Changes to dentin extracellular matrix following treatment with plant-based polyphenols

Bioengineered Injectable Hydrogel Based on the Dentin Extracellular Matrix and Chitosan

The extracellular matrix of dentin contains macromolecules of biological value that make it a natural source for the prospection of novel smart biomaterials. Here, we described the development of an injectable thermosensitive smart hydrogel resulting from the blending of insoluble macromolecules of the dentin matrix and chitosan. The extrudability and gelation parameters of the prehydrogel were optimized by varying the concentration of individual components. Three-dimensional constructs were fabricated upon injection of the prehydrogel into custom-made molds, followed by incubation at 37 °C. Specimens were characterized for spectral, physical, morphological, mechanical, and biocompatibility features. Fourier-transform infrared (FTIR) analyses confirmed the integration of the dentin organic matrix and chitosan. The degree of porosity of constructs was ∼51%. The water diffusion of constructs reached a plateau after 2 days. Their moduli of elasticity were at a low MPa order, decreasing after storage in simulated body fluid (SBF). The biodegradability of constructs rose following incubation in SBF containing lysozyme or zinc ions. Hydrogel bioactivity was confirmed by FTIR and ultramorphologically suggested by surface precipitates. Hydrogel constructs were shown to be biocompatible with undifferentiated pulp cells (OD-21). Overall, the novel engineered injectable hydrogel based on dentin extracellular macromolecules and chitosan holds promising features for use as a scaffold for the regeneration of damaged load-bearing tissues like dentin and bone.

Effects of cross-linking agents on hydroxyproline release and root caries lesion size: Systematic review and network meta-analysis of in vitro studies

A promising approach for managing root caries is the use of cross-linking agents to stabilize collagen. However, despite testing various natural and synthetic agents in vitro, their efficacy remains uncertain. The aim of this review was to examine which cross-linking agent performs better in reducing root caries lesion depth and the release of hydroxyproline, which is a marker of collagen degradation. Studies evaluating the impact of cross-linking agents on dentin were included, while studies performed on enamel surface/cell cultures and studies evaluating collagenase inhibitors were excluded, among others. A comprehensive search covered eight databases, and study quality was assessed using the QUINN Tool for in vitro dental studies. Synthesis of the results was done using a Bayesian network meta-analysis to compare agents. Fifty studies involving 31 cross-linking agents were included for qualitative synthesis. The network meta-analysis for lesion depth involved 284 samples across 36 comparisons and ranked cross-linking agents in terms of their caries lesion depth-reducing effect (from best to worst): naringin > quercetin > riboflavin > proanthocyanidins > hesperidin > glutaraldehyde > cranberry > grape seed extract > untreated controls. Only naringin, quercetin, proanthocyanidins, and glutaraldehyde showed statistically significant efficacy over untreated controls. Cranberry extract excelled in reducing hydroxyproline release, followed by proanthocyanidins. In conclusion, proanthocyanidins positively affected both outcomes, suggesting they are prime candidates for translational research. Clinical studies are now essential to evaluate their real-world effectiveness against root caries. PROSPERO-CRD42023404911.

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.

Use of marine occurrent extracts to enhance the stability of dentin extracellular matrix

Chitosan (CS) and phloroglucinol (PhG), two extracts abundantly found in marine life, were investigated for their ability to biomodify demineralized dentin by enhancing collagen crosslinks and improving dentin extracellular matrix (ECM) mechanical and biochemical stability. Dentin obtained from non-carious extracted human molars were demineralized with phosphoric acid. Baseline Fourier-transform infrared (FTIR) spectra, apparent flexural elastic modulus (AE) and dry mass (DM) of each specimen were independently acquired. Specimens were randomly incubated for 5 min into either ultrapure water (no-treatment), 1% glutaraldehyde (GA), 1% CS or 1% PhG. Water and GA were used, respectively, as a negative and positive control for collagen crosslinks. Specimens' post-treatment FTIR spectra, AE, and DM were obtained and compared with correspondent baseline measurements. Additionally, the host-derived proteolytic activity of dentin ECM was assessed using hydroxyproline assay (HYP) and spectrofluorometric analysis of a fluorescent-quenched substrate specific for matrix metalloproteinases (MMPs). Finally, the bond strength of an etch-and-rinse adhesive was evaluated after application of marine compounds as non-rinsing dentin primers. Dentin specimens FTIR spectral profile changed remarkably, and their AE increased significantly after treatment with marine compounds. DM variation, HYP assay and fluorogenic substrate analysis concurrently indicated the biodegradation of CS- and PhG-treated specimens was significantly lesser in comparison with untreated specimens. CS and PhG treatments enhanced biomechanical/biochemical stability of demineralized dentin. These novel results show that PhG is a primer with the capacity to biomodify demineralized dentin, hence rendering it less susceptible to biodegradation by host-proteases.

From medical strategy to foodborne prophylactic strategy: Stabilizing dental collagen with aloin

Infectious oral diseases are longstanding global public health concerns. However, traditional medical approaches to address these diseases are costly, traumatic, and prone to relapse. Here, we propose a foodborne prophylactic strategy using aloin to safeguard dental collagen. The effect of aloin on the stability of dental collagen was evaluated by treating dentin with a solution containing aloin (0.1 mg/mL) for 2 min. This concentration is comparable to the natural aloin content of edible aloe. Furthermore, we investigated the mechanisms underlying the interactions between aloin and dentin collagen. Our findings, obtained through fluorescence spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, Gaussian peak fitting, circular dichroism spectroscopy, and X-ray diffraction, revealed that aloin interacts with dental collagen through noncovalent bonding, specifically hydrogen bonding in situ. This interaction leads to a reduction in the distance between molecules and an increase in the proportion of stable α-helical chains in the dental collagen. The ultimate tensile strength and thermogravimetric analysis demonstrated that dental collagen treated with aloin exhibited improved mechanical strength and thermostability. Additionally, the release of hydroxyproline, cross-linked carboxy-terminal telopeptide of type I collagen, and C-terminal cross-linked telopeptide of type I collagen, along with weight loss, indicated an enhancement in the enzymatic stability of dental collagen. These findings suggest that aloin administration could be a daily, nondestructive, and cost-effective strategy for managing infectious oral diseases.

Cnicus benedictus extract-loaded electrospun gelatin wound dressing for treating diabetic wounds: An in vitro and in vivo study

In the current study, Cnicus benedictus extract was loaded into electrospun gelatin scaffolds for diabetic wound healing applications. Scaffolds were characterized in vitro by mechanical testing, cell culture assays, electron microscopy, cell migration assay, and antibacterial assay. In vivo wound healing study was performed in a rat model of diabetic wound. In vitro studies revealed fibrous architecture of our developed dressings and their anti-inflammatory properties. In addition, Cnicus benedictus extract-loaded wound dressings prevented bacterial penetration. In vivo study showed that wound size reduction, collagen deposition, and epithelial thickness were significantly greater in Cnicus benedictus extract-loaded scaffolds than other groups. Gene expression studies showed that the produced wound dressings significantly upregulated VEGF and IGF genes expression in diabetic wounds.

In vitro assessment of antimicrobial potential of low molecular weight chitosan and its ability to mechanically reinforce and control endogenous proteolytic activity of dentine

AIMS

Chitosan-based biomaterials exhibit several properties of biological interest for endodontic treatment. Herein, a low molecular weight chitosan (CH) solution was tested for its antimicrobial activity against Enterococcus faecalis (E. faecalis) and effects on dentine structure.

METHODOLOGY

The root canal of 27 extracted uniradicular teeth were biomechanically prepared, inoculated with a suspension of E. faecalis and randomly assigned to be irrigated with either 5.25% sodium hypochlorite (NaClO), 0.2% CH or sterile ultrapure water (W). Bacteriologic samples were collected from root canals and quantified for of E. faecalis colony-forming units (CFUs). The effectiveness of CH over E. faecalis biofilms was further measured using the MBEC Assay®. Additionally, dentine beams and dentine powder were obtained, respectively, from crowns and roots of 20 extracted third molars. Dentine samples were treated or not with 17% EDTA and immersed in either CH or W for 1 min. The effects of CH on dentine structure were evaluated by assessment of the modulus of elasticity, endogenous proteolytic activity and biochemical modifications.

RESULTS

The number of E. faecalis CFUs was significantly lower for samples irrigated with CH and NaClO. No significant differences were found between CH and NaClO treatments. Higher modulus of elasticity and lower proteolytic activity were reported for dentine CH-treated specimens. Chemical interaction between CH and dentine was observed for samples treated or not with EDTA.

CONCLUSIONS

Present findings suggest that CH could be used as an irrigant during root canal treatment with the triple benefit of reducing bacterial activity, mechanically reinforcing dentine and inhibiting dentine proteolytic activity.

Dentin primer based on a highly functionalized gelatin-methacryloyl hydrogel

Gelatin-methacryloyl hydrogels (GelMA) have demonstrated their utility as scaffolds in a variety of tissue engineering applications.

OBJECTIVES

In this study, a highly functionalized GelMA hydrogel was synthesized and assessed for degree of functionalization. As the proposed GelMA hydrogel was coupled to a visible-light photoinitiator, we hypothesized it might serve as base to formulate a model dentin primer for application in restorative dentistry.

METHODS

GelMA was mixed with photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), photopolymerized for 0-40 s using a dental light-curing device and tested for extrudability, degree of photo-crosslinking (DPxlink), water sorption/solubility/swelling (WS/SL/SW) and apparent modulus of elasticity (AE). Model dentin primer was prepared by mixing GelMA+LAP with a primer of a commercial three-step etch-and-rinse adhesive. After application of GelMA-based primer to acid-etched dentin, samples were bonded with correspondent adhesive agent, photopolymerized and had their immediate bond strength compared to control samples primed and bonded with the same commercial material.

RESULTS

Extrudability of hydrogel was confirmed using a microsyringe to write the acronym "CDMI". DPxlink of GelMA+LAP changed significantly as a function of photopolymerization time (20 s < 30 s ≤ 40 s). WS, SL and SW were significantly reduced in hydrogels polymerized for 30 and 40 s. AE of hydrogels varied significantly as a function of photopolymerization time (20 s < 30 s ≤ 40 s; 20 s ‡ 40 s). Bond strength of dentin primed with GelMA-based primer was lower (∼29.3 MPa) but not significantly of that of control (∼34.6 MPa).

CONCLUSIONS

Optimization of a GelMA-based dentin primers can lead to the development of promising biomimetic adhesives for dentin rehabilitation.

Treated Dentin Matrix in Tissue Regeneration: Recent Advances

Tissue engineering is a new therapeutic strategy used to repair serious damage caused by trauma, a tumor or other major diseases, either for vital organs or tissues sited in the oral cavity. Scaffold materials are an indispensable part of this. As an extracellular-matrix-based bio-material, treated dentin matrixes have become promising tissue engineering scaffolds due to their unique natural structure, astonishing biological induction activity and benign bio-compatibility. Furthermore, it is important to note that besides its high bio-activity, a treated dentin matrix can also serve as a carrier and release controller for drug molecules and bio-active agents to contribute to tissue regeneration and immunomodulation processes. This paper describes the research advances of treated dentin matrixes in tissue regeneration from the aspects of its vital properties, biologically inductive abilities and application explorations. Furthermore, we present the concerning challenges of signaling mechanisms, source extension, individualized 3D printing and drug delivery system construction during our investigation into the treated dentin matrix. This paper is expected to provide a reference for further research on treated dentin matrixes in tissue regeneration and better promote the development of relevant disease treatment approaches.

Effect of foliage applied chitosan-based silicon nanoparticles on arsenic uptake and translocation in rice (Oryza sativa L.)

In this study, chitosan-based silicon nanoparticles (Chsi-NPs) are prepared that primarily consists of C (57.9%), O (31.3%), N (5.6%), and Si (3.5%) and are 10-180 nm in size. We then explore the effect on the foliage applied on rice planted on soil contaminated with 104 mg·kg^-1 arsenic (As); low (3 mg·L^-1)and high (15 mg·L^-1) doses of the foliar Chsi-NPs are administered during the rice grain filling stage. The results showed that the higher dose foliar Chsi-NPs treatment reduced the As concentration in the grain by 61.2% but increased As concentration in the leaves by 47.1% compared to the control treatment. The foliar spraying of the Chsi-NPs inhibited As transport to the grain by facilitating the attachment of As to the cell wall, with higher doses of the foliar Chsi-NPs treatment increased by 8.7%. The foliar spraying of Chsi-NPs increased the malondialdehyde levels by 18.4%, the catalase activity by 49.0%, and the glutathione activity by 99.0%. These results indicated that the foliar Chsi-NPs application was effective for alleviating As toxicity and accumulation in rice. This study provides a novel method for effectively alleviating As accumulation in rice.