Dentin Collagen Research Articles

Metalloproteinase inhibitors in the adhesion process dental

Matrix metalloproteinases (MMPs) are enzymes involved in tooth physiological development, caries processes, and hybrid layer degradation, in addition to being associated with dentin collagen breakdown. The interplay of MMP activity, masticatory forces, and biofilm action may, over time, compromise composite resin restorations. To reduce hybrid layer degradation by endogenous proteases and extend the longevity of resin restorations, MMP inhibitors and collagen cross-linking agents have been extensively studied. This work aims to identify, through a literature review, agents capable of inactivating MMPs at the dentin adhesive interface. This integrative review, based on studies retrieved from PUBMED/MEDLINE, LILACS, BBO, and VHL databases, identified 19 agents able to inhibit MMP activity at the adhesive-dentin interface in studies published between January 2018 and June 2023. It can be concluded that several agents can partially or completely block MMP activity, thereby enhancing restoration longevity. However, further studies are required to facilitate the clinical use of these agents, beyond chlorhexidine, in dental practice, with the application techniques suited to dentists’ daily clinical routines.

Challenges of the minimum postmortem interval (PMImin) estimation in forensic scenarios: Is dental histology an alternative?

Postmortem interval (PMI) estimates the time since death. Teeth are perennial elements capable of remaining intact in taphonomic environmental circumstances. The objective was to evaluate the feasibility of estimating the minimum postmortem interval (PMImin) through histological analyses of dental tissues exposed to burial and drowning conditions, simulating common scenarios in forensic practice. A total of n = 99 teeth were analyzed and divided into four groups: control (T0), one month (T1), three months (T2), and six months (T3). The control sample comprised 10 teeth, while T1, T2 e T3 were divided into three different subgroups: controlled environment, buried, and drowned. For each subgroup, ten samples were used. Following exposure to taphonomic conditions, the specimens were processed, and histological sections were obtained. The two-way ANOVA test and the Tukey’s post-hoc test were employed for the quantitative analysis of dentin collagen fibrils, revealing statistically significant differences (α = 5 %). This allowed for the estimation of the PMImin at three months by observing pixel counts exceeding 13e+05 in drowned teeth and greater than 8e+05 in buried teeth. Qualitative analysis revealed that the PMImin of drowned teeth was estimated at one month due to the absence of the periodontal ligament (PDL) and at six months due to the absence of predentin and partial degradation of the cementum. For buried teeth, the three-month PMImin was indicated by the absence of PDL and partial cementum degradation. The absence of pulp and remnants of predentin characterized the six-month PMImin. Qualitative and quantitative histological characteristics and parameters are potential to estimate PMImin in forensic scenarios spanning up to six months.

Constructing the Enamel-Like Dentin Adhesion Interface to Achieve Durable Resin-Dentin Adhesion.

Enamel adhesion is acknowledged as durable; however, achieving long-lasting dentin adhesion remains a formidable challenge due to degradation of exposed collagen matrix after acid-etching of dentin. The idea of developing an enamel-like adhesion interface holds great promise in achieving enduring dentin adhesion. In this study, we constructed an enamel-like adhesion interface using a rapid remineralization strategy comprising an acidic primer and a rapid remineralization medium. Specifically, the acidic primer of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and epigallocatechin-3-gallate (EGCG) nanocomplex (MDP@EGCG primer) was utilized to partially demineralize dentin within 30 s, and the MDP@EGCG nanocomplex showed a strong interaction with exposed collagen, enhancing collagen remineralization properties. Then, the rapid remineralization medium containing polyaspartate (Pasp) stabilized amorphous calcium and phosphorus nanoclusters (rapid Pasp-CaP) was applied to modified dentin collagen for 1 min, which caused rapid collagen remineralization within a clinically acceptable time frame. This strategy successfully generated an inorganic rough and porous adhesive interface resembling etched enamel, fundamentally addressed issues of collagen exposure, and achieved durable dentin adhesion in vitro and in vivo while also ensuring user-friendliness. It exhibited potential in prolonging the lifespan of adhesive restorations in clinical settings. In addition, it holds significant promise in the fields of caries and dentin sensitivity treatment and collagen-based tissue engineering scaffolds.

Riboflavin-ultraviolet-A collagen crosslinking treatments in improving dentin bonding and resistance to enzymatic digestion

Background/purposeThe efficacy of riboflavin-ultraviolet-A (RF-UVA) treatment in crosslinking collagen and improving dentin bonding has been proven. However, biodegradation of the hybrid layer may compromise the bonding. The purpose of this study was to evaluate different RF-UVA treatments regarding their ability to preserve dentin bonding from enzymatic digestion. Materials and methodsCollagen subjected to different RF (0.1 %, 1 %)-UVA (1, 2, 5 min) treatments and 5 % glutaraldehyde (GA), without or with enzymatic digestion, were examined by gel electrophoresis (SDS-PAGE). Twenty-five teeth with exposed dentin were primed with one of three RF-UVA treatments (0.1 %RF/1-minUVA, 0.1 %RF/2-minUVA, and 1 %RF/1-minUVA), GA, or distilled water after acid-etching, then restored with an adhesive and a resin composite. After 24-h storage, these teeth were sectioned into microbeams. Half of them received an early microtensile bond strength (μTBS) test, while the other half was stored in enzyme solution for 7 days before testing. Nanoleakage and hybrid layer degradation were examined by TEM. ResultsAccording to SDS-PAGE results, all groups showed the dissipation of intense γ bands of collagen after digestion. For the early bonded specimens and after enzymatic digestions, 0.1 %RF/2-minUVA treated group presented the highest μTBS and none of premature failure. Its TEM images showed less nanoleakage after digestion, which is contributed to the well suspended collagen fibrils and resin infiltration in the hybrid layer. ConclusionRF-UVA treatment attained collagen crosslinking effects to improve resin-dentin bonding. 0.1 %RF/2-minUVA effectively enhanced dentin bond strength and resistance to enzymatic digestion by optimally expanding dentinal collagen matrix to facilitate hybrid layer formation.

Promotion effect of proanthocyanidin on dentin remineralization via the polymer induced liquid precursor process

Proanthocyanidin (PA) has demonstrated promise as a dental biomodifier for maintaining dentin collagen integrity, yet there is limited evidence regarding its efficacy in dentin repair. The aim of this study was to investigate the effect of PA on dentin remineralization through the polymer induced liquid precursor (PILP) process, as well as to assess the mechanical properties of the restored dentin. Demineralized dentin was treated with a PA-contained remineralization medium, resulting in the formation of PA-amorphous calcium phosphate (ACP) nanoparticles via the PILP process. The kinetics and microstructure of remineralized dentin were examined through the use of Fourier transform infrared spectroscopy(FTIR), attenuated total reflectance-FTIR, scanning electron microscopy, transmission electron microscopy. The results showed that the application of PA facilitated the process of dentin remineralization, achieving completion within 48 h, demonstrating a notable reduction in time required. Following remineralization, the mechanical properties of the dentin exhibited an elastic modulus of 15.89 ± 1.70 GPa and a hardness of 0.47 ± 0.08 GPa, which were similar to those of natural dentin. These findings suggest that combining PA with the PILP process can promote dentin remineralization and improve its mechanical properties, offering a promising new approach for dentin repair in clinical practice.

Impact of cathepsin K-induced proteoglycans degradation on dentin collagen

ObjectivesThis study aimed to investigate the effects of cathepsin K (catK) on proteoglycans (PGs) and the subsequent impacts on dentin collagen degradation. Materials and MethodsDemineralized dentin samples were prepared and divided into the following groups: deionized water (DW), 0.1 U/mL chondroitinase ABC (C-ABC), and 1 μM odanacatib (ODN). Then, they were immersed for 48 h and then incubated in 1 mL of PBS (pH=5.5) at 37 °C for 5 d. Glycosaminoglycan (GAG) were examined to explore the degradation of PGs by catK. To determine the effect of catK-mediated PGs on dentin collagen degradation, hydroxyproline (HYP) assays, assessment of the degree of dentin crosslinking, and scanning electron microscopy (SEM) were assessed. Statistical analysis was conducted using one-way ANOVA followed by Tukey’s tests or Welch's ANOVA followed by Dunnett's tests at a significance level of 0.05. ResultsThe production of GAG was significantly lower in the ODN group than in the DW group (P < 0.05), revealing that PG degradation was reduced in dentin after ODN treatment. Additionally, ODN treatment minimized the gaps in collagen fibers, improved fiber arrangement, and significantly increased the degree of collagen crosslinking, subsequently reducing the total amount of collagen fiber degradation in the dentin (P < 0.05). ConclusionsCatK-mediated degradation of PGs negatively impacted the stability of collagen fibers, promoted gaps, led to a less organized arrangement of dentin collagen fibers, ultimately increasing collagen degradation.

Effect of Bleaching Treatments on the Mechanical Properties of the Dentin Matrix and on Collagen Biodegradation by Endogenous Protease.

This study evaluated the mechanical properties of demineralized dentin matrix submitted to different bleaching treatments, as well as the changes in mass and collagen biodegradation brought about by endogenous protease. Dentin collagen matrices were prepared to receive the following treatments (n=12): no bleaching treatment (C-control), 10% carbamide peroxide (CP-Opalescence PF, Ultradent, South Jordan, UT, USA) 10%/8 hours/ day/14 days, and 40% hydrogen peroxide (HP-Opalescence Boost, Ultradent), 40 minutes per session/3 sessions. The dentin matrices were evaluated for elastic modulus and mass before and after treatments and ultimate tensile strength after treatments. The solution collected during storage was evaluated for hydroxyproline release. There was no statistically significant difference between CP and C in terms of the elastic modulus (p=0.3697) or mass variation (p=0.1333). Dentin beams treated with HP and C presented significant mass loss after the first session (p=0.0003). HP treatment led to complete degradation of collagen matrices after the second bleaching session. After the second session, CP showed higher hydroxyproline concentration than C (p<0.0001). Ultimate tensile strength was lower for CP than C (p=0.0097). CP did not affect the elastic modulus or the dentin collagen matrix mass but did promote hydroxyproline release by endogenous protease and reduce the ultimate tensile strength. HP significantly affected the mechanical properties of dentin and promoted complete degradation of the demineralized dentin collagen matrix.

Surface Modification of Dentin Powder With Alginate and Evaluation of Its Effects on the Viability and Proliferation of Dental Pulp Stem Cells (In Vitro), Its Biocompatibility (In Vivo)

IntroductionThis study aimed to synthesize dentin powder surface modified with alginate, a potential substance for dental pulp regeneration, and evaluate its effects on the viability and proliferation of human dental pulp stem cells in vitro and its biocompatibility in vivo. MethodsIn the in vitro phase, dentin powder was synthesized in 3 size groups (150–250 μm, 250–500 μm, and 500–1000 μm) after demineralization and atelopeptidization which is used to remove dentin collagen telopeptides and eliminate host immune response. Surface modification with alginate was performed and followed by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and cell viability and proliferation testing for 14 days with human dental pulp stem cells studied. In the in vivo phase, dentin powders were implanted in rat calvarial defects for 8 weeks, and histologic analysis was conducted. All nonparametric data were analyzed with the Kruskal–Wallis test, and all the quantitative data were analyzed by 1-way analysis of variance using SPSS, and P < .05 was considered statistically significant. ResultsDemineralization and atelopeptidization were successful in all groups. Cell viability was optimal and equal (P > .05) in all groups. The 500- to 1000-μm group exhibited significantly higher cell proliferation (P < .05). Histologic assessment shows acceptable biocompatibility in all groups; the angiogenesis score was significantly greater in both 250–500 and 500–1000, and minimal inflammatory response was noted in the 500- to 1000-μm group, and the amount of newly formed bone in this group was higher than other groups. ConclusionsSurface modification of demineralized and atelopeptidized dentin powder with alginate enhanced surface physical properties and cell proliferation while showing great biocompatibility within tissue and reducing the host immune response. These findings hold promise for dentin-pulp complex regeneration.

The effect of different conditioning agents on dentin roughness and collagen structure

ObjectivesTo assess the impact of various organic and inorganic acids on the roughness, demineralization, and collagen secondary structures of human dentin and to compare these effects with those of traditional agents, specifically phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA). MethodsCoronal dentin discs (n = 10) were examined by optical profilometry (roughness) and ATR-FTIR before and after conditioning with 32 % PA, 3 % nitric acid (NA), 20 % citric acid (CA), 20 % phytic acid (IP6) or 17 % EDTA. Spectra data were processed to quantify dentin demineralization (DM%) and percentage area of amide I curve-fitted components of β-turns, 310-helix, α-helix, random coils, β-sheets, and collagen maturation index. Statistical analysis was performed by one-way ANOVA or Kruskal-Wallis for DM% and roughness parameters, and paired t-test/Wilcoxon test for amide I components at significance level set at α = 0.05. ResultsAll treatments resulted in increased roughness parameters, with the most significant changes occurring primarily with PA, while EDTA exhibited the least changes. DM% was NA>PA>IP6>CA>EDTA in a descending order. Regarding amide I components, NA demonstrated a significant reduction in β-turns, 310-helices, and α-helices and it increased β-sheets and random coils. PA resulted in reduction in β-turns and α-helices while it increased β-sheets. CA and EDTA did not cause significant changes. The collagen maturation index significantly increased only after IP6 treatment. ConclusionsThe effect on dentin roughness parameters, demineralization, and collagen secondary structures varied based on the type of dentin surface treatment. Clinical significanceUnderstanding the impact of acids on the intrinsic properties of dentin is clinically essential for gaining insights into how these effects influence adhesion to dentin, the long-term stability of resin-based restorations, and the success of remineralization therapies.

New Monomer Capable of Dual Chemical Binding with Dentin to Improve Bonding Durability.

The water-rich nature of the dentin bonding microenvironment, coupled with the stresses on the bonding interface, contributes to the hydrolytic degradation of the hybrid layer, resulting in a decline in bonding durability and, ultimately, restoration failure. Currently, the 3-step etch-and-rinse technique remains the gold standard for dentin bonding, and the bonding mechanism mainly involves a physical interaction with little chemical bonding. In this study, we have developed a siloxane-modified polyurethane monomer (SPU) with acrylate and siloxane modifications that chemically binds to both collagen and hydroxyapatite in dentin. Formulated as a bisphenol A-glycidyl methacrylate alternative, the SPU monomer-based adhesive was designed to improve dentin bonding quality and durability. Attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscope, and hydroxyproline release assays were performed on SPU-treated collagen, hydroxyapatite, and acid-etched dentin slices to dentin. The physicochemical properties of the configured SPU adhesives were profiled for polymerization behavior, water contact angle, and tensile strain and strength. The bonding effectiveness was assessed through micro-tensile strength, nano-leakage tests conducted on the bonded samples before and after thermal cycle aging. Finally, we further conducted in vivo and in vitro experiments to assess the biocompatibility of adhesives. The results showed that the siloxane groups of SPU monomer could covalently bind to dentin collagen and hydroxyapatite. The incorporation of SPU in the adhesive led to a significant increase in adhesive polymerization (P < 0.05) and tensile strain at break up to 134.11%. Furthermore, the SPU adhesive significantly improved dentin bond strength (P < 0.05), reduced interfacial nano-leakage (P < 0.05), and displayed good biocompatibility. In conclusion, the application of SPU, which achieves dual chemical bonding with dentin, can improve the quality of the hybrid layer, buffer the interfacial stresses, enhance the interfacial resistance to hydrolysis, and provide a feasible strategy to extend the service life of adhesive restorations.

Prodelphinidins enhance dentin matrix properties and promote adhesion to methacrylate resin

ObjectiveInvestigate the bioactivity and stability of Rhodiola rosea (RR) fractions as a natural source of prodelphinidin gallate (PDg) on dentin collagen via analysis of the viscoelastic and resin-dentin adhesive properties of the dentin matrix. MethodsThe biomimicry and stability of RR subfractions (F1, F2, F3 and F4) with collagen were determined by dynamic mechanical analysis (DMA). DMA used a strain sweep method to assess the dentin matrix viscoelastic properties [storage (E’), loss (E”), and complex (E*) moduli and tan δ] after treatment, 7-, 30- and 90-days of storage in simulated body fluids (SBF). Resin-dentin interface properties were assessed after 1 and 90-days in SBF by microtensile bond strength test and confocal laser scanning microscopy. Data were analyzed using two and one-way ANOVA and post-hoc tests (α = 0.05). ResultsRR fractions increased dentin matrix complex (96 - 69 MPa) and storage (95 - 68 MPa) moduli, compared to the control (∼9 MPa) in the ranking order: F2 ≥ F3 = F1 = F4 > control (p < 0.001). Treatment did not affect tan δ values. After 30- and 90-days, RR-treated dentin E*, E’ and tan δ decreased (p < 0.001). F2 fraction yielded the highest microtensile bond strength (43.9 MPa), compared to F1, F4 (35.9 - 31.7 MPa), and control (29 MPa). RR-treated interfaces mediated stable surface modifications and enhanced collagen-methacrylate resin interactions at the bioadhesive interface. SignificanceProdelphinidin gallates from RR are potent and reasonably stable biomimetic agents to dentin. Higher potency of F2 fraction with the dentin matrix and the adhesive interface is associated with a degree of polymerization of 2–3 and gallo(yl) motifs.

Dentin Collagen versus Er:YAG Laser as Surface Biomodifiers for Intact Root Slices Simulating Delayed Replanted Roots.

Objective: To evaluate effects of dentin collagen versus Er:YAG laser application through enhancing human periodontal ligament fibroblast (PDLF) cells to attach to intact root surfaces imitating delayed replanted roots. Background Data: Accidental traumatic injuries with teeth avulsion are managed by replantation. Root resorption, poor conditioning, and non-viable fibroblasts are factors responsible for failure. Methods: Thirty six human healthy single-rooted premolars were collected. Six teeth were used for PDLF, six teeth used for dentin collagen, whereas the remaining 24 teeth (48 root slices) were used for PDLF cell density and morphology. Each root was soaked in 5.25% NaOCl. Three groups (n = 16 slices/each) were planned as follows: I: Control (untreated); II: dentin collagen application; III: Er:YAG laser irradiation (4 mm distance, 40 mJ/pulse, under coolant). Following incubation, cell density and morphology of PDLF were investigated under SEM. Statistical analysis was performed using analysis of variance with Scheffé's test, and p < 0.05 was considered significant. Results: All groups showed increased cultured PDLF following incubation. Regarding cell density, attached PDLFs were significantly lower in untreated controls (36.5 ± 6.36) (p < 0.00001 i.e., <0.05) in negative empty and/or light cellular areas, compared with dentin collagen (65 ± 6) and laser-irradiated (66.75 ± 5.77) groups that did not show significant differences (p = 0.940 i.e., >0.05) and showed intermediate and/or heavy cellular areas. Regarding cell morphology, controls showed round and/or oval appearance with less lamellipodia, whereas dentin collagen and laser groups showed flat morphology with cytoplasmic processes. Conclusions: Both dentin collagen and Er:YAG laser showed comparable effectiveness as biomodification tools with good biocompatibility for human PDLF cell attachment on intact root slices imitating delayed replantation. Dentin collagen as a natural bioactive material is considered an alternative to Er:YAG laser to enhance the regenerative effects.

Theaflavin -3,3'-digallate/ethanol: a novel cross-linker for stabilizing dentin collagen.

To study the ability of theaflavin-3,3'-digallate (TF3)/ethanol solution to crosslink demineralized dentin collagen, resist collagenase digestion, and explore the potential mechanism. Fully demineralized dentin blocks were prepared using human third molars that were caries-free. Then, these blocks were randomly allocated into 14 separate groups (n = 6), namely, control, ethanol, 5% glutaraldehyde (GA), 12.5, 25, 50, and 100mg/ml TF3/ethanol solution groups. Each group was further divided into two subgroups based on crosslinking time: 30 and 60s. The efficacy and mechanism of TF3's interaction with dentin type I collagen were predicted through molecular docking. The cross-linking, anti-enzymatic degradation, and biomechanical properties were studied by weight loss, hydroxyproline release, scanning/transmission electron microscopy (SEM/TEM), in situ zymography, surface hardness, thermogravimetric analysis, and swelling ratio. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were utilized to explore its mechanisms. Statistical analysis was performed using one and two-way analysis of variance and Tukey's test. TF3/ethanol solution could effectively crosslink demineralized dentin collagen and improve its resistance to collagenase digestion and biomechanical properties (p < 0.05), showing concentration and time dependence. The effect of 25 and 50mg/ml TF3/ethanol solution was similar to that of 5% GA, whereas the 100mg/mL TF3/ethanol solution exhibited better performance (p < 0.05). TF3 and dentin type I collagen are mainly cross-linked by hydrogen bonds, and there may be covalent and hydrophobic interactions. TF3 has the capability to efficiently cross-link demineralized dentin collagen, enhancing its resistance to collagenase enzymatic hydrolysis and biomechanical properties within clinically acceptable timeframes (30s/60s). Additionally, it exhibits promise in enhancing the longevity of dentin adhesion.

Isotopic evidence of high reliance on plant food among Later Stone Age hunter-gatherers at Taforalt, Morocco

The transition from hunting-gathering to agriculture stands as one of the most important dietary revolutions in human history. Yet, due to a scarcity of well-preserved human remains from Pleistocene sites, little is known about the dietary practices of pre-agricultural human groups. Here we present the isotopic evidence of pronounced plant reliance among Late Stone Age hunter-gatherers from North Africa (15,000–13,000 cal BP), predating the advent of agriculture by several millennia. Employing a comprehensive multi-isotopic approach, we conducted zinc (δ66Zn) and strontium (87Sr/86Sr) analysis on dental enamel, bulk carbon (δ13C) and nitrogen (δ15N) and sulfur (δ34S) isotope analysis on dentin and bone collagen, and single amino acid analysis on human and faunal remains from Taforalt (Morocco). Our results unequivocally demonstrate a substantial plant-based component in the diets of these hunter-gatherers. This distinct dietary pattern challenges the prevailing notion of high reliance on animal proteins among pre-agricultural human groups. It also raises intriguing questions surrounding the absence of agricultural development in North Africa during the early Holocene. This study underscores the importance of investigating dietary practices during the transition to agriculture and provides insights into the complexities of human subsistence strategies across different regions.

Effect of Salvadora persica on resin-dentin bond stability

BackgroundThe stability of resin–dentin interfaces is still highly questionable. The aim of this study was to evaluate the effect of Salvadora persica on resin–dentin bond durability.Materials and methodsExtracted human third molars were used to provide mid-coronal dentin, which was treated with 20% Salvadora persica extract for 1 min after acid-etching. Microtensile bond strength and interfacial nanoleakage were evaluated after 24 h and 6 months. A three-point flexure test was used to measure the stiffness of completely demineralized dentin sticks before and after treatment with Salvadora persica extract. The hydroxyproline release test was also used to measure collagen degradation by endogenous dentin proteases. Statistical analysis was performed using two-way ANOVA followed by post hoc Bonferroni test and unpaired t-test. P-values < 0.05 were considered statistically significant.ResultsThe use of Salvadora persica as an additional primer with etch-and-rinse adhesive did not affect the immediate bond strengths and nanoleakage (p > 0.05). After 6 months, the bond strength of the control group decreased (p = 0.007), and nanoleakage increased (p = 0.006), while Salvadora persica group showed no significant difference in bond strength and nanoleakage compared to their 24 h groups (p > 0.05). Salvadora persica increased dentin stiffness and decreased collagen degradation (p < 0.001) compared to their controls.ConclusionSalvadora persica extract pretreatment of acid-etched dentin preserved resin–dentin bonded interface for 6 months.Clinical significanceDurability of resin-dentin bonded interfaces is still highly questionable. Endogenous dentinal matrix metalloproteinases play an important role in degradation of dentinal collagen within such interfaces. Salvadora persica may preserve resin-dentin interfaces for longer periods of time contributing to greater clinical success and longevity of resin composite restorations.

Tunable polymer-peptide hybrids for dentin tissue repair

ObjectivesThis study targets to assess the remineralization capability of conditioned dentin infiltrated with polymeric nanoparticles (NPs) doped with tideglusib (TDg) (TDg-NPs). MethodsDentin conditioned surfaces were infiltrated with NPs and TDg-NPs. Bonded interfaces were created, stored for 24 h and submitted to mechanical and thermal challenging. Resin-dentin interfaces were evaluated through nanohardness, Masson's trichrome staining microscopy, and Raman analysis. ResultsDentin surfaces treated with TDg-NPs and load cycled produced higher nanohardness than the rest of the groups at the hybrid layer. At the bottom of the hybrid layer, all samples treated with TDg-NPs showed higher nanohardness than the rest of the groups. Active remineralization underneath the hybrid layer was detected in all groups after TDg application and load cycling, inducting new dentinal tubuli formation. After thermocycling, remineralization at the hybrid layer was not evidenced in the absence of NPs. Raman analysis showed increase mineralization, enriched carbonate apatite formation, and improved crosslinking and scaffolding of the collagen. ConclusionsMechanical loading on the specimens obtained after TDg-NPs dentin infiltration inducts an increase of mineralization at the resin/dentin interface, indicating remineralization of peritubular and intertubular dentin with augmented crystallographic maturity in crystals. Enriched collagen quality was produced, generating an adequate matrix organization to promote apatite nucleation, after tideglusib infiltration. Clinical significanceAt the present research, it has been proved the creation of reparative dentin, at the resin-dentin interface, after tideglusib dentin infiltration. Chemical stability, to favor integrity of the resin-dentin interface, is warranted in the presence of the TDg-NPs in the demineralized dentin collagen.

The effect of the irrigation solutions on dentin organic components: Pilot study

INTRODUCTION. Tooth decay and its complications are prevalent dental issues among adults. Endodontic treatment is the standard of care for complicated caries, specifically pulpitis and periodontitis. Endodontic irrigants, which are placed in the root canal lumen for a specific duration, can affect the intracanal dentin structure (organic and inorganic substances) in various ways. The use of polyhexanide-based antiseptic products in endodontics is a promising idea to overcome microbial resistance and minimize microbial-related endodontic treatment failures.AIM. The aim of this study is to investigate the qualitative impact of standard irrigation solutions and a polyhexanide-based composition on the collagen matrix of dentin.MATERIALS AND METHODS. The study investigated the effect of nine solutions on the dentin of the tooth root. Twelve intact maxillary third molars extracted for orthodontic reasons were taken for the study. The teeth were fixed in a 10% neutral formalin solution for at least one day and were decalcinated. 5–10 μm thick sample sections were made and stained with picrosirius (Picrosirius Red, Biovitrum, Russia) before being examined under polarized light. The histological slice was analyzed using a Carl Zeiss (Germany) software and hardware complex based on ZEN v3.0 and light microscope Axioimager M.1. All microphotos were loaded into the Fiji distribution program of ImageJ for microscopy pixel classification.RESULTS. Upon analysis of the diagrams, it appears that there is a lower amount and density of stained dentin collagen array after exposure to sodium hypochlorite solutions of 3% and 1.5%, as well as polyhexanide.CONCLUSIONS. The data obtained from the histogram analyzer of samples stained with picrosirius suggests that polyhexanide may have a qualitative effect on the organic structure of hard tissues, particularly collagen.

Assessing the diet of modern and archaeological guanacos from the Great Chaco in Córdoba, Argentina, through stable isotope analysis (δ13C, δ15N) of bone and dentin collagen: Implications for paleoenvironmental and zooarchaeological studies

The application of stable isotope analyses allows a diachronic characterisation of species habitat and feeding behaviour, information of utmost importance for zooarchaeological research. In South America, the former distribution of the guanaco ( Lama guanicoe) encompassed a much larger territory than the current one. Within the Argentinean Great Chaco, only a small native population persists in Northwestern Córdoba province, Central Argentina, where it was once widely distributed. In this paper, we present the first set of dentin and collagen δ13C and δ15N values for this relict population ( N = 18) along with archaeological data of guanaco specimens ( N = 19) dated to the Middle and Late Holocene from the nearby Ongamira valley. Neither deciduous and permanent teeth nor males and females show marked differences within the modern samples. Both modern and archaeological guanaco δ13C values indicate a mixed diet of C3 and, to a lesser extent, C4 plants. Conversely, the δ15N values exhibit distinct signals between the Arid and the Mountain Chaco subregions. The diet breadth of the archaeological guanacos suggests the use of transitional or ecotonal environments, also reflected in the size of their isotopic niche as opposed to modern guanacos. Regarding the timing of the species retraction in the region, there is no evidence of a shift in its habitat during the period between ~4700 and 190014C years BP. We suggest their retraction probably occurred later than previously proposed in regional zooarchaeological models.

Dentin surface modification by MDP to improve dentin bonding stability: Topological enhancement and mineralization of collagen structure in hybrid layers

Decades of research have been conducted on 10-Methacryloyloxydecyl dihydrogen phosphate (MDP) through numerous studies. The mechanisms by which its residual calcium salts benefit dentin bonding remain undetermined. The objective of the research was to investigate the role and process of remaining calcium salts in the priming procedure and their capacity for remineralization. The investigation focused on the variations in topological structure, mechanical properties, and chemical interactions between the main agent and the dentin surface. Two adhesive modes including prime-and-rinse(P&R) and prime-and-nonrinse (P&NR) utilized to evaluate the bonding performance and remineralization ability. The findings indicated that both P&R and P&NR methods could eliminate the smear-layer, uncover dentinal-tubules, and generate a textured/rough surface on the dentin. Collagen fibrils exhibited a greater presence of inorganic minerals in the P&NR mode. Compared to control group, both P&R and P&NR groups improved immediate and aging bond strength significantly (P < 0.05). AFM and 3D-STORM revealed MDP and its residual calcium salts distributed in collagen fibrils and expanded collagen matrix. In the P&NR group, TEM revealed that the dentin collagen matrix experienced some remineralization, and there was also mineralization within the collagen fibrils embedded in the bonding interface. Thus, MDP priming improved dentin bonding stability. Residual calcium salts of P&NR process can enhance topological structure of the collagen matrix and induce intrafibrillar mineralization.

Influence of Piperine on Collagen Color and Degree of Conversion of a Universal Adhesive System Applied to Bleached Dentin

Aims: The aim was to evaluate the influence of piperine on the collagen staining and on the degree of conversion of the universal adhesive system applied to the bleached dentin. Methods: The piperine extraction process was carried out using a water reflux system and confirmed by UV-Vis spectrophotometry. For collagen staining analysis, dentin collagen disk were analyzed with a spectrophotometer. Regarding the collagen color evaluation, there was no statistically significant difference between the groups regarding ΔL, Δa, Δb e ΔE (p&gt;0,05). Results: Regarding the degree of conversion, there was no statistically significant difference between without hydrogen peroxide, PH + 0,001% piperine, PH + 0,002% piperine and PH + 0,004% piperine (p&gt;0,05). Conclusions: It is possible to conclude that piperine, did not change the color of the dentin collagen and avoided the reduction in the degree of conversion of a universal adhesive system applied immediately after bleaching with 35% hydrogen peroxide.