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Schweizer Monatsschrift Fur Zahnmedizin... 1991Dentin hypersensitivity is a painful manifestation resulting from a response of the openings of dentin tubules to oral environment. It is probably caused by movements of... (Review)
Review
Dentin hypersensitivity is a painful manifestation resulting from a response of the openings of dentin tubules to oral environment. It is probably caused by movements of intratubular fluids, under the influence of different types of stimuli at the dentin surface. Hypersensitivity has been known for a long time and its treatment has always been difficult. Sometimes, by a kind of natural reaction to aggression, dentin is able to increase its degree of mineralisation but, most of the time, an active treatment has to be performed. Unfortunately the mechanism of dentinal pain is not well known and the symptoms of sensitivity are unspecific and subjective, so that the ideal compound for treatment does not exist. Many products have been tested, but the results are most of the time contradictory and the placebo effect is often very significant. In all cases the aim of the treatment remains the obliteration of dentin tubules, in order to obtain a decrease of dentin permeability.
Topics: Dental Plaque; Dentin; Dentin Sensitivity; Humans; Iontophoresis; Saliva
PubMed: 1947969
DOI: No ID Found -
Biomaterials Jan 2013The crack growth resistance of human dentin was characterized as a function of relative distance from the DEJ and the corresponding microstructure. Compact tension...
The crack growth resistance of human dentin was characterized as a function of relative distance from the DEJ and the corresponding microstructure. Compact tension specimens were prepared from the coronal dentin of caries-free 3rd molars. The specimens were sectioned from either the outer, middle or inner dentin. Stable crack extension was achieved under Mode I quasi-static loading, with the crack oriented in-plane with the tubules, and the crack growth resistance was characterized in terms of the initiation (K(o)), growth (K(g)) and plateau (K(p)) toughness. A hybrid approach was also used to quantify the contribution of dominant mechanisms to the overall toughness. Results showed that human dentin exhibits increasing crack growth resistance with crack extension in all regions, and that the fracture toughness of inner dentin (2.2 ± 0.5 MPa·m(0.5)) was significantly lower than that of middle (2.7 ± 0.2 MPa·m(0.5)) and outer regions (3.4 ± 0.3 MPa·m(0.5)). Extrinsic toughening, composed mostly of crack bridging, was estimated to cause an average increase in the fracture energy of 26% in all three regions. Based on these findings, dental restorations extended into deep dentin are much more likely to cause tooth fracture due to the greater potential for introduction of flaws and decrease in fracture toughness with depth.
Topics: Computer Simulation; Dentin; Hardness; Humans; Materials Testing; Models, Biological; Models, Chemical; Surface Properties
PubMed: 23131531
DOI: 10.1016/j.biomaterials.2012.10.032 -
Journal of the Mechanical Behavior of... Oct 2017The aim of this study was to ascertain the effect of Zn-doping of dental adhesives and mechanical load cycling on the micromorphology of the resin-dentin interdiffusion...
The aim of this study was to ascertain the effect of Zn-doping of dental adhesives and mechanical load cycling on the micromorphology of the resin-dentin interdiffusion zone (of sound and caries affected dentin). The investigation considered two different Zn-doped adhesive approaches and evaluated the interface using a doubled dye fluorescent technique and a calcium chelator fluorophore under a confocal laser scanning microscopy. Sound and carious dentin-resin interfaces of unloaded specimens were deficiently resin-hybridized, in general. These samples showed a rhodamine B-labeled hybrid layer and adhesive layer completely affected by fluorescein penetration (nanoleakage) through the porous resin-dentin interface. It was thicker after phosphoric acid-etching and more extended in carious dentin. Zn-doping promoted an improved sealing of the resin-dentin interface, a decrease of the hybrid layer porosity, and an increment of dentin mineralization. Load cycling augmented the sealing of the Zn-doped resin-dentin interfaces, as porosity and nanoleakage diminished, and even disappeared in caries-affected dentin substrata conditioned with EDTA. Sound and carious dentin specimens analyzed with the xylenol orange technique produced a clearly outlined fluorescence when resins were Zn-doped, due to a consistent Ca-mineral deposition within the bonding interface and inside the dentinal tubules. It was more evident when load cycling was applied on specimens treated with self-etching adhesives that were Zn-doped. Micropermeability at the resin-dentin interface diminished after combining EDTA pretreatment, ZnCl-doping and mechanical loading stimuli on restorations. It is clearly preferable to include the zinc compounds into the bonding constituents of the self-etching adhesives, instead of into the primer ingredients. The promoted new mineral segments contributed to reduce or avoid both porosity and nanoleakage from the load cycled Zn-doped resin dentin interfaces. EDTA+SB-ZnCl or SEB·Bd-Zn doping are preferred to treat caries-affected dentin surfaces. ZnO-doping encouraged for etch-and-rinse adhesives.
Topics: Adhesives; Chlorides; Dental Bonding; Dental Caries; Dentin; Dentin-Bonding Agents; Humans; Microscopy, Confocal; Microscopy, Electron, Scanning; Resin Cements; Zinc Compounds
PubMed: 28535395
DOI: 10.1016/j.jmbbm.2017.04.030 -
Journal of Endodontics Jun 1992The effect of a CO2 laser on the structure and permeability of smear layer-covered human dentin was evaluated in vitro. Three different energy levels were used (11, 113,...
The effect of a CO2 laser on the structure and permeability of smear layer-covered human dentin was evaluated in vitro. Three different energy levels were used (11, 113, and 566 J/cm2). The lowest exposure to the laser energy increased dentin permeability, measured as a hydraulic conductance, due to partial measured as a hydraulic conductance, due to partial loss of the superficial smear layer and smear plugs. The intermediate energy level also increased dentin permeability by crater formation, making the dentin thinner. The lack of uniform glazing of the surface of the crater, leaving its surface porous and in communication with the underlying dentinal tubules also contributed to the increase in dentin permeability seen with the intermediate laser energy. The highest laser energy produced complete glazing of the crater surfaces and sealed the dentinal tubules beneath the crater. However, it also completely removed the smear layer in a halo zone about 100-microns wide around each crater which increased the permeability of the pericrater dentin at the same time it decreased the permeability of the dentin within the crater. The combined use of scanning electron microscopy and permeability measurements provides important complementary information that is essential in evaluating the effects of lasers on dentin.
Topics: Adolescent; Adult; Dentin; Dentin Permeability; Female; Humans; Lasers; Male; Microscopy, Electron, Scanning; Smear Layer; Surface Properties
PubMed: 1402582
DOI: 10.1016/s0099-2399(06)80951-9 -
Photobiomodulation, Photomedicine, and... May 2019This study was performed to determine the bactericidal effects of erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation and the morphological and chemical...
This study was performed to determine the bactericidal effects of erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation and the morphological and chemical composition changes in bovine dentin. Dentin slabs were prepared from bovine incisors, and then cultured with to produce bacteria-infected dentin samples. The samples were randomly divided into five groups with Er:YAG laser irradiation energy densities of 0, 6.37, 12.73, 19.11, and 25.47 J/cm. After irradiation, samples were stained and observed by confocal laser scanning microscopy. The bactericidal abilities were measured using live/dead staining. The morphology and chemical components were investigated by scanning electron microscopy and energy-dispersive spectrometry. After irradiation, the elimination of bacteria and the smear layer were significantly better in the high energy density groups (19.11, 25.47 J/cm) than in the low energy density groups (6.37, 12.73 J/cm; < 0.001). On morphological examination, the group with minimum energy density (6.37 J/cm) showed superficial melting. In the high energy density groups (12.73, 19.11, and 25.47 J/cm), laser-irradiated dentin showed a clean surface with open orifices. Significant increases were observed in the weight percentages of calcium (from 19.75 ± 0.69 to 34.47 ± 2.91, < 0.001) and phosphate (from 8.58 ± 0.43 to 15.10 ± 1.81, < 0.001), whereas significant decreases were observed for oxygen (from 49.84 ± 0.69 to 36.39 ± 2.86, < 0.001) and carbon (from 26.06 ± 3.58 to 12.80 ± 2.26, < 0.01) with increasing energy density. This study confirmed that Er:YAG laser irradiation has bactericidal and dentin conditioning effects.
Topics: Animals; Cattle; Dentin; Lasers, Solid-State; Low-Level Light Therapy; Microscopy, Confocal; Streptococcus mutans; Tissue Culture Techniques
PubMed: 31084558
DOI: 10.1089/photob.2018.4586 -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... Jul 2020The purpose of this study was to investigate the effect of G4.5 carboxyl-terminated poly dendrimer (PAMAM-COOH) on the dentin remineralization and the matrix...
OBJECTIVE
The purpose of this study was to investigate the effect of G4.5 carboxyl-terminated poly dendrimer (PAMAM-COOH) on the dentin remineralization and the matrix metalloproteinases (MMPs) activity.
METHODS
The dentine samples were averagely divided into four groups: 100 mg/mL PAMAM-COOH group (A group), 10 mg/mL PAMAM-COOH group (B group), 2% (wt) chlorhexidine (CHX) group (C group) and deionized water group (Control group). MMP Activity Assay Kit was used to detect the activity of dentin endogenous MMPs in the four groups. The loss of dry mass of dentin after 30 d were measured. zymography analysis was performed to detect the effects of PAMAM dendrimer in each group (except A group) on gelatinase activity in dentin. After incubation in artificial saliva for 7 and 14 d incubated, the remineralization of each group (except A group) in dentin surfaces were examined using a field emission-scanning electron microscope (FESEM).
RESULTS
Compared with the control group, the dentin endogenous MMPs activity in A, B and C groups were all decreased ( <0.05). The activity of endogenous MMPs in C group was lower than that of A and B groups ( <0.001), but the difference between A and B groups was not statistically significant. The loss of dry mass in A, B and C groups were lower than that in control group ( <0.05), but there were no significant difference in A, B and C groups. The zymography analysis showed that 48 h later, the dentin gelatinase activity in B group was inhibited compared with the control group, but the inhibitory effect was weaker than that of CHX. After 7 d and 14 d, there were no obvious mineralization in the control group, while distinct mineralization were observed in B group. The mineralization effect in group B was better than group C.
CONCLUSION
G4.5 PAMAM-COOH could introduce remineralizationin and demineralizeddentin by effectively inhibiting endogenous MMPs and gelatinase, thus contributes as novel material to enhancing durability of adhesion.
Topics: Dendrimers; Dentin; Enzyme Activation; Humans; Matrix Metalloproteinases; Saliva, Artificial; Tooth Remineralization
PubMed: 32691557
DOI: 10.12182/20200760203 -
Journal of Biomedical Materials... Sep 2003The objective of this study was to show the influence of dissolved dentinal polyelectrolytes on the characteristics of dentin (bonding substrate) demineralized by citric...
The objective of this study was to show the influence of dissolved dentinal polyelectrolytes on the characteristics of dentin (bonding substrate) demineralized by citric acid in the absence or presence of ferric chloride. The demineralizing agent was an aqueous mixture of 0, 1, 3, or 10% ferric chloride in 10% citric acid (10-0, 10-1, 10-3, 10-10, respectively). The hypothesis was that the concentration of dissolved dentinal noncollagenous substances, mainly polyelectrolytes soluble in water, must be decreased by their aggregation with ferric ions, which changes the characteristics of demineralized dentin, the rates of demineralization, and dehydration. Cervical bovine dentin was prepared in 3 x 2 x 2-mm blocks, each weighing 20.0 +/- 0.5 mg. The rate of demineralization was investigated by measuring the weight loss resulting from demineralization by immersion in 10 mL of conditioner at 2-h intervals. The dehydration rate of wet demineralized dentin was determined using two methods: (1) weight loss in a desiccator under 263 Pa pressure and (2) differential scanning calorimetry (DSC). Twenty, 12, 8, and 4 h were required to complete demineralization of the blocks with the 10-0, 10-1, 10-3, and 10-10 solutions, respectively. The 10-10 wet demineralized dentin showed the highest rate of dehydration, followed in descending order by the 10-3, 10-1, and 10-0 specimens. Ferric chloride in dentin conditioners provided both a higher rate of dentin demineralization and a higher dehydration rate of wet demineralized dentin. These results suggest that in the presence of ferric chloride, a decreasing amount of dissolved polyelectrolytes aggregated with ferric ions in the substrates may increase the permeability of dentin to water and citric acid. Improvement of monomer permeability is essential to the preparation of good hybridized dentin, providing a more stable and reliable bonding and also protecting the dentin and pulp from infection. A further study of bonding substrates is required in order to understand the role of hybridized dentin in improved dental treatment.
Topics: Animals; Cattle; Dentin; Electrolytes
PubMed: 12926030
DOI: 10.1002/jbm.a.10572 -
Lasers in Medical Science Sep 2017The aim of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan gel where the...
The aim of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan gel where the subsurface microhardness, chemical composition, and morphological changes of the residual caries-affected dentin were examined. Artificial dentinal lesions were created by pH-cycling method (14 days) in 104 bovine specimens (5 × 5 mm). Specimens were randomly divided according to the carious removal method: bur (low-speed handpiece) or Er:YAG laser (250 mJ/4 Hz). Specimens were treated with 35% phosphoric acid and were subdivided into two groups according to dentin biomodification: without chitosan (control) and 2.5% chitosan. Forty specimens were restored with an adhesive system and composite resin. Subsurface microhardness tests were performed in sound dentin, caries-affected dentin, residual caries-affected dentin, and after the restoration. The other 64 specimens were subjected to SEM-EDS atomic analysis. Data were statistically analyzed (p < 0.05). After the Er:YAG laser excavation, the microhardness value of residual caries-affected dentin was higher (p < 0.05) than bur-treated dentin. A significant decrease in the amount of Ca, P, and Ca/P ratio was found after the removal of carious lesions with Er:YAG laser (p < 0.05). The biomodification with chitosan did not influence the microhardness and atomic percentage of Ca, P, and Ca/P ratio of residual caries-affected dentin (p > 0.05). SEM analysis showed morphological changes on residual caries-affected dentin (p > 0.05). The selective removal of carious dentin with Er:YAG laser increased microhardness of residual caries-affected dentin, changing its surface morphology and chemical composition. The biomodification with chitosan did not influence the structural and chemical composition of residual caries-affected dentin.
Topics: Animals; Cattle; Chitosan; Confidence Intervals; Dental Caries; Dentin; Hardness; Lasers, Solid-State
PubMed: 28762194
DOI: 10.1007/s10103-017-2287-6 -
Journal of the Mechanical Behavior of... Oct 2009An evaluation of the crack growth resistance of human coronal dentin was performed on tissue obtained from patients between ages 18 and 83. Stable crack extension was...
An evaluation of the crack growth resistance of human coronal dentin was performed on tissue obtained from patients between ages 18 and 83. Stable crack extension was achieved over clinically relevant lengths (0< or = a < or =1mm) under Mode I quasi-static loading and perpendicular to the nominal tubule direction. Results distinguished that human dentin exhibits an increase in crack growth resistance with extension (i.e. rising R-curve) and that there is a significant reduction in both the initiation (K(o)) and plateau (K(p)) components of toughness with patient age. In the young dentin (18< or =age< or =35) there was a 25% increase in the crack growth resistance from the onset of extension (K(o)=1.34 MPa m(0.5)) to the maximum or "plateau" toughness (K(p)=1.65 MPa m(0.5)). In comparison, the crack growth resistance of the old dentin (55< or =age) increased with extension by less than 10% from K(o)=1.08 MPa m(0.5) to K(p)=1.17 MPa m(0.5). In young dentin toughening was achieved by a combination of inelastic deformation of the mineralized collagen matrix and microcracking of the peritubular cuffs. These mechanisms facilitated further toughening via the development of unbroken ligaments of tissue and posterior crack-bridging. Microstructural changes with aging decreased the capacity for near-tip inelastic deformation and microcracking of the tubules, which in turn suppressed the formation of unbroken ligaments and the degree of extrinsic toughening.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aging; Biomechanical Phenomena; Dentin; Humans; Microscopy, Electron, Scanning; Middle Aged; Molar; Tooth Fractures; Young Adult
PubMed: 19627862
DOI: 10.1016/j.jmbbm.2009.01.008 -
American Journal of Dentistry Feb 1992This study determined the effect of phosphoric acid (H3PO4) application to dentin on the shear bond strength (SBS) and microleakage of an experimental bonding system....
This study determined the effect of phosphoric acid (H3PO4) application to dentin on the shear bond strength (SBS) and microleakage of an experimental bonding system. Thirty human maxillary permanent first and second molars were used for the SBS evaluation. In 15 of the teeth the Dentin Conditioner was applied to dentin for 30 seconds (A), while in the remaining 15 teeth the smear layer was removed by the application of a 37% H3PO4 gel for 20 seconds (B). The Primers 1 and 2 were mixed and applied to the conditioned dentin followed by the application of the Dentin Bonding Resin prior to the placement in three increments of the Bisfil-M composite. The specimens were stored in physiological saline at 37 degrees C for 24 hours prior to applying a shear load at a crosshead speed of 0.5 mm. inch-1 in an Instron machine. Shear bond strengths were expressed in MPa. Circular Class V preparations were made on the roots of 30 maxillary permanent canines, 15 restored using the Dentin Conditioner (C) and 15 by removing the smear layer with the H3PO4 gel (D). Microleakage of the restorations was determined quantitatively by means of a spectrophotometric method. The quantitative microleakage was expressed as microgram dye/restoration. The data were analyzed by the Student t-test. The following results were obtained: A: 14.2 +/- 2.2 MPa; B: 7.2 +/- 4.2 MPa; C: 30.0 +/- 28.6 micrograms dye/restoration; (D) 10.3 +/- 8.2 micrograms dye/restoration. Removing the smear layer with H3PO4 reduced the SBS to dentin but decreased the quantitative microleakage significantly.
Topics: Acid Etching, Dental; Dental Bonding; Dental Leakage; Dental Stress Analysis; Dentin; Dentin Permeability; Humans; Microscopy, Electron, Scanning; Molar; Phosphoric Acids; Smear Layer; Surface Properties; Tensile Strength
PubMed: 1524738
DOI: No ID Found