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European Cells & Materials Nov 2021Matrix metalloproteinases (MMPs) have been implicated not only in the regulation of developmental processes but also in the release of biologically active molecules and... (Review)
Review
Matrix metalloproteinases (MMPs) have been implicated not only in the regulation of developmental processes but also in the release of biologically active molecules and in the modulation of repair during tertiary dentine formation. Although efforts to preserve dentine have focused on inhibiting the activity of these proteases, their function is much more complex and necessary for dentine repair than expected. The present review explores the role of MMPs as bioactive components of the dentine matrix involved in dentine formation, repair and regeneration. Special consideration is given to the mechanical properties of dentine, including those of reactionary and reparative dentine, and the known roles of MMPs in their formation. MMPs are critical components of the dentine matrix and should be considered as important candidates in dentine regeneration.
Topics: Dentin; Dentin, Secondary; Humans; Matrix Metalloproteinases
PubMed: 34818431
DOI: 10.22203/eCM.v042a24 -
Acta Biomaterialia Sep 2014Dentin contains 1-2μm diameter tubules extending from the pulp cavity to near the junction with enamel. Peritubular dentin (PTD) borders the tubule lumens and is...
Dentin contains 1-2μm diameter tubules extending from the pulp cavity to near the junction with enamel. Peritubular dentin (PTD) borders the tubule lumens and is surrounded by intertubular dentin (ITD). Differences in PTD and ITD composition and microstructure remain poorly understood. Here, a (∼200nm)(2), 10.1keV synchrotron X-ray beam maps X-ray fluorescence and X-ray diffraction simultaneously around tubules in 15-30μm thick bovine and equine specimens. Increased Ca fluorescence surrounding tubule lumens confirms that PTD is present, and the relative intensities in PTD and ITD correspond to carbonated apatite (cAp) volume fraction of ∼0.8 in PTD vs. 0.65 assumed for ITD. In the PTD near the lumen edges, Zn intensity is strongly peaked, corresponding to a Zn content of ∼0.9mgg(-1) for an assumed concentration of ∼0.4mgg(-1) for ITD. In the equine specimen, the Zn K-edge position indicates that Zn(2+) is present, similar to bovine dentin (Deymier-Black et al., 2013), and the above edge structure is consistent with spectra from macromolecules related to biomineralization. Transmission X-ray diffraction shows only cAp, and the 00.2 diffraction peak (Miller-Bravais indices) width is constant from ITD to the lumen edge. The cAp 00.2 average preferred orientation is axisymmetric (about the tubule axis) in both bovine and equine dentin, and the axisymmetric preferred orientation continues from ITD through the PTD to the tubule lumen. These data indicate that cAp structure does not vary from PTD to ITD.
Topics: Animals; Calcium; Cattle; Crystallography, X-Ray; Dentin; Fluorescence; Horses; Radiography; X-Ray Absorption Spectroscopy; Zinc
PubMed: 24911530
DOI: 10.1016/j.actbio.2014.05.027 -
Journal of Dentistry Aug 2014To evaluate, in vitro, the effects of ionizing radiation on the mechanical and micro-morphological properties of enamel and dentin of permanent teeth. (Comparative Study)
Comparative Study
OBJECTIVES
To evaluate, in vitro, the effects of ionizing radiation on the mechanical and micro-morphological properties of enamel and dentin of permanent teeth.
METHODS
Enamel and dentin microhardness (n=12 hemi-sections) was evaluated at three depths (superficial, middle and deep) prior to (control) and after every 10Gy radiation dose up to a cumulative dose of 60Gy by means of longitudinal microhardness. Data were analyzed using two-way analysis of variance and Tukey's test at a significance level of 5%. Enamel and dentin morphology was assessed by scanning electron microscopy (SEM) for semi-quantitative analysis (n=8 hemi-sections). Data were analyzed using Kruskal-Wallis and Dunn's or Fisher exact tests at a significance level of 5%.
RESULTS
The application of ionizing radiation did not change the overall enamel microhardness, although an increase in superficial enamel microhardness was observed. The micro-morphological analysis of enamel revealed that irradiation did not influence rod structure but interprismatic structure became more evident. Dentin microhardness decreased after 10, 20, 30, 50 and 60Gy cumulative doses (p<0.05) compared with non-irradiated dentin, mainly in the middle portion of the tissue. The micro-morphological analysis revealed fissures in the dentin structure, obliterated dentinal tubules and fragmentation of collagen fibers after 30 and 60Gy cumulative doses.
CONCLUSIONS
Although ionizing radiation did not affect the enamel microhardness of permanent teeth as a whole, an increase in superficial enamel microhardness was observed. Dentin microhardness decreased after almost all radiation doses compared with the control, with the greatest reduction of microhardness in the middle depth region. The morphological alterations on enamel and dentin structures increased with the increase of the radiation dose, with a more evident interprismatic portion, presence of fissures and obliterated dentinal tubules, and progressive fragmentation of the collagen fibers.
CLINICAL SIGNIFICANCE
This study shows that irradiation affects microhardness and micro-morphology of enamel and dentin of permanent teeth. The effects of gamma irradiation on dental substrate might contribute to increased risk of radiation tooth decay associated with salivary changes, microbiota shift and high soft and carbohydrate-rich food intake.
Topics: Cobalt Radioisotopes; Collagen; Dental Enamel; Dentin; Dose Fractionation, Radiation; Hardness; Humans; In Vitro Techniques; Microscopy, Electron, Scanning; Molar; Radiotherapy Dosage; Radiotherapy, High-Energy
PubMed: 24887361
DOI: 10.1016/j.jdent.2014.05.011 -
Journal of Indian Prosthodontic Society 2023To compare the effect of polymerization of resin-modified glass ionomer cement and dual-cure resin cement on the crystalline structure and to correlate it clinically...
Comparison and evaluation of the effect of polymerization of resin-modified glass ionomer cement and dual-cure resin cement on the crystalline structure of dentin using synchrotron X-ray diffraction and its clinical correlation with postoperative sensitivity.
AIM
To compare the effect of polymerization of resin-modified glass ionomer cement and dual-cure resin cement on the crystalline structure and to correlate it clinically with postoperative sensitivity.
SETTINGS AND DESIGN
The evaluation of crystalline strain in the dentin slabs was done using Synchrotron X-ray diffraction. The post operative sensitivity was measured clinically using Schiff's sensitivity scale.
MATERIALS AND METHODS
A total of 44 extracted and noncarious premolars were collected. Dentin slabs of dimensions 2 mm × 2 mm × 1.5 mm were prepared from the buccal aspect of the extracted teeth. The dentin slabs were then divided into two groups, Group A dual-cured resin cement and Group B resin-modified glass ionomer cement was applied. The dentin slabs first underwent synchrotron X-ray diffraction before and after the application of cement. Forty-two patients who were undergoing complete metal fixed prostheses on vital posterior abutments were selected. In this, 21 vital abutments were included in each group. Tooth preparation and fabrication of complete metal prostheses were done in the conventional manner and cemented using the 2 luting cements in Groups A and B, respectively. Dentinal hypersensitivity was measured using Schiff 's scale, postcementation, after 1 week and 1 month.
STATISTICAL ANALYSIS
Independent t-test was done for comparing the two cements in two cements in terms of lattice strain. Mann-Whitney U-test was done for comparing the cements with respect to dentinal hypersensitivity. Spearman's correlation coefficient was used for clinical correlation between dentinal hypersensitivity and crystalline strain.
RESULTS
The lattice strain generated in dual cure resin cement was higher than that in resin-modified glass ionomer cement and was statistically significant. Postcementation hypersensitivity was higher in dual-cured resin than resin-modified glass ionomer cement but was not statistically significant in the follow-up visits. Spearman's correlation coefficients did not reveal any significant clinical correlation between lattice strain and dentinal hypersensitivity.
CONCLUSION
Dual cure resin cements generate greater lattice strain as compared to resin modified glass ionomer cements.
Topics: Humans; Glass Ionomer Cements; Resin Cements; Polymerization; Synchrotrons; X-Ray Diffraction; Resins, Plant; Dentin
PubMed: 37102536
DOI: 10.4103/jips.jips_84_22 -
PLoS Pathogens May 2024The role of bacteria in the etiology of dental caries is long established, while the role of fungi has only recently gained more attention. The microbial invasion of...
The role of bacteria in the etiology of dental caries is long established, while the role of fungi has only recently gained more attention. The microbial invasion of dentin in advanced caries especially merits additional research. We evaluated the fungal and bacterial community composition and spatial distribution within carious dentin. Amplicon 16S rRNA gene sequencing together with quantitative PCR was used to profile bacterial and fungal species in caries-free children (n = 43) and 4 stages of caries progression from children with severe early childhood caries (n = 32). Additionally, healthy (n = 10) and carious (n = 10) primary teeth were decalcified, sectioned, and stained with Grocott's methenamine silver, periodic acid Schiff (PAS) and calcofluor white (CW) for fungi. Immunolocalization was also performed using antibodies against fungal β-D-glucan, gram-positive bacterial lipoteichoic acid, gram-negative endotoxin, Streptococcus mutans, and Candida albicans. We also performed field emission scanning electron microscopy (FESEM) to visualize fungi and bacteria within carious dentinal tubules. Bacterial communities observed included a high abundance of S. mutans and the Veillonella parvula group, as expected. There was a higher ratio of fungi to bacteria in dentin-involved lesions compared to less severe lesions with frequent preponderance of C. albicans, C. dubliniensis, and in one case C. tropicalis. Grocott's silver, PAS, CW and immunohistochemistry (IHC) demonstrated the presence of fungi within carious dentinal tubules. Multiplex IHC revealed that fungi, gram-negative, and gram-positive bacteria primarily occupied separate dentinal tubules, with rare instances of colocalization. Similar findings were observed with multiplex immunofluorescence using anti-S. mutans and anti-C. albicans antibodies. Electron microscopy showed monomorphic bacterial and fungal biofilms within distinct dentin tubules. We demonstrate a previously unrecognized phenomenon in which fungi and bacteria occupy distinct spatial niches within carious dentin and seldom co-colonize. The potential significance of this phenomenon in caries progression warrants further exploration.
Topics: Humans; Dental Caries; Dentin; Male; Child; Female; Child, Preschool; Bacteria; Fungi; RNA, Ribosomal, 16S
PubMed: 38805482
DOI: 10.1371/journal.ppat.1011865 -
International Journal of Nanomedicine 2021Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no...
BACKGROUND
Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no treatment regimen demonstrates long-lasting efficacy in treating DH, and unesthetic yellow tooth color is a concern to many patients with DH.
AIM
To develop a bi-functional material which can occlude dentinal tubules in-depth and remineralize dentin for long-lasting protection of the dentin-pulp complex from stimuli and bleach the tooth at the same time.
METHODS
A mixture containing CaO, HPO, polyethylene glycol and HO at a specific ratio was mechanically ground using a planetary ball. The mineralizing complex paste was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dentin was exposed to the synthesized paste for 8 h and 24 h . The mineralizing property was evaluated using SEM and microhardness tests. Red tea-stained tooth slices were exposed to the synthesized paste for 8 h and 24 h . The bleaching effect was characterized by a spectrophotometer.
RESULTS
The complex paste had very a fine texture, was injectable, and had a gel-like property with 2.6 (mass/volume) % HO concentration. The X-ray diffraction pattern showed that the inorganic phase was mainly monetite (CaHPO). The mineralizing complex paste induced the growth of inorganic crystals on the dentin surface and in-depth occlusion of dentin tubules by up to 80 μm. The regenerated crystals were integrated into the dentin tissue on the dentin surface and the wall of dentinal tubules with a microhardness of up to 126 MPa (versus 137 Mpa for dentin). The paste also bleached the stained dental slices.
CONCLUSION
The mineralizing complex paste is a promising innovative material for efficient DH management by remineralizing dentin and in-depth occlusion of dentin tubules, as well as tooth bleaching.
Topics: Calcium Phosphates; Dentin; Hardness; Humans; Hydrogen Peroxide; Phosphoric Acids; Tooth Bleaching; Tooth Remineralization; X-Ray Diffraction
PubMed: 33442248
DOI: 10.2147/IJN.S287393 -
International Journal of Molecular... Aug 2021The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ...
The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth ( = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups ( < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time.
Topics: Chelating Agents; Chitosan; Dentin; Humans; Materials Testing; Matrix Metalloproteinases
PubMed: 34445554
DOI: 10.3390/ijms22168852 -
Journal (Canadian Dental Association) Apr 2000Commercially available caries-detector dyes are purported to aid the dentist in differentiation of infected dentin, yet research has established that these dyes are not... (Review)
Review
Commercially available caries-detector dyes are purported to aid the dentist in differentiation of infected dentin, yet research has established that these dyes are not specific for infected dentin. They are non-specific protein dyes that stain the organic matrix of less mineralized dentin, including normal circumpulpal dentin and sound dentin in the area of the amelo-dentinal junction. A considerable body of evidence indicates that conventional tactile and optical criteria provide satisfactory assessment of caries status during cavity preparation. There is reason for concern that subsequent use of a caries-detector dye would result in unnecessary removal of sound tooth structure. The use of caries-detector dyes has also been suggested as a diagnostic aid for occlusal caries. Although diagnosis of carious dentin beneath apparently sound enamel can be challenging, there is a lack of substantive evidence supporting the use of dyes for this purpose and false positives are a significant concern. Careful visual inspection combined with bitewing radiographic diagnosis has been shown to be the most reliable diagnostic method for the presence of infected dentin requiring operative treatment.
Topics: Coloring Agents; Dental Caries; Dental Cavity Preparation; Dental Enamel; Dentin; False Positive Reactions; Humans; Radiography, Bitewing; Reproducibility of Results
PubMed: 10789171
DOI: No ID Found -
Scientific Reports Feb 2017A novel agarose hydrogel biomimetic mineralization system loaded with calcium and phosphate was used to remineralize dentin and induce the oriented densely parallel...
A novel agarose hydrogel biomimetic mineralization system loaded with calcium and phosphate was used to remineralize dentin and induce the oriented densely parallel packed HA layer on defective dentin surface in vivo in a rabbit model. Firstly, the enamel of the labial surface of rabbits' incisor was removed and the dentin was exposed to oral environment. Secondly, the hydrogel biomimetic mineralization system was applied to the exposed dentin surface by using a custom tray. Finally, the teeth were extracted and evaluated by scanning electron microscopy, X-ray diffraction, and nanoindentation test after a certain time of mineralization intervals. The regenerated tissue on the dentin surface was composed of highly organised HA crystals. Densely packed along the c axis, these newly precipitated HA crystals were perpendicular to the underlying dental surface with a tight bond. The demineralized dentin was remineralized and dentinal tubules were occluded by the grown HA crystals. The nanohardness and elastic modulus of the regenerated tissue were similar to natural dentin. The results indicated a potential clinical use for repairing dentin-exposed related diseases, such as erosion, wear, and dentin hypersensitivity.
Topics: Animals; Biomimetics; Dentin; Elastic Modulus; Hydrogels; Male; Rabbits; Sepharose; Tooth Remineralization
PubMed: 28167823
DOI: 10.1038/srep41955 -
Australian Dental Journal Sep 2004'Adhesive' restorative dentistry originated with the work of Buonocore in 1955 in bonding resin to etched enamel. Since then, adhesive materials and techniques have... (Review)
Review
'Adhesive' restorative dentistry originated with the work of Buonocore in 1955 in bonding resin to etched enamel. Since then, adhesive materials and techniques have developed at a rapid rate. The first chemically adhesive material (zinc polycarboxylate cement) was marketed in the late 1960s, and glass-ionomer cements and dentine bonding agents have since become available. This review focuses on the latter two products. Glass-ionomer cements have a particular role in adhesive dentistry because of their reliable chemical adhesion to enamel and dentine, and because of their apparent ability to promote the remineralization of 'affected' dentine. Dentine bonding agents have undergone marked changes in presentation over the last 15 years, but all have an essentially similar bonding system, that of hybrid layer formation. However, the most recent systems have limited clinical data supporting their use.
Topics: Dental Bonding; Dental Enamel; Dental Restoration, Permanent; Dentin; Dentin-Bonding Agents; Glass Ionomer Cements; Humans
PubMed: 15497354
DOI: 10.1111/j.1834-7819.2004.tb00059.x