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European Journal of Oral Sciences Feb 2010The effects of dentin surface treatments on the microtensile bond strengths and on the interfacial characteristics of self-adhesive resin cements were investigated. Flat...
The effects of dentin surface treatments on the microtensile bond strengths and on the interfacial characteristics of self-adhesive resin cements were investigated. Flat dentin surfaces were obtained from human molars and were treated as follows: (i) no treatment of dentin; (ii) 0.1 M EDTA scrubbed for 60 s; or (iii) 10% polyacrylic acid applied for 30 s. Three self-adhesive cements were used to lute composite overlays on deep-coronal dentin surfaces in the presence of simulated pulpal pressure (15 cm of H(2)O). Bonded specimens were cut into beams 1 mm thick and stressed in tension until failure. Fractured sticks were examined under a scanning electron microscope. Additional specimens were stained with Masson's trichrome and observed under light microscopy for interfacial evaluations. The bond strength to dentin of the hydrophobic and solvent-free cement (RelyX Unicem) was unaffected by the tested dentin treatments. The bond strength of the 2-hydroxyethyl methacrylate (HEMA)-based cement (Bis-Cem) decreased after treatment of dentin with EDTA and/or polyacrylic acid. The hydrophilic and water-containing cement (G-Cem) attained a higher bond strength when luted on polyacrylic acid-conditioned dentin. In conclusion, smear layer removal, opening of dentinal tubules, and the water content of dentin differently influence the bond strengths and the interfacial characteristics of self-adhesive cement-dentin interfaces.
Topics: Acrylic Resins; Composite Resins; Dental Bonding; Dental Etching; Dental Stress Analysis; Dentin; Dentin Permeability; Dentin-Bonding Agents; Edetic Acid; Humans; Materials Testing; Resin Cements; Tensile Strength; Wettability
PubMed: 20156269
DOI: 10.1111/j.1600-0722.2009.00703.x -
Journal of Oral Rehabilitation Oct 2016One of the greatest challenges to modern dentistry is the progressive destruction of tooth material due to chemical erosion. Dental erosion is the loss of dental hard... (Review)
Review
One of the greatest challenges to modern dentistry is the progressive destruction of tooth material due to chemical erosion. Dental erosion is the loss of dental hard tissue, without the action of bacteria, in which demineralisation of enamel and dentine results due to a decrease in intra-oral pH. The aim of this review was to appraise the scientific literature on the factors that can affect intra-oral pH. The review will examine (i) the protective role of human saliva, in terms of its mineral composition, flow rates and buffering systems and (ii) sources of in-mouth acids such as extrinsic acids, which are derived from the diet and environment, as well as intrinsic acids, which are related to disorders of the gastro-oesophageal tract. This review may assist clinicians to identify the risk factors for tooth wear and to recommend adequate preventive measures to patients.
Topics: Dental Enamel; Dentin; Dentin Sensitivity; Diet; Humans; Hydrogen-Ion Concentration; Saliva; Tooth Erosion
PubMed: 27573678
DOI: 10.1111/joor.12429 -
Microscopy Research and Technique Aug 2017Oxalate-based products are effective against dentine sensitivity and have been studied as an option to improve long-term adhesive bonding strength. Our aim was to...
Oxalate-based products are effective against dentine sensitivity and have been studied as an option to improve long-term adhesive bonding strength. Our aim was to evaluate the effect of potassium oxalate on the microtensile bond strength (µTBS) of the dentin/resin interface after 24 h, 1, and 6 years. Dentin on the occlusal surface of 16 human premolars was exposed and etched with 35% phosphoric acid. The teeth were divided into four groups. Two groups received 3% monohydrated potassium oxalate and the following adhesive systems and composites: Adper Scotchbond Multipurpose + FiltekZ350 (3M/ESPE) and Prime & Bond NT + Esthet-X (Dentsply). Two control groups did not receive potassium oxalate. Teeth were cut into sticks and kept in distilled water at 37°C for 24 h, 1, and 6 years. The sticks underwent µTBS testing after storage. ANOVA, Tukey's post hoc test, and paired t test were used to compare storage times (α = 0.05). The fracture mode of the specimens was classified under a stereomicroscope (40×). Morphology of the hybrid layer and the fracture pattern were observed with scanning electronic microscopy (SEM). Mean µTBS was high at 24 h and decreased after 1 and 6 years. After 6 years, the mean µTBS values were similar with no statistically significant difference between the groups (p = .121). SEM images showed proper dentin hybridization. Dentin pretreatment with potassium oxalate did not affect hybrid layer formation, but bond strength decreased over time after 24 h. Therefore, the clinical use of potassium oxalate to increase dentin bond durability is not indicated.
Topics: Dental Bonding; Dental Stress Analysis; Dentin; Dentin-Bonding Agents; Follow-Up Studies; Humans; Oxalic Acid
PubMed: 28401681
DOI: 10.1002/jemt.22876 -
Advances in Clinical and Experimental... Jul 2017The FEM is often used in investigations of dentin loading conditions; however, its anisotropy is mostly neglected.
BACKGROUND
The FEM is often used in investigations of dentin loading conditions; however, its anisotropy is mostly neglected.
OBJECTIVES
The purpose of the study was to evaluate the anisotropy and the elastic properties of an equivalent homogenous material model of human dentin as well as to compare isotropic and anisotropic dentin FE-models.
MATERIAL AND METHODS
Analytical and numerical dentin homogenization according to Luciano and Barbero was performed and E-modulus (E), Poisson's ratios (v) G-modulus (G) were calculated. The E-modulus of the dentin matrix was 28.0 GPa, Poisson's ratio (v) was 0.3; finite element models of orthotropic and isotropic dentin were created, loaded and compared using Ansys® 14.5 and CodeAster® 11.2 software.
RESULTS
Anisotropy of the dentin ranged from 6.9 to 35.2%. E-modulus and G-modulus were as follows: E1 = 22.0-26.0 GPa, E2/E3 = 15.7-23.0 GPa; G12/G13 = 6.96-9.35 GPa and G23 = 6.08-8.09 GPa (highest values in the superficial layer). In FEM analysis of the displacement values were higher in the isotropic than in the orthotropic model, reaching up to 16% by shear load, 37% by compression and 23% in the case of shear with bending. Strain values were higher in the isotropic model, up to 35% for the shear load, 31% for compression and 35% in the case of shear with bending. The decrease in the volumetric fraction and diameter of tubules increased the G and E values.
CONCLUSIONS
Anisotropy of the dentin applied during FEM analysis decreased the displacements and strain values. The numerical and analytical homogenization of dentin showed similar results.
Topics: Anisotropy; Dentin; Finite Element Analysis; Humans; Stress, Mechanical; Tensile Strength
PubMed: 28691430
DOI: 10.17219/acem/67441 -
Journal of Biomedical Materials... Feb 2011The molecular structure, weight loss, and mechanical properties of demineralized dentin of noncrosslinked/crosslinked by glutaraldehyde (GA) were investigated when being...
The molecular structure, weight loss, and mechanical properties of demineralized dentin of noncrosslinked/crosslinked by glutaraldehyde (GA) were investigated when being challenged by bacterial collagenase solution over time in this study. Raman spectra proved that crosslinking occurred in demineralized dentin matrices after being treated with GA. Meanwhile, the weight of the cross-linked demineralized dentin matrices did not change after being challenged by bacterial collagenase solution up to 1 week. However, the weight of noncross-linked dentin collagen fell by almost 45% after degradation for 5 h, and up to 100% after 19 h. The tensile strength of demineralized dentin matrices did not show a significant change after being crosslinked, while the stiffness of demineralized dentin matrices showed more improvement than that of noncross-linked collagen. The toughness of demineralized dentin matrices decreased slightly after being crosslinked. Importantly, neither the tensile strength of GA-cross-linked demineralized dentin nor its stiffness changed over time in either control buffer or collagenase solution compared with that of noncross-linked controls. These results suggested that improving the degree of crosslinking in dentin collagen could be one method to inhibit its biodegradation and further to increase the durability of dental restorations.
Topics: Bacteria; Collagenases; Cross-Linking Reagents; Dentin; Glutaral; Materials Testing; Mechanical Phenomena
PubMed: 21210503
DOI: 10.1002/jbm.b.31759 -
Journal of Dental Research Apr 1985The major channels for solute diffusion across dentin are the dentinal tubules. Since dentin permeation is proportional to the product of tubule number and diameter,...
The major channels for solute diffusion across dentin are the dentinal tubules. Since dentin permeation is proportional to the product of tubule number and diameter, both of which increase as the tubules converge on the pulp, we find that dentin permeability increases rapidly as the pulp chamber is approached. The presence of a smear layer of cutting debris on top of cut dentin decreases dentin permeability, especially when permeability is measured by fluid filtration. Further, intratubular material--such as mineral deposits, collagen fibrils, proteoglycan linings, bacteria, etc.--can greatly reduce dentin permeability. Although the presence of irregular or irritation dentin has been thought to greatly reduce dentin permeability, recent in vivo experiments in dogs indicate that the dentin permeability of freshly cut cavities prepared in sound dentin falls very rapidly (i.e., 50-60% in the first six hours) before any histologic changes can be detected, either in the pulp or the dentin. When dogs were depleted of their plasma fibrinogen, this rapid decline in dentin permeability following cavity preparation failed to take place. The results implicate leakage of plasma proteins from the underlying pulpal vessels. The proteins subsequently permeate the tubules, where they are either adsorbed to the tubule walls or physically trapped in such a way as to reduce dentin permeability.
Topics: Animals; Biological Transport; Blood Proteins; Capillaries; Capillary Permeability; Dental Cavity Preparation; Dental Pulp; Dentin; Dentin Permeability; Dentin Sensitivity; Dentin, Secondary; Diffusion; Exudates and Transudates; Fibrinogen; Humans; Odontoblasts; Osmosis; Pressure; Rheology; Tooth Permeability
PubMed: 3857264
DOI: 10.1177/002203458506400419 -
European Journal of Oral Sciences Feb 2018This study investigated the effect of application of non-thermal atmospheric plasma (NTAP) on the topography and composition of the dentin surface, as well as the...
This study investigated the effect of application of non-thermal atmospheric plasma (NTAP) on the topography and composition of the dentin surface, as well as the microtensile bond strength (μTBS) of a universal adhesive to NTAP-treated dentin. Exposed flat dentin surfaces from human third molars were either treated with NTAP for 10 and 30 s or untreated (control). The dentin-surface topography and chemical composition were characterized by atomic force microscopy (n = 3) and Raman confocal spectroscopy (n = 5), respectively. The μTBS (n = 8) of Scotchbond Universal to dentin was determined after storage for 24 h and 1 yr, either by direct water exposure or under simulated pulpal pressure. In-situ zymography was used to evaluate the influence of NTAP on the dentin-enzymatic activity. Non-thermal atmospheric plasma produced no remarkable topographical or chemical alterations at the dentin surface; only the amount of phosphate decreased following 10 s of treatment with NTAP. After 1 yr of direct water exposure, the μTBS of NTAP-treated specimens did not differ statistically significantly from that of untreated controls, whereas simulated pulpal pressure-aging resulted in a significantly higher μTBS for NTAP-treated dentin. The dentin-enzymatic activity appeared to be treatment-dependent, but the untreated controls showed more intense fluorescence within the hybrid layer. Scotchbond Universal maintained its μTBS strength after 1 yr of direct water exposure and simulated pulpal pressure, although remarkable statistical differences between treatments were observed depending on the aging condition.
Topics: Dental Bonding; Dentin; Dentin-Bonding Agents; Humans; Microscopy, Electron, Scanning; Molar; Plasma Gases
PubMed: 29130564
DOI: 10.1111/eos.12388 -
Acta Biomaterialia Apr 2011Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties...
Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential preventive or reparative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interaction, biodegradation rates, proteoglycan interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent-dentin interaction was observed with GSE, which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates decreased remarkably following biomodification of dentin matrices after 24h collagenase digestion. A significant decrease in the proteoglycan content of GSE-treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and the control. The tensile strength properties of GD-biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD- and GSE-treated samples were observed following exposure to collagenase and 8 months water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry, but also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities.
Topics: Calorimetry, Differential Scanning; Dentin; Glycosaminoglycans; Humans; Preventive Dentistry; Temperature; Tensile Strength; Wound Healing
PubMed: 21167964
DOI: 10.1016/j.actbio.2010.12.013 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Dec 2022The purpose of the study was to evaluate the effect of hydroxyapatite (HA)-based desensiti-zing agents and determine their influence on the bonding performance of mild... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
The purpose of the study was to evaluate the effect of hydroxyapatite (HA)-based desensiti-zing agents and determine their influence on the bonding performance of mild universal adhesives.
METHODS
Mid-coronal dentin samples were sectioned from human third molars and prepared for a dentin-sensitive model. According to desensitizing applications, they were randomly divided into four groups for the following treatments: no desensitizing treatment (control), Biorepair toothpaste (HA-based desensitizing toothpaste) treatment, Dontodent toothpaste (HA-based desensitizing toothpaste) treatment, and HA paste treatment. Dentin tubular occlusion and occluded area ratios were evaluated by scanning electron microscopy (SEM). Furthermore, All-Bond Universal, Single Bond Universal, and Clearfil Universal Bond were applied to the desensitized dentin in self-etch mode. The wettability and surface free energy (SFE) of desensitized dentin were evaluated by contact angle measurements. Bonded specimens were sectioned into beams and tested for micro-tensile bond strength to analyze the effect of desensitizing treatment on the bond strength to dentin of universal adhesives.
RESULTS
SEM revealed that the dentin tubule was occluded by HA-based desensitizing agents, and the area ratios for the occluded dentin tubules were in the following order: HA group>Biorepair group>Dontodent group (<0.05). Contact angle analysis demonstrated that HA-based desensitizing agents had no statistically significant influence on the wettability of the universal adhesives (0.05). The SFE of dentin significantly increased after treatment by HA-based desensitizing agents (<0.05). The micro-tensile bond strength test showed that HA-based desensitizing toothpastes always decreased the μTBS values (<0.05), whereas the HA paste group presented similar bond strength to the control group (0.05), irrespective of universal adhesive types.
CONCLUSIONS
HA-based desensitizing agents can occlude the exposed dentinal tubules on sensitive dentin. When mild and ultra-mild universal adhesives were used for subsequent resin restoration, the bond strength was reduced by HA-based desensitizing toothpastes, whereas the pure HA paste had no adverse effect on bond strength.
Topics: Humans; Dental Cements; Dentin; Durapatite; Tensile Strength; Toothpastes
PubMed: 36416319
DOI: 10.7518/hxkq.2022.06.007 -
Stomatologiia 2023Dentinal fluid is very close in its physical and mechanical properties and composition to blood plasma, which makes it a potentially aggressive biological environment...
BACKGROUND
Dentinal fluid is very close in its physical and mechanical properties and composition to blood plasma, which makes it a potentially aggressive biological environment for modern adhesive systems. An in-depth study of the physiological processes of the functioning of tooth dentin remains relevant in order to solve problems associated with its artificial restoration.
PURPOSE OF THE STUDY
Study using computer simulation speed of movement and pressure distribution of dentinal fluid in the dentinal tubule of the tooth to assess the possibilities of their regulation.
MATERIAL AND METHODS
To model the distribution of flow velocity and pressure of dentinal fluid in the dentinal tubule, the finite element method (Fluent ANSYS computer program) was used.
RESULTS
Immediately behind the spherical tip of the odontoblast, there is a rapid increase in the hydraulic diameter of the flow section of the dentinal tubule, and, accordingly, a decrease in capillary pressure, while the tip of the odontoblast creates a large local hydraulic resistance. The resulting distribution of pressure drop in the damaged dentinal tubule is consistent with the fact that fluid movement is due, to a greater extent, to the capillary effect rather than the inlet pressure into the dentinal tubule.
CONCLUSION
By changing the length of the odontoblast process, it is possible to influence the parameters of the hydrodynamics of dentinal fluid in the space of the dentinal tubule.
Topics: Humans; Dentin; Dentinal Fluid; Computer Simulation; Hydrodynamics
PubMed: 38096387
DOI: 10.17116/stomat20231020625