Shear bond strength of repaired composite resins using a hybrid composite resin.

The shear bond strength of different types of composite resins repaired with a hybrid composite was evaluated. The hybrid composite resin was repaired with itself as a control. The results of this study showed that the shear bond strength of the repair with most types of composite resins was minimally adequate.     

Diametral tensile strength of a resin composite core with nonmetallic prefabricated posts: an in vitro study

STATEMENT OF PROBLEM: A number of prefabricated nonmetallic posts are currently available for use in conjunction with resin composite cores before fabrication of crowns for endodontically treated teeth. Information is needed regarding the strength of the composite and the nature of attachment between its components. PURPOSE: The aim of this study was to determine the influence of different types of posts on the fracture resistance of a resin composite core material using the diametral tensile strength (DTS) test. MATERIAL AND METHODS: Cylindrical specimens, 6 mm in diameter and 3 mm high, were prepared from resin composite (Tetric Ceram) and a group of prefabricated posts (n=10) as follows: resin composite only (control); Vectrispost (VTS); FiberKor (FKR); AEstheti-Plus post (ATP); Light-Post (LTP); Dentorama post (DRM), and Para-Post (PRP) as a second control. Specimens were stored for 7 days in water at 37 degrees C and then subjected to DTS test in a universal testing machine until failure occurred and load was recorded (N). Mean values and SD for DTS values (MPA) were calculated, and data were analyzed statistically with 1-way analysis of variance, followed by the Tukey test (alpha=.05). Representative specimens from each group were examined with SEM to determine nature of failure. RESULTS: Mean values (SD) in MPa for DTS were as follow: Control group: 49.64 (3.36); VTS: 29.77 (3.36); FKR: 31.9 (2.39); ATP: 28.92 (2.2); LTP: 34.26 (3.37); DRM: 33.45 (2.46), and PRP: 27.90 (2.40). Analysis of variance indicated significant differences among the groups (P<.05). SEM examination indicated that for PRP failure was adhesive in nature, whereas with all nonmetallic posts, cohesive failure was more predominant. CONCLUSION: The use of posts did not result in reinforcement of resin composite core when diametral tensile force was applied. When used with the core material, LTP, DRM, and FKR resulted in the highest DTS values, whereas PRP resulted in the lowest values.     

Flexural and diametral tensile strength of composite resins

This study evaluated the flexural strength (sf) and the diametral tensile strength (st) of light-cured composite resins, testing the hypothesis that there is a positive relation between these properties. Twenty specimens were fabricated for each material (Filtek Z250- 3M-Espe; AM- Amelogen, Ultradent; VE- Vit-l-escence, Ultradent; EX- Esthet-X, Dentsply/Caulk), following ISO 4049 and ANSI/ADA 27 specifications and the manufacturers instructions. For the st test, cylindrical shaped (4 mm x 6 mm) specimens (n = 10) were placed with their long axes perpendicular to the applied compressive load at a crosshead speed of 1.0 mm/min. The sf was measured using the 3-point bending test, in which bar shaped specimens (n = 10) were tested at a crosshead speed of 0.5 mm/min. Both tests were performed in a universal testing machine (EMIC 2000) recording the fracture load (N). Strength values (MPa) were calculated and statistically analyzed by ANOVA and Tukey (a = 0.05). The mean and standard deviation values (MPa) were Z250-45.06 +/- 5.7; AM-35.61 +/- 5.4; VE-34.45 +/- 7.8; and EX-42.87 +/- 6.6 for st; and Z250-126.52 +/- 3.3; AM-87.75 +/- 3.8; VE-104.66 +/- 4.4; and EX-119.48 +/- 2.1 for sf. EX and Z250 showed higher st and sf values than the other materials evaluated (p < 0.05), which followed a decreasing trend of mean values. The results confirmed the study hypothesis, showing a positive relation between the material properties examined.     

The strength of multilayer and repaired composite resin.

Composite resin surfaces that formed against a plastic matrix or that polymerized while exposed to air were excellent substrates for the adhesion of new resin. Samples formed by the addition of composite resin to a cut surface had a tensile strength of one half of the cohesive strength of the resin. Coating the cut surface with a thin layer of unfilled resin enhanced bonding of the second composite resin layer. The use of a thin layer of unfilled catalyst resin as a bonding agent caused the most rapid development of strength and the greatest strength in samples tested after 7 days.     

Effect of surface treatments on the tensile bond strength of repaired water-aged anterior restorative micro-fine hybrid resin composite

OBJECTIVES: The purpose of this study was to characterize changes in surface topography associated with different surface treatments and their effect on tensile bond strength (TBS) of repaired water-aged anterior restorative micro-fine hybrid resin composite. METHODS: The TBS of repaired resin-based composite slabs either non-treated or exposed to different mechanical and/or chemical surface treatment procedures were measured. The cohesive tensile strength of non-repaired intact slabs was used as a control group. The topographical effects of acid etching, grinding, and grinding followed by acid etching were characterized by AFM and SEM. RESULTS: All repaired groups showed significantly lower TBS than the control group. The TBS of repaired groups was ranged from 15% to 59% of the cohesive tensile strength of the control group (18.8+/-4.5MPa). The surface roughness of the non-treated aged specimens was significantly higher than other treated specimens. Specimens treated by acid etching showed significant increase in surface area compared to the non-treated and treated specimens. CONCLUSIONS: Aging process resulted in the formation of degradable surface layer which adversely affects the repair bond strength. The use of silane primer prior to the application of the adhesive after mechanical grinding, with or without the use of 37% phosphoric acid etching; improves the repair bond strength.     

Correlation between tensile and bond strength of composite resins

The purpose of the present work was to measure the bond strength of five composite resins (two microfilled and three conventional) to human etched enamel and to correlate the findings with previously published results on the tensile strength of the same resins. The two microfilled composites showed a significantly lower bond strength than the three conventional products. The coefficient of correlation between tensile and bond strength was 0.74.     

Effect of fatigue upon the interfacial bond strength of repaired composite resins

A comparative study of the fatigue limits of repaired samples of three composite resins was undertaken using the staircase technique. Following storage in water for 21 days at 23 degrees C the surfaces of the specimens to be bonded were ground with a fine Soflex disc, washed and dried. The surface was treated with either Scotchbond or a silane coupling agent, or left untreated, and a composite repair of the same material added. The specimens were thermally cycled and tested sequentially for 5000 cycles at different stress instruments using a transverse impact load. A statistically valid value for mean fatigue limit was determined for each design. This showed that resistance to fatigue forces was lower in repaired specimens than in complete specimens. The use of Scotchbond Dual Cure bonding agent gave the strongest repair.     

An in vitro study of the tensile strength of the resin bond between chemically etched non-noble alloy and enamel

A model was made to represent the in vivo situation for resin-bonded restorations using metal bonded to enamel. The tensile bond strength of chemically etched metal bonded to enamel was compared with that obtained with electrolytically etched metal. Four resin luting agents were used with the following results: the tensile bond strength of chemically etched non-noble alloy bonded to enamel was lower than strengths obtained for electrolytically etched alloy. The differences, however, were not statistically significant. Of the four luting resins, Comspan Regular gave the highest mean bond strength.     

二期处理光固化复合树脂径向抗张强度和硬度

目的：探讨经过二期处理的光固化复合树脂其径向抗张强度和硬度与单纯光固化复合树脂的差异。方法：Ｓｔａｒｆｉｌ Ａ２０ 、后牙用复合树脂、Ｒｅｓｔｏｒａｔｉｖｅ Ｚ１００ 三种光固化复合树脂光固化４０ｓ 后,分别光照５ｍｉｎ,１４０℃加热处理７．５ｍｉｎ 和０ ．６ＭＰａ １２０℃加热加压处理７ｍｉｎ ,测量其径向抗张强度和硬度。结果：径向抗张强度测试：经过处理的光固化复合树脂除光照５ｍｉｎ 组外,其它两个处理组均高于对照组（ 仅光固化４０ｓ）,且有统计学差异（ Ｐ＜ ０．０５） 。硬度测试：除Ｓｔａｒｆｉｌ Ａ２０ 和后牙用复合树脂光照５ｍｉｎ 组外,其余各处理组均高于对照组,且有统计学差异（Ｐ＜ ０ ．０５） 。结论：与单纯光固化复合树脂相比,经过二期处理的光固化复合树脂,其径向抗张强度和硬度不同程度的提高。     

Effect of procedure on diametral tensile strength of composite resin

The sensitivity of the test for diametral tensile strength to variations in testing procedure was investigated. Composite resin specimens of four different surface roughnesses at both ends of the specimens were loaded at one of three crosshead speeds. The diametral tensile strength values varied between 43.9 and 65.7 MPa. Diametral tensile strength was found to decrease with increasing loading rate, with decreasing roughness of the specimens, and with increasing length of the cylindrical specimens. The significant influence of the surface roughness is suggested to be a result of the correlation between roughness and length of specimens, and not the expression of a true influence on diametral tensile strength of surface roughness of the specimens' ends.     

Diametral tensile strength of composite resins submitted to different activation techniques

The aim of this study was to evaluate the diametral tensile strength (DTS) of composite resins submitted to different curing techniques. Four composite resins were tested in this study: Targis (Ivoclar), Solidex (Shofu), Charisma (Heraeus-Kulzer) and Filtek Z250 (3M Espe). Sixty-four cylindrical specimens were prepared and divided into eight groups according to each polymerization technique (n = 8). The indirect composite resins (Targis and Solidex) were polymerized with their respective curing systems (Targis Power and EDG-lux); Charisma and Filtek Z250 were light-cured with conventional polymerization (halogen light) and additionally, with post-curing systems. Specimens were stored in artificial saliva at 37 degrees C for one week. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). The data were statistically analyzed by ANOVA and Duncan tests. The results were (MPa): Z250/EDG-lux: 69.04 feminine; Z250/Targis Power: 68.57 feminine; Z250/conventional polymerization: 60.75b; Charisma/Targis Power: 52.34c; Charisma/conventional polymerization: 49.17c; Charisma/EDG-lux: 47.98c; Solidex: 36.62d; Targis: 32.86d. The results reveal that the post-cured Z250 composite resin showed the highest DTS means. Charisma composite presented no significant differences when activation techniques were compared. Direct composite resins presented higher DTS values than indirect resins.     

Influence of surface treatments on the bond strength of repaired resin composite restorative materials

ObjectivesThe purpose of this study was to investigate the effect of different surface treatments on the bond strength (σ) of repaired, aged resin composites (ARC).MethodsForty blocks of Filtek Z250? (Z2) and Filtek Supreme? (SU) were made, stored in deionized water for 9 days, and randomly assigned to different surface treatment groups: hydrofluoric acid etching (HA), abrasion using a coarse diamond bur (AB), sandblasting with alumina particles (AO), and silica coating (SC). The average roughness (Ra) of the treated surfaces was measured with a profilometer. An adhesive system (SB-Adper Single Bond Plus?), a silane (SI) or a combination of both (SI + SB) were applied after each surface treatment. The blocks were restored with the same composite (RC) and cut to produce bars that were turned into dumbbell-shaped specimens (0.5 mm²) using a precision grinding machine. The specimens (n = 30) were tested in tension to fracture and the microtensile bond strength (σ) values were calculated (MPa). Data were analyzed using three-way ANOVA/Tukey test (α = 0.05) and Weibull statistics.ResultsAO and SC produced similar Ra values, which were greater than the value produced by HA. The σ values were statistically influenced by the type of RC (p < 0.0001), by the surface treatment (p < 0.0001) and by the surface coating (p < 0.0001). Treating the surface of Z2 with SC + SB produced the greatest m value.SignificanceAO and SC produced the greatest σ values, irrespective of the primer (SI, SB or SI + SB) used. Yet, the RC microstructure influenced the mean σ values, which were greater for Z2 than for SU. The HA should not be used for repairing ARC.     

Effect of procedure on diametral tensile strength of composite resin.

The sensitivity of the test for diametral tensile strength to variations in testing procedure was investigated. Composite resin specimens of four different surface roughnesses at both ends of the specimens were loaded at one of three crosshead speeds. The diametral tensile strength values varied between 43.9 and 65.7 MPa. Diametral tensile strength was found to decrease with increasing loading rate, with decreasing roughness of the specimens, and with increasing length of the cylindrical specimens. The significant influence of the surface roughness is suggested to be a result of the correlation between roughness and length of specimens, and not the expression of a true influence on diametral tensile strength of surface roughness of the specimens' ends.     

光照强度对光固化复合树脂抗压和抗拉强度的影响

目的 :探讨光照强度对光固化复合树脂抗压、抗拉强度的影响。方法 :用WDW 10 0型微机控制电子万能试验机 ,测试比较不同光照强度 [第 1组 ,3 0 0mW /cm2 × 40s ;第 2组 ,5 0 0mW /cm2 × 40s ;第 3组 ,80 0mW /cm2 × 40s ;第 4组 ,(3 0 0mW /cm2 × 10s) + (5 0 0mW /cm2 × 3 0s) ;第 5组 ,(3 0 0mW /cm2 × 10s) + (80 0mW /cm2 × 3 0s) ]对光固化复合树脂抗压强度、微拉伸强度的影响。结果 :采用弱光引导固化方法固化的光固化复合树脂的抗压强度、微拉伸强度明显优于采用传统方法固化的树脂。结论 :采用弱光引导固化对提高复合树脂抗压和抗拉强度有积极意义     

An in vitro investigation of bond strength of veneering composite resin to glass fibre veil reinforced composite

Experimental light-curing polymer-monomer-gel-impregnated E-glass-fibre veil reinforced composite (i.e. a composite with randomly oriented fibres) was used as an adhesional substrate for veneering composite resin (VCR). Continuous unidirectional glass fibre composite was used as a control substrate. Both the fibre-reinforced composite substrate surfaces were ground or, optionally, the substrate surface was left untreated (containing oxygen-inhibited resin layer) before attaching to the VCR. No adhesive resin was used between the composites. Shear bond strength of VCR to the substrate was determined for dry and thermocycled specimens. The results of this study suggested that the VCR can better be bonded to the randomly oriented veil fibre-reinforced composite substrate than to the continuous unidirectional fibre-reinforced composite substrate.     

Bond strengths of chemically dissimilar repaired composite resins

Expanded use of composite resins has necessitated repair of fractured, discolored, and former restorations. Laboratory investigations have demonstrated that new composite resin can be bonded to cured composite resin of the same chemistry. The surface chemistry of three composite resins of dissimilar matrix formulae were examined by infrared spectroscopy and the tensile bond strengths of heterogeneous repairs and the site of repair failures were determined.     

Shear bond strength of provisional restoration materials repaired with light-cured resins

This study evaluated the repair bond strengths of light-cured resins to provisional restoration materials with different chemical compositions and polymerization techniques. Fifty discs (10 mm in diameter and 1.5 mm thick) were fabricated for each provisional resin base material, including a self-cured methacrylate (Alike), self-cured bis-acrylate (Protemp 3 Garant), light-cured bis-acrylate (Revotek LC) and a heat-cured methacrylate (Namilon). All specimens were stored in distilled water at 37 degrees C for seven days before undergoing repair with one of four light-cured resins, including AddOn, Revotek LC, Dyractflow and Unifast LC and a self-cured resin (Alike), according to the manufacturers' instructions, for a total of 200 specimens. After 24 hours of storage in 37 degrees C water, the shear bond strengths were measured with a universal testing machine and fracture surfaces were examined under a stereomicroscope. Two-way ANOVA revealed that provisional resin-base material (p < 0.001), repair material (p < 0.001) and their interactions (p < 0.001) significantly affected the repair strength. Tukey's multiple comparisons showed that the lowest bonding strengths were found in specimens of heat-cured methacrylate resin materials repaired with bis-acryl resins, with their failure modes primarily being of the adhesive type. The highest bond strengths were recorded when the provisional resin-base materials and repairing resins had similar chemical components and the failure modes tended to be of the cohesive type.