1,721,086 research outputs found
Sealing properties of one-step root-filling fibre post-obturators vs. two-step delayed fibre post-placement
No full textOBJECTIVES:
The sealing properties of a one-step obturation post-placement technique consisting of Resilon-capped fibre post-obturators were compared with a two-step technique based on initial Resilon root filling following by 24h-delayed fibre post-placement.
METHODS:
Thirty root segments were shaped to size 40, 0.04 taper and filled with: (1) InnoEndo obturators; (2) Resilon/24h-delayed FibreKor post-cementation. Obturator, root filling and post-cementation procedures were performed using InnoEndo bonding agent/dual-cured root canal sealer. Fluid flow rate through the filled roots was evaluated at 10psi using a computerised fluid filtration model before root resection and after 3 and 9mm apical resections. Fluid flow data were analysed using two-way repeated measures ANOVA and Tukey test to examine the effects of root-filling post-placement techniques and root resection lengths on fluid leakage from the filled canals (alpha=0.05).
RESULTS:
A significantly greater amount of fluid leakage was observed with the one-step technique when compared with two-step technique. No difference in fluid leakage was observed among intact canals and canals resected at different lengths for both materials.
CONCLUSIONS:
The seal of root canals achieved with the one-step obturator is less effective than separate Resilon root fillings followed by a 24-h delay prior to the fibre post-placement. Incomplete setting of the sealer and restricted relief of polymerisation shrinkage stresses may be responsible for the inferior seal of the one-step root-filling/post-restoration technique
Effect of clinical use on the cyclic fatigue resistance of ProTaper nickel-titanium rotary instruments
No full textThe resistance of ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments to cyclic fatigue was examined after their initial use in straight or curved canals in vivo. These instruments were rotated freely inside a steel phantom until separation. The number of rotations before failure and the lengths of the separated fragments were compared with data derived from new instruments under the same experimental setup (n = 20). With the exception of F1 and F3, instruments previously used in curved canals were more susceptible to cyclic fatigue than those previously used in straight canals (p < 0.05). Separation occurred predominantly at the D10 to D12 level. For the F series, a negative correlation (p < 0.05) was observed between the number of rotations before failure and the file diameters at their separation levels. ProTaper F3 instruments are highly susceptible to cyclic fatigue failure and should be reused with caution irrespective of whether they are initially used for shaping straight or curved canals
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
Interfacial strength of Resilon and gutta-percha to intraradicular dentin
No full textStrengthening of Resilon-filled roots via an adhesive interface should be reflected by improvement in the interfacial strength and dislocation resistance between the root fillings and intraradicular dentin. This study compared the interfacial strengths of Resilon/Epiphany and gutta-percha/AH Plus using a thin-slice push-out test design. Failure modes of root slices after push-out testing were examined with environmental scanning electron microscopy. The gutta-percha group exhibited significantly higher interfacial strength than the Resilon group, when premature failures that occurred in Resilon root slices were included in the statistical analysis. The gutta-percha root slices failed exclusively along the gutta-percha/sealer interface. The Resilon root slices failed predominantly along the sealer/dentin interface with recognizable, fractured resin tags. Detachment of the Resilon from the Epiphany sealer was also surprisingly observed in some specimens. The similarly low interfacial strengths achieved with both types of root filling challenges the concept of strengthening root-filled teeth with the new endodontic material. Copyright © 2005 by the American Association of Endodontists
In vivo fluid movement through dentin adhesives in endodontically treated teeth
No full textFluid transudation through simplified dentin adhesives can occur in bonded vital crown dentin, since these adhesives behave as permeable membranes after polymerization. The effect of adhesive permeability in endodontically treated teeth is unknown. This study examined the hypothesis that in vivo fluid movement through simplified adhesives occurs when they are applied to root canals. Dowel spaces were prepared in endodontically treated teeth with single root canals. Six adhesives were applied to the intraradicular dentin of canal walls. Impressions were obtained with polyvinyl siloxane, and replicas were fabricated with the use of polyether impression material. Replica hemisections were gold-coated for SEM examination. Fluid transudation was evident on the adhesive surfaces of all simplified total-etch and self-etch adhesives. Conversely, most of the specimens bonded with the control three-step total-etch adhesive were devoid of fluid droplets. Permeability of simplified adhesives results in water movement, even in root-treated dentin. This may adversely affect the coupling of auto-/dual-cured resin cements
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