Components Of Dentin Research Articles

Intrafibrillar mineralization of type I collagen with calcium carbonate and strontium carbonate induced by polyelectrolyte-cation complexes.

Calcium carbonate (CaCO3), possessing excellent biocompatibility, bioactivity, osteoconductivity and superior biodegradability, may serve as an alternative to hydroxyapatite (HAp), the natural inorganic component of bone and dentin. Intrafibrillar mineralization of collagen with CaCO3 was achieved through the polymer-induced liquid precursor (PILP) process for at least 2 days. This study aims to propose a novel pathway for rapid intrafibrillar mineralization with CaCO3 by sequential application of the carbonate-bicarbonate buffer and polyaspartic acid (pAsp)-Ca suspension. Fourier transform infrared (FTIR) spectroscopy, zeta potential measurements, atomic force microscopy/Kelvin probe force microscopy (AFM/KPFM), and three-dimensional stochastic optical reconstruction microscopy (3D STORM) demonstrated that the carbonate-bicarbonate buffer significantly decreased the surface potential of collagen and CO32-/HCO3- ions could attach to collagen fibrils via hydrogen bonds. The electropositive pAsp-Ca complexes and free Ca2+ ions are attracted to and interact with CO32-/HCO3- ions through electrostatic attractions to form amorphous calcium carbonate that crystallizes gradually. Moreover, like CaCO3, strontium carbonate (SrCO3) can deposit inside the collagen fibrils through this pathway. The CaCO3-mineralized collagen gels exhibited better biocompatibility and cell proliferation ability than SrCO3. This study provides a feasible strategy for rapid collagen mineralization with CaCO3 and SrCO3, as well as elucidating the tissue engineering of CaCO3-based biomineralized materials.

A glycol chitosan derivative with extrafibrillar demineralization potential for self-etch dentin bonding

ObjectivesExtrafibrillar demineralization is an etching technique that removes only minerals from around the collagen fibrils for resin infiltration. The intrafibrillar minerals are left intact to avoid their replacement by water that is hard for adhesive resin monomers to displace. The present work reported the synthesis of a water-soluble methacryloyloxy glycol chitosan-EDTA conjugate (GCE-MA) and evaluated its potential as an extrafibrillar demineralization agent for self-etch dentin bonding. MethodsGlycol chitosan-EDTA was functionalized with a methacryloyloxy functionality. Conjugation was confirmed using Fourier transform-infrared spectroscopy. The GCE-MA was used to prepare experimental self-etch primers. Extrafibrillar demineralization of the primers was evaluated with scaning electron microscopy and transmission electron microscopy. The feasibility of this new self-etch bonding approach was evaluated using microtensile bond strength testing and inhibition of dentin gelatinolytic activity. The antibacterial activity and cytotoxicity of GCE-MA were also analyzed. ResultsConjugation of EDTA and the methacryloyloxy functionality to glycol chitosan was successful. The functionalized conjugate was capable of extrafibrillar demineralization of mineralized collagen fibrils. Tensile bond strength of the experimental self-etch primer to dentin was comparable to that of phosphoric acid-etched dentin and the commercial self-etch primer Clearfil SE Bond 2. The GCE-MA also inhibited soluble rhMMP-9. In-situ zymography detected minimal fluorescence in hybrid layers conditioned with the experimental primer. The GCE-MA was noncytotoxic and possessed antibacterial activities against planktonic bacteria. SignificanceSynthesis of GCE-MA brought into fruition a self-etch conditioner that selectively demineralizes the extrafibrillar mineral component of dentin. A self-etch primer prepared with GCE-MA achieved bond strengths comparable to commercial reference adhesive systems.

Poisson’s ratio of fluorapatite crystals

Introduction. It is known that in the pathogenesis of caries and non-carious lesions of teeth, an important role is played by enamel resistance, which is determined by numerous factors, among which the structure and physical and mechanical properties of tooth tissues are considered to be among the most important. This report summarizes the literature data on the Poisson’s ratio of fluorapatite (FAp), a biomaterial and one of the mineral components of dental hard tissues. The literature search was carried out in electronic databases Scopus, Web of Science, PubMed, Medline, Elibrary, MatWeb for the period from January 1970 to March 2023 inclusive. Some of the data are supplemented by our own calculations based on formulas for crystalline hexagonal systems (systems). As is known, Poisson’s ratio determines the volumetric response of materials and biological tissues to mechanical load, but its anisotropic properties have not been studied in detail. Material and methods. Calculations of the Poisson’s ratio of fluorapatite were carried out in the computer algebra system Mathcad 15.0, using the online analysis of elasticity tensors ELATE, and an integrated molecular modeling system was used - the graphic package VESTA (Visualization for Electronic and STructural Analisis). Results and discussion. The Poisson’s ratio values of fluorapatite crystals varied: minimum values 0.057–0.283, maximum values 0.302–0.494, average values obtained by integration in all directions 0.24–0.308. The coefficient of elastic anisotropy of the fluorapatite crystal lattice, calculated based on the values of Poisson’s ratio, is 1.21–5.29. The results obtained were compared with those of hydroxyapatite (HAp) crystals, dentin, enamel and filling materials. The highest values of the parameters μ and μmax are found in dentin (0.312 and 0.54), the lowest μmin are also found in dentin (0.13). Conclusions. Fluorapatite crystals are elastically anisotropic, and Poisson’s ratio μmax/μmin varies over a wide range. The Poisson’s ratio of fluorapatite showed similarity with the transverse strain coefficient of isomorphic hydroxyapatite crystals (0.207–0.374), dentin (0.13–0.54), enamel (0.16–0.47) and dental composite filling materials (0.24–0 ,35). The latter should help improve the quality of restorations using filling materials for replacing hard dental tissues. It has been established that the organic component of dentin increases its Poisson’s ratio as a biocomposite and the anisotropy of elastic properties.

A Study of the Effects of Medical Dental Laser and Diamond Drill on Dentin Tissue during Dental Restoration Based on Spectral Imaging and Multivariate Analysis of Synchrotron FTIR Microspectroscopy Data

In our work, the effect of a dental Er:YAG pulsed laser and a diamond cylindrical drill with a turbine handpiece on dentin tissue was studied using spectral imaging. The combination of spectral imaging of FTIR microspectroscopy data and subsequent multivariate analysis (hierarchical cluster analysis (HCA) and principal component analysis (PCA)) was shown to unambiguously detect visually indistinguishable structural changes occurring in the hard dental tissue (dentin) depending on the method used for their pre-processing, and to classify and differentiate the identified features at the submicron level with high spatial resolution. The detectable spectral transformations indicate that the preparation of dental tissue with a dental laser leads to significant changes in the organic components of dentin, which may affect adhesion. The use of a diamond cylindrical drill with a turbine handpiece is characterized by a larger area (depth) of the altered hard tissue than in the case of a dental laser for dental cavity preparation. The observed redistribution of the phase composition of the inorganic component in the tissue is associated with the emergence of additional phases of weak calcium phosphates, and changes in the organic component with transformations in the secondary structure of proteins. Active use of the proposed integrated approach in the future will clarify the areas of its applicability to the analysis of biological tissues and pathologies in them, which will help in the clinical setting to choose the optimal personalized approach for patients.

Clinical Implementation of Comprehending Dentin on a Microscopic Level

The aim of the present in vitro study is to visualize dentin to get an in-depth knowledge of the nature of dentin that could provide useful information regarding conditioning dentinal substrate when treating dentinal lesions. Forty-nine extracted human third molars were obtained and prepared to produce artificial dentinal lesions through demineralizing with acetic acid for 7 and 14 days, or lactic acid for 7 days. The teeth were divided into groups and treated with either NaOCl, pepsin, trypsin, or phosphoric acid. To obtain information on the morphology of the treated dentinal surfaces, all samples were visualized under high resolution field emission scanning electron microscope. With high magnification reaching x50000 dentin was clearly visualized together with its constitutes. The effect of various demineralization approaches and various treatment protocols were demonstrated clearly. The relationship between the conditioning procedure steps and the subsequent bond strength was discussed. To our best knowledge, there is no previous clear highly magnified scanning electron microscope images for dentin, and dentinal components and constitutes with and without various treatments. The current in vitro study suggests the complexity nature of dentin as a substrate that should be treated carefully especially with technique sensitive procedures such as adhesive restorations.

RAMAN SPECTROSCOPY ANALYSIS OF CORONARY DENTIN OF VITAL AND ENDODONTICALLY TREATED TEETH

PURPOSE: The present study aimed to investigate the properties of coronary dentin of vital and endodontically treated human teeth using Raman Spectroscopy. MATERIAL/METHODS: The samples used were taken from coronary dentin of intact extracted human teeth, ultrasonically cleaned and stored in a 0.2% thymol solution at 4 degrees Celsius for up to 3 months. They were divided into two groups – “vital dentin” and “endodontically treated dentin” samples. Each sample was crossed-sectioned, embedded in resin, polished and subjected to Raman spectroscopy with a Horiba Jobin-Yvon T64000 triple-grating spectrometer, using a CdHe laser with 4 μm diameter of the laser spot and 2.5mW of power on the examined surface. The resultant diagrams were analyzed using the software package Origin 9.6 andunderwent baseline correction and normalization. A comparison between the two studied groups was made. RESULTS: The results from the “vital dentin” group showed a well-expressed crystalline structure, with clear peaks corresponding to pure and b-carbonated hydroxyapatite. The results of the “endodontically treated dentin” group showed the presence of new chemical compounds – octacalcium phosphate, tricalcium phosphate and dicalcium phosphate dihydrate, as well as increased intensity of the b-carbonated hydroxyapatite peaks. CONCLUSIONS: The presence of mineral substances with low calcium content could contribute to a decrease in dentin toughness, which in turn can lessen the mechanical properties of endodontically treated teeth. Raman spectroscopy can be a useful tool in the detection of these dentin components.

Ultrastructural Analysis of Er:YAG Lased Bovine Dentin Contaminated by Cariogenic Bacteria.

Objective: The purpose of this study is to investigate the crystal structure of bacteria-contaminated bovine dentin after Er:YAG laser irradiation at various energy densities from macroscale, microscale, and nanoscale. Background: Er:YAG laser can change the morphology and chemical components of dentin. Few preliminary researchers investigate the laser effect on crystal in dentin tissue. Methods: Twenty dentin specimens from bovine incisors were cocultured with S. mutans (UA 159) and divided into four groups with diverse Er:YAG laser irradiation energy (0, 6.37, 12.73, 19.11 J/cm2). The ultrastructure of dentin before and after laser irradiation was investigated with nanoanalytical electron microscopy. X-ray diffraction provided the information of lattice parameters in dentin. The morphology of dentin was observed by scanning electron microscopy. High-resolution transmission electron microscope images and selected-area electron diffraction patterns were obtained for characterizing crystal domain size, structure, and microenvironment of dentin. Results: The combination of these methods disclosed that there exist mineralized, demineralized, and remineralized dentin in the bacteria-invaded dentin and can be feasibly recognized using morphological features. Laser treatments influence hydroxyapatite (HAp) crystals in dentin tissue in different ways: needle HAp in mineralized dentin tissue keeps intact with laser irradiation of no higher than 19.11 J/cm2; laser irradiation improves the crystallinity of lamella HAp by domain growth and rearranges its growth orientations. Conclusions: We report an unprecedented presence of remineralization zone consisting of lamella HAp crystals with distinct high-index planes. These findings have broad implications on the role of laser operation in driving biomineralization and shed new insights into a possible relationship between laser irradiation and remineralization.

Ameloblastic Fibro-Odontoma

Introduction: Ameloblastic fibro-odontoma (AFO) is a benign odontogentic tumor without an aggressive behavior, unlike the similar ameloblastic fibroma. Case Presentation: A 9-year-old boy, with tooth eruption failure, underwent enucleation and curettage of a well-defined variable radiolucent and radio-opaque right mandible lesion. There was odontogenic epithelium with peripheral palisading in a loose myxoid stroma as well as a disorganized component of dentin, enamel, and cementum, features of an AFO. Conclusion: AFO is an odontogenic mixed tumor of epithelium and mesenchyme.

Molecular evolutionary analyses of tooth genes support sequential loss of enamel and teeth in baleen whales (Mysticeti)

The loss of teeth and evolution of baleen racks in Mysticeti was a profound transformation that permitted baleen whales to radiate and diversify into a previously underutilized ecological niche of bulk filter-feeding on zooplankton and other small prey. Ancestral state reconstructions suggest that postnatal teeth were lost in the common ancestor of crown Mysticeti. Genomic studies provide some support for this hypothesis and suggest that the genetic toolkit for enamel production was inactivated in the common ancestor of living baleen whales. However, molecular studies to date have not provided direct evidence for the complete loss of teeth, including their dentin component, on the stem mysticete branch. Given these results, several questions remain unanswered: (1) Were teeth lost in a single step or did enamel loss precede dentin loss? (2) Was enamel lost early or late on the stem mysticete branch? (3) If enamel and dentin/tooth loss were decoupled in the ancestry of baleen whales, did dentin loss occur on the stem mysticete branch or independently in different crown mysticete lineages? To address these outstanding questions, we compiled and analyzed complete protein-coding sequences for nine tooth-related genes from cetaceans with available genome data. Seven of these genes are associated with enamel formation (ACP4, AMBN, AMELX, AMTN, ENAM, KLK4, MMP20) whereas two other genes are either dentin-specific (DSPP) or tooth-specific (ODAPH) but not enamel-specific. Molecular evolutionary analyses indicate that all seven enamel-specific genes have inactivating mutations that are scattered across branches of the mysticete tree. Three of the enamel genes (ACP4, KLK4, MMP20) have inactivating mutations that are shared by all mysticetes. The two genes that are dentin-specific (DSPP) or tooth-specific (ODAPH) do not have any inactivating mutations that are shared by all mysticetes, but there are shared mutations in Balaenidae as well as in Plicogulae (Neobalaenidae + Balaenopteroidea). These shared mutations suggest that teeth were lost at most two times. Shared inactivating mutations and dN/dS analyses, in combination with cetacean divergence times, were used to estimate inactivation times of genes and by proxy enamel and tooth phenotypes at ancestral nodes. The results of these analyses are most compatible with a two-step model for the loss of teeth in the ancestry of living baleen whales: enamel was lost very early on the stem Mysticeti branch followed by the independent loss of dentin (and teeth) in the common ancestors of Balaenidae and Plicogulae, respectively. These results imply that some stem mysticetes, and even early crown mysticetes, may have had vestigial teeth comprised of dentin with no enamel. Our results also demonstrate that all odontocete species (in our study) with absent or degenerative enamel have inactivating mutations in one or more of their enamel genes.

83 - Verification of Collagenase Production by Streptococcus Mutans

The oral environment contains multiple collagenases which are believed to play a role in dentin caries formation, as collagen is one of the major components of dentin. In the laboratory, biofilm and collagenase-containing chemical models have been used to study dental degradation. However, the numerous collagenase sources in the oral cavity pose a challenge when it comes to comparing in vitro and in vivo data. Streptococcus mutans, one of the important cariogenic oral streptococcu, contains genes for at least two collagenases (SMU_759 and SMU_761), which have been shown to be expressed in samples collected from active caries. Here, we investigate if the collagenases produced by S. mutans contribute to dentin degradation. S. mutans UA159 (ATCC700610) was cultured in BHI with/without KHCO3 using different concentrations of sucrose (0%, 0.05%, 0.2%, and 1%) at 37 C and 5% CO2 for 48 hrs. The pH of the media at 48 hrs was measured by using pH test paper strips. RNA from S. mutans biofilms cultured without KHCO3 was collected to measure collagenase gene expression by RT qPCR. To measure collagenase activity, KHCO3-buffered BHI was used for culturing to avoid collagenase denaturing caused by low pH. Supernatants of the same culture were centrifuged, filter sterilized and dialyzed, and exposed to a commercially available colorimetric assay kit. Absorbance readings were collected every 20 min for 16 hrs. With KHCO3 buffering, the pH of the media containing 48-hrs S. mutans cultured with 0%, 0.05%, 0.2%, and 1% sucrose were around 7.6, 6.5, 6.0, and 5.5, respectively. The corresponding pH values of media without KHCO3 were around 7.0, 5.5, 5.0, and 4.5. Addition of 1% W/V sucrose in BHI led to an approximately 20-fold increase in the expression of both SMU_759 and 761 collagenases compared to BHI only. Collagenase expression increased by less than 3-fold when 0.05% and 0.2% W/V sucrose was added. Although quite slow, a continuous reduction in absorbance was observed in the 16-hr collagenase activity test, indicating collagenase activity of the media containing S. mutans. The collagenase activities of the samples with 0%, 0.05%, 0.2%, and 1% sucrose were: 0.00106, 0.000679, 0.000679, and 0.000931 U/ml, respectively. Gene expression and collagenase activity test showed that S. mutans produced active collagenase(s) in response to sucrose during the 48 hrs of culturing, which supports the idea that S. mutans contributes to dentin degradation.

The Amelogenin-Derived Peptide TVH-19 Promotes Dentinal Tubule Occlusion and Mineralization.

In this study, the amelogenin-derived peptide, TVH-19, which has been confirmed to promote mineralization, was evaluated to derive its potential to induce dentinal tubule occlusion. The binding capability of fluorescein isothiocyanate (FITC)-labeled TVH-19 to the demineralized dentin surface was analyzed by confocal laser scanning microscopy (CLSM). Additionally, the sealing function of the peptide was studied through the remineralization of demineralized dentin in vitro. The adsorption results showed that TVH-19 could bind to the hydroxyapatite and demineralized dentin surfaces, especially to periodontal dentin. Scanning electron microscopy analysis further revealed that TVH-19 created mineral precipitates. The plugging rate in the TVH-19 group was higher than that in the PBS group. Moreover, energy-dispersive X-ray spectroscopy (EDX) results indicated that the calcium/phosphorus (Ca/P) ratio of the new minerals induced by TVH-19 was close to that of the hydroxyapatite. Attenuated total internal reflection-Fourier transform infrared (ATR-FTIR) spectrometry and X-ray diffraction (XRD) results indicated that the hydroxyapatite crystals formed via remineralization elongated the axial growth and closely resembled the natural dentin components. These findings indicate that TVH-19 can effectively promote dentin sealing by binding to the periodontal dentin, promoting mineral deposition, and reducing the space between the dentin tubules.

Effect of Demineralizing Agents on Organic and Inorganic Components of Dentine

There is a requirement to ensure that in vitro studies that use demineralized human dentine models are reliable and clinically relevant. The literature reports several strategies for these studies with a lack of consensus on the mode of action of the different demineralizing acids on human dentine. This in vitro study aims to characterize the effect of clinically relevant acids on human dentine, using standardized substrates and complementary analytical techniques. The study focuses on an analysis of the mineral content and the integrity of the collagen following partial demineralization. Samples of human dentine were exposed to a range of acids commonly encountered in the oral cavity. Characterization of the mineral content used Vickers micro-hardness, energy-dispersive spectroscopy, and X-ray fluorescence. Characterization of the collagen integrity was undertaken by means of scanning electron microscopy and hydroxyproline assay. The following conclusions were reached: (i) each demineralizing agent tested had a unique effect on the mineral levels; (ii) chelating agents, strong acids, and weak acids affect the mineral and organic phases of dentine in significantly different ways with no correlation between them; and (iii) the demineralizing agents caused some degree of collagen denaturation, citric acid causing the most damage. Overall, there is no clear link between the type of demineralizing agent and the effect on the organic and inorganic dentine. The choice of demineralizing agent should be aligned to the experiment objectives so that the selected dentine (caries or erosion) model is fit for the purpose.

Nanoscopic wear behavior of dentinogenesis imperfecta type II tooth dentin

ObjectivesThe aim of this study was to investigate the wear behavior of Dentinogenesis imperfecta type II (DGI-II) dentin and elucidate the correlation between its tribological properties and components. MethodsThe mid-coronal dentin of normal and DGI-II teeth were divided into two groups: perpendicular and parallel to the dentin tubules. The microstructure of dentin was detected using atomic force microscopy (AFM). The wear behavior of dentin was evaluated by nanoscratch tests and scanning electron microscopy (SEM). Meanwhile, changes in molecular groups and chemical composition were analyzed by Raman and Energy-Dispersive X-ray (EDX) tests, respectively. Nanohardness was also evaluated. ResultsAFM images of DGI-II dentin illustrated a decrease in the number of tubules and the tubule diameter. Nanoscratch test showed a higher friction coefficient and a greater depth-of-scratch in DGI-II dentin. The wear resistance of DGI-II dentin was reduced independent of tubule orientation. EDX results indicated that DGI-II dentin mineral content decreased and Raman spectra results showed DGI-II dentin had a decreased collagen matrix structure stability coupled with hypomineralization. Furthermore, a significant reduction in nanohardness and elastic modulus of DGI-II dentin was observed. Regression analysis revealed a close correlation between dentin components and inferior wear resistance. ConclusionsAll results indicated the wear behavior of DGI-II dentin was significantly deteriorated, presumably caused by the disorder in microstructures and the reduction of chemical composition.

Microstructure and mineral components of the outer dentin of Chimaera phantasma tooth plates.

Tooth plates are a unique dental organ found in holocephalan fishes and lungfish. The chimaeroid tooth plates are atypical in terms of biomineralization, due to the hard tissue composition of whitlockite and apatite, while those of lungfish and other vertebrates are composed of apatite. The tooth plates are overlaid by a thin veneer-outer dentin-whose composition and role are not known. We aimed to test whether the outer dentin is composed of whitlockite or apatite, and whether it protects the osteodentin from abrasion and supports its overall strength. For this purpose, the mineral components and microstructure of outer dentin were studied. Our analyses of the outer dentin from the anterior (vomerine) tooth plates of Chimaera phantasma revealed that the mineral component is magnesium- and carbonate-containing calcium-deficient apatite and that the outer dentin has a three-zone structure. The main body is sandwiched between thin zones, which are less mineralized than the main body. Furthermore, in the outer zone and the main body, a higher-order structure was formed in accordance with the organization of wide and narrow fibers. Mineralization made the main body a composite of bundles of fibers and apatite. Transmission electron microscopy showed a structural relationship between apatite and the fibrous component on which the apatite was formed. Such a structure of the main body could be highly effective as a framework to resist abrasion and support the overall strength of the tooth plate.

The effects of low-dose 2-hydroxyethyl methacrylate on apoptosis and survival in human dental pulp cells

2-hydroxyethyl methacrylate (HEMA) is one of the most major components in dentin bonding systems. Uncured HEMA is eluted through the dentin and harmful to pulp cells. The study aimed to investigate the death pattern, morphological change and factors of human dental pulp cells (HDPCs) cultured with low-dose HEMA. HDPCs were cultured with low-dose concentration of HEMA at 0mM (control), 0.125mM, 0.25mM, 1mM, 2mM and 4mM on Day 3 and 5. The cell morphology was observed with F-actin immunocytochemical staining. The flow cytometry was used to analyze the death pattern. NF-κB and Trx-1 were measured using ELISA kits. The major death pattern was early apoptosis and late apoptosis. The morphological characteristics of apoptosis were observed clearly at 4mM on Day 3 and Day 5. The phosphorylated NF-κB normalized to total NF-κB protein was significantly higher at 2mM and 4mM on Day 5. There was no difference of Trx-1 on Day 3, but significantly higher at 0.25mM and 1mM on Day 5. The trend line of phosphorylated NF-κB and Trx-1 showed highly positive correlations with HEMA concentration. The significant cellular morphology characteristics of apoptosis can be observed at higher dose and longer period after exposed to uncured HEMA. The expression of NF-κB was following the ratio of late apoptosis at longer exposure period. Clinically, the remaining dentin thickness should be enough to decrease HEMA concentration and thus to protect pulp cells free from harm.

Effect of aspartic acid on the crystallization kinetics of ACP and dentin remineralization

Type I collagen and non-collagen proteins are the main organic components of dentin. This study aimed to investigate the biomimetic remineralization of demineralized dentin by aspartic acid (Asp), which is abundant in non-collagenous proteins (NCPs). Asp was added to a mineralizing solution containing polyacrylic acid (PAA) to explore the mechanism of Asp regulating the pure amorphous calcium phosphate (ACP) phase transition process. The remineralization process and superstructure of the remineralized layer of demineralized dentin were evaluated and analyzed by transmission electron microscope (TEM) and scanning electron microscope (SEM), and the biological stability of the remineralized layer was investigated by collagenase degradation experiment. It demonstrated that Asp promoted the crystallization kinetics of PAA-stabilized amorphous calcium phosphate to hydroxyapatite (HAP), and shortened the remineralization time of demineralized dentin from 7 days to 2 days. The newly formed remineralized dentin had similar morphology and biological stability to the natural dentin layer. The presence of a large number of Asp residues in NCPs promoted the phase transformation of ACP, and further revealed the mechanism of action of NCPs in dentin biomineralization. This experiment also showed that Asp promoted the biomimetic remineralization of dentin; the morphology and hierarchical structure of remineralized layer was similar to that of natural teeth, and had good biological properties.

Advanced in Vitro Experimental Models for Tissue Engineering-based Reconstruction of a 3D Dentin/pulp Complex: a Literature Review.

Experimental procedures have been used to monitor cellular responses at the dentin/pulp interface. Aiming to divert from in vivo studies and oversimplified two-dimensional assays, three-dimensional (3D) models have been developed. This review provides an overview of existing literature, regarding 3D in vitro dentin/pulp reconstruction. PubMed, Scopus, Cochrane Library and Web of Science- were systematically searched for attributes between 1998 and 2020. The search focused on articles on the development of three-dimensional tools for the reconstruction of a dentin/pulp complex under in vitro conditions, which were then screened and qualitatively assessed. Article grouping according to mode of implementation, resulted in five categories: the customised cell perfusion chamber (CPC) (n = 8), the tooth bud model (TBM) (n = 3), the 3D dentin/pulp complex manufactured by tissue engineering (DPC) (n = 6), the entire tooth culture (ETC) (n = 4) and the tooth slice culture model (TSC) (n = 5). A total of 26 publications, applying nine and eight substances for pulp and dentin representation respectively, were included. Natural materials and dentin components were the most widely utilized. The most diverse category was the DPC, while the CPC group was the test with the highest longevity. The most consistent categories were the ETC and TSC models, while the TBM presented as the most complete de novo approach. All studies presented with experimental protocols with potential upgrades. Solving the limitations of each category will provide a complete in vitro testing and monitoring tool of dental responses to exogenous inputs. The 3D dentin/pulp complexes are valid supplementary tools for in vivo studies and clinical testing. Graphical Abstract.

Reduced mesiodistal tooth dimension in individuals with osteogenesis imperfecta: a cross-sectional study

Objective Osteogenesis imperfecta (OI) is a rare, hereditary disease affecting collagen type-1 in connective tissue. Collagen type-1 is a substantial component of dentine, and it is speculated, whether affected dentine could cause altered mesiodistal tooth dimension possibly affecting restorative treatment regimen. Therefore, the aim of the present study was to measure mesiodistal tooth dimensions in individuals with OI and compare them with healthy controls. Materials and methods Fifty-seven individuals aged 20–77 years with OI type 1–4 were included and 70 control patients aged 11–34 years were drawn from an orthodontic database. Mesiodistal tooth dimensions of all tooth types, except third molars, were measured in mm (two decimals) on digital 3 D-models of the tooth-bearing arches. Results Multilevel mixed-effects linear regression analysis showed that mesiodistal tooth dimension on average was 0.17 mm (95% CI = (−0.33; −0.01)) reduced for the OI group compared to controls. The analysis revealed variation between tooth types; incisors and first premolars were most affected and molars minimally affected. Conclusions The mesiodistal tooth dimension in individuals diagnosed with OI is significantly smaller compared to healthy controls, which should be taken into consideration in the restorative treatment planning of individuals with OI, although the magnitude of the deviation is relatively small. The results on mesiodistal tooth dimensions of the present controls may be used as a standard for comparisons in future studies on tooth dimensions.

L-histidine controls the hydroxyapatite mineralization with plate-like morphology: Effect of concentration and media

Hydroxyapatite (HA) is the main inorganic component of bone and dentin, and their non-stoichiometric compositions and plate-shaped morphology is responsible for their bioactivity and osteoconductive nature. Collagenous (CPs) and non-collagenous proteins (NCPs) facilitate mineralization and regulate structural properties of HA through their side-chains. The bioactivity of synthetic HA does not usually match with the HA found in bone and, therefore, there is a need to understand the role of biomolecules in bone mineralization in order to develop non-stoichiometric plate-shaped HA for bone grafts. Role of several amino acids has been investigated but the role of L-his has been rarely investigated under physiological conditions even though it is a part of HA inhibitor proteins, like albumin, amelogenin, and histidine-rich proteins. In this study, L-his and L-glu were used to modify the structural properties of HA in different experimental conditions and buffer systems (tris and hepes). The results showed that L-his was able to regulate the plate-shaped morphology of HA in every experimental condition, unlike the L-glu, where the crystal morphology was regulated by experimental conditions. Both amino acids behaved differently in DI water, tris, and hepes buffer, and the media used influenced the precipitation time and structural properties of HA. Hepes and tris buffers also influenced the HA precipitation process. Overall, the studies revealed that L-his may be used as an effective regulator of plate-shaped morphology of HA, instead of large NCPs/proteins, for designing biomaterials for bone regeneration applications and the choice of buffer system is important in designing and evaluating the systems for mineralization. In cell culture studies, mouse osteoblast precursor cells (MC3T3-E1) showed highest proliferation on the bone-like plate-shaped HA, among all the HA samples investigated.

Analysis of sodium hypochlorite effect on dentin structural components

The aim of this review article is detailed analyzation of the effect of sodium hypochlorite on the structural components of dentin. This compound is one of the strongest antimicrobial medicines for root canal treatment. However, sodium hypochlorite in certain concentrations has a detrimental effect on dentin, which leads to the loss of its physicochemical properties.Materials and methods. The study of publications was produced in the electronic databases such as Google Scholar, PubMed and ScienceDirect in the course of a systematic review of the literature. Included articles contain information about the on the effect of sodium hypochlorite on the structural components of dentin and the harmful effects of medicines for root canal treatment on organic elements.Results. 67 articles were viewed during the rview. After analyzing the literature for inclusion criteria, the total number of publications has become 43.Conclusions. According to the literature, it can be assumed that an increase in sodium hypochlorite concentration and its exposure time can lead to depletion of dentin organic matrix, which in turn, is responsible for the root fracture.