D. CAKIR-USTUN’s research while affiliated with University of Alabama at Birmingham and other places

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Publications (5)


Effects of Grain Size and Transformation in Partially Stabilized Zirconia
  • Conference Paper

March 2014

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22 Reads

T.J. LUCAS

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D. CAKIR-USTUN

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J. BURGESS

Objective: Low-temperature-degradation (LTD) in partially stabilized zirconia (PSZ) has been reported which results in property changes. LTD is known to begin at the surface and progress inward, producing possible increased surface roughness. The current study measured transformation of PSZ with differing grain sizes and the corresponding property changes due to artificial accelerated aging. Null hypothesis: the grain size of the PSZ will influence the amount of transformation, and more transformation will result in greater property degradations. Methods: Two groups of PSZ materials were provided from two manufacturers, with differing grain sizes (4 groups n=5). SEM images were used to determine grain sizes using line intercept technique. Artificial accelerated aging was accomplished using a MidMark M11 Ultraclave Automatic Sterilizer for 5 hours. A Siemens D500 XRD device with Cu-K-alpha radiation was used to measure tetragonal to monoclinic transformation (t→m). Surface roughness analysis was performed using Scantron Proscan 2000, a non-contact surface-measuring instrument. Nano-hardness and Modulus of Elasticity were measured using MTS Nano G200. Results: Grain sizes, monoclinic transformations, surface roughness, modulus, and nano-hardness values are indicated below for each group. Grain Size (μm) Aging Transformation(%Tm) Surface roughness (Ra) Modulus (GPa) Hardness (GPa) LK Group 1 0.224 (0.019) Before 0 0.204(0.054) 241.2(3.63) 15.9(0.61) After 0.39(0.46) 0.324(0.142) 267.7(2.82) 16.6(0.32) LK Group 2 0.239 (0.015) Before 0 0.328(0.089) 266.7(5.37) 16.6(0.50) After 2.54(0.61) 0.360(0.161) 270.8(4.61) 15.6(0.33) Lava Plus 0.274 (0.013) Before 0 0.156(0.051) 299.6(5.39) 17.0(0.32) After 4.03(0.54) 0.184(0.047) 269.4(12.9) 16.4(1.05) Lava 0.368 (0.035) Before 0 0.168(0.075) 285.1(5.34) 16.4(0.26) After 6.64(1.01) 0.220(0.082) 276.3(4.81) 16.5(0.42) Conclusions: Within the limits of this study, the monoclinic transformation decreases with smaller grains and the zirconia samples experienced a surface roughening upon aging. Furthermore, the modulus and hardness decreased after aging in all but one group. However, grain size did not appear to influence the amount of roughening.


Bond Strength of Four Universal Adhesives to Metal and Ceramic

March 2014

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29 Reads

B.J. CHANG

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Y. CHOI

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J. BURGESS

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[...]

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L.C. RAMP

Objective: This study measured bond strengths of 4 adhesives to metal and ceramic with and without thermocycling. Method: 194 metal and 160 ceramic coupons were polished (300- and 600-grit SiC/15 sec/90° rotation), metal only abraded (50 µm Al2O3/15 sec), and sonicated (acetone, 10 min). Adhesives were applied following manufacturers’ instructions. Z100 A2 composite in a Teflon tube (d = 1.5 mm), applied over the cured adhesive was light-cured (20 sec/90° rotation, Elipar/S10/3M-ESPE/970 mW/cm2). After incubation (24 hrs, 37°C) half were debonded; remainder thermocycled (5°C/50°C/15 sec dwell time/10,000 cycles) and debonded (Instron, 1 mm/min crosshead speed). Data was analyzed using 3-way ANOVA and Tukey-Kramer tests Significant differences in bonding agents and metal, ceramics and thermocycling (p < 0.05). Peak Universal and Prime and Bond Elect had significantly lower bond strengths than All-Bond Universal and Scotchbond Universal (p<.05) to CrCo alloy. Significantly greater bonds were produced with CrCo metal vs. gold. Result: (n=12) Adhesive: Scotchbond U All Bond U Peak U Prime & Bond Elect Bonding substrate CrCo-24 hr 23.56 ± 6.48 26.70 ± 8.11 10.71 ± 3.31 10.35 ± 3.44 Type IV Gold-24 hr 8.40 ± 2.21 8.08 ± 2.91 7.23 ± 3.32 7.91 ± 3.06 Zirconia-24 hr 33.92 ± 5.61 28.24 ± 5.80 25.21 ± 4.38 14.33 ± 3.88 Lithium Disilicate-24 hr 23.46 ± 4.89 41.01 ± 8.42 35.32 ± 8.07 33.34 ± 5.17 Themocycled CrCo 27.16 ± 6.19 26.87 ± 5.43 10.39 ± 3.47 9.86 ± 2.50 Thermocycled IV Gold 9.85 ± 3.84 7.40 ± 1.78 7.35 ± 2.46 7.88 ± 3.41 Thermocycled Zirconia 39.21 ± 5.41 31.82 ± 4.34 25.16 ± 9.83 19.44 ± 6.89 Thermocycled Lithium Disilicate 16.89 ± 3.16 27.09 ± 9.19 18.39 ± 3.26 18.93 ± 3.03 Conclusion: Adhesives with MDP monomers (Scotchbond Universal and All Bond Universal) are effective additives for increasing metal adhesion.


Shear Bond Strength Universal Bonding Agents to Enamel and Dentin

March 2014

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32 Reads

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3 Citations

Objective: Measure 24hr and thermocycled shear bond strength (SBS) of universal bonding agents tested on etched enamel, uncut enamel and dentin surfaces. The line of universal bonding agents produced by several companies are intended to bond to enamel, dentin, glass ceramic, zirconia, noble and non-precious alloys, and composites without using a primer. Method: Enamel and dentin surfaces were polished (320-grit SiC-paper/4mins) and the root was cut off. Following surface treatments according to each manufacturer’s instructions, bonding agent was applied, Z100 composite cylinders (d=1.5mm) were bonded and light-cured (40 sec, Elipar/S10/3M-ESPE/1000mW/cm2). Half (n=10) were debonded after 24hrs storage/37°C (Instron-1mm/min) and the rest were debonded after thermocycling (10,000cycles/5-50°C/15sec dwell time). Data were analyzed with ANOVA and Tukey/Kramer post-hoc tests (p=0.05). Result: MPa/ (Mean ± SD) for SBS Table 1. All surfaces 320-grit SiC-paper finished. Same letters in a column are not statistically different (p>0.05) Universal Bonding Agents Treatments 24 Hours Thermocycled 10,000 cycles Scotchbond Universal Enamel 30.3±2.9 AB 24.9±7.7AB Dentin 30.5±2.5 AB 23.5±10.3 AB Prime & Bond Enamel 33.4±5.3A 36.6±7.7 A Dentin 33.3±5.8 A 33.4±7.2 A Bisco Universal Enamel 27.8±6.6 ABC 29.7±4.4 AB Dentin 26.6±4.5 BC 21.4±6.2 BC Conclusion: The highest mean bond strength in the etched enamel and dentin were seen in Prime & Bond. Thermocycling etched enamel showed no significant decrease in bond strength when compared to that of 24-hour group. Storage treatment had no significant effect.


In Vitro Wear of Eight Bulk Placed and Cured Composites

March 2013

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748 Reads

Wear resistance is a clinical concern for composites (flowable and packable) that are being developed for bulk placement and curing in posterior restorations. Objective: To determine and compare in vitro three-body wear of 8 commercially available bulk placed composites. Methods: Eight flat disc specimens (n=8) of each composite material (d=8mm/h=2mm) were prepared using a cylindrical elastomeric mold following manufacturers' instructions, and were light-cured in a single increment (Elipar S10/3M ESPE/1000 mW/cm2). The specimens were mounted in brass holders (d=15mm) using self-cured acrylic resin, wet ground (320-, 800- and 1200- grit SiC paper) and finished (0.05 alumina slurry/polishing cloth). After polishing they were rinsed, cleaned (ultrasonic bath in distilled water for 5 minutes) and stored (24h/distilled water/37C). Wear test was conducted on an Alabama Wear Testing Device for 100,000 cycles (load=75N/1.2 Hz). 50 PMMA beads were used as third body media. Volumetric loss for each material was determined using a 3-D non-contact surface profilometer (Proscan2000/Scantron/UK). Data were analyzed with one-way ANOVA and post-hoc Tukey/Kramer test (p=0.05). Results: (MeanSD). Same letters are not statistically different. Materials Type Volume/(mm3) Venus Bulk Fill-Flowable/Heraeus Kulzer Flowable/nano-hybrid 0.0240.004A,F Filtek Bulk Fill/3M ESPE 0.0120.001B,C Tetric Evo Ceram BulkFill/Ivoclar Nano-hybrid 0.0110.002C SureFil High Density Posterior Restorative (HDR)/Dentsply Packable 0.0070.001D SureFil SDR Flow/Dentsply Flowable 0.040.01E Sonic Fill/Kerr Packable/nano-hybrid/sonically activated delivery 0.020.004F Z100/3M ESPE/(Control) Packable/microhybrid 0.0040.001G Z100 produced the least amount of wear whereas SureFil SDR Flow produced the highest compared to rest of the materials (p<.0001). Conclusions: Since wear differs significantly between materials, it should be a factor in the selection of bulk filled composite resins. Materials that do not have high wear resistance should be covered with a wear resistant composite.


Polymerization Shrinkage Strain Produced By Composite Resins

March 2013

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23 Reads

Polymerization shrinkage is a primary concern when placing composite restorations. Strain produced during polymerization shrinkage may initiate failure at the composite-tooth interface producing marginal gaps, post-operative sensitivity, micro-leakage and caries. Objectives: To measure and compare polymerization shrinkage strain of commercially available composite resin materials. Method: Z100 composite blocks (7mmx7mmx10mm) with a rectangular (2mmx4mmx4mm) cavity preparation were mounted in acrylic in brass rings and stored (37˚C/24-hours). Strain gauges (Vishay) were attached to the specimen using M-Bond200 (Vishay) and connected to a Model 5100 Analog to Digital Scanner. The cavity was treated with aluminum oxide (50u/45psi/15sec) followed by Rocatec Soft (3M ESPE) (30u/45psi/15sec). Then silane (RelyX/3M ESPE) was applied to the preparation surfaces and dried. Adper Single Bond Plus bonding agent (3M ESPE) was applied and composite resin placed in the preparation and light cured (Bluephase20i/Ivoclar/1010mW/cm2) according to manufacturer's instructions. The strain on the composite surface was recorded (strain units/StrainSmart), as a graph showing peak strain (positive) and residual strain (negative) after 15-min. Data were analyzed using one-way ANOVA. Tukey's test was used for pairwise group comparisons (p=.05). Results: (MeanSD). Same letters are not statistically different (p>.05). Material Strain(strain units) Peak Residual Total/(Peak-Residual) Filtek Bulk Fill/3M ESPE 187.039.5 -156.443.5a 343.447.6 Venus Bulk Fill/Heraeus Dental 167.942.1 -222.092.1a,b 389.984.7 SureFil Posterior/Dentsply 215.436.0 -175.884.1a,b 391.290.8 Sonic Fill/Kerr 10043.4 -192.365.1a,b 292.364.1 Quixx/Dentsply 62.127.0 -229.874.6a,b 291.957.2 SureFil SDR flow/Dentsply 182.432.3 -155.355.8a 337.752.0 Z100/3M ESPE 25.328.5 -251.570.2b 276.867.4 Conclusion: Tukey HSD test showed that the residual strain was significantly lower for Filtek Bulk Fill and SureFil SDR flow (p<.05). The residual strain for Z100 was significantly higher than all other materials (p<.05). This model shows significant promise for evaluating shrinkage strain in composite resins and can be used as a method to rank order materials. Study supported in part by a grant from 3M ESPE.

Citations (1)


... 12 Una vez cementados los postes, las muestras se sometieron a envejecimiento por almacenamiento a temperatura constante (27 o C) durante 30 días; este método se realizó con el fin de valorar el rendimiento clínico de los materiales en el tiempo, simulando la degradación de la restauración. [13][14][15] Otro de los métodos más utilizados es el envejecimiento por termociclado, mediante el cual se simulan los cambios térmicos de la cavidad oral. Recientemente, en la convención de Charlotte de 2014, Kwon, Burgess y Beck señalaron, como una de sus conclusiones, que 10.000 ciclos no presentan diferencia significativa con el método de almacenamiento realizado durante 24 horas. ...

Reference:

EVALUACIÓN DE LA RESISTENCIA ADHESIVA MEDIANTE LA PRUEBA DE DESALOJO EN POSTES DE FIBRA DE VIDRIO CEMENTADOS EN DIENTES NATURALES USANDO DIFERENTES PROTOCOLOS DE CEMENTACIÓN
Shear Bond Strength Universal Bonding Agents to Enamel and Dentin
  • Citing Conference Paper
  • March 2014