncommon within these 19th century London populations. SignificanceChronic physiological stress prior to death may be seen in the incrementally sampled dentine of non-adults who die during tooth formation. LimitationsThe temporal resolution of current dentine micro-sampling methods may mask or minimise visibility of shorter-term periods of stress or dietary change. Suggestions for further researchFuture research should further explore the relationship between specific skeletal pathologies and isotopic evidence for stress.

Theaflavins as a novel cross-linker quickly stabilize demineralized dentin collagen against degradation

To investigate the ability of theaflavins (TF) from black tea to protect dentin collagen against enzymatic degradation via cross-linking effect under clinically relevant conditions. 10-µm-thick dentin films were microtomed from dentin slabs of human molars. Following demineralization, films or slabs were treated with TF at two concentrations (0.4% and 2%) for 30 s. A well-known collagen cross-linker grape seed proanthocyanidins (PA) was used as control. Collagen cross-linking interactions and stabilization against enzymatic degradation were investigated by Fourier transform infrared spectroscopy, weight loss, hydroxyproline release, and scanning/transmission electron microscopy. Data were analyzed by ANOVA, Tukey’s and Student’s T test (α = 0.05%). The results showed collagen cross-linking and stabilization efficacy was dependent on TF/PA concentrations. At 2.0%, TF and PA offered nearly full protection to collagen; at 0.4%, TF exhibited a significantly better collagen stabilization effect than PA (P < 0.05), while untreated collagen was completely digested. It’s concluded that TF cross-links dentin collagen within a clinically relevant time (30 s) and offers excellent collagen protection against enzymatic degradation, with efficacy comparable to or better than PA. The study supports the potential use of TF as a novel, promising collagen cross-linker for degradation resistant, long-lasting dentin bonding in composite restorations.

Distinct effects of polyphenols and solvents on dentin collagen crosslinking interactions and biostability

ObjectiveTo evaluate the effects of different polyphenols and solvents on dentin collagen’s crosslinking interactions and biostabilization against MMPs and collagenase degradation. MethodsTwo polyphenols [proanthocyanidin (PA) and quercetin (QC)] with different water solubility were prepared as treatment solutions using ethanol (EtOH) or dimethyl sulfoxide (DMSO) as solvents. 6-um-thick dentin films were microtomed from dentin slabs of third molars. Following demineralization, films or slabs were subject to 60-s treatment (PA or QC) or no treatment (control) with subsequent extended-rinse with original solvent (EtOH or DMSO) or distilled water (DW). Collagen crosslinking interactions were assessed by FTIR. Biostability was assessed through endogenous MMPs activity via confocal laser scanning microscopy, and exogenous collagenase degradation via weight loss, hydroxyproline release and SEM. Finally, direct collagenase inactivation was also evaluated. Data were analyzed by three-way ANOVA and post-hoc tests (α=0.05%). ResultsDistinct effects of two polyphenols and solvents on collagen crosslinking and biostabilization were observed. Higher crosslinking and biostability efficacy occurred with PA than QC (p<0.001) that demonstrated negligible collagen interactions. With DMSO solvent, efficacy results were significantly reduced with both polyphenols (p<0.05). DMSO-rinse further weakened interactions of PA with collagen, diminishing biostability (p<0.05). Low biostability was detected with QC and DW-rinse, suggesting direct enzymatic inhibition due to physical presence in collagen. SignificanceCollagen crosslinking interactions and biostability depend on polyphenol chemical characteristics. Treatment-solution solvents may affect interactions between polyphenols and collagen, specifically, DMSO showed detrimental effects on collagen crosslinking and biostability and should be used with caution.

Unveiling structure–activity relationships of proanthocyanidins with dentin collagen

ObjectiveTo elucidate the structure–activity relationships (SARs) of proanthocyanidins (PACs) with type I collagen using sixteen chemically defined PACs with degree of polymerization (DP) 2–6. MethodsUnder a dentin model, the biomimicry of PACs with type I collagen was investigated by dynamic mechanical analysis (DMA) and infrared spectroscopy. The dentin matrix was modified with PACs from Pinus massoniana [monomers (Mon-1 and Mon-2), dimers (Dim-1-Dim-4), trimers (Tri-1-Tri-4), tetramers (Tet-1-Tet-5), and hexamer (Hex-1)]. A strain sweep method in a 3-point bending submersion clamp was used to assess the viscoelastic properties [storage (E’), loss (E”), and complex moduli (E*) and tan δ] of the dentin matrix before and after biomodification. Biochemical analysis of the dentin matrix was assessed with FTIR spectroscopy. Data were statistically analyzed using one-way ANOVA and post-hoc tests (α = 0.05). ResultsDP had a significant effect on modified dentin moduli (tetramers ≈ trimers > hexamers ≈ dimers > monomers ≈ control, p < 0.001). Trimers and tetramers yielded 6- to 8-fold increase in the mechanical properties of modified dentin and induced conformational changes to the secondary structure of collagen. Modifications to the tertiary structure of collagen was shown in all PAC modified-dentin matrices. SignificanceFindings establish three key SARs: (i) increasing DP generally enhances biomimicry potential of PACs in modulating the mechanical and chemical properties of dentin (ii) the secondary structure of dentin collagen is affected by the position of B-type inter-flavanyl linkages (4β → 6 and 4β → 8); and (iii) the terminal monomeric flavan-3-ol unit plays a modulatory role in the viscoelasticity of dentin.

Isotopic analysis in teeth of contemporary brazilians with known diet and geolocation and its forensic value for human identification

Dental anthropological data may provide valuable information about an individual's life, including age at death, health, signs of violence, ancestry, diet features, intentional modifications, and geographic origin. These pieces of information may be further detailed by diet and residential mobility estimates provided by isotopic analyses. The use of isotope data in the modern population is strongly dependent on the diverse origin of food supply, thus requiring an updated and location-specific database. In this study, we have analyzed the isotopic ratio of strontium, carbon, and nitrogen in enamel and dentin collagen of third molars individuals from three main cities in Brazil. Besides the isotope data, we have also surveyed their diet in adolescence habits to develop models to be applied for forensic studies in the Brazilian territory. We show that the forensic value of the place of origin estimation based 87Sr/86Sr levels is reduced in these highly urbanized samples. Among the outliers, most individuals are older than the mean age (25.1) or had water from wells in childhood. The sample's diet has a robust C4 presence and mean trophic levels consistent with the declared high frequency of chicken, meat, and dairy products, also compatible with the high consumption of sugar, rice, and beans in the local culture. Individuals with special diets, either by choice or therapeutic needs, were potential outliers among the group. Our results also contribute to the international human tissues isotopic database and can contribute for human identification of Brazilians or foreigners with distinct isotopic signatures.