Repair Bond Strength Of Composite Research Articles

Effect of Varying Working Distances between Sandblasting Device and Composite Substrate Surface on the Repair Bond Strength.

This study investigates the effect of defined working distances between the tip of a sandblasting device and a resin composite surface on the composite–composite repair bond strength. Resin composite specimens (Ceram.x Spectra ST (HV); Dentsply Sirona, Konstanz, Germany) were aged by thermal cycling (5000 cycles, 5–55 °C) and one week of water storage. Mechanical surface conditioning of the substrate surfaces was performed by sandblasting with aluminum oxide particles (50 µm, 3 bar, 10 s) from varying working distances of 1, 5, 10, and 15 mm. Specimens were then silanized and restored by application of an adhesive system and repair composite material (Ceram.x Spectra ST (HV)). In the negative control group, no mechanical surface pretreatment or silanization was performed. Directly applied inherent increments served as the positive control group (n = 8). After thermal cycling of all groups, microtensile repair bond strength was assessed, and surfaces were additionally characterized using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The negative control group reached the significantly lowest microtensile bond strength of all groups. No significant differences in repair bond strength were observed within the groups with varying sandblasting distances. Composite surfaces sandblasted from a distance of 1 mm or 5 mm showed no difference in repair bond strength compared to the positive control group, whereas distances of 10 or 15 mm revealed significantly higher repair bond strengths than the inherent incremental bond strength (positive control group). In conclusion, all sandblasted test groups achieved similar or higher repair bond strength than the inherent incremental bond strength, indicating that irrespective of the employed working distance between the sandblasting device and the composite substrate surface, repair restorations can be successfully performed.

Effect of adhesive application method on repair bond strength of composite.

ObjectivesThis study aimed to evaluate the effect of the application method of universal adhesives on the shear bond strength (SBS) of repaired composites, applied with different thicknesses.Materials and MethodsThe 84 specimens (Filtek Z350 XT) were prepared, stored in distilled water for a week and thermocycled (5,000 cycles, 5°C to 55°C). They were roughened using 400-grit sandpapers and etched with phosphoric acid. Then, specimens were equally divided into 2 groups; Single Bond Universal (SU) and Prime&Bond Universal (PB). Each group was subdivided into 3 subgroups according to application methods (n = 14); UC: 1 coat + uncuring, 1C: 1 coat + curing, 3C: 3 coats + curing. After storage of the repaired composite for 24 hours, specimens were subjected to the SBS test and the data were statistically analyzed by 2-way analysis of variance and independent t-tests. Specimens were examined with a stereomicroscope to analyze fracture mode and a scanning electron microscope to observe the interface.ResultsAdhesive material was a significant factor (p = 0.001). Bond strengths with SU were higher than PB. The highest strength was obtained from the 1C group with SU. Bonding in multiple layers increased adhesive thicknesses, but there was no significant difference in SBS values (p = 0.255). Failure mode was predominantly cohesive in old composites.ConclusionsThe application of an adequate bonding system plays an important role in repairing composite resin. SU showed higher SBS than PB and the additional layers increased the adhesive thickness without affecting SBS.

SHEAR BOND STRENGTH FOR IMMEDIATE AND DELAYED REPAIR OF COMPOSITE WITH MICROHYBRID AND NANOHYBRID RESINS USING DIFFERENT BONDING AGENTS

Introduction: Repair is indicated mainly in the event of localized short­comings that are clinically unsatisfactory and no longer acceptable; it implies in any case the addition of a restorative material. Objectives:Shear bond strength for immediate and delayed repair of composite with microhybrid and nanohybrid resins using different bonding agents. Materials and methods: One hundred sixty nanohybrid composite discs were prepared. They were divided into 16 groups (10 each) according to 3 factors: Factor 1: Repair time, Factor 2: Repair protocol and Factor 3: Repair composite material. For immediate repair (I), discs (n=80) were divided into 4 subgroups 20 discs each. Each subgroup was divided into 2 groups as follows Group 1 (a): no conditioning with nanohybrid composite, Group 1 (b): no conditioning with microhybrid composite, Group 2 (a) Adhese Universal bond with nanohybrid composite, Group 2 (b) Adhese Universal bond with microhybrid composite, Group 3 (a) All-Bond Universal with Nano-hybrid composite ,Group 3 (b) All-Bond Universal with microhybrid composite, Group 4 (a) Scotchbond™ Universal with nanohybrid composite, and Group 4 (b) Scotchbond™ Universal with microhybrid composite. After 3 months of storage for delayed repair (II), the repair procedures were performed similar to the immediately repaired groups. After 1000 thermal cycles, all specimens were subjected to shear bond strength test. Results:repair time and surface treatment revealed statistically significant effect on the shear bond strength values of all groups (p ≤ 0.05). Highest shear bond strength value was recorded in group I4b (21.97 ± 1.19) MPa and the lowest value was recorded in group II1a (4.42 ± 0.88 MPa) Conclusions: Time of repair, bonding agent and repair material affected repair bond strength of composite.

Silane Effect of Universal Adhesive on the Composite-Composite Repair Bond Strength after Different Surface Pretreatments.

This study investigated the impact of a separate silanization step on the repair bond strength of composite substrates using a universal adhesive after various mechanical surface treatments. Composite specimens were aged and exposed to the following mechanical roughening treatments: diamond bur abrasion, aluminum oxide sandblasting, or silica coating. The specimens were then either left untreated or conditioned with universal adhesive (Scotchbond Universal), or a silane coupling agent was applied before the use of the universal adhesive or a conventional adhesive (Optibond FL). The conditioned surfaces and fresh substrate (positive control group) were covered with repair composite, and microtensile bond strength testing was performed. The significantly highest bond strength was obtained in the positive control group. Repair bond strength of the universal adhesive applied after a separate silanization step was similar to that without prior silanization, independent of the mechanical surface treatment. Moreover, after silica coating, no significant differences in the repair bond strength were detected among the different adhesive treatments. In conclusion, a separate silanization step before surface conditioning with the universal adhesive does not enhance the repair bond strength. On silica-coated composite substrates, repair bond strength values of the universal adhesive were similar to those of the conventional adhesive.

Repair bond strength of composite: Effect of surface treatment and type of composite.

BackgroundBy an increase in use of composite restorations, some defects are also seen in these restorations, which need to be repaired. Since complete replacement of an old restoration may compromise the tooth structure, repair of defect is a more practical approach if there is no caries recurrence. Risk of pulp injury also decreases as such. One major challenge in restoration repair is to obtain a durable bond between the new and old composite. Laser irradiation has been suggested for surface preparation of old composite. This study aimed to assess the effect of composite surface preparation with Er,Cr:YSGG laser on microtensile bond strength to new composite.Material and MethodsA total of 18 blocks were fabricated in three groups of nanohybrid, microhybrid and Beautiful II giomer measuring 4x7x7 mm and subjected to 10,000 thermal cycles between 5-55°C with 30 seconds of dwell time. The samples were randomly assigned to no surface treatment (etching and bonding) or laser plus etching and bonding groups. Composite cylinders measuring 4x7x7 mm were fabricated of Beautiful, nanohybrid and microhybrid composites on old composite surfaces and subjected to 500 thermal cycles for 50 seconds between 5-55°C with 30 seconds of dwell time. Each block was sectioned into 10 samples and they were subjected to microtensile bond strength test. Data were analyzed using ANOVA and Tukey’s test.ResultsIn all composites, the mean bond strength in laser subgroups was higher than that in control subgroups except for giomer, which showed lower bond strength in laser subgroup. The lowest mean bond strength was noted in repair of Z350XT with Z350XT when the surface of old composite was etched (10.92 MPa). The highest mean bond strength was noted in repair of Z250 with giomer when the old composite surface was irradiated with laser (30.55 MPa).ConclusionsEr,Cr:YSGG laser plus etching increased the bond strength in all groups except for giomer group, which showed a reduction in bond strength. Key words:Composite resins, surface treatment, tensile bond strength, laser, er,cr:ysgg, giomer.

Comparative approach to analyse the effects of different surface treatments on CAD/CAM resin nanoceramics–resin composite repair bond strength

ABSTRACTLimited data are available on the repair bond strength between computer-aided design and manufacturing (CAD/CAM) resin nanoceramics and composite repair materials. Therefore, the purpose of this study was to test the influence of several different surface treatment modalities, intermediate agents and phosphoric acid on the shear bond strength (SBS) of repair composites with water-aged CAD/CAM resin nanoceramics. Three pretreatment and four conditioning methods comprised 12 different groups. A universal testing machine was used to test the SBS. Specimens were examined with a stereomicroscope and scanning electron microscope to determine the fracture mode. The results showed that a combination of the pretreatment and conditioning methods significantly enhanced the SBS of the resin nanoceramic (p:0.001; p < 0.01), while etching with phosphoric acid did not affect the SBS (p:0.841; p > 0.05). This study showed that surface pretreatment in combination with a conditioning method should be used in the repair of CAD/CAM nanoceramics. The highest SBS values were achieved by grinding the surface with a diamond bur followed by silane and adhesive application, whereas the lowest values were obtained in the non-conditioned non-pretreated group.

In vitro evaluation of repair bond strength of composite: Effect of surface treatments with bur and laser and application of universal adhesive.

This study aimed to assess the effect of surface treatment by bur and laser and application of universal adhesive on repair bond strength of composite resin. A total of 120 composite blocks measuring 6×4×4 mm were fabricated of Filtek Z250 composite. All samples were subjected to 5,000 thermal cycles and divided into two groups for surface preparation by bur and by Er,Cr:YSGG laser (n = 60). The surfaces were then etched with orthophosphoric acid, rinsed with water and divided into three groups (silane, silane plus Single Bond and silane plus Single Bond Universal). Repair composite was then bonded to aged composite. Half of the samples in each group were stored in distilled water at 37°C for 24 hours and the other half underwent 5000 thermal cycles. All samples were then subjected to shear bond strength testing using a universal testing machine at a crosshead speed of 1 mm/minute. The data were analyzed using one-way ANOVA and Tukey's HSD test. Mode of failure was determined using a stereomicroscope. Bur preparation plus universal adhesive yielded the highest bond strength (30.16 µ 2.26 MPa). Laser plus silane yielded the lowest bond strength (5.63 µ 2.43 MPa). Bur preparation yielded significantly higher bond strength than laser (P < 0.001). Also, application of universal adhesive significantly improved bond strength compared to conventional adhesive and silane (P < 0.001). Bond strength after aging (5000 thermal cycles) had no significant difference with primary bond strength at 24 hours within each group (P = 0.182). Surface preparation of aged composite by bur and application of universal adhesive can improve the repair bond strength of composite. Application of silane (without adhesive) in the process of repair cannot provide adequately high repair bond strength.

Effect of thermocycling and surface treatment on repair bond strength of composite.

BackgroundRepair of composite restorations is a conservative method that can increase the longevity and durability of restorations while preserving the tooth structure. Achieving a suitable bond between the old and new composite is difficult. To overcome this problem, some methods have been recommended to increase the repair bond strength of composite.This study aimed to assess the effect of aging by thermocycling (5,000 and 10,000 cycles) and mechanical surface treatments (Er,Cr:YSGG laser and bur) on repair shear bond strength of composite resin.Material and MethodsTotally, 120 composite blocks measuring 6x4x4 mm were fabricated of Filtek Z250 composite and were randomly divided into three groups (n=40) based on initial aging protocol: (a) no aging: storage in distilled water at 37°C for 24 hours, (b) 5,000 thermal cycles, (c) 10,000 thermal cycles. Each group was then randomly divided into two subgroups (n=20) based on mechanical surface treatment (laser and bur). The laser and bur-prepared surfaces were silanized and Adper Single Bond 2 was then applied. The repair composite was bonded to surfaces. Half of the samples in each subgroup (n=10) were subjected to 5,000 thermal cycles to assess durability of bond. The remaining half were stored in distilled water at 37°C for 24 hours and all samples were then subjected to shear bond strength testing in a universal testing machine with a crosshead speed of 1mm/min. Data (in megapascals) were subjected to one-way ANOVA and Tukey’s test (P=0.05). Mode of failure was determined under a stereomicroscope.ResultsBur preparation significantly improved the bond strength compared to laser (P<0.001). Aging by 10,000 thermal cycles significantly decreased the repair bond strength of composite (P<0.001). No significant difference was noted in this regard between distilled water and 5,000 thermal cycles groups (P=0.699). Primary bond strength and bond strength after 5,000 thermal cycles in the same subgroups were not significantly different either (P=0.342).ConclusionsAging by 10,000 thermal cycles significantly decreases the repair bond strength of composite and surface preparation by bur provides a higher bond strength compared to laser. Key words:Thermocycling, Composite, Repair, Laser.

Effect of curing and silanizing on composite repair bond strength using an improved micro-tensile test method

Objectives: To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed.Methods: Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane. Each group was divided into subgroups: (1) Adper Scotchbond Multi-Purpose, (2) Adper Scotchbond Multi-Purpose adhesive, (3) Adper Scotchbond Universal, (4) Clearfil SE Bond and (5) One Step Plus. For each adhesive group, the adhesive was (a) cured according to manufacturer’s instructions or (b) not cured before repair. The substrate blocks were repaired with Filtek Supreme XLT. After aging, they were serially sectioned, producing 1.1 × 1.1 mm square test rods. The rods were prepared for tensile testing and tensile strength calculated at fracture. Type of fracture was examined under microscope.Results: Leaving the adhesive uncured prior to composite repair placement increased the mean tensile values statistically significant for all adhesives tested, with or without silane pretreatment. Silane surface treatment improved significantly (p < 0.001) tensile strength values for all adhesives, both for the cured and uncured groups. The mean strength of the control composite was higher than the strongest repair strength (p < 0.001).Conclusions: Application of freshly made silane and a thin bonding layer, rendered higher tensile bond strength. Not curing the adhesive before composite placement increased the tensile bond strength.

Influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives.

The influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives was investigated. The surface free-energies were determined by measuring the contact angles of test liquids placed on composites that had been immersed in different concentrations of methyl mercaptan (0.01, 0.1, and 1.0 M). To determine the repair bond strength, self-etch adhesives were applied to the aged composite, and then newly added composites were condensed. Ten samples of each specimen were subjected to shear testing at a crosshead speed of 1.0 mm min(-1). Samples were analyzed using two-way ANOVA followed by Tukey's honestly significant difference (HSD) test. Although the dispersion force of the composites remained relatively constant, their polar force increased slightly as the concentration of methyl mercaptan increased. The hydrogen-bonding forces were significantly higher after immersion in 1.0 M methyl mercaptan, leading to higher surface-free energies. However, the repair bond strengths for the repair restorations prepared from composites immersed in 1.0 M methyl mercaptan were significantly lower than for those immersed in 0.01 and 0.10 M methyl mercaptan. Considering the results of this study, it can be concluded that the repair bond strengths of both the aged and newly added composites were affected by immersion in methyl mercaptan solutions.

Vliv povrchové úpravy kompozitní výplně na dlouhodobou životnost vazby při její opravě

Vliv povrchové úpravy kompozitní výplně na dlouhodobou životnost vazby při její opravě

Repair bond strength of composites: Effect of 1% hydrofluoric acid

Repair bond strength of composites: Effect of 1% hydrofluoric acid

Effect of different surface treatments on the composite–composite repair bond strength

The aim of this study was to investigate the effect of different mechanical and adhesive treatments on the bond strength between pre-existing composite and repair composite using two aging times of the composite to be repaired. Standardized cylinders were made of a microhybrid composite (Spectrum TPH) and stored in saline at 37 degrees C for 24 h (n = 140) or 6 months (n = 140). Three types of mechanical roughening were selected: diamond-coated bur followed by phosphoric acid etching, mini sandblaster with 50-microm aluminum oxide powder, and 30-microm silica-coated aluminum oxide powder (CoJet Sand), respectively. Adhesive treatment was performed with the components of a multi-step bonding system (OptiBond FL) or with a one-bottle primer-adhesive (Excite). In the CoJet Sand group, the effect of a silane coupling agent (Monobond-S) was also investigated. The repair composite (Spectrum TPH) was applied into a mould in three layers of 1 mm, each separately light-cured for 40 s. Repair tensile bond strengths were determined after 24-h storage. Mechanical and adhesive treatment had significant effects on repair bond strength (P < 0.001). The age of the pre-existing composite had no significant effect (P = 0.955). With one exception (CoJet Sand/OptiBond FL Adhesive), adhesive treatments significantly increased repair bond strengths to 6-month-old composite when compared to the controls without adhesive. Adhesive treatment of the mechanically roughened composite is essential for achieving acceptable repair bond strengths. The more complicated use of silica-coated particles for sandblasting followed by a silane coupling agent had no advantage over common bonding systems.

Effect of Physicochemical Aging Conditions on the Composite-Composite Repair Bond Strength

This study evaluated the effect of different physicochemical aging methods and surface conditioning techniques on the repair bond strength of composite. It was hypothesized that the aging conditions would decrease the repair bond strength and surface conditioning methods would perform similarly for the repair of resin composites. Disk-shaped resin composite specimens (Clearfil Photo Bright, Kuraray) were randomly assigned to one of the three aging conditions (N=120, n = 12/per group): (1) immersion in deionized water (37 degrees C, 1 week), (2) immersion in citric acid (pH: 3.0, 1 week), (3) boiling in water (8 h), (4) thermocycling (5000 times, 5 degrees C to 55 degreesC), (5) immersion in water (37 degrees C, 2 months). After aging procedures, the specimens were subjected to one of the following surface conditioning methods: (1) chairside silica coating (30-microm SiOx) (CoJet, 3M ESPE) + silane (ESPE-Sil) (SC method), (2) silane (Clearfil SE Bond Primer and Clearfil Porcelain Bond Activator) + bonding agent (Clearfil SE Bond) (SB method). The fresh and aged composite surfaces were also examined using SEM (n=6, 1/group). Resin composite (Quadrant Anterior Shine) was bonded to the conditioned substrates using polyethylene molds and then light polymerized. Shear force was applied to the adhesive interface in a universal testing machine (1 mm/min). The failure types were categorized as: (A) cohesive in the substrate, (B) adhesive at the interface, or C) cohesive in the adherend. Bond strength values were statistically analyzed using two-way ANOVA and Tukey's test (alpha < 0.05). A significant influence of the conditioning method (p < 0.0001) and aging method was observed (p < 0.01) (two-way ANOVA, Tukey-Kramer). The SC method showed significantly higher bond values (7.8 +/- 1.2 to 11.6 +/- 5 MPa) than those of SB method (4.6 +/- 2.3 to 7.6 +/- 3.9 MPa) in all groups (p < 0.0001). While the SC method showed 96% cohesive (A type), the SB method demonstrated 92% adhesive failures (B type). SEM images showed distinct pattern of microcracks in the boiled specimens and filler dissolution with disorganized matrix resin in the other aged specimens. Aging the composite substrates through water storage for 2 months produced significantly lower bond strengths than those of water or acid storage for 1 week (p = 0.011). Chairside silica coating and silanization provided the highest bond strength values with almost exclusively cohesive failures on aged composites. Aging methods showed significant differences on the composite-composite repair strength.