Dentin Collagen Research Articles

Effect of Collagen-Reactive Functional Monomer on Etch-and-Rinse Adhesives

In this study, we evaluated a novel functional monomer (4-formylphenyl acrylate [FA]) that can specifically and covalently bind to the dentin collagen matrix as a potential alternative hydrophobic diluent-like monomer for improving the durability of dentin bonding. Experimental adhesives with different FA contents (0%, 10%, 20%, and 30%) were evaluated as partial substituents for the hydrophilic monomer 2-hydroxyethyl methacrylate, with the commercial adhesive One-Step (Bisco, Inc.) employed as the positive control. Their degree of conversion, viscosity, hydrophobicity, mechanical properties, and water absorption/solubility were measured as the comprehensive characterization. In situ zymographic assays were performed to determine the extent to which FA inhibits the endogenous hydrolytic activity of dentin. Finally, the bonding performances of the novel adhesives were evaluated with microtensile strength tests and scanning electron microscopy. The results showed that the incorporation of FA significantly improved the mobility of experimental adhesives attributable to the dilution property of FA. In contrast to the possible compromised rate of polymerization by hydroxyethyl methacrylate, FA exhibited typical characteristics of favorable copolymerization with polymerizable monomers in adhesives and improved the degree of conversion of experimental adhesives. The rigidity and hydrophobic properties of the phenyl framework of the FA molecule conferred superior mechanical properties and hydrolysis resistance to the novel experimental adhesives. An inhibitory effect on gelatinolytic activities within the hybrid layer was also observed in the in situ zymographic assays, even at a low FA concentration (10%). In conjunction with the significantly improved infiltration found via scanning electron microscopy, the experimental adhesives containing FA possessed significantly better-maintained microtensile strength, even after aging. Thus, the incorporation of this novel monomer endowed the experimental adhesives with multiple enhanced functionalities. These remarkable advantages highlight the suitability of the monomer for further applications in clinical practice.

Enhancing bioactivity and stability of polymer-based material-tissue interface through coupling multiscale interfacial interactions with atomic-thin TiO2 nanosheets.

Supplementary material (further details of fabrication and characterization of TiO2 NSs and TiO2-ARCs, the bioactivity evaluation of TiO2-ARCs on hDPSCs, and the measurement of interaction with demineralized dentin collagen) is available in the online version of this article at 10.1007/s12274-022-5153-1.

Salivary esterases dramatically reduce biostability of dentin collagen treated with galloylated polyphenols.

To investigate the effects of salivary esterases on biostability of collagen treated by galloylated polyphenols. Human dentin was microtomed into 6-μm-thick films, which were demineralized and treated for 60s using solutions containing 0.6% and 2% of one of the crosslinkers: tannic acid (TAC), epigallocatechin gallate (EGCG), epigallocatechin (EGC), and N-[3-dimethylaminopropyl]-N'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS), and for 1h using EDC/NHS. Half of the treated and untreated (control) films were subjected to human saliva incubation. Collagen biostability was assessed via exogenous protease biodegradation by weight loss and hydroxyproline release, and endogenous MMPs by in situ zymography. The degradation products of galloylated polyphenols (TAC and EGCG) by saliva were monitored using proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). The esterase activity of saliva induced by the crosslinkers was also assessed. Collagen films treated with TAC and EGCG exhibited significantly improved biostability (p<0.05); however, the enhanced biostability was severely reduced after saliva incubation (p<0.001). For EDC/NHS treated collagen, saliva incubation showed negligible effect on the biostability. 1H NMR studies confirmed the esterase-catalyzed hydrolysis of the galloyl. GPC measurements showed decreased molecular weight of TAC in saliva indicating its chemical degradation. Both TAC and EGCG showed much higher esterase activity than other treatment groups. The galloyl group plays important role in collagen crosslinking, inducing higher biostability. However, galloylated polyphenols crosslinked on collagen are highly susceptible to metabolism of human saliva by salivary esterase, dramatically compromising the enhanced biostability.

Dual function of quercetin as an MMP inhibitor and crosslinker in preventing dentin erosion and abrasion: An in situ/in vivo study.

The aim of the present study was to evaluate the in situ/in vivo effect of quercetin on dentin erosion and abrasion. Human dentin blocks (2× 2× 2mm) were embedded and assigned to 6 groups: 75μg/mL, 150μg/mL and 300μg/mL quercetin (Q75, Q150, Q300); 120μg/mL chlorhexidine (CHX, positive control); and deionized water and ethanol (the negative controls). The specimens were treated with the respective solutions for 2min and then subjected to in situ/in vivo erosive/abrasive challenge for 7 d as follows: in vivo erosion 4 times a day and then in vivo toothbrush abrasion after the first and last erosive challenges of each day. Dentin loss was assessed by profilometry. An additional dentin specimen was used to evaluate the penetration depth of quercetin into dentin by tracking the spatial distribution of its characteristic Raman peak. Moreover, dentin blocks (7× 1.7× 0.7mm) were used to detect the impact of quercetin on dentin-derived matrix metalloproteinase (MMP) inhibition by in situ zymography, and the inhibition percentage (%) was calculated. Additionally, the potential collagen crosslinking interactions with quercetin were detected by Raman spectroscopy, and the crosslinking degree was determined with a ninhydrin assay. Fully demineralized dentin beams (0.5× 0.5× 10mm) were used to evaluate the impact of quercetin on the mechanical properties of dentin collagen fibre by the ultimate micro-tensile strength test (μUTS). The data were analysed by one-way analysis of variance and Tukey's test (α=0.05). Compared to the negative controls, all treatment solutions significantly reduced dentin loss. The dentin loss of Q150 and Q300 was significantly less than that of CHX (all P<0.05). The amount of quercetin decreased with increasing dentin depth, and the maximum penetration depth was approximately 25-30µm. In situ zymography showed that quercetin significantly inhibited the activities of dentin-derived MMPs. The inhibitory percentages of Q75 and Q150 were significantly lower than that of CHX (all P<0.05), but no significant difference was found between Q300 and CHX (P=0.58). The collagen crosslinking interactions with quercetin primarily involved hydrogen bonding and the degree of crosslinking increased in a concentration-dependent manner. Statistically significant increases in μUTS values were observed for demineralized dentin beams after quercetin treatment compared with those of the control treatments (all P<0.05). This study provides the first direct evidence that quercetin could penetrate approximately 25-30µm into dentin and further prevent dentin erosion and abrasion by inhibiting dentin-derived MMP activity as well as crosslinking collagen of the demineralized organic matrix.

Streptococcus mutans Proteases Degrade Dentinal Collagen.

Here, we explored the role of S. mutans's whole cell and discrete fractions in the degradation of type I collagen and dentinal collagen. Type I collagen gels and human demineralized dentin slabs (DS) were incubated in media alone or with one of the following: overnight (O/N) or newly inoculated (NEW) cultures of S. mutans UA159; intracellular proteins, supernatant or bacterial membranes of O/N cultures. Media from all groups were analyzed for protease-mediated release of the collagen-specific imino acid hydroxyproline. Images of type I collagen and DS were analyzed, respectively. Type I collagen degradation was highest for the supernatant (p &lt; 0.05) fractions, followed by intracellular components and O/N cultures. Collagen degradation for DS samples was highest for O/N samples, followed by supernatant, and intracellular components (p &lt; 0.05). There was lower detectable degradation for both type I collagen and DS from NEW culture samples (p &lt; 0.05), and there was no type I collagen or DS degradation detected for bacterial membrane samples. Structural changes to type I collagen gel and dentinal collagen were observed, respectively, following incubation with S. mutans cultures (O/N and NEW), intracellular components, and supernatant. This study demonstrates that intracellular and extracellular proteolytic activities from S. mutans enable this cariogenic bacterium to degrade type I and dentinal collagen in a growth-phase dependent manner, potentially contributing to the progression of dental caries.

Combining δ 13C and δ 15N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales

ABSTRACT Stable carbon (δ 13C) and nitrogen (δ 15N) isotopic compositions of bone and dentine collagen extracted from museum specimens have been widely used to study the paleoecology of past populations. Due to possible systematic differences in stable isotope values between bone and dentine, dentine values need to be transformed into bone-collagen equivalent using a correction factor to allow comparisons between the two collagen sources. Here, we provide correction factors to transform dentine δ 13C and δ 15N values into bone-collagen equivalent for two toothed whales: narwhal and beluga. We sampled bone and dentine from the skulls of 11 narwhals and 26 belugas. In narwhals, dentine was sampled from tusk and embedded tooth; in belugas, dentine was sampled from tooth. δ 13C and δ 15N were measured, and intra-individual bone and dentine isotopic compositions were used to calculate correction factors for each species. We detected differences in δ 13C and δ 15N. In both narwhals and belugas, we found lower average δ 13C and δ 15N in bone compared with dentine. The correction factors provided by the study enable the combined analysis of stable isotope data from bone and dentine in these species.

Effect of Endodontic Irrigating Solutions on Radicular Dentine Structure and Matrix Metalloproteinases-A Comprehensive Review.

Irrigating solutions play an important role in the eradication of intracanal microbes and debris dissolution during endodontic treatment. Different combinations of solutions and protocols have been advocated, with sodium hypochlorite (NaOCl), ethylenediamine tetra acetic acid (EDTA), and chlorhexidine (CHX) remaining the most widely used ones by many clinicians. Although these solutions provide efficient inorganic dissolution and antimicrobial capacity, their use has also been reported to cause undesired effects on root dentin composition and mechanical and biomechanical properties, such as microhardness, surface roughness, bond strength, and matrix metalloproteinase (MMP) activity. Several corroborating studies attribute these changes in mechanical properties of dentine to the use of irrigating solutions, and there are limited reports on how the solutions affect the expression of MMPs, which may be a correlating link to understanding the role of these enzymes in dentin collagen and changes in the mechanical properties of dentin. Hence, using the basis of several studies from the literature, the objective is to comprehensively review the influence of individual and combined irrigating solutions on root dentine structure and the activity of the MMPs.

The durability of resin-dentine bonds are enhanced by epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica.

Biomimetic nanohydroxyapatite (nHAp) has long been used as a biocompatible material for bone repair, bone regeneration, and bone reconstruction due to its low toxicity to local or systemic tissues. Various cross-linkers have been employed to maintain the structure of collagen; these include epigallocatechin-3-gallate (EGCG), which can fortify the mechanical properties of collagen and withstand the degradation of collagenase. We hypothesized that EGCG combined with nHAp may promote resin-dentin bonding durability. Here, we examined the effect of epigallocatechin-3-gallate-encapsulated nanohydroxyapatite/mesoporous silica (EGCG@nHAp@MSN) on thermal stability and remineralization capability of dentin collagen. Dentin slices (2 × 2 × 1 mm3 ) were obtained and completely demineralized in a 10% phosphoric acid water solution. The resulting dentin collagen matrix was incubated with deionized water, EGCG, nHAp@MSN, and EGCG@nHAp@MSN. The collagen thermal degradation temperature was assessed utilizing differential scanning calorimetry analysis, which indicated that EGCG, nHAp@MSN, and EGCG@nHAp@MSN reinforced collagen's capability to resist thermal degradation. EGCG@nHAp@MSN resulted in the highest increase in denaturation temperature. Thermogravimetric analysis showed that both nHAp@MSN and EGCG@nHAp@MSN achieved a higher residual mass than the EGCG and control groups. Fourier transform infrared spectroscopy was performed to examine the interaction between EGCG@nHAp@MSN and dentin collagen. The EGCG@nHAp@MSN sample exhibited stronger dentin microhardness and uppermost bond strength after thermocycling. EGCG significantly enhanced collagen's capability to resist thermal degradation. In summary, EGCG and nHAp@MSN may work together to assist the exposed collagen to improve resistance to thermal cycling and promote remineralization while also strengthening the durability of resin-dentin bonds.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin

ObjectivesTo study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6. MethodsDemineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet–visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined. ResultsAt 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol. ConclusionsIP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD. Clinical significanceThese findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

Medieval and early modern diets in the Polack region of Belarus: A stable isotope perspective.

In western and north-western Europe there has been a growing focus on exploring how major economic, political, and social changes during the Medieval period impacted the lived experience of different populations and sectors of society. Stable isotope analysis has proven particularly powerful in this regard, providing direct insights into the long-term diets of individuals and communities. Despite experiencing similarly dramatic social reconfigurations and changes, eastern Europe has, however, received far less attention in this regard. The territory of Belarus has, especially, so far remained a relative blank spot on the bioarchaeological map of Europe, though cities such as Polack emerged rapidly as key nodes within a growing economic and religious network. To gain direct insight into the diets of inhabitants of the Polack region of Belarus in the 11-18th centuries, we applied stable carbon and nitrogen isotope analysis to bone and dentine collagen from human (n = 143) and animal (n = 105) individuals from the city of Polack and surrounding rural sites. Results indicate a diet based on C3 terrestrial resources, which did not differ between sexes and showed limited variation over time. Contrary to expectations, it appears that animal products were commonly consumed by rural dwellers, but no significant reliance on fish resources or millet consumption is found. In contrast to examples from western Europe, we argue that the diets in the city and the surrounding villages remained broadly similar for the majority of the population, and similar to commoners analysed in Poland and Lithuania, perhaps suggestive of slightly different economic changes operating in this part of the Medieval world.

Dynamic dentin: A quantitative microscopic assessment of age and spatial changes to matrix architecture, peritubular dentin, and collagens types I and III

To investigate age and site-related changes to human dentin collagen, sound human teeth collected from donors aged 13–29 (young) and 50–74 (aged) years (n = 9/group) were cut to shallow and deep sites. Dentin collagen orientation and fibril bundling was investigated using the Picrosirius Red (PSR) stain observed under cross-polarized light microscopy (Pol), and collagen distribution was investigated using Confocal Laser Scanning Microscopy (CLSM). Collagen types III to I distribution in peritubular dentin (PTD) was revealed using Herovici stain and brightfield microscopy. Image analysis software and linear mixed modelling quantified outcomes. In situ dentin collagen was observed using Xenon Plasma Focussed Ion Beam Scanning Electron Microscopy (Xe PFIB-SEM). The PSR-Pol analysis revealed less coherently aligned and more bundled collagen fibrils in aged dentin (P = 0.005). Deep inner dentin collagen in both groups were less coherently aligned with reduced bundling. Regardless of age, CLSM showed collagen distribution remained stable; and more collagen type III was detectable in PTD located in inner dentin (Young: P = 0.006; Aged: P = 0.008). Observations following Xe PFIB-SEM cross-sectioning showed apatite-like deposits surrounding large intratubular collagen fibers, and evidence of smaller intertubular dentin collagen fibrils in situ. In conclusion, aging changes collagen network architecture, but not distribution or content.

Biodegradation of Dental Resin-Based Composite—A Potential Factor Affecting the Bonding Effect: A Narrative Review

In recent years, although resin composite has played an important role in the restoration of tooth defects, it still has several disadvantages, including being biodegraded by saliva, bacteria and other enzymes in the oral cavity, which may result in repair failure. This factor is not conducive to the long-term survival of the prosthesis in the mouth. In this article, we review the causes, influencing factors and prevention methods of resin biodegradation. Biodegradation is mainly caused by esterase in saliva and bacteria, which breaks the ester bond in resin and causes the release of monomers. The mechanical properties of the prosthesis can then be affected. Meanwhile, cathepsin and MMPs are activated on the bonding surface, which may decompose the dentin collagen. In addition, neutrophils and residual water on the bonding surface can also aggravate biodegradation. Currently, the primary methods to prevent biodegradation involve adding antibacterial agents to resin, inhibiting the activity of MMPs and enhancing the crosslinking of collagen fibers. All of the above indicates that in the preparation and adhesion of resin materials, attention should be paid to the influence of biodegradation to improve the prosthesis’s service life in the complex environment of the oral cavity.

Effectiveness of experimental adhesive systems containing carbodiimide and solvated in different solvents

ObjectivesTo evaluate the influence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide – EDC (C) on the degree of conversion (DC%), resin-dentin bonding stability, collagen degradation, and MMP inactivation produced by experimental adhesive systems solvated in acetone (A), ethanol (E) or tetrahydrofuran (T). MethodsEDC was added to experimental primers consisting of HEMA, PMGDM, and water, solvated in A, E, or T, performing six groups (A, AC, E, EC, T, TC). The adhesive consisted of BISGMA, HEMA, camphorquinone, and EDMAB. DC% was evaluated by FT-IR spectroscopy. The μTBS was evaluated after 24 h or 1 yr of artificial saliva storage at 37°C. The degradation of the dentin collagen was evaluated using FT-IR spectroscopy at three periods: after primer application, 15, and 30 days, and the enzymatic activity within the hybrid layer using in situ zymography. Data was analyzed using ANOVA and Tukey's HSD test (α = 0.05). ResultsNo statistical significance in DC% was found among all adhesive systems (p > 0.05). EDC-containing primers maintained μTBS stability after 1 yr of artificial saliva storage (p > 0.05). The intensity of the Amide I and II bands from the dentin collagen was preserved for AC and EC after immersion in collagenase solution. The dentin treated with EDC-containing primers presented reduced fluorescein in the hybrid layer. ConclusionsThe incorporation of EDC into primers contributed to resin-dentin bonding stability and reduced the enzymatic activity and collagen degradation.

Silver diamine fluoride therapy for dental care.

Silver diamine fluoride (SDF) was developed in Japan in the 1960s. It is used to control early childhood caries, arrest root caries, prevent fissure caries and secondary caries, desensitise hypersensitive teeth, remineralise hypomineralised teeth, prevent dental erosion, detect carious tissue during excavation and manage infected root canals. SDF is commonly available as a 38% solution containing 255,000 ppm silver and 44,800 ppm fluoride ions. Silver is an antimicrobial and inhibits cariogenic biofilm. Fluoride promotes remineralisation and inhibits the demineralisation of teeth. SDF also inactivates proteolytic peptidases and inhibits dentine collagen degradation. It arrests caries without affecting dental pulp or causing dental fluorosis. Indirect pulp capping with SDF causes no or mild inflammatory pulpal response. However, direct application of SDF to dental pulp causes pulp necrosis. Furthermore, SDF stains carious lesions black. Patients must be well informed before SDF treatment. SDF therapy is simple, painless, non-invasive, inexpensive, and requires a simple armamentarium and minimal support. Both clinicians and patients generally accept it well. In 2021, the World Health Organization included SDF as an essential medicine that is effective and safe for patients. Moreover, it can be used for caries control during the COVID-19 pandemic because it is non-aerosol-generating and has a low risk of cross-infection.

Methacrylic monomer derived from cardanol incorporated in dental adhesive as a polymerizable collagen crosslinker

ObjectivesThe aim of this study was to evaluate the influence on MMP inhibition, dentin adhesion and physicochemical properties of an adhesive system incorporated with polymerizable collagen crosslinker monomer derived from cardanol. MethodsThe intermediary cardanol epoxy (CNE) was synthesized through cardanol epoxidation, followed by synthesis of cardanol methacrylate through methacrylic acid solvent-free esterification. Zymographic analysis was performed to evaluate the substances’ ability to inhibit gelatinolytic enzymes. Collagen crosslinkers were added into adhesives systems according to the following groups: Ybond Universal® (Control), Ybond® + 2 % proanthocyanidin (PAC), Ybond® + 2 % unsaturated cardanol (Cardanol) and Ybond® + 2 % cardanol methacrylate (CNMA). Degree of conversion (DC) of the adhesives was assessed by FT-IR. Disk-shaped specimens were prepared for water sorption (WS) and solubility (SL) tests. Human third molars were sectioned to expose medium dentin and restored according to the different adhesives used (n = 5). Then, the specimens were cut into 1 mm2 sticks to evaluate, after 24 h and 6-month aging, microtensile bond strength (µTBS) and nanoleakage by scanning electron microscopy. Data were analysed with ANOVA and Tukey's post-test (α = 0.05). ResultsCNMA and PAC completely inhibited all forms of gelatinolytic enzymes. Cardanol achieved a significantly lowest DC, while the other groups did not differ from each other (p > 0.05). PAC achieved significantly higher water sorption, while CNMA solubility was significantly lower when compared to the other adhesives (p < 0.05). PAC provided a statistically higher 24 h and 6-month aging bond strength. Intermediary similar µTBS were presented by control and CNMA (p = 0.108). All adhesives applied attained significantly reduced bond strength after aging (p < 0.05). Interfaces created using CNMA were almost devoid of silver deposits initially, however all groups showed large amounts of silver deposits on resin-dentin interface subjected to water aging. SignificanceAlthough CNMA was effective in inhibiting gelatinolytic enzymes, when incorporated into a universal adhesive it could not promote less degradation of the adhesive interface after water aging. Since it is a hydrophobic monomer, CNMA did not interact well with dentin collagen, however it reduced the solubility of the adhesive system besides not interfering in its polymerization.

Biomodification of dentin collagen by primers with crosslinking reagents using ethanol wet bonding technique

To evaluate the association between Ethanol Wet Bonding (EWB) and collagen cross-linking agents (CLA) on the mechanical properties of collagen and on the physical chemical proprieties of an etch-and-rise adhesive to dentin. Demineralized dentin bars (n = 10) were immersed, for 1 min or 1 h, according to the respective groups: distilled water control (WC); absolute ethanol (EA); absolute ethanol with the incorporation of proanthocyanidins 6,5% (PAC + AE); absolute ethanol with the incorporation of 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide 0.3 M (EDC + EA); absolute ethanol with the incorporation of 5% glutaraldehyde (GA + AE). All as solutions used as dentin primer per 1-min of application, for 3-point bending test was performed to evaluate the modulus of elasticity (ME) and mass change (MC) of collagen treated with the respective solutions, at different times of application (1min and 1h). The in situ degree conversion [DC] (n = 3), microtensile bond strength testing [μTBS] (n = 6) and micropermeability [MI] (n = 3) of the teeth restored with the respective treatments were analyzed. After 1 min and 1 h of application, it was observed that WC group showed the lowest ME (p < 0,05). The groups EDC + AE, GA + AE and AE presented a better ME with 1 h of application (p < 0,05), since the PAC + AE and WC were statistically similar. Treatments did not influence DC and μTBS (p > 0,05). In the micropermeability the WA showed the worst results. The association of EWB technique and CLA improved the mechanical properties of the collagen, but it showed no influence in the adhesive procedure.

Current strategies for biomimetic remineralization of human dentin: a scoping review

The purpose of this scoping review was to present the published successful techniques and strategies for biomimetic remineralization of human dentin. Studies whose primary objective was to present the strategy of successful dentin biomimetic remineralization were included. No language, participant age, or time restrictions were set. Stud-ies were retrieved via CENTRAL, LILACS, PubMed/MEDLINE, SciELO, SCOPUS and Web of Science. Gray literature searches on Google Scholar and OpenGrey were also conducted to find additional references. Based on the main research objectives, articles were classified by technique according to the methodology used for the research. One hundred forty-five articles, published be-tween 2003 and 2019, were included in the final scoping review. Protocols that imitate dentin's natural mineralization seek to restore lost minerals in dental tissues. Biomimetic remineralization proposes different ways to replace demineralized collagen in dentin by using inorganic materials like natural minerals, with the primary purpose of optimizing the clinical longevity of restorations and improving dental treatment.

Effects of the Combined Application of Trimethylated Chitosan and Carbodiimide on the Biostability and Antibacterial Activity of Dentin Collagen Matrix.

The structural integrity of a dentin matrix that has been demineralized by the clinical use of etchants or calcium-depleting endodontic irrigants, such as endodontic ethylenediaminetetraacetic acid (EDTA), is often deteriorated due to the collagenolytic activities of reactivated endogenous enzymes as well as the infiltration of extrinsic bacteria. Therefore, the biomodification of dentin collagen with improved stability and antibacterial activity holds great promise in conservative dentistry. The purpose of this study was to evaluate the effects of the combined application of trimethylated chitosan (TMC) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) on the biostability and antibacterial activity of the demineralized dentin collagen matrix. The morphological changes in the collagen matrix were observed by scanning electron microscopy (SEM), the amount of TMC adsorbed on the collagen surface was detected by X-ray photoelectron spectroscopy, and the elastic modulus was measured by a three-point bending device. Dry weight loss and amino acid release were detected to evaluate its anti-collagenase degradation performance. The antibacterial performance was detected by confocal microscopy. The TMC-treated group had less collagen space and a more compact collagen arrangement, while the untreated group had a looser collagen arrangement. The combined application of TMC and EDC can increase the elastic modulus, reduce the loss of elastic modulus, and result in good antibacterial performance. The current study proved that a dentin collagen matrix biomodified by TMC and EDC showed improved biodegradation resistance and antibacterial activities.

Dental Age Estimation Using Multiphoton Microscopy: A Potential Tool for Forensic Science.

Normal aging affects the different structures of teeth, in particular, the dentine. These changes are useful in forensic disciplines as a tool for age estimation. Although multiphoton (MP) microscopy has been used to explore dental pieces, a relationship between age and MP response of the human dentine has not been proposed yet. The relationship between MP signals and natural dentine aging is investigated herein. An index of age (INAG) combining two-photon excitation fluorescence (TPEF) and second harmonic generation (SHG) images has been used to quantify these changes. The results show that the INAG significantly decreases with age. Moreover, peritubular dentine size and collagen internal properties are also modified with age. This information confirms the usefulness of this technique in forensic age estimation after disasters (natural or manmade) with a lack of comprehensive fingerprint database. Courts and other government authorities might also benefit from this tool when the official age of individuals under special circumstances is required for legal or medical reasons.

THE EFFECT SODIUM HYPOCHLORITE 2,5% AND SODIUM THIOSULPHATE AS IRRIGATION ON THE CLEANLINESS OF THE APICAL THIRD ROOT

Background: Sodium hypochlorite produces free oxygen and free radicals that cause damage to dentin collagen. Combination with Sodium thiosulfate with the aim of improving root canal hygiene and restoring the oxidizing effect on the dentin surface.The apical third of the root canal is the most difficult part, due to its narrower anatomy, curvature and frequent branching of the root canal. Method: The study used 30 specimens which were divided into 3 groups, group I was irrigated with 2.5% NaOCl, 5% sodium thiosulfate and saline, group II was irrigated with 2.5% NaOCl, 10% sodium thiosulfate and saline and group III was irrigated with 2.5% NaOCl and saline. The tooth length 14 mm measured from apical to crown. The crown down technique was prepared using the M3 Pro gold file. Observation of the level of cleanliness of the root canal was carried out using a Scanning Electron Microscope (SEM) with 5000x magnification at apical third . The results of micrographic photographs are then given a score of 1-4. Result: Irrigated with 5% and 10% sodium thiosulfate showed no significant difference. Conclusion: The differences is not significant, 2,5% irrigation with sodium thiosulfate resulted in a higher cleanliness apical third of the root canalthan 2,5% NaOCl irigation with saline