Dentin Tissue Research Articles

Total Pulpotomy with MTA in Young Permanent Teeth: Case Series

Vital pulp therapy is a way to preserve the vitality and function of pulp damaged by trauma, caries or restorative procedures. Vital pulp therapy procedures include direct pulp capping, indirect pulp capping, partial and coronal pulpotomy treatments where diseased pulp tissue is removed. Over the years, the focus of vital pulp therapy has been on the preservation of the radicular pulp in immature permanent teeth to ensure the completion of root formation (apexogenesis). Today, it has been reported that vital pulp therapy can be considered as an alternative to root canal treatment, including in teeth with certain conditions that are considered to have irreversibly inflamed pulp. Coronal amputation therapy, a vital pulp treatment, involves complete removal of the coronal pulp, placement of a biologically acceptable material into the pulp chamber and restoration. The covering material must be able to relieve inflammation and initiate healing of the pulp tissue and allow new dentin tissue to form. The oldest material used in pulpotomy is calcium hydroxide. Mineral trioxide aggregate, which is a more recent material, is frequently preferred today due to its biocompatible and bioactive properties. In this case report, the results of 4 cases of coronal pulpotomy with mineral trioxide aggregate in young permanent teeth with a follow-up of 18 months are presented.

Evaluation of Shear Bond Strength of Universal Adhesives to Dentin: in Vitro Study

Aim: Universal adhesives are widely used in restorative dentistry. The aim of this study was to evaluate the shear bond strength (SBS) of universal adhesives to dentin in different application modes. Materials and Methods: The study utilized seven universal adhesives and one total-etch adhesive. The sixty-four extracted intact human molars used in the study were embedded in acrylic blocks to the enamel-cement junction. The occlusal surface was removed to expose the dentin surface. After applying self-etch and total-etch adhesives to the dentin, flowable composite (Clearfil Majesty Flow, Kuraray) was placed in a transparent mold (2.38 mm diameter and 2 mm height) and polymerized. After thermal aging (1000 cycles), a SBS test has been carried out on a universal testing machine. The fracture types formed on the surface of the teeth were examined under a microscope. Data were analyzed by two-way analysis of variance (ANOVA) test (p<0.05). Results: SBS values of universal adhesives on dentin showed statistically significant differences according to adhesive and application mode (p<0.05). Total-etch application produced statistically higher SBS than self-etch application (p<0.05). The two-step universal adhesive (G2 Bond Universal) had the highest SBS in both the self-etch and total-etch application modes (p<0.05). When the bond surfaces of the universal adhesives were examined, fractures occurred most frequently in the adhesive type. Conclusion: The use of universal adhesives in the total-etch mode results in greater bond strength to dentin tissue. Universal adhesive type influences bond strength.

The comparative evaluation of cell viability, inflammatory response, and antimicrobial activity of calcium hydroxide-bovine dentin grain

Abstract Objectives Dentin tissue can act as a reservoir for bioactive molecules that create signals for cellular proliferation and differentiation to initiate tissue regeneration. Therefore, the aim of this study is to compare the cell viability, inflammatory response, and antimicrobial activity of bovine dentin grain-added calcium-hydroxide (CH-BDG) with different pulp-capping materials. Methods ProRoot MTA, Biodentine, Dycal, TheraCal-LC, and an experimental material, CH-BDG, were examined. Cell viability was determined via the WST-1 assay. The inflammatory response was analysed by the monocyte chemoattractant protein-1 (MCP-1/CCL2) and macrophage inflammatory protein-1α (MIP-1α/CCL3) levels. The antimicrobial activity was evaluated by agar-diffusion. Results The cell viability of CH-BDG was analogous with Biodentine and control at 24 h. The cell viability of CH-BDG decreased at 48 h, but the rate was higher than ProRoot MTA and Dycal (p<0.05). For MCP-1 and MIP-1α values, there was no significant difference between the control and CH-BDG. The MCP-1 level of CH-BDG was lower compared to other pulp-capping materials (p<0.05). The MIP-1α level of CH-BDG was lower compared to ProRoot MTA, Biodentine, and TheraCal-LC (p<0.05). No inhibition zone was detected against oral microorganisms for CH-BDG. Conclusions The experimentally developed CH-BDG showed competing properties and additional advantages compared to the existing pulp-capping materials.

Comparison of the biomechanical effects of the post-core crown, endocrown and inlay crown after deep margin elevation and its clinical significance

BackgroundThe purpose of this in vitro study was to compare and evaluate the stress distribution of maxillary first premolar residual crowns restored with post-core crowns, endocrowns and inlay crowns after deep margin elevation, to explore the fitting restoration for residual crowns using finite element analysis.MethodsA healthy complete right maxillary first premolar from a male adult was scanned by cone beam computed tomography (CBCT). The finite element model of the tooth was established by reverse engineering software such as Mimics, Geomagic and Hypermesh. On this basis, the residual crown model after deep margin elevation was made, and the experimental group models were divided into three groups, those restored with post core crowns, endocrowns and inlay crowns. Vertical and oblique static loads were applied to the experimental models to simulate the force on the tooth during mastication (the loading position was located in the central fossa of the occipital surface, and the load was 100 N) using Abaqus software.ResultsThe peak value and distribution of von Mises stress in each part of the experimental model were observed. After deep margin elevation, the peak dentin von Mises stresses were lower than the tensile strength of normal dentin in the post-core crown, endocrown, and inlay crown groups; the lowest stress results were found in the post-core crown group for the dentin, restoration, enamel, and deep margin elevation (DME) layers under vertical and oblique loading. In terms of stress distribution clouds, the peak stresses in the dentin tissue were located in the apical 1/3 of the root after postcore crown restorations for both loads, while stress concentrations were evident in the cervical and root areas after endocrown and inlay crown restorations; regardless of the load and restoration method, the corresponding stress concentration areas appeared at the junction of the DME and dentin tissue at the loading site of the restorations;ConclusionsPost-core crowns, endocrowns and inlay crowns can be used to restore residual crowns after deep margin elevation, and post-core crowns can better protect the residual tooth tissue.

Evolution, development, and regeneration of tooth-like epithelial appendages in sharks

Sharks and their relatives are typically covered in highly specialized epithelial appendages embedded in the skin called dermal denticles; ancient tooth-like units (odontodes) composed of dentine and enamel-like tissues. These ‘skin teeth’ are remarkably similar to oral teeth of vertebrates and share comparable morphological and genetic signatures. Here we review the histological and morphological data from embryonic sharks to uncover characters that unite all tooth-like elements (odontodes), including teeth and skin denticles in sharks. In addition, we review the differences between the skin and oral odontodes that reflect their varied capacity for renewal. Our observations have begun to decipher the developmental and genetic shifts that separate these seemingly similar dental units, including elements of the regenerative nature in both oral teeth and the emerging skin denticles from the small-spotted catshark (Scyliorhinus canicula) and other chondrichthyan models. Ultimately, we ask what defines a tooth at both the molecular and morphological level. These insights aim to help us understand how nature makes, replaces and evolves a vast array of odontodes.

Comparative evaluation of the effect of 2% graphene oxide and 5% hydroxyapatite nanoparticles in isolation and in combination on micro tensile bond strength of 5th generation adhesive

Background Graphene is the thinnest, strongest, and stiffest imaginable material. The biocompatible property of graphene oxide can initiate and facilitate cell adhesion, proliferation, and differentiation of periodontal ligament, osteogenic, and oral epithelial cells. Furthermore, the antibiofilm and anti-adhesion properties of graphene oxide in the prevention of dental biofilm infections, dental caries, and dental erosion as well as for implant surface modification and as an anti-quorum sensing agent. Composites are the most often utilized materials for restoration in the field of dentistry due to adhesive resins' improved mechanical and cosmetic properties. To safeguard the dentin and prevent dental cavities, dentin adhesives are utilized to affix hydrophobic resin composites to hydrophilic dentin tissue. Materials and Method Dental adhesives have a harder time adhering to dentin because it contains more water and is less mineralized than enamel. This makes the method more sensitive. Result As a result, it was chosen to assess and contrast the impact of 5% Hydroxyapatite nanoparticles and 2% Graphene oxide nanoparticles, both separately and together, on the Micro tensile bond strength of 5th generation adhesive. Conclusion Graphene oxide is the most versatile form of Graphite in structural and functional configuration. Graphene oxide possesses extraordinary physical, chemical, optical, electrical and mechanical properties. Among the graphene family nanomaterials, the reduced form of Graphite adding the oxygenated functional group to the structure increases the surface area and therefore exhibits enviable excellent interaction ability with metal and ions as well as organic species. Graphene oxide in dentistry has provided outstanding results in antimicrobial action, regenerative dentistry, bone tissue engineering, drug delivery, physicochemical properties, enhancement of dental biomaterials and oral cancer treatment.

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.

Photo-crosslinkable hydrogel incorporated with bone matrix particles for advancements in dentin tissue engineering.

The objective of this study was to create injectable photo-crosslinkable biomaterials, using gelatin methacryloyl (GelMA) hydrogel, combined with a decellularized bone matrix (BMdc) and a deproteinized (BMdp) bovine bone matrix. These were intended to serve as bioactive scaffolds for dentin regeneration. The parameters for GelMA hydrogel fabrication were initially selected, followed by the incorporation of BMdc and BMdp at a 1% (w/v) ratio. Nano-hydroxyapatite (nHA) was also included as a control. A physicochemical characterization was conducted, with FTIR analysis indicating that the mineral phase was complexed with GelMA, and BMdc was chemically bonded to the amide groups of gelatin. The porous structure was preserved post-BMdc incorporation, with bone particles incorporated alongside the pores. Conversely, the mineral phase was situated inside the pore opening, affecting the degree of porosity. The mineral phase did not modify the degradability of GelMA, even under conditions of type I collagenase-mediated enzymatic challenge, allowing hydrogel injection and increased mechanical strength. Subsequently, human dental pulp cells (HDPCs) were seeded onto the hydrogels. The cells remained viable and proliferative, irrespective of the GelMA composition. All mineral phases resulted in a significant increase in alkaline phosphatase activity and mineralized matrix deposition. However, GelMA-BMdc exhibited higher cell expression values, significantly surpassing those of all other formulations. In conclusion, our results showed that GelMA-BMdc produced a porous and stable hydrogel, capable of enhancing odontoblastic differentiation and mineral deposition when in contact with HDPCs, thereby showing potential for dentin regeneration.

Enhancing clinical safety in bioengineered-root regeneration: The use of animal component-free medium

BackgroundMost studies used animal serum-containing medium for bioengineered-root regeneration, but ethical and safety issues raised by animal serum are a potentially significant risk for clinical use. Thus, this study aimed to find a safer method for bioengineered-root regeneration. MethodsThe biological properties of human dental pulp stem cells (hDPSCs) cultured in animal component-free (ACF) medium or serum-containing medium (5%, 10% serum-containing medium, SCM) were compared in vitro. hDPSCs were cultured in a three-dimensional (3D) environment with human-treated dentin matrix (hTDM). The capacity for odontogenesis was compared using quantitative real-time PCR (qPCR) and Western blot. Subsequently, the hDPSCs/hTDM complexes were transplanted into nude mice subcutaneously. Histological staining was then used to verify the regeneration effect in vivo. ResultsACF medium promoted the migration of hDPSCs, but slightly inhibited the proliferation of hDPSCs in the first three days of culture compared to SCM. However, it had no significant effect on cell aging and apoptosis. After 7 days of 3D culture in ACF medium with hTDM, qPCR showed that DMP1, DSPP, OCN, RUNX2, and β-tubulin III were highly expressed in hDPSCs. In addition, 3D cultured hDPSCs/hTDM complexes in ACF medium regenerated dentin, pulp, and periodontal ligament-like tissues similar to SCM groups in vivo. ConclusionACF medium was proved to be an alternative medium for bioengineered-root regeneration. The strategy of using ACF medium to regenerate bioengineered-root can improve clinical safety for tooth tissue engineering.

Comparative histologic evaluation of teeth decalcified by conventional method versus microwave induced decalcification

Abstract Introduction: Complete demineralization of hard tissues with preservation of organic components to retain their tissue architecture and to obtain thin section for histological examination is done by a process known as “decalcification”. Tooth decalcification may be achieved by subjecting the tissue to a decalcifying chemical agent and employing heat, vacuum, or electric current to enhance the procedure. Completion of decalcification is adjudged by determination of end-point. Histological examination of hard tooth tissues and pulp is essential for diagnosis of developmental pathologies, pulp pathologies, and forensic odontology analysis as well as for research purpose. Aim: In our study, we studied the time consumed for decalcification procedure by conventional decalcification method and with the microwave-assisted decalcification method for teeth, using 5% nitric acid, 5% trichloracetic acid, and 14% EDTA (Ethylenediaminetetraacetic acid), respectively, along with morphological preservation of dentin and pulp tissue by analyzing preservation of their issue structure (pulp shrinkage, odontoblastic layer damage) and staining efficacy (patchy staining) for the three types of decalcifying agents used. Materials and Method: The sample for this study included 120 freshly extracted teeth consisting of teeth of mandibular dentition. Samples were divided into two study groups: Group I: Decalcified by Conventional method Group II: Decalcified by Microwave method. Each group consisted of, three sub-groups employing a different decalcifying agent from among the three decalcifying agents used, that is, 5% nitric acids, 5% trichloroacetic acid, and 14%EDTA respectively. Result: The difference in speed of decalcification for both groups showed significant result. In either group, decalcification was fastest using 5% nitric acid. The difference in number of decalcified teeth sections showing shrinkage of pulp was not statistically significant for both groups. Damaged odontoblastic layer was evident only in the teeth treated with 5% nitric acid by microwave method. Patchy staining was observed in a few samples of all sample groups except those decalcified with EDTA by conventional method but the results were not statistically different on intercomparison. Discussion and Conclusion: Our results are similar to those of previous studies and we found that microwave method is an option that can reduce the time of decalcification. Tooth tissue morphology also was noted to be well preserved with 5% trichloracetic acid and 14% EDTA in comparison to 5% Nitric acid.

STUDY OF THE COMPOSITION OF MICROFLORA OF ROOT CANALS IN PRIMARY AND CHRONIC PERIODONTITIS

The problem of chronic focal infection of the pulp and periodontal tissues is relevant for both therapeutic and surgical dentistry. It has been proven that the long-term effect of microbial flora on the filling material, root dentin, periodontium and bone tissue often leads to destructive lesions of the periodontal tissues. Objective: to determine the qualitative and quantitative composition of the microflora of root canals in people with different degrees of manifestation of the inflammatory process. Materials and methods. The article defines the qualitative and quantitative composition of microflora of root canals in acute and chronic periodontitis. A study included 35 patients aged 25 to 35 years who applied to the dental center at the Department of Therapeutic Dentistry of the Dnipro State Medical University for treatment. A clinical and bacteriological study was conducted according to WHO recommendations. Root canal contents were collected with a paper sterile pin on Ames transport sterile medium (10 ml). Within 2-3 hours, the material was delivered to the microbiological laboratory for quantitative bacteriological research using anaerobic cultivation techniques. Isolation of pure cultures of anaerobic microorganisms and their subsequent identification was carried out using nutrient media intended for their cultivation. In order to identify aerobic or facultative anaerobic microflora in the studied material, inoculation was carried out on blood agar and sugar agar. Cultures were incubated for 24–72 hours in a thermostat at 37°C. At the second stage, macroand microscopic examination of colonies, smear preparation and Gram staining were performed. Isolation of pure cultures was carried out by generally accepted measures of bacteriological research. On the basis of the data obtained, microorganisms were identified according to the binary nomenclature with the determination of the amount of the selected strain in the material. Results and discussion. In the content of root canals of teeth in chronic and acute forms of periodontitis, pathogens are more often in the composition of microbial associations, which were detected in 61.1% of acute cases, and in 52.9% of chronic cases, respectively. Microbiological research of the content of root canals indicates different intensity and composition of microbial insemination in different forms of periodontitis. Streptococcus spp., Peptostreptococcus spp., Candidia albicans, Staphylococcus aureus, Staphylococcus epidermidis are more often detected in patients with acute pulpitis, and in patients with chronic forms bacteria from the group of gram-negative obligate anaerobic bacilli Porphyromonas spp., Prevotella intermedia, Streptocoсcus sanguis, Fusobacterium spp., Staphylococcus aureus. Therefore, the prospect of further research consists in studying the influence of the formation of biological film of microorganisms in various forms of periodontitis and the ability to increase resistance to antibiotics.

Comparative cell viability of dentin-bonding adhesive systems on human dental pulp stem cells: time-dependent analysis

BackgroundRestorative materials are in prolonged contact with living tissues such as oral mucosa, dentin, pulp, periodontal, and periapical tissues. Therefore, the potentially harmful effects of these materials and their components on oral tissues should be evaluated before clinical use. This study aimed to compare the cell viability of different adhesive systems (ASs) on human dental pulp stem cells (hDPSCs).MethodsThree ASs that combining methacryloyloxydecyl dihydrogen phosphate (MDP) monomer with new hydrophilic amide monomers [Clearfil Universal Bond Quick(CUBQ), Kuraray Noritake], self-reinforcing 3D monomer [Bond Force II(BFII), Tokuyama)], and dual-cure property [Futurabond DC(FBDC), VOCO] were used. Three (n = 3) samples were prepared for each group. Dental pulp stem cells were isolated from ten patients’ extracted third molar teeth. Samples were incubated in Dulbecco’s modified Eagle’s medium (DMEM) for 24 h (h), 72 h, and 7 days (d) to obtain extracts. For the control group, cells were cultured without DBA samples. Cell viability of ASs extracts was measured using a cell proliferation detection kit (WST-1, Roche). Statistical analysis was performed using two-way ANOVA and post-hoc (Duncan) tests (p < 0.05).ResultsAt 24 and 72 h statistically significant differences were determined between control and BFII, control and FBDC groups (p < 0.05), while no differences between control and CUBQ groups (p > 0.05). On the 7th d, statistically significant differences were found between the control and experimental groups (p < 0.05), while no differences between experimental groups (p > 0.05). A statistically significant difference was detected for the BFII group over the three-time interval (p < 0.05). The lowest cell viability was observed for the FBDC group at 24 h, and the difference was statistically significant when compared with 72 h and 7th d (p < 0.05).ConclusionAll ASs showed different cell viability values at various exposure times. It should be taken into consideration that pH values, as well as the contents of ASs, have a significant effect on the cell viability.

Dental caries from the past to the future: is it possible to reduce caries prevalence?

Dental caries is a significant oral health issue encountered globally. Unlike bone tissue, dental tissue lacks the capacity for self-renewal, leading to the permanence of pathological changes in teeth. Dental caries is primarily the result of acid production by microorganisms that metabolise sugary foods, which demineralises tooth enamel. If left untreated, caries can progress beyond the enamel and damage the dentin and pulp tissue. The development and spread of dental caries is influenced by an individual’s dietary habits, oral hygiene practices and various socio-economic factors. Throughout history, dental decay has consistently posed a major health issue across both ancient and contemporary communities. The incidence of dental caries has been influenced by factors such as dietary preferences, oral hygiene routines, and shifts in societal lifestyles. In particular, increased consumption of fermentable carbohydrates significantly increases the risk of caries formation. Conversely, preventive measures such as fluoride applications and a balanced diet can substantially reduce the incidence of caries. Other factors impacting the risk of caries include the chemical composition of saliva, the individual’s general health and various medical conditions. Fluoride applications, healthy eating habits and regular dental visits stand out as effective methods for preventing dental caries. Therefore, the success of dental caries prevention strategies depends on raising health awareness at the individual level and strengthening public health policies. This multifaceted approach will help to create healthier oral conditions for future generations.

Therapeutic management of cavitated caries lesion in a patient with sensory processing disorder

Caries disease is still an important public health problem. Although preventing the disease is simple, it is still a challenge due to the interaction of cariogenic factors. One of the forms of treatment is the selective removal of carious tissue, which consists of the total removal of carious tissue from the surrounding walls, preserving the affected tissue in the pulp wall, as it is a tissue capable of remineralization. In the conservative philosophy, there are alternative therapies to the use of manual cutting instruments and the use of rotary instruments - such as the use of chemical agents. These materials help the professional in the selective removal of decayed dentin tissue. The more conservative philosophy is an excellent alternative for patients with Sensory Processing Disorder, as it generates less sound, olfactory, thermal and tactile stimuli – also improving the pain experience. This makes it possible to provide the patient with individualized care, taking into account and respecting their limitations and needs.

A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation

Hard tissue engineering scaffolds especially 3D printed scaffolds were considered an excellent strategy for craniomaxillofacial hard tissue regeneration, involving crania and facial bones and teeth. Porcine treated dentin matrix (pTDM) as xenogeneic extracellular matrix has the potential to promote the stem cell differentiation and mineralization as it contains plenty of bioactive factors similar with human-derived dentin tissue. However, its application might be impeded by the foreign body response induced by the damage-associated molecular patterns of pTDM, which would cause strong inflammation and hinder the regeneration. Ceria nanoparticles (CNPs) show a great promise at protecting tissue from oxidative stress and influence the macrophages polarization. Using 3D-bioprinting technology, we fabricated a xenogeneic hard tissue scaffold based on pTDM xenogeneic TDM-polycaprolactone (xTDM/PCL) and we modified the scaffolds by CNPs (xTDM/PCL/CNPs). Through series of in vitro verification, we found xTDM/PCL/CNPs scaffolds held promise at up-regulating the expression of osteogenesis and odontogenesis related genes including collagen type 1, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein-2, osteoprotegerin, alkaline phosphatase (ALP) and DMP1 and inducing macrophages to polarize to M2 phenotype. Regeneration of bone tissues was further evaluated in rats by conducting the models of mandibular and skull bone defects. The in vivo evaluation showed that xTDM/PCL/CNPs scaffolds could promote the bone tissue regeneration by up-regulating the expression of osteogenic genes involving ALP, RUNX2 and bone sialoprotein 2 and macrophage polarization into M2. Regeneration of teeth evaluated on beagles demonstrated that xTDM/PCL/CNPs scaffolds expedited the calcification inside the scaffolds and helped form periodontal ligament-like tissues surrounding the scaffolds.

Interpretation of the concepts of dentinal tubule and dentinal canaliculus

The biology of dentin occupies a central place in the theory of tooth integrity as an organ, and knowledge about the microstructure of dentin changes with the development of new research methods, such as scanning electron microscopy. The structures that form dentin, and the odontoblast processes, are an extremely complex biological structure due to cellular polarization. The structure of the dentin of crowns from 30 intact teeth extracted for orthodontic reasons has been studied. Dentin was examined on longitudinal chips using scanning electron microscopy, determining the average number of dentinal tubules per unit area of dentin, the length and diameter of the dentinal canaliculi along the dentinal tubule. Scanning electron microscopy of demineralized teeth showed that numerous fine fibrillar structures were found in the predentin, connecting the odontoblast processes (dentinal canaliculi) and the walls of the dentinal tubules. The odontoblast processes were always in close contact with the microfibrillar network and were located within the dentinal tubule. It was found that the dentinal canaliculi have their own anchoring microfibrillar system, which allows each dentinal canaliculus to be held in a central position. The microfibrils are attached to the wall of the dentinal tubule and form a continuous mesh structure among the dentin tissue and are directly fixed on one side to the wall of the dentinal tubule, and on the other side to the wall of the dentinal canaliculus, which is a derivative of the odontoblast process. In different areas of the dentin, the length, number, and diameter of the microfibrils have a wide variative range. Microstructures were numerous in different regions of the dentinal tubule. Their number decreased with distance from the level of the outer dentin. In the inner third of the dentinal tubule, microfibrillar structures are observed that form a dense network of different types, thicknesses and diameters. The most common direction of the microfibrils was from the surface of the odontoblast process to the wall of the dentinal tubule, and in other cases these microfibrils were attached to both opposite inner surfaces of the dentinal tubule. The base of the microfibril is attached to the wall of the dentinal tubule, as if forming a continuous structure among the dentin tissue and the surface of the odontoblast process. It is shown that the microfibrillar structures may be a previously unknown framework system that ensures the stabilization of odontoblast processes inside the dentinal tubule. In the scientific classification of dentin ultrastructure, it is advisable to use the term "dentinal tubule" and "dentinal canaliculus", since this structure is a derivative of the odontoblast process.

Predentin's influence on clastic cell behavior in human external cervical resorption: Evidence from a case study

External cervical resorption (ECR) is an aggressive disease characterized by resorption of the tooth root structure. While the pericanalar resorption-resistant sheet (PRRS) impedes ECR progression towards the pulp, the underlying mechanisms of its protective role in human teeth remain unclear. This study aimed to elucidate the pathology of ECR in a 31-year-old female patient by employing radiographic, histological, and immunohistochemical analyses of an extracted tooth. Histological examination revealed that the PRRS comprised dentin, predentin, and reparative bone-like tissue. Notably, clastic cells were observed on the surfaces of all three tissues within the same specimens. Immunohistochemical staining for cathepsin K demonstrated diminished resorptive activity of clastic cells on predentin compared to dentin and bone-like tissue. These findings suggest a potential role for predentin in attenuating clastic cell activity, potentially serving as the final barrier safeguarding the pulp tissue.

ВЛИЯНИЕ ВНУТРИКОРОНКОВОГО ОТБЕЛИВАНИЯ НА МИКРОТВЕРДОСТЬ ДЕНТИНА: КЛИНИЧЕСКИЙ СЛУЧАЙ С ОБЗОРОМ ЛИТЕРАТУРЫ

Aim. Analysis of literature sources about the effect of intracoronal bleaching on the microhardness of dentin, as well as demonstration of a clinical case of successful correction of tooth discoloration caused by endodontic sealant using the method of intracoronal bleaching with a one-year follow-up period. Materials and methods. A search of literature sources was carried out in the PubMed, Google Scholar, CyberLeninka databases on September 24, 2023 using keywords. Articles in English and Russian were selected for analysis. Inclusion criteria: original articles, in vitro and in situ studies, studies on extracted human teeth, studies that assessed dentin microhardness. As a result of the search, 11 sources were found in the PubMed database, 171 in the scientific electronic library e-library, and 2 in the CyberLeninka database. After eliminating duplication and assessing the inclusion/non-inclusion criteria, 7 literary sources remained. The presented clinical case demonstrates the successful correction of discoloration caused by endodontic sealant using intracoronal bleaching with 35 % hydrogen peroxide gel. Results. When analyzing the literature, laboratory studies revealed various conditions that make it possible to reduce the negative effect of the bleaching agent on dentin tissue, namely activation with an ultraviolet lamp, addition of a dye, and treatment with fluoride varnish after bleaching. In the clinical case, the desired shade was achieved in three bleaching procedures, then the existing defective restoration was replaced with a new shade-matching one. During the year of observation, there was no return of color, the aesthetic result was assessed as stable, the patient expressed high satisfaction with the result obtained. Conclusion. The intracoronal bleaching procedure can have a negative effect of varying severity on dentin microhardness. Identifying approaches that reduce this impact is a promising direction for future research. The clinical case demonstrates that intracoronal bleaching provides acceptable esthetic results and high patient satisfaction.

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.

An in vitro assessment of the residual dentin after using three minimally invasive caries removal techniques

To evaluate the efficiency and effectiveness of three minimally invasive (MI) techniques in removing deep dentin carious lesions. Forty extracted carious molars were treated by conventional rotary excavation (control), chemomechanical caries removal agent (Brix 3000), ultrasonic abrasion (WOODPECKER, GUILIN, China); and Er, Cr: YSGG laser ablation (BIOLASE San Clemente, CA, USA). The assessments include; the excavation time, DIAGNOdent pen, Raman spectroscopy, Vickers microhardness, and scanning electron microscope combined with energy dispersive X-ray spectroscopy (SEM–EDX). The rotary method recorded the shortest excavation time (p < 0.001), Brix 3000 gel was the slowest. DIAGNOdent pen values ranged between 14 and 18 in the remaining dentin and laser-ablated surfaces recorded the lowest reading (p < 0.001). The Ca:P ratios of the remaining dentin were close to sound dentin after all excavation methods; however, it was higher in the ultrasonic technique (p < 0.05). The bur-excavated dentin showed higher phosphate and lower matrix contents with higher tissue hardness that was comparable to sound dentin indicating the non-selectiveness of this technique in removing the potentially repairable dentin tissue. In contrast, the MI techniques exhibited lower phosphate and higher organic contents associated with lower microhardness in the deeper dentin layers. This was associated with smooth residual dentin without smearing and patent dentinal tubules. This study supports the efficiency of using MI methods in caries removal as conservative alternatives to rotary excavation, providing a promising strategy for the clinical dental practice.