Human Dental Tissues Research Articles

Mesenchymal Stem/Stromal Cells Derived from Dental Tissues Mediate the Immunoregulation of T Cells through the Purinergic Pathway.

Human dental tissue mesenchymal stem cells (DT-MSCs) constitute an attractive alternative to bone marrow-derived mesenchymal stem cells (BM-MSCs) for potential clinical applications because of their accessibility and anti-inflammatory capacity. We previously demonstrated that DT-MSCs from dental pulp (DP-MSCs), periodontal ligaments (PDL-MSCs), and gingival tissue (G-MSCs) show immunosuppressive effects similar to those of BM, but to date, the DT-MSC-mediated immunoregulation of T lymphocytes through the purinergic pathway remains unknown. In the present study, we compared DP-MSCs, PDL-MSCs, and G-MSCs in terms of CD26, CD39, and CD73 expression; their ability to generate adenosine (ADO) from ATP and AMP; and whether the concentrations of ADO that they generate induce an immunomodulatory effect on T lymphocytes. BM-MSCs were included as the gold standard. Our results show that DT-MSCs present similar characteristics among the different sources analyzed in terms of the properties evaluated; however, interestingly, they express more CD39 than BM-MSCs; therefore, they generate more ADO from ATP. In contrast to those produced by BM-MSCs, the concentrations of ADO produced by DT-MSCs from ATP inhibited the proliferation of CD3+ T cells and promoted the generation of CD4+CD25+FoxP3+CD39+CD73+ Tregs and Th17+CD39+ lymphocytes. Our data suggest that DT-MSCs utilize the adenosinergic pathway as an immunomodulatory mechanism and that this mechanism is more efficient than that of BM-MSCs.

Microhardness and characterization of human dental tissue after application of enzymatic chemical agents: In vitro study.

The use of enzymatic chemical agents are papain-based materials used in the selective removal of decayed dentin tissue, assisting in conservative techniques and reducing the chances of accidental pulp exposure. A research protocol was subjected to and approved by an Ethics Committee. Using a reporting guide for laboratory studies (CRIS). Healthy human teeth comprised the produced dentin discs subjected to polishing and washing in an ultrasonic bath. Next, the discs received material application according to the experimental groups: water-soluble gel for two minutes, 37% phosphoric acid for 15 seconds in dentin and 30 seconds in enamel, Papacárie Duo (PD) for 30 seconds and two minutes, and Brix 3000 (BX) for two minutes and 30 seconds. The measurement of material pH used solutions at concentrations of 0.1 ml and 2.7 ml prepared for each enzymatic agent. Then, a bench pH meter (n=10) and pH indicator strips determined pH values. The discs underwent the Knoop hardness test (n=10). The sample calculation was performed using the GPower software with α = 0.05, effect 0.63 and power of 95%. Descriptive statistical analysis was carried out for pH, one way ANOVA supplemented by Tukey for knoop hardness and Spearman correlation for pH measurement techniques. The enamel hardness findings indicated that, after material application, ECAs do not statistically differ from water-soluble gel (p<0.05). The dentinal hardness analysis presented a statistical difference in phosphoric acid from the other groups (p<0.05). In the pH test, BX values were lower (4.37 ± 0.01) than PD (4.85 ± 0.06). The groups statistically differed (p<0.05). ECAs for removing decayed dentin tissue did not significantly alter the hardness of enamel and dentin, removal of the smear layer is time-dependent and presents acidity. Key words:Dental caries, Hardness, Dental materials, Papain.

Deciphering the fate of granulation tissue in the human inflammatory alveolar microenvironment using single-cell RNA sequencing

Objective: To investigate the cellular composition and heterogeneity of granulation tissue in human alveolar sockets and construct single-cell transcriptomic maps to elucidate the potential outcomes of natural resolution in the inflammatory microenvironment. Methods: Granulation tissues from 12 alveolar sockets undergoing tooth extraction due to periodontitis and scheduled for delayed site preservation or autologous tooth transplantation were collected in the Department of Oral and Maxillofacial Surgery, School of stomatology Fourth Military Medical University from September 2022 to August 2023. This study used HE staining and single-cell RNA sequencing (scRNA-seq) to observe the cellular composition and morphological changes of different types of granulation tissues. This approach enabled us to identify cellular sequence variations in the inflammatory dental alveolar granulation tissue within specific microenvironments, construct single-cell atlases for different types of human dental alveolar granulation tissues, and explore the spatiotemporal patterns of cell type distribution and key gene changes during the resolution process of inflammatory granulation tissue. Results: HE staining revealed extensive infiltration of inflammatory cells in the dental alveolar inflammatory granulation tissue. After allowing the inflammatory granulation tissue to naturally resolve for three weeks, its histological morphology was essentially consistent with that of reparative granulation tissue. ScRNA-seq captured a total of 20 448 cells from granulation tissues, and the gene expression quantification analysis revealed total gene counts of 33 835 for inflammatory granulation tissue, 36 058 for naturally resolved granulation tissue, and 34 719 for reparative granulation tissue. At the single-cell level, granulation tissue was annotated into ten cell subgroups, including vascular endothelial cells, mesenchymal stem cells, and fibroblasts. Differences were observed in the proportion of cell compositions between inflammatory and naturally resolved granulation tissues. Pseudo-temporal analysis illustrated two main outcomes in tissue resolution and healing, involving immune responses and angiogenesis. Among these, genes associated with inflammation regulation and immune response, such as Igbp5, Zfp36, and Hspa1b, as well as genes involved in extracellular matrix secretion and the formation of vessels and fibers such as Timp3, Postn, and Rgs5, showed significant differences in expression between the two types of granulation tissues. Conclusions: Inflammatory granulation tissue exhibits heterogeneity in cell composition, gene expression, and biological functions compared to naturally resolved granulation tissue. When the inflammatory granulation tissue in the alveolar socket is left undisturbed to undergo natural resolution, it displays a cellular composition similar to that of reparative granulation tissue at both the histological and single-cell levels. Moreover, it modulates the inflammatory response and the healing process through immune reactions and tissue remodeling.

A V-shaped bis-coumarin based fluorescence probe for F- detection in tea infusions and potable water and bioimaging applications in living systems

Fluorine (F) is a pivotal element in the formation of human dental and skeletal tissues, and the consumption of water and tea constitutes a significant source of fluoride intake. However, prolonged ingestion of water and tea with excessive fluoride content can lead to fluorosis, which poses a serious health hazard. In this manuscript, a novel turn-on fluorescent probe DCF synthesized by bis-coumarin and tert-butyldiphenylsilane (TBDPS) was introduced for detecting F- in potable water and tea infusions. By leveraging the unique chemical affinity between fluoride and silicon, F- triggers the silicon-oxygen bond cleavage in DCF, culminating in a conspicuous emission of yellow fluorescence. Validated through a succession of optical tests, this probe exhibits remarkable advantages in terms of superior selectivity, a low detection limit, a large Stokes shift, and robust interference resistance when detecting inorganic fluoride. Moreover, it can serve as portable test strips for on-site real-time identification and quantitative analysis of F-. Furthermore, the application of DCF for in-situ monitoring and imaging of F- in zebrafish and soybean root tissues proved its significant value for F- detection in both animal and plant systems. This probe potentially functions as an efficient instrument for delving into the toxic mechanisms of fluoride in physiological processes.

Correction to: Nd: YAG laser irradiation consequences on calcium and magnesium in human dental tissues

Correction to: Nd: YAG laser irradiation consequences on calcium and magnesium in human dental tissues

Erosive potential of vitamin waters, herbal drinks, carbonated soft drinks, and fruit juices on human teeth: An in vitro investigation.

Dental erosion is the loss of dental hard tissues through the acid dissolution of tooth minerals. One of the major factors that cause erosion is the consumption of acidic food and drinks. This study investigated and compared the effect of vitamin waters, herbal beverages, carbonated soft drinks, and fruit juices on the loss of human dental hard tissue. Human tooth samples were immersed in various drinks: vitamin waters, herbal beverages, carbonated soft drinks, and fruit juices. The pH value of each drink was measured using a pH meter. The weight of each sample was determined before and after six days of immersion in the tested drink, and the weight loss percentage was calculated. The exposed tooth surfaces were also examined under a scanning electron microscope. Most of the tested drinks were acidic and displayed pH values lower than the critical pH for enamel erosion. Significant weight loss of the tooth samples was found in all tested drink groups. Additionally, the samples immersed in fruit juices and herbal beverages exhibited significantly greater weight loss than those immersed in carbonated soft drinks. Scanning electron micrographs showed samples immersed in the tested drinks to demonstrate structural disintegration with occasional void spaces, except for samples immersed in Doi Kham® Lemongrass drink. Most of the tested drinks have the potential to cause dissolution and destruction of dental hard tissues. Consumers should be aware that prolonged exposure to these drinks could lead to permanent loss of tooth mineral and dental erosion.

Erosion behaviour of human, bovine and equine dental hard tissues

Dental hard tissues from different species are used in dental research, but little is known about their comparability. The aim of this study was to compare the erosive behaviour of dental hard tissues (enamel, dentin) obtained from human, bovine and equine teeth. In addition, the protective effect of the pellicle on each hard tissue under erosive conditions was determined. In situ pellicle formation was performed for 30 min on enamel and dentin samples from all species in four subjects. Calcium and phosphate release was assessed during 120 s of HCl incubation on both native and pellicle-covered enamel and dentin samples. SEM and TEM were used to examine surface changes in native enamel and dentin samples after acid incubation and the ultrastructure of the pellicle before and after erosive exposure. In general, bovine enamel and dentin showed the highest degree of erosion after acid exposure compared to human and equine samples. Erosion of human primary enamel tended to be higher than that of permanent teeth, whereas dentin showed the opposite behaviour. SEM showed that eroded equine dentin appeared more irregular than human or bovine dentin. TEM studies showed that primary enamel appeared to be most susceptible to erosion.

Composite materials of amorphous calcium phosphate and bioactive glass nanoparticles for preventive dentistry

Amorphous calcium phosphates and bioactive glasses are two of the most used materials in dentistry thanks to their ability to release remineralizing ions and reduce dentinal hypersensitivity by occluding exposed dentinal tubules. Here, we have synthesized composites of fluoride-doped amorphous calcium phosphate (FACP) and mesoporous bioactive glass nanoparticles (MBGNs) to obtain functional materials that possess both the capability to release dental remineralizing ions of FACP and both the excellent desensitizing activity of MBGNs. The procedure described in this work allows us to obtain FACP/MBGN composites with different compositions (i.e., FACP:MBGN weight ratio) in which the components have formed a deeply intertwined nanostructure. Composites’ ion release (i.e. Ca, P, F, and Si) in acidic artificial saliva is different from that of the single components or their physical mixture, corroborating the formation of composite materials. Moreover, thanks to the presence of FACP, the composites have superior bioactivity than the MBGNs alone. Dental enamel remineralization and efficacy of dentinal tubules occlusion by the investigated composites were preliminarily tested in vitro on human dental hard tissues using scanning electron microscopy. Data revealed that the composites induced a satisfactory remineralization of enamel and dentin thanks to the FACP component, and a positive tubule occlusion thanks to the MBGNs component. Finally, our results demonstrate that FACP/MBGN composites are highly promising materials for preventive dentistry.

Three-Dimensional Culture of Human Dental Pulp Tissue: A Preliminary Experimental In Vitro Model for Regenerative Endodontic Procedures

Introduction: Dental pulp regeneration is fundamental in dentistry and endodontics; however, few in vitro experimental models are available to study its biological process. This study aimed to develop a three-dimensional (3D) culture model of human dental pulp-like tissue mimicking the possible complexity of human pulp tissue. This new and innovative human-like tissue model could be used for testing drugs and materials, particularly those involved in regenerative endodontics. Methods: Vital pulp tissue samples were obtained from human third molars (n = 4) immediately after extraction and cultured in a 3D fibrin matrix to create a sustainable ex vivo experimental model. The angiogenesis degrees and the nitric oxide levels were evaluated following the culture of pulp-like tissues in the fibrin matrix for 21 days. The expression of Transforming growth factor- beta (TGF-β1), TGF-β2, TGF-β3, and their relevant receptors, tumor necrosis factor (TNF) and vascular endothelial growth factor A (VEGFA) was evaluated using a reverse transcription polymerase chain reaction (RT-PCR) method. Results: Pulp tissue angiogenesis was initiated, and completed on days 7 and 21, and pulp-like tissue cells expressed TGF-β1, TGF-β2, TGF-β3, and their relevant receptors, TNF and VEGFA. Conclusion: This model provided a precise observation of dental pulp angiogenesis at early stages.

A novel ODAPH mutation causing amelogenesis imperfecta and its expression in human dental tissues

Background/purposeAmelogenesis imperfecta (AI), an assemblage of genetic diseases with dental enamel malformations, is generally grouped into hypoplastic, hypomaturation, and hypocalcified types. This study aimed to identify the genetic etiology for a consanguineous Iranian family with autosomal recessive hypocalcified AI. Materials and methodsDental defects were characterized, and whole exome analysis conducted to search for disease-causing mutations. Minigene assay and RT-PCR were performed to evaluate molecular consequences of the identified mutation and expression of the causative gene in human dental tissues. ResultsThe defective enamel of erupted teeth showed extensive post-eruptive failure and discoloration. Partial enamel hypoplasia and indistinct dentino-enamel junction were evident on unerupted teeth, resembling hypocalcified AI. A novel homozygous ODAPH (previously designated C4orf26) mutation of single-nucleotide deletion (NG_032974.1:g.5103del, NM_178497.5:c.67+1del) was identified to be disease-causing. The mutation would cause a frameshift to different ODAPH transcript variant (TV) products: p.(Ala23Hisfs∗29) for TV1 and p.(Gly23Aspfs∗140) for TV2. Both dental pulps of developing and exfoliating primary teeth expressed ODAPH TV2. ConclusionLoss-of-function ODAPH mutations can cause AI type IIIB (the hypocalcified, autosomal recessive type), rather than type IIA4 (the hypomaturation, pigmented autosomal recessive type). This study supports a hypothesis that the product of ODAPH TV2 is the single dominant ODAPH protein isoform critical for dental enamel formation and may also play an unappreciated role in development and homeostasis of dentin-pulp complex. Due to genetic heterogeneity and a nonideal genotype-phenotype correlation of AI, it is essential to perform genetic testing for patients with inherited enamel defects to make a definitive diagnosis.

Comparison of human dental tissue RNA extraction methods for RNA sequencing

ObjectiveThe purpose of this study was to identify an efficient RNA extraction method for periodontal ligament (PDL) and dental pulp (DP) tissues to be used in RNA sequencing studies, given the increased use of these techniques in dental research and the lack of standard protocols. DesignPDL and DP were harvested from extracted third molars. Total RNA was extracted with four RNA extraction kits. RNA concentration, purity and integrity were assessed by means of NanoDrop and Bioanalyzer and statistically compared. ResultsRNA from PDL was more likely to be degraded than that of DP. The TRIzol method yielded the highest RNA concentration from both tissues. All methods harvested RNA with A260/A280 close to 2.0 and with A260/A230 above 1.5, except for the A260/A230 from PDL obtained with the RNeasy Mini kit. For RNA integrity, the RNeasy Fibrous Tissue Mini kit yielded the highest RIN values and 28 S/18 S from PDL, while the RNeasy Mini kit obtained relatively high RIN values with an appropriate 28 S/18 S for DP. ConclusionSignificantly different results were obtained for PDL and DP when using the RNeasy Mini kit. The RNeasy Mini kit provided the highest RNA yields and quality for DP, while the RNeasy Fibrous Tissue Mini kit obtained the highest quality RNA from PDL.

Structural Features of Oxyapatite

One of the most widely known representatives of the apatite family is hydroxyapatite, Ca10(PO4)6(OH)2. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine. Less known is oxyapatite, Ca10(PO4)6O, which has the same biocompatibility as hydroxyapatite. In this work, it is shown that oxyapatite can be obtained by heating hydroxyapatite powder at 1000 °C in vacuum. IR and NMR spectroscopy proved the absence of the hydroxyl groups in the apatite obtained. In the IR spectrum, the presence of new absorption bands of phosphate groups, indicating a symmetry disorder, was observed. Density functional theory modeling confirmed lowering of symmetry for the oxyapatite structure. Modeling the IR spectrum of oxyapatite made it possible to identify the experimentally observed new absorption bands. According to the modeling, the presence of a vacancy in a hydroxyl channel of the apatite structure lowered the symmetry. Powder X-ray diffraction data confirmed that full dehydroxylation of hydroxyapatite led to a decrease in symmetry to triclinic phase. Comparison of the formation energies showed that formation of the hydroxyapatite phase was more preferable than that of oxyapatite, which explains apatite’s tendency to rehydroxylation. It was shown that the solubility of oxyapatite in water was comparable to that of hydroxyapatite.

Evaluation of elements in human dental tissue in terms of determination of postmortem interval: Experimental study

Despite many methods, there has not been a method yet that exactly determines PMI. This study aims to examine the relationship between the element levels in the dental tissue and the postmortem process in a corpse whose exact time of death is unknown and in the open field and to evaluate its use in determining the time of death by evaluating the increase-decrease-changes. For the study, the healthy and extracted third molars of the patients who applied to the Oral and Maxillofacial Surgery Polyclinic for the extraction of their third molars for various reasons and whose third molars were extracted by the dentists were taken. The samples were divided into 6 groups, with 10 samples in each group. The teeth were left to decay in the open air in a jaw-like plastic model. Na, Mg, P, Ca, Fe, Mn, Co, Zn, Cd, Pb, and Si elements were measured using Inductively Coupled Plasma-Mass Spectrometer analysis method. In our study, it was determined that there were statistically significant changes in the Na, Mg, Fe, Co, Pb, Si elements in the tooth structure. For the Co and Na elements, 2 regression equations were created that can be used to predict the time of death. This work showed that postmortem tooth element concentration changes can be used to predict the time of death. As a result of experiments that will cover longer periods with more elements and be carried out in different environments, a great contribution will be made to the subject of estimation of time of death which is not clear yet.

Effects of Infantile Hypophosphatasia on Human Dental Tissue

Hypophosphatasia (HPP) is an inherited, systemic disorder, caused by loss-of-function variants of the ALPL gene encoding the enzyme tissue non-specific alkaline phosphatase (TNSALP). HPP is characterized by low serum TNSALP concentrations associated with defective bone mineralization and increased fracture risk. Dental manifestations have been reported as the exclusive feature (odontohypophosphatasia) and in combination with skeletal complications. Enzyme replacement therapy (asfotase alfa) has been shown to improve respiratory insufficiency and skeletal complications in HPP patients, while its effects on dental status have been understudied to date. In this study, quantitative backscattered electron imaging (qBEI) and histological analysis were performed on teeth from two patients with infantile HPP before and during asfotase alfa treatment and compared to matched healthy control teeth. qBEI and histological methods revealed varying mineralization patterns in cementum and dentin with lower mineralization in HPP. Furthermore, a significantly higher repair cementum thickness was observed in HPP compared to control teeth. Comparison before and during treatment showed minor improvements in mineralization and histological parameters in the patient when normalized to matched control teeth. HPP induces heterogeneous effects on mineralization and morphology of the dental status. Short treatment with asfotase alfa slightly affects mineralization in cementum and dentin. Despite HPP being a rare disease, its mild form occurs at higher prevalence. This study is of high clinical relevance as it expands our knowledge of HPP and dental involvement. Furthermore, it contributes to the understanding of dental tissue treatment, which has hardly been studied so far.

Qualitative Histological Evaluation of Various Decalcifying Agents on Human Dental Tissue.

Dental hard tissue is among the hardest tissue of humans because it contains high amounts of inorganic substances. This leads to difficulty in preparing histological sections for histopathological examination. Acid and chelating agents are generally used to decalcify teeth. We aimed to compare the histological quality of teeth decalcified with various calcifying agents including 5% nitric acid, 50% formic acid with 20% sodium citrate (Anna Morse solution), 10% formic acid, commercial solution, and 14.4% neutral EDTA. Freshly extracted premolar teeth were fixed and submitted for decalcification using different agents. Histological examination was qualitatively evaluated for tissue integrity and staining quality. Dentin integrity of teeth decalcified with all decalcifying agents did not show any statistical differences except that with the formic acid, whereas cementum integrity decalcified with neutral EDTA showed a superior score compared with other agents. Tissue integrity and staining quality of dental pulp cells were the best decalcified with neutral EDTA or Anna Morse solution. Our findings demonstrated that EDTA and Anna Morse solution gave a similar efficiency in the preservation of tissue integrity while Anna Morse solution may be recommended as a decalcification agent in routine use due to the more satisfying decalcification time than EDTA.

Effect of Ta Content on Microstructure and Phase Transformation Temperatures of Ti75.5-Nb25.5 (%at.) Alloy

β-titanium shape memory alloys are used as shape memory-based biomedical applications and superelastic materials because they are made up of non-toxic components. Also, their behaviors are more semilar with that of human bone and dental biological tissues, such as biocompatibility, superior corrosion resistance, low density, and low modulus of elasticity. In the current study, the effect of Ta additive on the physical properties of Ti-Nb alloy has been investigated. Ti-Nb-Ta alloy samples were produced such that the Tantalum (Ta) element was substituted instead of Niobium (Nb), and the induction arc melting was used to melting the mixed powders. To investigate the crystal structure, microstructure, and phase transformation temperatures of all samples, the X-Ray Diffraction (XRD), Scanning Electron Microscopic (SEM), and Diffraction Scanning Calorimetry (DSC) measurements have been used. Both β-rich and α peaks were observed in the XRD and SEM measurements. Also, the DSC results revealed that the Ti-Nb-Ta alloys have only austenite transformation temperatures and their phase austenite phase transformation were decreased by the effect of Ta additive, additionally, the enthalpy change in〖 E〗_3 sample ( Ti_75.5 Nb_22.5 Ta_2 (%at)) has the highest value, while E_4 sample ( Ti_75.5 Nb_21.5 Ta_3 (%at)) has the lowest respective value.

Dental follicle cells show potential for treating Parkinson's disease through dopaminergic-neuronogenic differentiation.

Among all the adult stem cells, odontogenic stem cells inherit the characterization of neurogenic potential of their precursor ones-the cranial crest cells. Dental follicle cells (DFCs), one of the special kind of odontogenic stem cells, are raising interest in applying to regenerative medicine for they possess multi-differentiation potential, relatively free access and ethic-friendly characteristic. Parkinson's disease (PD), as one of the common neurodegenerative disorders, affects about 0.3% of the general population. Stem cell therapies are thought to be effective to treat it. Aiming at tackling ethical-concernings, confined sources and practically applicational limits, we made use of dopaminergic neurongenic differentiation potential of the DFCs and dedicated every effort to applying them as promising cell source for treating PD. Dental follicle cells were cultured from human dental follicle tissues collected from 12 to 18-year-old teenagers' completely impacted third molars. Our data demonstrated that hDFCs were expressing mesenchymal stem cell-associated surface markers, and possessed the ability of osteogenic, adipogenic and neurogenic differentiation in vitro. Additionally, hDFCs formed neuron-like cells in vitro and in vivo, as well as expressing dopaminergic-neuronogenic marker-TH. Moreover, hDFCs survived in the transplanted areas of the Parkinson's disease model of mouse over six weeks post-surgery, and the number of TH-positive DFCs in the DFCs-Grafted group surpassed its counterpart of the MPTP group with statistically significant difference. This study indicated that hDFCs might be a promising source of dopaminergic neurons for functional transplantation, and encouraged further detailed studies on the potential of hDFCs for treating PD.

Nd: YAG laser irradiation consequences on calcium and magnesium in human dental tissues

Nd: YAG laser irradiation consequences on calcium and magnesium in human dental tissues

The nature of metabolic processes in human dental hard tissues depending on their morphological structure

Was to give a comparative assessment of the movement of enamel and dentin fluid depending on the morphological structure of different sections of human dental hard tissues. The research involved 140 female subjects aged 21-30 years. Sizes, form, surface of enamel-dentin junction, enamel prisms and their crystals in superficial, middle and deep sections, width, tortuosity, facing of dentin tubules of tested teeth were analyzed by scanning electron microscope Jeol JCM-5700 and atomic force microscope NTEGRA Prima. The biochemical study examined the quantitative content of water in the samples of enamel, dentin, enamel-dentin junction by weighing sample weights before and after drying. The data obtained were processed by methods of variation statistics using standard packages Microsoft Excel 2008, Statistica 12.0. The enamel-dentine junction of large-fastened type is characterized by zones of dentin integration into enamel at the distance of more than 10 mm, with regular arrangement of enamel prisms and wide dentine tubules of 3.55 to 4.70 μm in diameter; no water content reduction was found. The small-fastened type has less pronounced spots of dentin interference with enamel from 2 to 10 μm, the dentinal tubules are slightly curved with a diameter of 2.90 to 3.60 μm, the water content in dentin is reduced. In microfastened type, a linear structure with interpenetration zones up to 2 μm, enamel prisms slightly ordered, dentin tubules narrowed and curved in diameter from 1.30 to 1.95 μm, water content in enamel and dentin is reduced. At microfastened type of enamel-dentin junction, chaotic arrangement of enamel prisms and narrow dentin tubules water movement is broken and metabolic processes are reduced that determines high probability of exposure of dental hard tissue diseases.

Biomimetic strategy of a hybrid biointerface creation between native human dental tissue and dental composite

The aim of the studyis the peculiarities of the molecular composition of the biointerface between the native human dental tissue and the dental composite, created in an alkaline environment, based on synchrotron chemical infrared micro-mapping. When creating a biomimetic interface under alkaline conditions, we used an original bioprimer, dentin conditioner, nanofilled universal adhesive, and a light-curing compomer based on BIS-GMA. Biointerface analysis was carried out on the basis of chemical infrared micro-mapping, implemented using the equipment of the Australian Synchrotron, and subsequent multivariate cluster analysis of the collected spectral data array. It was shown that the use of a primer modified with a set of polar amino acids additionally facilitated the opening of dentinal tubules and the penetration of the bioprimer components into the dentin with the formation of a deeper transitional hybrid layer. At the same time, modification of the Bis-GMA adhesive using nanocrystalline carbonate-substituted hydroxyapatite, which has a structural and morphological organization similar to natural dental tissue apatite, led to an increase in the degree of conversion of the used adhesive material during polymerization. Using a biomimetic strategy and nanocrystals of carbonate-substituted hydroxyapatite as a filler of a universal adhesive, the necessary conjugation at the interface with dentin can be achieved without disrupting the polymerization processes, as well as preserving the natural structural complexity of the intact tissue, which makes it possible to take into account the individual characteristics of the patient.