1,720,979 research outputs found
Hydrocolloid impressions of multirooted teeth: A clinical report
No full textAn indirect technique for taking hydrocolloid impressions of multirooted teeth is described. Advantages of both hydrocolloid impression material and the teehnique are discussed. © 1993, Quintessence Publishing Co. Inc. All rights reserved
Evaluation of Glyde File Prep in combination with sodium hypochlorite as root canal irrigant: a scanning electron microscopic study
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Scanning electron microscopic investigation of the surface of fiber posts after cutting
No full textThis study evaluated the surface of different types of fiber posts after cutting and investigated whether different cutting procedures can affect the integrity of the posts. Six types of fiber posts were selected for this study (Carbon Fiber Posts, Quartz Fiber Posts, Aesthetic Posts, Aesthetic Plus Posts, Translucent Posts, Dentatus, FRC Postec Posts). Fifteen posts of each type were studied. All posts had a diameter of 1.2 to 1.4 mm and were between 14 and 16 mm long. Each group was divided into three subgroups (n = 5) according to cutting method: diamond bur, carborundum disk, or scissors. The samples were then processed for scanning electron microscopic investigation. At low magnifications, no microscopic differences were found among the samples of groups 1-4 and 6. Surfaces from group 5 were more irregular, but only when cut using rotating instruments. All groups showed differences between surfaces cut with scissors and those cut with either diamond bur or carborundum disk. Posts displayed regular surfaces after cutting with a diamond bur. Cutting with a carborundum disk produced a mostly regular surface but sometimes produced irregularities close to the surface borders. The surfaces cut with scissors showed two plane and convergent flanges, and because of the formation of fracture lines these posts lost their integrity not only at the cutting surface but also along their length. The results of this study indicated that fiber posts can be cut using a diamond bur mounted in a handpiece under copious water coolant. Although the carborundum disk cutting procedure showed a less regular post surface, it can be speculated that it might be clinically acceptable. The cutting procedure using scissors should be avoided. Copyright © 2002 by The American Association of Endodontists
Influence of abutment material on the fracture strength and failure modes of abutment-fixture assemblies when loaded in a bio-faithful simulation
No full textOBJECTIVES: The aim of the present study was to evaluate differences in the ultimate fracture resistance of titanium and zirconia abutments.
MATERIAL AND METHODS: Twenty titanium fixtures were embedded in 20 resin mandible section simulators to mimic osseointegrated implants in the premolar area. The embedded implants were then randomly divided into two groups. Afterwards, specimens in group A (n=10) were connected to titanium abutments (TiDesignTM 3.5/4.0, 5.5, 1.5 mm), while specimens in group B (n=10) were connected to zirconia abutments (ZirDesign TM 3.5/4.0, 5.5, 1.5 mm). Both groups were loaded to failure in a dynamometric testing machine. Fractured samples were then analyzed by scanning electron microscopy (SEM).
RESULTS: Group A showed a significantly higher fracture strength than that observed in group B. Group A failures were observed at the screw that connects the abutment with the implant while the abutment connection hexagons were plastically bent by the applied load. Group B failures were a result of abutment fractures. SEM analysis showed that in group A the screw failure was driven by crack nucleation, coalescence and propagation, while in group B, the SEM analysis of failed surfaces showed the conchoidal fracture profile characteristic of brittle materials.
CONCLUSIONS: The strength of both tested systems is adequate to resist physiologic chewing forces in the premolar area. Conversely, the titanium and zirconia failure modes evaluated here occurred at unphysiological loads. In addition, because the abutments were tested without crowns, the presented data have limited direct transfer to the clinical situation
Clinical trial of fiber posts luted with self-curing Excite in combination with an experimental resin cement
No full textClinical behavior of translucent fiber posts and luting restorative materials: a 2-year report.
No full textClinica trial of fiber posts luted with self-curing excite in combination with an experimental resin cement.
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