Home  About us  Contact
 

Fracture Force (fracture + force)

Distribution by Scientific Domains
Medical Sciences100%

Selected Abstracts

Fracture Force, Deflection, and Toughness of Acrylic Denture Repairs Involving Glass Fiber Reinforcement

JOURNAL OF PROSTHODONTICS, Issue 4 2008
Ioannis Kostoulas DDS
Abstract Purpose: Fractures in acrylic resin dentures occur quite often in the practice of prosthodontics. A durable repairing system for denture base fracture is desired to avoid recurrent fracture. The purpose of this study was to evaluate the fracture force, deflection, and toughness of a heat-polymerized denture base resin repaired with autopolymerized resin alone (C), visible light-polymerizing resin (VLC), or autopolymerizing resin reinforced with unidirectional (Stick) (MA-FS) and woven glass fibers (StickNet) (MA-SN). Another group was repaired with autopolymerized resin after wetting the repair site with methyl methacrylate (MA-MMA) for 180 seconds. A group of intact specimens was used as control. Materials and Methods: Heat-polymerizing acrylic resin was used to fabricate the specimens. The specimens (10 per group) were sectioned in half, reassembled with a 3-mm butt-joint gap, and repaired. A cavity was included when glass fibers were used. Three-point bending was used to test the repaired site, and data were analyzed with one-way ANOVA and the Tukey's post hoc test (,, 0.05). Results: Fracture force, deflection, and toughness for the repaired groups without reinforcement (MA: 46.7 ± 8.6 N, 2.6 ± 0.3 mm, 0.08 ± 0.001 J; MA-MMA: 41.0 ± 7.2 N, 2.7 ± 0.4 mm, 0.07 ± 0.002 J) were significantly lower (p < 0.05) than the control group (C: 78.6 ± 9.6 N, 5.9 ± 0.4 mm, 0.27 ± 0.003 J). Repair with visible light-polymerizing resin (VLC, 15.0 ± 4.0 N, 1.2 ± 0.4 mm, 0.02 ± 0.0001 J) resulted in significant reduction of mechanical properties (p < 0.05). Reinforcement with glass fibers restored (MA-SN: 75.8 ± 9.2 N) or increased (MA-FS: 124.4 ± 12.5 N) the original strength. Conclusion: The most effective repair method was the use of autopolymerized resin reinforced with unidirectional glass fibers. [source]

Load-bearing capacity of all-ceramic posterior four-unit fixed partial dentures with different zirconia frameworks

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2007
Philipp Kohorst
The aim of this in vitro study was to compare the load-bearing capacity of posterior four-unit fixed partial dentures (FPDs) produced with two different yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP) ceramics, one being a presintered material, the other a fully sintered, hot isostatically pressed material. Additionally, as a novel approach, the influence of preliminary mechanical damage upon the fracture force of an FPD has been investigated. A total of 20 frameworks each were milled from presintered zirconia and from fully sintered zirconia. Prior to veneering, 10 frameworks of each material were ,damaged' by a defined saw cut similar to an accidental flaw generated during shape cutting. Before fracture testing, all FPDs were subjected to thermal and mechanical cycling. Additionally, scanning electron microscopy was used to investigate fracture surfaces. Statistical analysis showed that FPDs milled from fully sintered zirconia had a significantly higher fracture resistance compared with specimens made from presintered material, whereas preliminary damage did not have a significant effect. After aging, FPDs made from both materials were capable of withstanding occlusal forces reported in the literature. Therefore, both types of Y-TZP may be suitable for posterior four-unit all-ceramic FPDs, although further prolonged aging experiments and prospective clinical trials are required to prove their fitness for clinical use. [source]

Fracture Force, Deflection, and Toughness of Acrylic Denture Repairs Involving Glass Fiber Reinforcement

JOURNAL OF PROSTHODONTICS, Issue 4 2008
Ioannis Kostoulas DDS
Abstract Purpose: Fractures in acrylic resin dentures occur quite often in the practice of prosthodontics. A durable repairing system for denture base fracture is desired to avoid recurrent fracture. The purpose of this study was to evaluate the fracture force, deflection, and toughness of a heat-polymerized denture base resin repaired with autopolymerized resin alone (C), visible light-polymerizing resin (VLC), or autopolymerizing resin reinforced with unidirectional (Stick) (MA-FS) and woven glass fibers (StickNet) (MA-SN). Another group was repaired with autopolymerized resin after wetting the repair site with methyl methacrylate (MA-MMA) for 180 seconds. A group of intact specimens was used as control. Materials and Methods: Heat-polymerizing acrylic resin was used to fabricate the specimens. The specimens (10 per group) were sectioned in half, reassembled with a 3-mm butt-joint gap, and repaired. A cavity was included when glass fibers were used. Three-point bending was used to test the repaired site, and data were analyzed with one-way ANOVA and the Tukey's post hoc test (,, 0.05). Results: Fracture force, deflection, and toughness for the repaired groups without reinforcement (MA: 46.7 ± 8.6 N, 2.6 ± 0.3 mm, 0.08 ± 0.001 J; MA-MMA: 41.0 ± 7.2 N, 2.7 ± 0.4 mm, 0.07 ± 0.002 J) were significantly lower (p < 0.05) than the control group (C: 78.6 ± 9.6 N, 5.9 ± 0.4 mm, 0.27 ± 0.003 J). Repair with visible light-polymerizing resin (VLC, 15.0 ± 4.0 N, 1.2 ± 0.4 mm, 0.02 ± 0.0001 J) resulted in significant reduction of mechanical properties (p < 0.05). Reinforcement with glass fibers restored (MA-SN: 75.8 ± 9.2 N) or increased (MA-FS: 124.4 ± 12.5 N) the original strength. Conclusion: The most effective repair method was the use of autopolymerized resin reinforced with unidirectional glass fibers. [source]