Bond Strength Of Composite Research Articles

Effect of thermal shocks on the interfacial bond strength of sandwich composites built with rigid and soft materials produced through extrusion process

The mechanical behavior and adhesion strength of the sandwich composite, which consists of a flexible and a rigid material, were examined using extruded polylactic acid (PLA) and thermoplastic polyurethane (TPU). Three types of binders were combined with the appropriate hardeners to bond the extruded materials. The fabricated specimens are subjected to a different number of thermal shock cycles, with a maximum and minimum temperature of 80 °C and −18 °C, respectively. The sandwich composite's mechanical properties, including tensile, flexural, and impact strength, were assessed after 20, 40, and 80 cycles of thermal shock. The results indicated that the ductility of PLA material was significantly impacted by the thermal shock cycles. After completing the maximal thermal shock cycles, the composites joined with polyester resin exhibited a lower strength reduction in the impact specimens. Maximum tensile strength of 22.3 MPa, flexural strength of 31.6 MPa, and impact strength of 8.3 J were recorded prior to the application of thermal shocks to the specimens. The specimens that were bonded with epoxy resin recorded the maximal tensile, flexural, and impact strength. Following the thermal shock cycles, the composites bonded with epoxy resin exhibited a lesser reduction in tensile and flexural strength, while the composites bonded with polyester resin showed a lower strength reduction for impact specimens. The tensile and flexural specimens encountered a 7.54 % and 20.24 % reduction in strength, respectively, after undergoing 80 cycles of thermal shocks. The impact specimens experienced an 8.62 % reduction in strength.

Silane and acid etch cross contamination of dentin and composite reduced µ-tensile bond strength.

To investigate whether acid etch contamination of silane-treated composite influenced repair bond strength and whether silane contamination on dentin influenced composite bond strength to dentin. Forty composite blocks stored in water for 4 weeks were divided into four groups. Specimens in groups 1-3 were coated with Bis-Silane and contaminated with acid etch + water spray (group 1) or water spray (group 2). Group 3 was not contaminated. Group 4 was untreated. The occlusal third of 60 third molars was cut off, ground flat, and divided into three groups. After etching, the surfaces in groups A and B were contaminated with Bis-silane. The contaminated surfaces in group A were re-etched.Each composite repair group and composite-dentin group was divided into two subgroups receiving Adper Scotchbond 1 XT or Clearfil SE Bond 2 adhesives followed by a composite build up. After ageing for 3 months, specimens were sectioned into 1.1 mm × 1.1 mm rods for tensile testing and strength calculated at fracture. The fracture was examined using microscope. Bis-Silane surface treatment increased the repair bond strength. Contamination with acid reduced the strength of the repair bond. Similar results were obtained for both adhesives. Tooth surface contamination with silane reduced the bond strength between dentin and composite. Additional acid etching or water spray on silane contaminated dentin did not influence the weakened bond strength. Most fractures were adhesive type. Silane contamination on etched dentin and acid etch contamination on silanized composite surfaces significantly reduced tensile bond strength.

Shear bond strength of a composite resin restoration in primary teeth following cavity preparation using laser- an in-vitro study.

To evaluate and compare the shear bond strength of composite resin restorations in primary teeth, following cavity preparation with both traditional dental burs and laser irradiation. One hundred primary molars extracted from the children visiting our department were collected and randomly divided into five groups (A-E) with 20 teeth in each group. In groups A, B, C, D, and E the teeth samples were etched with phosphoric acid, Er; YAG laser followed by acid etching, Er, Cr: YSGG laser followed by acid etching, Er; YAG laser etching only and Er, Cr: YSGG laser etching only, respectively. Following, all the samples were restored with composite resin and subjected to 500 cycles of thermocycling. The shear bond strength of the resin composite was analyzed. The type of fractures was also noted. Data obtained were subjected to statistical analysis. The mean value of shear bond strength of Group A, B, C, D, and E was 17.562 ± 0.810, 15.928 ± 0.415, 14.964 ± 0.566, 11.833 ± 0.533 and 11.187 ± 0.517, respectively. Adhesive failure was most commonly seen in all the groups. The phosphoric acid etching remains a highly effective technique for pre-treating dentin in composite resin restorations. The shear strength of composite resin to the dentin of laser-prepared cavity in primary teeth can be improved by the addition of acid etching.

RESISTÊNCIA DA UNIÃO DE SISTEMAS ADESIVOS À DENTINA: INFLUÊNCIA DO HIPOCLORITO DE SÓDIO

The modification of the root canal system is of paramount importance to the success of endodontic treatment. This study aimed to evaluate the influence of sodium hypochlorite at concentrations of 2.5% and 4.5% in times of 30 and 60 minutes on the bond strength of composite resin to dentin. We used for this study teeth 20, which were divided into five groups of four elements, each element of the experimental group was immersed in a characteristic time and concentration of sodium hypochlorite of their group and the control immersed in saline. Later there were three composite restorations on each tooth, totaling a sample of 60 restorations. Each restaurant had its bonding to dentin submitted to microshear test, and the results were analyzed through statistical tests: the normal, anova and multiple variations. No significant influence on the adhesion of composite resins to dentin at a concentration of 2.5% at times of 30 and 60 minutes, and concentration of 4.5% in 30 minutes time. There was only influences the concentration 4.5% after a time of 60 minutes. It is concluded that sodium hypochlorite at 4.5% in contact with the dentine for a time of 60 minutes because influence on the bond strength of resin composite, which may cause recontamination of the channel system.

Bond strength of epoxy-based composites at the interface with surface deposited metal layer: A comparative study with different dimensional fillers

With the complexity of the working environment, pure epoxy resin can no longer meet the requirements, and the weak interfacial bonding between metal layer and epoxy-based composites limits its development. In this work, we propose a novel molecular grafting modification technique by using the active functional groups of polymers, which can apply to epoxy-based composites with various fillers to improve the adhesive strength of the interface between the metal film and matrix. 3D surface profile and surface wettability were used to characterize the effect of fillers on the surface of epoxy composites. Scanning electron microscope (SEM) and Raman spectroscopy were utilized to judge the interface failure modes of the composites. Peeling test and surface-enhanced Raman scattering (SERS) were conducted to examine how fillers affected adhesion. The results showed that silane grafting substantially improved the bonding between the epoxy-based composite matrix and the metal layer without the need for alkaline washing and palladium (Pd) activation steps on the substrate. The average adhesive strength can reach a maximum of 17.76 N/cm. The study also revealed the effect of filler size on the interfacial adhesive strength. The interfacial adhesive strength was increased by two dimensional lamellar materials, decreased by one-dimensional tubular materials, and remained unaffected by zero-dimensional spherical materials. This study may have positive implications for improving interfacial bonding between metal and polymer composite surfaces.

High‐performance resistive/capacitive pressure sensor applied on smart insoles detecting abnormal activity

AbstractThis paper presents an approach to pressure sensors with dual‐function resistors and capacitors implemented with interdigitated capacitors fabricated on a flexible substrate for detecting abnormal actions during walking. In this study, we proposed a highly sensitive, broad‐range pressure sensor achieved through a combination of porous Ecoflex, carbon nanotubes (CNTs), coating single‐wall carbon nanotubes (SWCNTs), and interdigitated electrodes. First, characterizations of the capacitor and resistor sensor applied onto cotton fabric are completed by precision LCR meter across the frequency at 50 kHz. Subsequently, the presence of volume fraction CNTs enhances the bond strength of composites, and coating SWCNT improves sensor sensitivity. The robustness of our presented sensor is validated through testing under high pressure (50 kPa) for more than 1000 cycles. Furthermore, the combination of CNTs and porous dielectric, along with SWCNT coating, achieves a broad detection range (500 kPa) with a sensitivity range from 0.018 (at 500 kPa) to 0.15 (at 5 kPa). Finally, our high‐performance resistive/capacitive pressure sensor applied on smart insoles represents a significant advancement in wearable technology for health monitoring and safety applications. Leveraging an advanced autoencoder, our proposed sensor accurately detects abnormal activity patterns, such as sudden stops or irregular gait, thereby alerting users to potential safety concerns. Its ability to detect abnormal activity patterns enhances user safety and well‐being, making it a tool for various healthcare and fitness applications.

The Effect of Carbamide Peroxide Bleaching Gel with and without Remineralizing Agents on Microtensile Bond Strength of Resin Composites to Enamel

Introduction: Carbamide peroxide bleaching gel, along with remineralizing agents, can induce changes in the structure and mineral content of enamel, potentially leading to a decrease in the bond strength of resin composite to the enamel. Therefore, this laboratory study aimed to determine the effect of carbamide peroxide bleaching gel with and without remineralizing agents on the microtensile bond strength (µTBS) of resin composites with microhybrid and nanofill structures to enamel. Materials and Methods: Thirty extracted third molar teeth were randomly divided into five groups, each group subdivided into two equal subgroups: Group 1: Control group, Group 2: Bleaching gel without fluoride, Group 3: Bleaching gel containing fluoride, Group 4: Bleaching gel containing CPP-ACP, and Group 5: Bleaching gel containing fluoride and CPP-ACP. In the first subgroups, nanofilled resin composite Filtek Z350, while in the second subgroups, microhybrid resin composite Filtek Z250 were bonded to enamel surface. After specimen preparation, µTBS was measured using a universal testing machine. Data were analyzed using parametric tests (P value<0.05). Results: The highest µTBS of resin composite to enamel was observed in the control group, while the lowest bond strength was seen in the fluoride-containing bleaching group. Comparisons of µTBS between the study groups pairwise, except for the comparison between the control group and the bleaching group, the bleaching group with (CPP-ACP+Fluoride), and the (CPP-ACP) group with the fluoride group, showed significant differences in bond strength. Although, the mean µTBS of the Filtek Z250 composite was higher than the Filtek Z350 composite in all groups, but this difference was not statistically significant. Conclusion: The use of carbamide peroxide bleaching gel with remineralizing agents leads to a decrease in µTBS of the resin composite to the enamel.

One-Year Evaluation of High-Power Rapid Curing on Dentin Bond Strength.

This study investigated the effect of 3 s light-curing with a high-power LED curing unit on the shear bond strength of bulk-fill composites. Four bulk-fill composites were bonded to dentin with a universal adhesive (Scotchbond Universal Plus): two materials designed for rapid curing (Tetric PowerFill and Tetric PowerFlow) and two controls (Filtek One Bulk Fill Restorative and SDR Plus Bulk Fill Flowable). The 4 mm composite layer was light-cured with Bluephase PowerCure for 20 s at 1000 mW/cm2 ("20 s") or for 3 s at 3000 mW/cm2 ("3 s"). The samples were stored at 37 °C in distilled water and tested after 1, 6 and 12 months. The samples polymerised in the "3 s" mode had statistically similar or higher bond strength than the samples cured in "20 s" mode, except for the Tetric PowerFlow (1 month) and SDR+ (6 month). The flowable materials Tetric PowerFlow and SDR Plus initially showed the highest values in the "3 s" and "20 s" groups, which decreased after 12 months. The bond strength was statistically similar for all materials and curing protocols after 12 months, except for Tetric PowerFill cured with the "3 s" protocol (21.22 ± 5.0 MPa), which showed the highest value. Tetric PowerFill showed the highest long-term bond strength. While "3 s" curing resulted in equal or better shear bond strength, its use can only be recommended for a material with an AFCT agent such as Tetric PowerFill.

Bond strength and marginal adaptation of resin composites and correlations with clinical results

ObjectivesDue to innumerable confounding factors and a high number of types and brands of dental restorative materials, the clinical performance of restorative materials are sought predicted by various in vitro tests. However, only few such tests have been found to correlate well with clinical findings. Thus, the present study determined the in vitro dentin bond strength and marginal adaptation of Class II restorations and correlated the results to their clinical outcomes. MethodsDentin bond strength (µTBS and µSBS) and marginal gap formation of Class II restorations (replica technique and SEM) were measured after 24 h and 6 m water storage using eight combinations of adhesive and resin composite. Clinical outcomes (mean survival time, Hazard Ratio, annual failure rate; n = 10.695) were gained from a data set of a retrospective multicenter study of direct restorations. ResultsSignificant differences were found for dentin bond strength and marginal gap formation between the restorative material groups, and negative effects of long-term storage were observed. µTBS correlated significantly with certain clinical outcomes of Class I restorations, while µSBS correlated with certain clinical outcomes of Class II, III, IV and V restorations. Marginal gap formation in enamel and number of paramarginal fractures correlated with certain clinical outcomes of Class II restorations. SignificanceUsing the same restorative materials in vitro as in vivo, gave significant, but weak correlations between in vitro bond strength or marginal adaptation and clinical outcomes, lending support to the use of in vitro tests in early stages of material selection.

Effect of Polywave and Monowave Light Curing Units on the Microtensile Bond Strength and Failure Types of Different Bulk-Fill Resin Composites: An in vitro Study.

This study aimed to evaluate the effects of polywave and monowave light-emitting diode curing units on the microtensile bond strength and failure types of three bulk-fill resin composites. This in vitro experimental study was performed on 180 microbars obtained from human third molars and were distributed into 12 groups according to the type of bulk-fill resin composite and the light-curing unit. Third molars were restored using Filtek One Bulk Fill Restorative, Tetric® N-Ceram Bulk Fill, and Opus Bulk Fill resin composites was light-cured with Elipar Deep Cure L and Valo in three modes: standard, high power, and extra power. Subsequently, microtensile analysis was carried out with a universal testing machine and the type of failure with an optical stereomicroscope. For statistical analysis, the Kruskal-Wallis H-test was used, with the Bonferroni post hoc test and Fisher's exact test, considering a significance of p<0.05. There were significant differences in the microtensile bond strength between the Filtek One Bulk Fill restorative and Opus Bulk-Fill (p = 0.042) when light was cured with the polywave unit at standard power. On the other hand, the Filtek One Bulk Fill Restorative and Opus Bulk Fill resins showed significant differences in microtensile bond strength when light was cured with the monowave unit compared with the polywave unit (p<0.05). The presence of alternative photoinitiator systems that are more reactive than camphorquinone produced higher microtensile bond strength in Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins when light-cured with a high and standard polywave unit, respectively, compared to Filtek One Bulk Fill resins. Finally, Tetric N-Ceram Bulk Fill and Opus Bulk Fill resins had the highest percentage of mixed failures, while Filtek One Bulk Fill resin had adhesive failures, which was related to its lower microtensile bond strength.

Effect of Various Etching Techniques on Shear Strength of Newer Generation Composites

ABSTRACT Aim: To evaluate the effect of lasers on the shear bond strength of Giomer and G-aenial flo composite using three different etching techniques. Materials and Methods: 60 Samples (extracted human premolar teeth) are cut horizontally using a diamond disk to expose a flat occlusal surface involving enamel and dentin. On exposed occlusal surfaces, etching is done by various methods. These were divided into six groups of ten samples each as follows: group I (acid etched for Giomer), group II (acid etched for G-aenial flo composite), group III (laser etched for Giomer), group IV (Laser etched for G-aenial flo composite), group V (air abrasion etched for Giomer), group VI (Air abrasion etched for G-aenial flo composite). Then, restorative material is placed and cured with light for 20 seconds. The samples were thermocycled to simulate the oral environment. The samples were subjected to a universal testing machine for bond strength testing at a cross-head speed of 3 mm/min until the restoration will fracture. Results: The intergroup comparison between both the materials using Student’s t-test gives insignificant results. The intergroup comparison between different etching techniques using two-way ANOVA tests gives insignificant results. Conclusion: Within the limitation of this study, it can be concluded that Giomer and G-aenial flo composite achieved the same shear bond strength in all the etching techniques.

Blue Laser for Polymerization of Bulk Fill Composites: Influence on dentin bond strength and temperature rise during curing and co-curing method.

Blue diode lasers are alternative curing devices for dental composites. The aim of this study was to investigate the influence of blue diode laser polymerization on shear bond strength of bulk fill composites to human dentin and temperature rise during two types of polymerization. Composite cylinders of SDR Plus(SDR) and Ever X Flow(EX) were bonded to dentin slabs using Adhese Universal and curing devices blue diode laser (449nm, 1.6 W) and Power Cure LED. For each material and curing device there were two polymerization approaches: 1)conventional: separate curing of adhesive; 2)co-curing: simultaneous adhesive and composite curing. Polymerization modes for each material in conventional and co-curing(c) approach were: blue laser 2000 mW/cm2 for 5s (L5 and L5c); blue laser 1000 mW/cm2 for 10s (L10 and L10c); Power Cure 2000 mW/cm2 for 5s (LED5 and LED5c); Power Cure 1000 mW/cm2 for 10s (LED10 and LED10c). Temeperature was measured using thermal vision camera. For SDR, the highest bond strength was 24.3MPa in L10c, and the lowest 9.2MPa in LED5c. EX exhibited the highest bond strength(21.3MPa) in LED5, and the lowest in L5(7.7MPa). The highest temperature rise for SDR was in L10 and L5 (7.3 and 7.2°C), and the lowest in LED5(0.8°C). For EX, the highest temperature rise was in L5 (13.0°C), and the lowest in LED5 (0.7°C). Temperature rise was higher during blue laser polymerization, especially at high intensity and with conventional curing. Preferable blue laser curing mode is co-curing at 1000mW/cm2 for 10s.

Ultrasonic Nondestructive Evaluation of Composite Bond Strength: Quantification through Bond Quality Index (BQI)

This article presents a concept, materials, and methods to devise a Bond Quality Index (BQI) for assessing composite bond quality, approximately correlating to the respective bond strength. Interface bonding is the common mechanism to join two composite structural components. Ensuring the health and quality of the bond line between two load-bearing composite structures is crucial. The article presents the classification and data-driven distinction between two types of bond lines between similar structural components. The interface bonds in composite plates were prepared using polyester peel ply and TX-1040 nylon peel ply. For all the plates, ultrasonic inspection through scanning acoustic microscopy (SAM) (&gt;10 MHz) was performed before and after localized failure of the plate by impinging energy. Energy was impinged 0–10 J/cm2 of in the 16-ply plates, and 0–25 J/cm2 were impinged in 40-ply plates. Followed by bond failure and SAM, a new parameter called the Bond Quality Index (BQI) was formulated using ultrasonic scan data and energy data. The BQI was found to be 0.55 and 0.45, respectively, in plates with polyester peel ply and TX-1040 nylon peel ply bonds. Further, in 40-ply plates with polyester peel ply resulted in a BQI equivalent to 3.49 compared to 0.75 in plates with a TX-1040 nylon peel ply bond. Currently, the BQI is not normalized; however, this study could be used for AI-driven normalized BQIs for all types of bonds in the future.

Effects of Wood Particle Sizes on Bonding and Mechanical Strength of Wood Plastic Composites

Effects of Wood Particle Sizes on Bonding and Mechanical Strength of Wood Plastic Composites

The Effect of Different Ageing Protocols on the Shear Bond Strength of the Ceromer Indirect Composite on Two Different Substructure Materials.

The evolution of restorative materials in prosthodontics has led to the emergence of indirect composite resins, including ceromers, as alternatives to traditional metal-ceramic restorations. However, research gaps exist regarding the impact of ageing protocols on the bond strength of ceromer composites to different metal substructures, necessitating further investigation in this area. This study aimed to determine the effect of five different ageing protocols on the shear bond strength (SBS) of ceromer indirect composites on two different substructures. In this in vitro study, 120 metallic discs (10 × 2 mm) were cast from cobalt-chromium (Co-Cr) alloy (n = 60) and spark erosion treated from grade V titanium (n = 60). Each sample was sandblasted. The M.L. primer (Shofu, Germany) and layers of opaque were applied to the surface following the manufacturer's instructions. A special jig (6 × 2 mm) was placed on each disc. The ceromer was condensed in it and light-cured separately for 90 s. Following polishing, specimens were separated into five ageing groups: distilled water (as a control), thermal cycling, tea, coffee, and gastric acid immersion. All samples were placed in 37°C incubation for 28 days for distilled water, coffee, and tea, and 7 days for gastric acid immersion and thermal cycling for 5000 cycles (5-55°C). A universal test machine was used to measure the SBS. The samples were evaluated for failure modes using stereomicroscopy. Data were analyzed using one-way analysis of variance (ANOVA) (P < 0.05). According to one-way ANOVA, the mean SBS (MPa) between the two groups was compared in each ageing protocol, and there were no significant differences between the Co-Cr-C and Ti-C groups (P > 0.05). The most frequent mode of failure in all groups was mixed. Applying the ageing protocols, the type of substructure material had no significant effect on the SBS of the ceromer indirect composite except for tea immersion.

Effect of Preheating of Resin Composite on Microtensile Bond Strength In Vitro Study

BACKGROUND: Preheating resin composite was one of the latest achievements to improve the mechanical properties of composite. AIM: This study was conducted to assess the effect of preheating of resin composite on microtensile bond strength to dentin. METHODS AND MATERIALS: A total of 32 human molars were selected and divided into two groups according to the type of resin composites either microhybrid (P60) (R1) or nanohybrid (Z250 XT) (R2). The molar teeth were embedded in acrylic resin blocks then the occlusal enamel was removed parallel to cementoenamel junction to expose the dentin. Each group was subdivided into four subgroups according to the number of preheating cycles of resin composite either no heating (C0), one preheating cycle at 68℃ (C1), two preheating cycles at 68℃ (C2), or three preheating cycles at 68℃ (C3). After bonding of resin composite, specimens were cut into beams 1 mm thick and stressed in tension using a universal testing machine (4 teeth per group/12 beams per tooth). STATISTICAL ANALYSIS USED: Two-way ANOVA and Tukey’s post hoc tests were used to test the effect of preheating resin composites for the interaction of different variables. RESULTS: In both variables of the study, the type of resin composite and the number of preheating cycles have a statistically significant effect on the microtensile bond strength to dentin. There was a significant interaction between the variables. CONCLUSION: Pre-heating of Filtek P60 as a packable composite at 68℃ can achieve significantly higher microtensile bond strength compared to Filtek Z250 as a microhybrid composite. Key Messages: Preheating of resin composite enhances the mechanical properties of resin composite. Furthermore, better adaptation is due to easily flow of the material in additional to the improvement of microtensile bond strength of resin composite due to monomer and radical mobility due to complete polymerization during preheating.

Interface Bonding Properties and Mechanism of Steel Fiber and Hot Melt Adhesive via Interface Design Engineering.

Steel fiber textile, which is composed of steel fibers and glass fibers, has a support layer impregnated with hot melt adhesive (HMA). During long-term service, the bonding force between the steel fiber/HMA system interfaces is poor. In order to improve the bond strength and durability of the interface, this paper introduced sandblasting, acid-etching, and phosphating treatments on the surface of the steel fibers. Also, the effects of these three pretreatment methods on the bond strength of the steel fiber/HMA interface were investigated. The results indicate that the interfacial bond strength of composites made from steel fibers is improved via surface treatment. Under a hydrothermal and simulated concrete pore solution environment, the durability of the steel fiber/HMA interface after sandblasting and acid-etching pretreatment is not as good as that after phosphating pretreatment. The mechanical properties of the phosphating/HMA composite were maintained at 4.56 and 2.24 times compared to those of the untreated/HMA composite, respectively. This is because the pinning effect formed by the phosphating film on the surface of steel fibers at the interface of steel fiber/HMA can serve as a physical barrier against corrosion, preventing the invasion of chloride ions and water vapor and improving the durability of the interface.

Bond Strength, Microleakage, Microgaps, and Marginal Adaptation of Self-adhesive Resin Composites to Tooth Substrates with and without Preconditioning with Universal Adhesives.

This study investigated and compared the bond strengths, microleakage, microgaps, and marginal adaptation of self-adhesive resin composites (SAC) to dentin with or without universal adhesives. Dentin surfaces of 75 molars were prepared for shear and microtensile bond strength testing (SBS and µTBS). Silicon molds were used to build up direct restorations using the following materials to form 5 groups: 1. Surefil One; 2. Prime&Bond active Universal Adhesive + Surefil One; 3. Vertise Flow; 4. OptiBond Universal + Vertise Flow; 5. Scotchbond Universal + Filtek Z500 (control group). Bonded specimens were thermocycled 10,000x before being tested either for SBS or µTBS using a universal testing machine at a crosshead speed of 0.5 mm/min. Direct mesial and distal class-II cavities were created on 100 sound premolars, with the gingival margin of distal cavities placed below CEJ and restored according to the five groups. After thermocycling, microleakage scores were assessed following immersion of restored premolars in 2% methylene blue dye for 24 h, while marginal gaps and adaptation percentages were investigated on epoxy resin replicas under SEM at magnifications of 2000X and 200X, respectively. Results were statistically analyzed with parametric and non-parametric tests as applicable, with a level of significance set at α = 0.05. Bond strengths, microleakage scores, microgaps, and percent marginal adaptation of Surefil One and Vertise Flow were significantly (p < 0.001) inferior to the control group. Dentin preconditioning with universal adhesives significantly increased the study parameter outcomes of Surefil One and Vertise Flow, yet they were still significantly below the performance of the control group. Conventional resin composite outperformed the SAC whether applied solely or in conjunction with their corresponding universal adhesives.

Comparison of the Shear Bond Strength of Orthodontic Composites Containing Silver and Amorphous Tricalcium Phosphate Nanoparticles: an ex vivo Study

Comparison of the Shear Bond Strength of Orthodontic Composites Containing Silver and Amorphous Tricalcium Phosphate Nanoparticles: an ex vivo Study

Effect of Aging and Different Surface Treatments on Repair Bond Strength of Hybrid Resin Composites

Background: With the trend for minimally invasive dentistry and the rapid evolution of composite resin materials, repair of defective composite resin restorations is a popular choice rather than replacement of the restoration. The durability of the bond between the old and repaired composite restoration is important for a successful outcome. Objective: To evaluate the immediate and delayed shear bond strength of two types of repaired hybrid resin composites using different chemical and mechanical surface treatments. Methods: Two types of hybrid resin composites, micro-hybrid resin composite and nanohybrid resin composite, were used to prepare 288 pre-polymerized resin composite specimens. After polymerization, repair was done after 24 hours and 6 months. Each hybrid resin composite group was divided into 3 groups according to surface treatment used to repair the substrate: group 1: no surface treatment, group 2: treated by medium abrasive stone, and group 3: treated by fine abrasive stone. Each group was further subdivided into 3 subgroups according to different agents used for repair: group 1: Silane, group 2: Universal adhesive, and group 3: Silane + adhesive. Shear bond strengths of the repaired specimens were measured using a Universal testing machine. Failure modes were evaluated under a stereomicroscope. Results: Different chemical and mechanical surface treatments had a significant effect on the shear bond strength values of all groups (p ≤ 0.05). The highest mean shear bond strength values were found in nano-hybrid composites immediately repaired by silane after treatment by a medium abrasive stone while the lowest mean shear bond strength values were found in micro-hybrid composites with delayed repair and no surface treatment. Conclusion: Diamond burs using silane with adhesive improved the repair bond strength of the tested hybrid composites. In composite repair, using abrasive mechanical pretreatment followed by adhesive conditioning is crucial for the success of the repair restoration.