17 research outputs found
Relationship Between Simulated Gap Wear and Generalized Wear of Resin Luting Cements
No full textSUMMARY
Objective:
The relationship between the simulated gap wear and generalized wear of resin luting cements was investigated.
Methods:
Five resin luting cements, G-Cem LinkForce (GL), Multilink Automix (MA), NX3 Nexus, Panavia V5 (PV), and RelyX Ultimate were evaluated and subsequently subjected to a wear challenge in a Leinfelder-Suzuki (Alabama) wear simulation device. Half of the specimens from each resin luting cement were photo-cured for 40 seconds and the other half were not photo-cured. The simulated gap and generalized wear were generated using a flat-ended stainless steel antagonist. Wear testing was performed in a water slurry of polymethyl methacrylate beads, and the simulated gap and generalized wear were determined using a noncontact profilometer (Proscan 2100) in conjunction with the Proscan and AnSur 3D software.
Results:
A strong relationship was found between the gap wear and generalized wear simulation models. The simulated gap wear and generalized wear of the resin luting cements followed similar trends in terms of both volume loss and mean depth of wear facets with each curing method. Unlike the simulated gap wear and generalized wear of GL and PV, those of MA, NX, and RU were influenced by the curing method.
Conclusion:
The results of this study indicate that simulated gap wear of resin luting cements is very similar to simulated generalized wear. In most cases, dual curing appears to ensure greater wear resistance of resin luting cements than chemical curing alone. The wear resistance of some resin luting cements appears to be material dependent and is not influenced by the curing method.
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Influence of Different Curing Modes on Polymerization Behavior and Mechanical Properties of Dual-Cured Provisional Resins
No full textSUMMARY
This study determined the influence of curing mode on polymerization behavior and mechanical properties of dual-cured provisional resins. Three dual-cured bisacryl-based provisional resins were used: Tempsmart (TS; GC Corp), Luxatemp Automix Solar (LX; DMG Chemisch Pharmazeutishe Fabrik GmbH), and Integrity Multi·Cure (IG; Dentsply Caulk). A self-cured bisacryl-based provisional resin, Protemp Plus (PP; 3M ESPE) and a conventional poly(methyl methacrylate) (PMMA) provisional resin, Unifast III (UF; GC Corp) were used as controls. The inorganic filler content and coefficients of linear thermal expansion of the test materials were measured. Six specimens of each material were used to determine the flexural strength, elastic modulus, and resilience. The changes in ultrasound velocity during polymerization were measured. The average inorganic filler contents of the provisional resins, apart from UF, ranged from 24.4 to 39.3 wt%. The highest inorganic filler content was determined for LX, whereas TS showed the lowest value among the tested materials. The average coefficients of thermal expansion of the tested provisional resins ranged from 77.3 to 107.7 (×10−6/°C). TS and IG showed significantly lower thermal expansions than the other tested provisional resins. The mean flexural strengths of the provisional resins ranged from 70.4 to 122.6 MPa, the mean elastic moduli ranged from 1.8 to 3.7 GPa, and the mean resilience of the provisional resins ranged from 1.1 to 2.3 MJ/mm3, respectively. Dual-cured provisional resins showed significantly higher flexural strengths than the PMMA resin. However, in all cases, the light-curing mode showed significantly higher flexural strengths than the self-curing mode. In the initial polymerization phase, dual-cured resins in the light-curing mode showed a rapid increase in the speed of sound (V) during light irradiation, followed by a slower increase. Conversely, the dual-cured resins in the self-curing mode showed a slower initial increase, followed by a rapid increase. Although no significant difference in V was observed between 10 and 15 minutes in the light-curing mode of all tested dual-cured resins, a significantly higher V value was obtained at 15 minutes than at 10 minutes in the self-curing modes for LX and IG. Regardless of the curing mode, tested dual-cured provisional resins showed superior mechanical properties than the conventional PMMA provisional resin. However, dual-cured provisional resin flexural properties and polymerization behavior were affected by the curing mode. This study indicated that the light-curing mode might be recommended for all dual-cured provisional resins because of the enhancement of their mechanical properties and reduction of chair time.</jats:p
Comparison of laboratory and clinical wear rates of resin composites
No full textObjective: The purpose of this study was to use wear simulation to develop wear rates for two modern composite systems and then compare these rates with clinical studies on the same materials. Method and materials: A spring-loaded piston wear simulator was used to generate localized wear rates for P50 and Z100 at 100,000, 200,000, 300,000, and 400,000 cycles. Clinical studies on P50 and Z100 conducted at Creighton University and the Catholic University of Leuven were used for comparison of clinical wear to the laboratory values. Regression analysis was employed to define the wear rates. Results: The laboratory wear rates determined with simulation for P50 and Z100 were similar. Clinical occlusal contact area (OCA) wear for P50 and Z100 had small differences and were pooled to provide comparison with laboratory data. Wear rates determined from linear regression analysis provided equivalency factors between laboratory localized wear and clinical OCA wear that could be used for future studies. Further regression analysis comparing OCA and generalized clinical wear allowed a conversion factor of 4.5 to be determined. Conclusion: Localized wear from laboratory simulation may be a useful predictor of localized clinical wear and also clinical generalized wear using a conversion factor
Interfacial Characteristics and Bond Durability of Universal Adhesive to Various Substrates
No full textSUMMARY
Objective: This study investigated the interfacial characteristics and bond durability of universal adhesives to various substrates.
Methods and Materials: Two universal adhesives were used: 1) Scotchbond Universal and 2) G-Premio Bond. The substrates used were bovine enamel and dentin with or without phosphoric acid etching, resin composite, lithium disilicate and leucite-reinforced glass ceramics, zirconia, and metal alloys. The surface free energy and the parameters of various substrates and of substrates treated by adhesive after light irradiation were determined by measuring the contact angles of three test liquids. Resin composite was bonded to the various substrates to determine shear bond strength after 24 hours water storage and 10,000 thermal cycles. A one-way analysis of variance (ANOVA) and the Tukey post hoc test were used for the surface free energy data, and a two-way ANOVA and the Tukey post hoc test were used for analysis of shear bond strength data (α=0.05).
Results: The interfacial characteristics of the various substrates show significant differences depending on the type of substrate, but the interfacial characteristics of substrate treated by adhesive after light irradiation did not show any significant differences regardless of the substrate used. The bond durability of two universal adhesives to various substrates differs depending on the type of substrate and the adhesive.
Conclusions: The results of this study suggest that universal adhesives modify the interfacial characteristics of a wide range of substrates and create a consistent surface, but the bond durability of universal adhesive to various substrates differs depending on the type of substrate and the adhesive.</jats:p
Effect of Reduced Universal Adhesive Application Time on Enamel Bond Fatigue and Surface Morphology
No full textSUMMARY
Objective:
The purpose of this study was to evaluate the effect of reduced application times of universal adhesives on enamel bond fatigue and surface morphology of the treated enamel with constant force atomic force microscopy (AFM).
Methods:
Four universal adhesives—Adhese Universal (AU), Clearfil Universal Bond Quick (CU), G-Premio Bond (GP), and Scotchbond Universal Adhesive (SU)—were evaluated in a laboratory for their ability to adhesively bond resin composite to enamel. Shear bond strengths were initially determined using 15 specimens per test group for each adhesive. Shear fatigue strengths were then determined using 20 specimens per test group for each the adhesives. The fatigue specimens were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred. AFM observations, surface Ra roughness measurements, and geometric surface area evaluations of enamel surface treated with the adhesive agents were also conducted.
Results:
A strong relationship was found between the initial shear bond strength and shear fatigue strength for enamel surface Ra roughness but not for geometric surface area. The initial shear bond strength and shear fatigue strength of CU and GP were not influenced by different application times, unlike those of AU and SU. While the surface area of enamel treated with the adhesive agents was not significantly influenced by different application times and type of adhesive, surface Ra roughness of the enamel in the AU and SU groups significantly increased with increasing application time, unlike CU and GP.
Conclusions:
The results of this study suggest that universal adhesives, used with reduced application times, have adequate Ra surface roughness to provide sufficient resistance to enamel bond fatigue at application times from &lt;1 second to 20 seconds, while the geometric surface area of adhesive-treated enamel did not show any significant changes at these different application times.
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Effect of Oxygen Inhibition Layer of Universal Adhesives on Enamel Bond Fatigue Durability and Interfacial Characteristics With Different Etching Modes
No full textSUMMARY
Objective:
The purpose of this study was to evaluate the effect of the oxygen inhibition layer of universal adhesive on enamel bond fatigue durability and interfacial characteristics with different etching modes.
Methods:
The three universal adhesives used were Scotchbond Universal Adhesive (3M ESPE, St Paul, MN, USA), Adhese Universal (Ivoclar Vivadent, Schaan, Lichtenstein), and G-Premio Bond (GC, Tokyo, Japan). The initial shear bond strength and shear fatigue strength to enamel was determined in the presence and absence of the oxygen inhibition layer, with and without phosphoric acid pre-etching. The water contact angle was also measured in all groups using the sessile drop method.
Results:
The enamel bonding specimens with an oxygen inhibition layer showed significantly higher (p&lt;0.05) initial shear bond strengths and shear fatigue strengths than those without, regardless of the adhesive type and etching mode. Moreover, the water contact angles on the specimens with an oxygen inhibition layer were significantly lower (p&lt;0.05) than on those without, regardless of etching mode.
Conclusion:
The results of this study suggest that the oxygen inhibition layer of universal adhesives significantly increases the enamel bond fatigue durability and greatly changes interfacial characteristics, suggesting that the bond fatigue durability and interfacial characteristics of these adhesives strongly rely on its presence.
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Polymerization Behavior and Mechanical Properties of High-Viscosity Bulk Fill and Low Shrinkage Resin Composites
No full textSUMMARY
The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m3. There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and polymerization kinetics of these categories of current resin composite.</jats:p
