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Photodiagnosis and Photodynamic Therapy Dec 2023Violet LED has been used for internal bleaching, however its implications on coronary dentin composition are unclear. The present study aims to evaluate the effect of...
BACKGROUND
Violet LED has been used for internal bleaching, however its implications on coronary dentin composition are unclear. The present study aims to evaluate the effect of bleaching with violet LED, either associated with 35 % hydrogen peroxide or not, on microhardness, chemical composition, and morphological characteristics of coronal dentin.
METHODS
Thirty maxillary canines were selected to obtain 30 blocks of coronal dentin, distributed in 3 groups (n = 10): 35 % hydrogen peroxide (HP); violet LED (LED); HP 35 % + LED, (HP+LED). The chemical analysis was performed by FTIR and the morphological evaluation of the dentin structure by confocal laser scanning microscopy before (T0) and after treatment (T1). The microhardness analysis was performed by microdurometer after bleaching. The data were submitted to repeated measures ANOVA test (P> 0.05).
RESULTS
The intensity of the inorganic peaks decreased after bleaching for all groups (P = 0.003). There was an increase in the organic peak intensity after bleaching with HP, a decrease for LED, while HP+LED did not change the intensity (P = 0.044). Moreover, the inorganic/organic ratio decreased for HP (P = 0.022), while for LED and HP+LED there was no significant changes (P>0.05). HP and HP+LED showed lower microhardness values compared to LED (P< 0.05). Regarding morphological changes, an increase in the perimeter of the dentinal tubules was found for all groups, with the smallest increase being observed for LED.
CONCLUSION
HP bleaching decreased the chemical stability and microhardness of the coronal dentin, while the violet LED treatments had no significant impact on dentin stability. In all groups, there was an increase in exposure of the dentinal tubules after bleaching, which was less pronounced with the violet LED bleaching.
Topics: Hydrogen Peroxide; Tooth Bleaching; Dentin; Photochemotherapy; Photosensitizing Agents; Hypochlorous Acid
PubMed: 37890812
DOI: 10.1016/j.pdpdt.2023.103862 -
Photobiomodulation, Photomedicine, and... May 2022Herein, a feasible strategy based on a femtosecond laser (fs-laser) was provided to decelerate dentin wear, and the effect of wear resistance improvement and its...
Herein, a feasible strategy based on a femtosecond laser (fs-laser) was provided to decelerate dentin wear, and the effect of wear resistance improvement and its potential mechanism were explored. Tooth wear is a common phenomenon that exists throughout life. While once dentin is exposed, it wears away very quickly. Decelerating tooth wear, especially dentin wear, is an important issue, but there is no ideal treatment. Sixteen third molar dentin samples were randomly divided into the amalgam (N1 = 8) and polymer infiltrated ceramic network (PICN) (N2 = 8) groups. One half of the sample was used as the experimental object and the other for the blank self-control. Array microcavities were fabricated on the experimental parts of all the samples with an fs-laser and then filled with the corresponding materials. The experimental and control parts of all the samples were subjected to 3600 cycles of sliding wear tests with titanium balls. The coefficients of friction (COFs) of every friction pair and the temperature rise were recorded in real time. The wear volume and depth were measured by a laser confocal microscopy. Statistical differences of wear volume and depth between the experimental and self-control parts were calculated by paired -test. The wear mode was observed with scanning electron microscopy (SEM). The COFs in the two experimental groups were significantly decreased. The maximum temperature rise on the dentin surface was 2.0°C. The wear resistance in the amalgam and PICN groups was 4.48 and 3.53 times higher than blank dentin, respectively ( < 0.001). The SEM images showed fewer plough grooves and cracks in dentin after microtexturing. This method could significantly improve tooth wear resistance by reducing the COFs between the friction pairs and reducing the dentin's ploughing effect and provide new treatment ideas for slowing the loss of severely worn dentin.
Topics: Ceramics; Dentin; Humans; Lasers; Microscopy, Electron, Scanning; Polymers; Tooth Wear
PubMed: 35559712
DOI: 10.1089/photob.2021.0138 -
Journal of the American Dental... May 2010Bleaching and erosive processes have been reported to soften dental surfaces, possibly increasing their susceptibility to toothbrush abrasion. The authors conducted an... (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND
Bleaching and erosive processes have been reported to soften dental surfaces, possibly increasing their susceptibility to toothbrush abrasion. The authors conducted an investigation of the effect on enamel and dentin of the interaction among bleaching, erosion and dentifrice abrasivity.
METHODS
The authors prepared specimens of human enamel and root dentin and randomly divided them into eight groups that underwent 10 percent carbamide peroxide bleaching, erosion and dentifrice abrasion. The authors submitted the specimens to cycles of erosion, toothbrushing and bleaching for five days. They determined the change in surface loss by means of profilometry.
RESULTS
Dental erosion and the more abrasive dentifrice increased toothbrushing wear on enamel surfaces, while bleaching showed no deleterious effect. Dentin wear also increased after subjection to erosion and use of the more abrasive dentifrice. Bleaching increased surface loss on noneroded dentin and decreased loss on eroded dentin when it was brushed with the less abrasive dentifrice.
CONCLUSION
Bleaching did not increase the susceptibility of enamel to erosive and abrasive wear, regardless of the dentifrice used. Dentin wear was modulated by the interaction of bleaching, erosion and dentifrice.
CLINICAL IMPLICATIONS
Bleaching with 10 percent carbamide peroxide does not increase erosive and abrasive wear of enamel. However, it may change dentin's abrasive wear, depending on erosive and abrasive challenges.
Topics: Carbamide Peroxide; Citric Acid; Dental Enamel; Dentifrices; Dentin; Disease Susceptibility; Humans; Materials Testing; Oxidants; Peroxides; Saliva, Artificial; Time Factors; Tooth Abrasion; Tooth Bleaching; Tooth Demineralization; Tooth Erosion; Tooth Remineralization; Urea
PubMed: 20436102
DOI: 10.14219/jada.archive.2010.0227 -
Clinical Oral Investigations Dec 2016The objective of this study was to evaluate the effect of gamma irradiation on the wear behavior of human tooth dentin in terms of possible alterations in crystallinity,...
OBJECTIVES
The objective of this study was to evaluate the effect of gamma irradiation on the wear behavior of human tooth dentin in terms of possible alterations in crystallinity, grain size, and composition.
MATERIALS AND METHODS
Human premolars (n = 19) were collected to obtain the perpendicular or parallel to the direction of the dentin tubule specimens. Each specimen was subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The nanoscratch tests were conducted. The scratch traces were observed via scanning electron microscope (SEM) and surface profilometer. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the alteration of crystallography and chemical composition of dentin after irradiation. The change of surface microhardness (SMH) was also evaluated.
RESULTS
The nanoscratch results showed that the friction coefficient of dentin after irradiation became higher, and the depths and widths of scratch were greater than that of dentin before irradiation. Additionally, irradiation decreased the crystallinity of dentin and induced the formation of bigger crystals. The carbonate/mineral ratio was increased. Furthermore, a significant reduction in microhardness after irradiation was observed. The main damage mechanisms consisted of the formation of delamination and crack in both the specimens cut perpendicular and parallel to tubule dentin after irradiation.
CONCLUSION
Irradiation affected directly the wear behavior of tooth dentin, accompanied by the alterations in crystallography, chemical composition, and surface microhardness of dentin.
CLINICAL RELEVANCE
This would help extend understanding the influence of irradiation on dentin and provide suggestions for selecting more suitable materials for irradiated tooth.
Topics: Adolescent; Bicuspid; Crystallization; Dentin; Gamma Rays; Hardness; Humans; In Vitro Techniques; Microscopy, Electron, Scanning; Spectroscopy, Fourier Transform Infrared; Surface Properties; Tooth Wear; X-Ray Diffraction; Young Adult
PubMed: 26809432
DOI: 10.1007/s00784-016-1731-5 -
Journal of Dental Research Mar 2019The major goal in restorative dentistry is to develop a true regenerative approach that fully recovers hydroxyapatite crystals within the caries lesion. Recently, a...
The major goal in restorative dentistry is to develop a true regenerative approach that fully recovers hydroxyapatite crystals within the caries lesion. Recently, a rationally designed self-assembling peptide P-4 (Ace-QQRFEWEFEQQ-NH) has been developed to enhance remineralization on initial caries lesions, yet its applicability on dentin tissues remains unclear. Thus, the present study investigated the interaction of P-4 with the organic dentin components as well as the effect of P-4 on the proteolytic activity, mechanical properties of the bonding interface, and nanoleakage evaluation to artificial caries-affected dentin. Surface plasmon resonance and atomic force microscopy indicated that P-4 binds to collagen type I fibers, increasing their width from 214 ± 4 nm to 308 ± 5 nm ( P < 0.0001). P-4 also increased the resistance of collagen type I fibers against the proteolytic activity of collagenases. The immediate treatment of artificial caries-affected dentin with P-4 enhanced the microtensile bonding strength of the bonding interface ( P < 0.0001), reaching values close to sound dentin and decreasing the proteolytic activity at the hybrid layer; however, such effects decreased after 6 mo of water storage ( P < 0.05). In conclusion, P-4 interacts with collagen type I, increasing the resistance of collagen fibers to proteolysis, and improves stability of the hybrid layer formed by artificial caries-affected dentin.
Topics: Collagen; Dental Bonding; Dental Caries; Dentin; Dentin-Bonding Agents; Glycosyltransferases; Humans; Materials Testing; Proteolysis; Resin Cements; Tensile Strength
PubMed: 30612505
DOI: 10.1177/0022034518817351 -
Cryobiology Jun 2023This study focused on the biomechanical properties and microstructural changes in dentin of teeth in different age groups after cryopreserved for different durations....
This study focused on the biomechanical properties and microstructural changes in dentin of teeth in different age groups after cryopreserved for different durations. Ninety third molars from three age groups (youth group, middle-age group, and elderly group), were collected and randomly divided into three groups according to freezing time at -196 °C (7 days, 30 days, and 90 days). Control group was shored at ordinary temperature. After rewarming, the compressive strength and elastic modulus of the dentin were measured with an electronic universal tester. Scanning electron microscopy was used to evaluate the microstructure of dentin after cryopreservation. After cryopreservation, the compressive strength of the teeth in each experimental group was not significantly different from control group. With the increase of freezing time and age, dentin's elastic modulus showed a decreasing trend. There were statistically significances between the control group and freezing 90d group, freezing 7d and 90d group, youth and middle-aged group, youth and elderly group (P < 0.05). Both freezing time and age factors were significant for the elastic modulus of dentin(P<0.05). There was no interaction effect for age and freezing time. In transverse sections of scanning electron microscopy, the dentinal tubule became narrower, partially occluded, and more easily adhered to impurities in the long freezing time and elderly group. In longitudinal sections, with freezing time and age, the inner wall of the dentinal tubules became rough especially in the aged group cryopreserved for 90 days. No significant microcracks exited in any of the longitudinal sections of dentin.
Topics: Humans; Aged; Middle Aged; Adolescent; Infant; Cryopreservation; Dentin; Freezing; Microscopy, Electron, Scanning
PubMed: 37121387
DOI: 10.1016/j.cryobiol.2023.04.002 -
Journal of Biomedical Materials Research Jul 2002Dentin proteoglycans are fundamental constituents of the dentin matrix and are distributed ubiquitously both in dentin and cement. They have several important functional...
Dentin proteoglycans are fundamental constituents of the dentin matrix and are distributed ubiquitously both in dentin and cement. They have several important functional properties; in particular, they have a fundamental role in the maintenance and the correct stabilization of collagen fibers. The use of phosphoric acid on dentin, as proposed in most common dental adhesive systems to establish a reliable bond, may affect the molecular structure of proteoglycans. The aim of this study was to evaluate, after the application of EDTA or phosphoric acid on dentin, the dentin proteoglycans with an immunocytochemical approach with high resolution SEM. For this purpose, dentin disks obtained from recently extracted human molars were etched with a 35% water solution of phosphoric acid for 15 s, 30 s, and 60 s. Control specimens were conditioned with EDTA. Specimens were immunolabeled with a monoclonal antibody antichondroitin sulfate and visualized with a gold-conjugated secondary antibody. Conditioning dentin with EDTA resulted in a distinct labeling of the proteoglycans, as visualized on branching fibrillar structures in the order of 10-20 nm. The use of 35% phosphoric acid on dentin revealed a coagulation of proteoglycans after etching for 15 s while a very low labeling signal was detectable after 30 s. No labeling was obtained after etching dentin with phosphoric acid for 60 s. These results suggest that the use of 35% phosphoric acid on dentin is able to produce significant structural modifications of the dentin proteoglycans even after short application times. Additionally, when applied on the dentin surface for more than 30 s, phosphoric acid produces a dramatic decrease in proteoglycans' antigenicity, probably due to structural modifications of the three-dimensional conformation of these molecules.
Topics: Dentin; Edetic Acid; Humans; Immunohistochemistry; Microscopy, Electron, Scanning; Phosphoric Acids; Proteoglycans
PubMed: 12001244
DOI: 10.1002/jbm.10102 -
Journal of Dental Research Aug 2016In this study, we are introducing a new drug-delivery approach to demineralized dentin substrates through microsized dentinal tubules in the form of drug-loaded...
In this study, we are introducing a new drug-delivery approach to demineralized dentin substrates through microsized dentinal tubules in the form of drug-loaded nanocapsules. Chlorhexidine (CHX) is widely used in adhesive dentistry due to its nonspecific matrix metalloproteinase inhibitory effect and antibacterial activities. Poly(ε-caprolactone) nanocapsules (nano-PCL) loaded with CHX were fabricated by interfacial polymer deposition at PCL/CHX ratios of 125:10, 125:25, and 125:50. Unloaded nanocapsules (blank) were fabricated as control. The fabricated nanocapsules were characterized in vitro in terms of particle size, surface charges, particle recovery, encapsulation efficiency, and drug loading. Nanocapsule morphology, drug inclusion, structural properties, and crystallinity were investigated by scanning and transmission electron microscopes (SEM/TEM), energy-dispersive x-ray analysis, Fourier transform infrared spectroscopy, and x-ray diffraction. Initial screening of the antibacterial activities and the cytotoxicity of the nanocapsules were also conducted. Nanocapsules, as carried on ethanol/water solution, were delivered to demineralized dentin specimens connected to an ex vivo model setup simulating the pulpal pressure to study their infiltration, penetration depth, and retention inside the dentinal tubules by SEM/TEM. Nanocapsules were Ag labeled and delivered to demineralized dentin, followed by the application of a 2-step etch-and-rinse dentin adhesive. CHX-release profiles were characterized in vitro and ex vivo up to 25 d. Spherical nanocapsules were fabricated with a CHX core coated with a thin PCL shell. The blank nanocapsules exhibited the largest z-average diameter with negatively charged ζ-potential. With CHX incorporation, the nanocapsule size was decreased with a positive shift in ζ-potential. Nano-PCL/CHX at 125:50 showed the highest drug loading, antibacterial effect, and CHX release both in vitro and ex vivo. SEM and TEM revealed the deep penetration and retention of the CHX-loaded nanocapsules inside dentinal tubules and their ability to be gradually degraded to release CHX in vitro and ex vivo. Ag-labeled nanocapsules revealed the close association and even distribution of nanocapsules throughout the resin tag structure. This study demonstrated the potential of introducing this novel drug-delivery approach to demineralized dentin substrates and the resin-dentin interface with nanosized CHX-loaded nanocapsules through the microsized dentinal tubules.
Topics: Anti-Infective Agents, Local; Chlorhexidine; Composite Resins; Dentin; Dentin-Bonding Agents; Humans; In Vitro Techniques; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocapsules; Spectroscopy, Fourier Transform Infrared
PubMed: 27422859
DOI: 10.1177/0022034516656135 -
Archives of Oral Biology Feb 2008The aim of the present study is to investigate the ultrastructural changes within the different zones of carious dentine and compare those changes with sound dentine. (Review)
Review
OBJECTIVE
The aim of the present study is to investigate the ultrastructural changes within the different zones of carious dentine and compare those changes with sound dentine.
METHODS
Transmission electron microscopy and electron diffraction techniques were used to investigate the effect of caries on the inorganic phase of dentine. Areas of interest were identified with optical and scanning electron microscopes.
RESULTS
The results demonstrated that the intertubular mineral crystallites decrease in size as caries lesion progresses. In the transparent zone of carious lesion, both intratubular and intertubular dentine consisted of nano-size apatetic crystallites with smaller size in the former. The intratubular mineral phase in transparent zone was found to be chemically similar to the intertubular dentin.
CONCLUSIONS
The study suggests that a 'dissolution and precipitation' mechanism is important in understanding the process of formation of intratubular dentine within the transparent zone induced by caries attack. The observed partial demineralisation of intertubular dentine in transparent zone is discussed in terms of dissolution of tubule microbranches and exposure of intertubular dentin to acids.
Topics: Dental Caries; Dentin; Humans; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Molar; Tooth Calcification
PubMed: 17915189
DOI: 10.1016/j.archoralbio.2007.08.007 -
Journal of the Mechanical Behavior of... Sep 2019The aim of this study was to evaluate the mechanical resistance of dentin and restorative materials submitted to erosive/abrasive challenges with different dentifrices....
The aim of this study was to evaluate the mechanical resistance of dentin and restorative materials submitted to erosive/abrasive challenges with different dentifrices. The dentin was restored using a resin-modified glass-ionomer (RMGIC) or a composite resin (RC). One hemiface of the sample was protected, and the other was subdivided according to the applied dentifrice (n = 10): without fluoride (SF), sodium fluoride (NaF) and stannous fluoride (SnF). The specimens were submitted to erosive/abrasive cycles, the varnish was removed, and the Martens hardness (HMV) and elastic modulus (Eit) were evaluated. The data were analyzed by repeated two-way ANOVA measurements and Tukey tests (alpha = 0.05). When analyzing the HMV on the test side, there was no influence of the dentifrices in the dentin; however, the orders of NaF < SnF = SF in RC and SnF > NaF = SF in RMGIC were observed. Comparing the treated surfaces, there were no differences in the dentin, and only the SF since CR presented an HMV superior to that of RMGIC. Comparing control and test sides, both dentins obtained a decreased HMV after the erosive/abrasive challenge; for the restorative materials, superior values were found only for SnF in the RMGIC. The Eit values were influenced more by the dentifrices on the test side for the dentin adjacent to the RMGIC, with the lowest values shown for the SF, and for both materials, the highest values were shown for the SnF group. No differences were found when comparing each dentin treated with the same dentifrice; however, the RMGIC presented a superior Eit than the CR when brushed with both dentifrices with a fluoride. Comparing the control and test sides, the same results were obtained for the HMV. The dentifrices showed little influence on the dentin substrate, whereas the dentifrice with SnF enhanced the mechanical properties of the restorative materials, which was more evident in the RMGIC.
Topics: Acrylic Resins; Animals; Cattle; Composite Resins; Dentifrices; Dentin; Elastic Modulus; Hardness; In Vitro Techniques; Materials Testing; Pressure; Silicon Dioxide; Sodium Fluoride; Stress, Mechanical; Surface Properties; Tin Fluorides
PubMed: 31082715
DOI: 10.1016/j.jmbbm.2019.05.006