1,720,979 research outputs found
Adhesion testing with the microtensile method: effects of dental substrate and adhesive system on bond strength measurements
No full textPurpose: To evaluate the bond strength of a self-etching primer (SE, Clearfil SE Bond) and a one-bottle adhesive system (EX, Excite) on enamel and dentin. Materials and Methods: Twenty-eight sound human molars were used. The teeth were randomly divided into four groups (n = 7): SE applied to enamel (SE-E); SE applied to dentin (SE-D); EX applied to enamel (EX-E); EX applied to dentin (EX-D). A resin (Tetric Ceram) block of approximately 5 × 5 × 5 mm was built up on the tooth and cured for 40 s. After 24 h, samples were obtained by cutting along the x and y axis of the tooth. Stick-shaped samples of approximately 0.8 mm2 cross-sectional area were obtained. The sticks underwent microtensile testing. Results: The tensile bond strength (MPa) values of the test groups were: SE-E, 38.9 (± 4.8); SE-D, 44.5 (± 7.7); EX-E, 45.8 (± 4.7); EX-D, 42.9 (± 7.1). These values were not statistically significantly different. Conclusion: The null hypothesis was accepted that there is no difference between the self-etching primer and the one-bottle adhesive tested here. In addition, the bonding conditions provided by either bonding material on enamel were not significantly more favorable than on dentin. The majority of the specimens failed adhesively under load
Immediate and 24-hour evaluation of the interfacial strengths of fiber posts
No full textThis study examined the contribution of testing time on the interfacial strengths of fiber posts to radicular dentin. Twenty-five fiber posts were luted to root segments with resin cements and a zinc phosphate cement. Immediately upon setting of the materials, the roots were sectioned into slices and randomly divided into two subgroups, depending on testing time (immediate vs. 24-hours), for push-out test. The results showed an improvement on the interfacial strength after 24 hours of storage. When data were pooled for each cement, the interfacial strengths (MPa) were: Optibond Solo Plus/Nexus: 10.3 ± 3.8a; zinc phosphate cement: 10.1 ± 2.7a; Multilink: 9.6 ± 3.8ab; RelyX Unicem: 7.1 ± 4.9bc; AllBond 2/Duolink: 6.7 ± 3.5c (groups with same superscript letter were not statistically significant). It is concluded that bond strength can increase during the first 24 hours and that the interfacial strength is predominantly contributed by frictional retention. © 2006 American Association of Endodontists
Bond strength performance of different resin composites used as core materials around fiber posts
No full textObjectives. To evaluate the microtensile bond strengths of different resin composites used as core materials around fiber posts.
Methods. Forty DT Light-Posts (RTD) were randomly divided into eight groups, according to the resin composite used. They included two core materials specifically developed for core build-up-Group 1: Core-Flo (Bisco Inc.) and Group 2: UniFil Core (GC Corp.); three hybrid composites-Group 3: Tetric Ceram (Ivoclar-Vivadent), Group 4: Gradia Direct (GC Corp.), Group 5: Bisfil 2B (Bisco, Inc.); and three flowable composites-Group 6: iEliteflo (Bisco, Inc.), Group 7: Filtek Flow (3M ESPE) and Group 8: UniFil Flow (GC Corp). A cylindrical plastic matrix was placed around the silanized post and filled with the respective resin composite. Each bonded post provided five to eight sticks for microtensile testing. Each stick was loaded to failure under tension at a cross-head speed of 0.5 mm/min. One-way ANOVA and Tukey's test were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks.
Results. Resin composites exhibited a significant influence on microtensile bond strength (p < 0.05). Core-Flo showed the highest bond strength (11.00 +/- 0.69 MPa) although it was not statistically significantly different from all groups, except from the flowable composites. Under SEM, all the composites adapted well to the fiber post, with a variable extent of voids observed along the fractured composite interfaces.
Significance. Although good adaptation to the post surface was achieved, bond strength to fiber post remains relatively weak. Core build-up and hybrid composites are better alternatives to flowable composites as core build-up materials. (C) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved
The contribution of friction to the dislocation resistance of bonded fiber posts
No full textThis study tested the null hypothesis that the use of dentin adhesives produces no improvement on the fixation of fiber posts with resin cements in endodontically treated teeth. Post spaces were prepared in 36 single-rooted root-filled teeth. Silanized glass fiber posts were cemented to the post spaces using a self-etch (ED primer/Panavia 21) and a total etch resin cement (Excite DSC/Variolink II), with or without the accompanying dentin adhesives. Fixation strengths and interfacial ultrastructure were evaluated using a "thin slice" push-out test and transmission electron microscopy. For both resin cements, the fixation strengths obtained from specimens luted with resin cement only did not differ significantly from those in which the intraradicular dentin was first bonded with a dentin adhesive. In the presence of incomplete smear layer removal and interfacial gaps, the dislocation resistance of bonded fiber posts was contributed largely by sliding friction. Copyright © 2005 by the American Association of Endodontists
Microtensile bond strength of self-etching adhesives to enamel and dentin
No full textPurpose: To measure the microtensile bond strength to enamel and dentin of three self-etching adhesives in comparison with a total-etch two-step system as a control. Materials and Methods: A total of 40 extracted human molars were stored in saline solution until use, then divided into 4 groups of 10 teeth (one-group per adhesive system). Half of each of these groups underwent bond strength tests on enamel, and the other half was used for adhesion testing on dentin. The following experimental groups (n = 5) were then formed: E(1) Adper Prompt-L-Pop (AP, 3M ESPE) on enamel; E(2) Xeno CF II (X, Sanking Kogyo) on enamel; E(3) AdheSE (AS, Ivoclar-Vivadent) on enamel; E(4) Excite (EX, Ivoclar-Vivadent) on enamel; D(1) AP on dentin; D(2): X on dentin; D(3) AS on dentin; D(4) EX on dentin. Each tooth yielded 15 to 20 sticks about 0.9 x 0.9 mm in cross-sectional area for microtensile testing. Specimens were loaded in tension at a crosshead speed of 0.5 mm/minute, and bond strength at failure was calculated in MPa. A two-way ANOVA was applied to test for significance of the differences among the groups. Results: The bond strength values of Excite (the control) were significantly higher than those of the test products on enamel (42.92 ± 4.8 MPa) and on dentin (45.80 ± 5.79 MPa). The self-etching adhesives AdheSE (28.48 ± 4.71 MPa) and Xeno CF II (27.22 ± 2.74 MPa) revealed significantly stronger adhesion than Adper Prompt-L-Pop (20.16 ± 2.07 MPa) on dentin. On enamel, all self-etching test materials performed similarly. The substrate did not appear to have a significant influence on adhesion, as each material reached comparable levels of bond strength on enamel and dentin. Conclusion: On both substrates the self-etching adhesives tested performed significantly worse than did the total-etch system
Microtensile bond strength to ground enamel by glass-ionomers, resin-modified glass-ionomers, and resin composites used as pit and fissure sealants
No full textObjectives. To measure the microtensile bond strength to ground enamel of different types of materials used as pit and fissure sealants in combination with different substrate conditioners. Methods. From 40 sound extracted molars, eight groups of five teeth were randomly formed. The experimental groups were: (1) (C) 37% phosphoric acid/ClinPro Sealant (3M ESPE); (2) (G) 37% phosphoric acid/Guardian Seal (Kerr); (3) (E/TF) 37% phosphoric acid/Excite/Tetric Flow (Ivoclar-Vivadent) (4) (OS/UF) 37% phosphoric acid/One Step (Bisco)/UniFil Flow (GC); (5) (OS/Æ) 37% phosphoric acid/One Step/Æliteflo (Bisco); (6) (UB/UF) UniFil Bond/UniFil Flow (GC); (7) (CC/FVII) GC Cavity Conditioner/Fuji VII (GC); (8) (CC/FII) GC Cavity Conditioner/Fuji II LC Improved (GC). On the buccal of each tooth, a 5 mm high build-up was created by incrementally adding layers of the sealing material on the conditioned enamel. By serially cutting the built-up tooth, multiple beam-shaped specimens about 1 mm×1 mm in cross section were obtained, and loaded in tensile (0.5 mm/min) until failure occurred. Results. The bond strengths measured in MPa were: (C) 20.41±11.79; (G) 16.02±7.99; (E/TF) 24.06±9.67; OS/UF 15.63±9.00; (OS/AE) 9.31±6.05; (UB/UF) 4.96±3.46; (CC/FVII) 1.70±2.19; (CC/FII) 2.19±1.44. Conclusions. The conventional and the resin-modified glass ionomers measured bond strengths significantly lower than those of any resin-based materials. Failure frequently occurred cohesively within the cement. Flowable composites in combination with phosphoric acid and a total-etch adhesive performed similarly to resin-based materials specifically conceived for sealings, such as ClinPro Sealant and Guardian Seal. The bond achieved by resin composite when treating enamel with the self-etching primer used in this study (UniFil Bond) was significantly lower than that developed when the substrate was etched with 37% phosphoric acid. © 2004 Elsevier Ltd. All rights reserved
An investigation of the interfacial strengths of methacrylate resin-based glass fiber post-core buildups
No full textPurpose: To assess the microtensile bond strengths of a core composite with two different viscosities, MultiCore Flow (F) and Heavy Body (HB) (Ivoclar-Vivadent), on dentin and glass-fiber posts with methacrylate resin matrices, in combination with three dentin adhesives: Syntac Classic (S), Excite DSC (E), and AdheSE (A) (Ivoclar-Vivadent). The omission of an intermediate adhesive coating on silanized posts was also examined to see if this resulted in post-core bond strength reduction.
Materials and Methods: Six experimental dentin and 6 experimental post groups were formed with different core material viscosity/adhesive combinations. In two control post groups, no adhesive was applied on the silanized posts. The core material was stratified on deep dentin or on the posts. From the built-up teeth and the post-core units, microtensile sticks were obtained.
Results: The bond strengths measured on dentin were (MPa): S-F 12.7 +/- 6.4; S-HB 18.3 +/- 7.6; E-F 33.1 +/- 13.7; E-HB 34.1 +/- 10.2; A-F 33.5 +/- 14.8; A-HB 35.5 +/- 14.4. The post-core strengths were: S-F 9.4 +/- 2.5; S-HB 7.1 +/- 3.8; E-F 8.6 +/- 3.8; E-HB 8.1 +/- 4.4; A-F 8.1 +/- 2.7; A-HB 8.3 +/- 2.4; no adhesive-F 10.4 +/- 3.6; no adhesive-HB 6.3 +/- 2.7. Significantly higher interfacial strengths were achieved on dentin than on posts (p0.05). Omission of an intermediate adhesive layer had no effect on post-core adhesion (p>0.05).
Conclusions: Even after post surface silanization, the bond established by the composite core material with the post remains weaker than that created with coronal dentin
Tubular occlusion optimizes bonding of hydrophobic resins to dentin
No full textAlthough hydrophobic resins may be bonded to
acid-etched dentin with an ethanol wet-bonding
technique, the protocol is sensitive to moisture
contamination when bonding is performed in deep
dentin. This study tested the hypothesis that the
use of oxalate or poly(glutamic) acid-modified,
diluted ceramicrete (PADC) for dentinal tubule
occlusion prevents fluid contamination and
improves the bonding of an experimental
hydrophobic adhesive to acid-etched, ethanoldehydrated
dentin. Mid-coronal and deep acidetched
moist dentin pre-treated with oxalate or
PADC was dehydrated by ethanol wet-bonding
and infiltrated with the experimental three-step
etch-and-rinse hydrophobic adhesive under
simulated pulpal pressure. Tensile bond strengths
to deep dentin without pre-treatment were severely
compromised. Conversely, oxalate and PADC pretreatments
reduced dentin permeability, prevented
water contamination, and improved bond
strengths. Minimal nanoleakage was identified
within hybrid layers created in the oxalate- and
PADC-pre-treated deep dentin. The use of tubular
occluding agents optimized bonding of
hydrophobic resins to dentin
Susceptibility of a polycaprolactone-based root canal filling material to degradation using an agar-well diffusion assay
No full textPURPOSE:
To examine whether Resilon, a polycaprolactone-based thermoplastic root filling material was susceptible to biodegradation by cholesterol esterase using agar-well diffusion assay of serially-diluted aqueous Resilon emulsions that were dispersed in agar.
METHODS:
Emulsions of Resilon and polycaprolactone were prepared and dispersed in agar on culture plates. Two different concentrations of a cholesterol esterase (0.3 and 1.2 U/mL) were prepared and fed to wells prepared in the agar plates using an agar-well diffusion assay for examination of the degradation of polymeric materials.
RESULTS:
Degradation of the emulsified Resilon was manifested as the formation of clear zones of different sizes around the agar wells. No clear zones were observed in agar wells that contain sterile distilled water as the negative control
Early and 24-hour bond strength and degree of conversion of etch-and-rinse and self-etch adhesives
No full textPURPOSE:
To evaluate early and 24-hour microtensile bond strength (microTBS) and the degree of conversion (DC) of one representative adhesive system from each of the four current bonding approaches.
METHODS:
40 human molars were sectioned occluso-gingivally into two halves. Resin composite was bonded incrementally to flat, mid-coronal dentin, using the adhesives Adper Scotchbond MP (MP); Adper Scotchbond 2 (SB); Clearfil SE Bond (SE); and Adper Prompt L-Pop (LP) according to the respective manufacturer's instructions (n = 10). One half was immediately sectioned into sticks and subjected to muTBS test. As the sectioning process took approximately 1 hour, the results were designated as 1-hour bond strengths. The other half was stored in distilled water at 37 degrees C for 24 hours before being sectioned and tested. The DC of these systems was measured using Fourier Transform-Raman spectroscopy in three periods: immediately, 1 and 24 hours after polymerization. Data were analyzed with ANOVA and Tukey's tests.
RESULTS:
There were no significant differences between the 1-hour and 24-hour bond strengths (P > 0.05), or among the DC measured immediately, 1 hour and 24 hours after polymerization (P > 0.05). However, significant differences were observed among adhesives (P MP (35.3 +/- 10.9/38.6 + 6.7) > LP (25.5 + 1.1/26.0 + 1.5). The DC, in percentage (immediately/1 hour/24 hour), were: SE (81/82/87) > MP (79/77/81) > SB (60/63/65) > LP (39/37/42)
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