Bond Strength Of Composite Resin Research Articles

Do Various Laser Powers Affect the Repair Bond Strength of Composite Resin to Indirect Composite?

Do Various Laser Powers Affect the Repair Bond Strength of Composite Resin to Indirect Composite?

Effect of Surface Treatment with CO2 Laser on Bond Strength in Composite Resin Restorations.

Objective: Evaluate the bond strength of repairs made on composite resin following the treatment of the surface of the flaw with different bonding agents and/or CO2 laser. Background: The influence of CO2 laser and its interaction with other bonding agents on the surface of the flaw is not yet known. In this study, CO2 laser was chosen to treat the surface of the flaw due to its capacity to promote irregularities on the surface that enhance mechanical micro-retention. Methods: A block was created with Vitra APS nanohybrid composite resin (color: A3; FGM, Joinville, Brazil) measuring 5 mm in width, length, and depth (volume: 125 mm3). The surface of the flaw was treated before the repair with an adhesive, silane bonding agent, and/or CO2 laser. Six specimens were created in composite resin for each group (total: n = 36): G1: resin+resin; G2: adhesive+resin; G3: laser+adhesive; G4: laser+silane+adhesive; G5: silane+adhesive; G6: laser+silane. After the repair, the surfaces of the fracture of all specimens, which were submitted to the microtraction test, were analyzed under an optical microscope. Bond strength values obtained according to the type of surface treatment were tabulated and submitted to the Kruskal-Wallis test. Dunn's test was used to compare means. Results: G3 and G4 had significantly higher bond strength values compared to all other groups tested. Adhesive fractures predominated in all groups. However, G3 and G4 had a higher percentage of cohesive fractures compared to the other groups. Conclusions: The application of CO2 laser as a surface treatment led to greater bond strength of composite resin repairs in comparison with the groups that only received treatment with a burr and silanization. The groups submitted to CO2 laser also had a significantly lower number of adhesive failures when submitted to the microtraction test.

Effects of surface treatments on the bond strength of composite resin to hybrid computer-assisted design/manufacturing blocks

The aim of this study was to evaluate the repair bond strength of a dimethacrylate-based composite to two hybrid CAD/CAM blocks after different surface treatments. One hunded and twenty specimens were prepared from two different CAD/CAM blocks (Lava Ultimate (L), Cerasmart (C)). After thermal aging, specimens from each group (n = 60) were divided into 6 treatment groups (n = 10): (1) No treatment (2) Phophoric acid (37%) for 60 s, (3) Hydrofluoric acid (8%) for 60 s, (4) Sanblasting with 50-µm aluminium oxide (5) Er,Cr:YSGG laser treatment at 2 W and (6) Er,Cr:YSGG laser treatment at 3 W. Single Bond Universal was applied on all specimens and a dimethacrylate-based composite (Tetric N-Ceram) was bonded using Teflon tubes. After thermal cycling, shear bond strength (SBS) was tested, and failure modes were evaluated. Two-way ANOVA and independent t-test were used for statistical analysis (p < 0.05). The highest SBS values were detected at Er,Cr:YSGG laser treatment groups (3W) (L:22.7 MPa, C:22.6 MPa). Lowest SBS values were obtained at no surface pretreatment groups followed by phophoric acid treatment groups which were significantly lower than sandblasting, hydrofluoric acid treatment and Er,Cr:YSGG laser treatment groups (p = 0.001). The universal adhesive Single Bond Universal had no effect on promoting bond strength to hybrid ceramics alone or with phosphoric acid. Sandblasting, hydrofluoric acid and laser treatment were effective at increasing repair bond strength, for both Lava Ultimate and Cerasmart.

Comparative evaluation of effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel.

The use of antioxidants immediately after bleaching showed increased bond strength. This study aimed to compare the effects of natural antioxidants on the shear bond strength of composite resin to bleached enamel. Fifty extracted single-rooted upper incisors were decoronated by sectioning the roots 2 mm below the cementoenamel junction, and then, crowns were embedded in autopolymerizing acrylic resin block (3.0 cm × 3.0 cm × 3.0 cm) with the labial surface exposed. They were randomly divided into five groups, depending on the type of antioxidant used (n = 10): (i) Group 1: control (no bleaching), (ii) Group 2: bleaching only, (iii) Group 3: bleaching + 10% sodium ascorbate (antioxidant), (iv) Group 4: bleaching + green tea, and (v) Group 5: bleaching + white tea. Labial surfaces of 40 teeth were bleached with 38% hydrogen peroxide for 20 min following manufacturer's instructions. After that, the experimental groups (Groups 3, 4, and 5) were treated with respective antioxidant solutions before composite restorations were done using a cylindrical plastic mold (3 mm × 5 mm). Shear bond strength of the specimens was tested under universal testing machine. Data were analyzed with ANOVA and Tukey's post hoc test. There were statistically significant differences between shear bond strength of control groups (Groups 1 and 2) and experimental groups (P < 0.05), but no significant difference in bond strength was observed among the antioxidants used. Application of antioxidants immediately after bleaching showed increased bond strength. Green tea and white tea extract can be used as alternative antioxidants in improving the bond strength of enamel.

Effect of antioxidants on the shear bond strength of composite resin to enamel following extra-coronal bleaching.

BackgroundRecently patients need faster treatments, and delaying restoration is not possible following bleaching treatment. The purpose of this study was to determine the effect of antioxidants, namely 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extract on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide.Material and MethodsSeventy premolars were randomly assigned into 7 groups of 10 each. Group 1: bleaching treatment and no antioxidants application. Group 2: composite was built-up immediately after bleaching. Group 3: bleached specimens received composite build-up delayed by 2 weeks. Group 4, 5, 6 and 7: bleached specimens received an application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea, and 10% Aloe vera before composite build-up. Specimens were immersed in artificial saliva, stored in an incubator 37°C (24 hours), thermocycling, and tested using a universal testing machine. Data were analyzed by one-way ANOVA and Tukey’s test with 95% level of significance.ResultsBleaching caused significantly reduced shear bond strength (p<0.05), and application of 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera produced significantly greater shear bond strength compared to bleached group (P <0.05). However, no significant differences occurred between antioxidant groups (P >0.05).ConclusionsApplication of antioxidants increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. 10% sodium ascorbate, 10% alpha-tocopherol, 10% green tea and 10% Aloe vera extracts produced the same effect on the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. Key words:Antioxidants, shear bond strength, composite resin, extra-coronal bleaching.

Bond Strength of Composite Resin Restoration Repair: Influence of Silane and Adhesive Systems

The aim of this study is to evaluate the effect of silane (Si) application and different adhesive systems on the bond strength of composite resin repair. One hundred composite truncated cone-shaped specimens were prepared and submitted to 5,000 thermal cycles to simulate existing restorations. Their top surfaces were airborne particle abraded with aluminum oxide, etched with phosphoric acid, and divided into two groups (n = 50) with or without Si application. Each group was divided into five subgroups (n = 10) according to the adhesive system applied: Solobond Plus Primer and Adhesive (SPA)-two-bottle, Solobond Plus adhesive (SA), Admira Bond (A)-one bottle, Futurabond DC (FDC)-self-etch, and Futurabond M (FM)-self-etch. New composite resin was applied over the bonded area. A control group was prepared to evaluate the cohesive strength of the composite resin. Specimens were submitted to tensile stress. Data were analyzed with two-way analysis of variance (ANOVA), and the Tukey and Dunnett tests. Si application reduced the bond strength of all adhesives (p = 0.001). Groups SA and SPA showed higher bond strengths in relation to other groups (p = 0.01). Groups FDC + Si, FM, FM + Si, and A + Si showed smaller mean bond strength values than that of the control group (p < 0.05). Previous Si application reduced bond strength values. The two-bottle adhesive showed better results than one-bottle or self-etching systems for composite resin repairs. The kind of adhesive system applied for composite resin repairs has a great influence on bond strength values. The use of Si in this situation is not recommended.

Shear bond strength of composite resin to resin-modified glass ionomer cement using 2-hydroxyethyl methacrylate-based and 2-hydroxyethyl methacrylate-free adhesive system.

Background:Sandwich technique combines the properties of both composite resin and glass ionomer cement to make the most of the physical and esthetic properties of each material. Bonding agents improve the wettability of GIC surface and improves the bond between composite resin and GIC. The aim of this study was to evaluate and compare shear bond strength of composite resin to resin modified glass ionomer cement using HEMA-based and HEMA-free adhesive systems. An in vitro study.Materials and Methods:Total 30 disc-shaped samples were prepared with resin modified glass ionomer cement (RMGIC). Samples were divided into three groups, each group containing 10 samples. Group I (n=10): Nano-hybrid composite resin (NHCR) was bonded to RMGIC without any adhesive system. Group II (n=10): NHCR was bonded to RMGIC using hydroxyethylmethacrylate (HEMA)-based adhesive system. Group III (n=10): NHCR was bonded to RMGIC using HEMA-free adhesive system. The shear bond strength was tested using Universal testing Machine and the results were calculated using one way ANOVA and Post-Hoc test.Results:Maximum shear bond strength was recorded in group III where HEMA-free adhesive used with a mean value of 6.13±1.859 MPa followed by group II where HEMA-based adhesive used with mean value of 4.38±1.533 MPa. The control group showed least shear bond strength.Conclusion:Application of HEMA-free adhesive (OptiBond All-In-One) resulted in greater shear bond strength between RMGIC and composite resin than HEMA-based adhesive (Single bond Universal Adhesive).

A comparative evaluation of the three different antioxidant treatments on the bond strength of composite resin to bleached enamel: An in vitro study.

Context:Natural antioxidants have capacity to neutralize the action of free radicles, therefore, effective in reversal of compromised bond strength.Aims:The aim of this study was to investigate the effect of three different antioxidant treatments on the bond strength of composite resin to bleached enamel.Materials and Methods:Ninety extracted human anterior teeth were divided into five groups: Group I (n = 10) – control group no bleaching, Group II (n = 20) – bleaching with 35% carbamide peroxide gel, Group III (n = 20): bleaching with application of 10% sodium ascorbate, Group IV (n = 20): bleaching with application of 6.5% proanthocyanidin, and Group V (n = 20) – bleaching with application of 50% Aloe vera. These groups were further subdivided into two subgroups based on whether composite buildup was done immediately (Subgroup A) or after a delay of 2 weeks (Subgroup B). Shear bond strength of the specimens was tested under universal testing machine.Statistical Analysis Used:Data were statistically analyzed using Student's unpaired t-test, ANOVA test, and Tukey's Kramer multiple comparison test.Results:The mean bond strength of Group IVA was significantly higher (4.27 ± 1.86) which indicated that immediate application of proanthocyanidin showed higher bond strength after bleaching (P < 0.05).Conclusion:Within the limitations of this study, it can be concluded that immediate application of antioxidants on bleached enamel before composite restoration reversed the bond strength of composite restoration. The immediate application of proanthocyanidin proved superior followed by A. vera.

Comparative Evaluation of Shear Bond Strength of Composite Resin Bonded to Acid Etched and Lased Primary Enamel (Er, Cr: YSGG)

Comparative Evaluation of Shear Bond Strength of Composite Resin Bonded to Acid Etched and Lased Primary Enamel (Er, Cr: YSGG)

Repair bond strength of composite resin to zirconia restorations after different thermal cycles.

PURPOSEThis in vitro study investigated the repair bond strength of the zirconia ceramic after different aging conditions.MATERIALS AND METHODSIn order to imitate the failure modes of veneered zirconia restorations, veneer ceramic, zirconia, and veneer ceramic-zirconia specimens were prepared and were divided into 4 subgroups as: control (37℃ distilled water for 24 hours ) and 3000, 6000, 12000 thermal cycling groups (n=15). Then, specimens were bonded to composite resin using a porcelain repair kit according to the manufacturer recommendation. The repair bond strength (RBS) test was performed using a universal testing machine (0.5 mm/min). Failure types were analyzed under a stereomicroscope. Two-way ANOVA and Bonferroni test were used for statistical analysis.RESULTSThe RBS values of zirconia specimens were statistically significant and higher than veneer ceramic and veneer ceramic-zirconia specimens in control, 3000 and 6000 thermal cycling groups (P<.05). When 12000 thermal cycles were applied, the highest value was found in zirconia specimens but there was no statistically significant difference between veneer ceramic and veneer ceramic-zirconia specimens (P>.05). Veneer ceramic specimens exhibited cohesive failure types, zirconia specimens exhibited adhesive failure types, and veneer ceramic-zirconia specimens exhibited predominately mixed failure types.CONCLUSIONThermal cycling can adversely affect RBS of composite resin bınded to level of fractured zirconia ceramics.

Evaluation of Microshear Bond Strength of Light and Chemically-Cured Composite Resins to Light-Cured Glass-Ionomer Using Various Bonding Systems

Background: This study was conducted to compare the microshear bond strength (MSBS) of chemically-cured and light cured composite to resin-modified glass-ionomer (RMGI) based on different types of adhesive systems. Methods: Thirty-two discs of Vitrebond RMGI were prepared and randomly divided into 8 groups. Four cylinders of composite resin were placed on each RMGI sample. Z250 composite was bonded to the RMGI discs with Single-Bond, Clearfil SE-Bond, and Clearfil S3-Bond adhesive agent in groups 1, 2 and 3, respectively. Group 4 was considered to be the control group without any adhesive. In groups 5-8, the procedures were the same as those in groups 1-4, except that a chemically-cured composite (Master Dent) was used. All the samples were kept at 37˚C for 24 hours and tested for MSBS by a mechanical testing machine at a strain rate of 0.5 mm/min. Failure mode was assessed under a stereomicroscope. Data analysis was carried out by two-way ANOVA, independent t test, one-way ANOVA and Tukey honestly significant difference test. Results: Application of a bonding agent significantly increased MSBS (P=0.0001). MSBS was significantly higher in samples with light cured composite resin compared to the chemically-cured composite (P=0.0001). Conclusions: Application of an adhesive system significantly increased the MSBS of composite resins to RMGI. The bond strength of composite resin to RMGI could vary depending on the type of the composite resin and the adhesive system.

Efeito na resistência de união do esmalte compósito utilizando soluções redutoras após o clareamento dental

Objetivo: avaliar a resistência de união da resina composta ao esmalte bovino após o tratamento de duas substâncias redutoras. Material e Métodos: os dentes bovinos foram embutidos, tiveram sua face vestibular e foram divididos em 4 grupos (n = 10). O grupo 1 (controle) não foi submetido a clareamento, condicionamento ácido e restaurado com adesivo e resina composta. Os grupos 2 a 4 foram clareados com peróxido de hidrogênio a 35% durante 4 dias consecutivos por 40 min / sessão e submetidos ou não aos tratamentos de superfície propostos antes de serem restaurados. O Grupo 2 foi descorado e restaurado, enquanto os Grupos 3 e 4 foram clareados e imersos em solução de tiossulfato de sódio ou ascorbato de sódio, respectivamente, antes de serem restaurados. As amostras foram armazenadas por 24 horas e depois submetidas ao teste de resistência ao microestaca. Resultados: de acordo com os testes estatísticos, os resultados de resistência de união utilizando agentes redutores foram semelhantes aos do grupo controle e estatisticamente diferentes daqueles do grupo somente branqueado. Conclusão: as soluções redutoras foram capazes de recuperar a resistência de união de dentes recém-branqueados sem diferença estatisticamente significativa entre eles.

Effect of Various Bleaching Agents on the Surface Composition and Bond Strength of a Calcium Silicate-based Cement.

This study aimed to evaluate the morphological and elemental changes that occur on the surface of calcium silicate-based cement (CSC) and to analyze the bond strength of composite resin to CSC after application of various bleaching agents. One hundred twenty-five CSC blocks (Biodentine) were prepared and randomly divided into five groups according to the bleaching agent applied over the material surface (n=25): SP-DW (sodium perborate-distilled water mixture), SP-HP (sodium perborate-3% hydrogen peroxide [H2O2] mixture), CP (37% carbamide peroxide gel), HP (35% H2O2 gel), and a control group (no bleaching agent). After 1 week, scanning electron microscopy provided an analysis of the surface morphology and elemental composition for 10 specimens from each group. Composite resin was placed at the center of each cement surface in the remaining specimens (n=15). A universal testing machine determined shear bond strength (SBS) and fracture patterns were identified with a dental operating microscope. Data were analyzed using one-way analysis of variance and Tukey HSD tests. The cement surface in the CP and HP groups presented changes in structure and elemental distribution compared with the remaining groups. The former groups exhibited a decrease in the calcium level and an increase in the silicon level and presented significantly fewer SBS values than the remaining groups ( p<0.05). Most failures were adhesive in the CP and HP groups, while they were predominantly cohesive in the remaining groups. The bleaching agents with higher concentration induced deterioration of the cement surface and negatively affected the bond strength of the composite resin to CSC. The use of CSC is recommended as a cervical barrier when intracoronal bleaching is performed with a mixture of sodium perborate with water or 3% H2O2.

Comparison of bond strength of a composite resin with two different adhesive systems and a resin modified glass ionomer to calcium enriched mixture.

Context:It is necessary to have a proper bond between pulp-capping agent and composite materials to maintain effective coronal seal.Aims:This study aims to compare the shear bond strength of a composite resin with two different adhesive systems and a resin-modified glass ionomer (RMGI) to calcium-enriched mixture (CEM).Methods:In this study, 30 acrylic blocks (with a central hole 4 mm diameter and 2 mm height) were prepared and filled with CEM. The blocks were divided into three groups: single bond2 (SB) with Filtek Z250, single bond universal (SBU) with Filtek Z250, and RMGI. The restorative materials were placed on the CEM, and shear bond strength was measured. Data were analyzed using one-way ANOVA and games Howell tests. P < 0.05 was considered statistically significant.Result:Bond strength of both composite groups to CEM showed significantly higher values than RMGI-CEM group (both P < 0.001). The type of the adhesive system( total etch or universal) had no significant effect on the bond strength of composite to CEM (P > 0.05). All the failures in composite groups were as cohesive in CEM and in RMGI group was as adhesive.Conclusions:Shear bond strength of composite resin to CEM cement was higher than RMGI irrespective of the type of the adhesive system. The universal bonding system is recommended for bonding of composite to CEM for ease of use.

Bond strength of composite resin to white mineral trioxide aggregate: Effect of different surface treatments.

Background:The main aim of restorative dentistry is to restore and preserve dental health with the use of appropriate restorative modalities to protect the pulp and restore its function. This study compared the effect of different surface treatments of mineral trioxide aggregate (MTA) on the bond strength of composite resin to MTA.Materials and Methods:Forty cylindrical acrylic blocks with a hole were prepared and filled by ProRoot MTA. The samples were assigned to four groups: Group 1 – no surface treatment; Group 2 – phosphoric acid etching; Group 3 – sandblasting; and Group 4 – hydrofluoric acid (HF) etching, rinsing, and silane application. OptiBond Solo Plus adhesive was utilized in all the groups. Then, composite resin cylinders were bonded to sample surfaces. The samples were thermocycled and tested for microshear bond strength using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with Kruskal–Wallis and Mann–Whitney tests. Scanning electron microscopy images were prepared for each study group after surface treatments.Results:Means and standard deviations of bond strength values in study groups 1–4 were 14.83 ± 7.76, 21.85 ±7.99, 6.48 ± 3.89, and 26.01 ± 11.09 Mpa, respectively.Conclusions:Within the limitations of this study, phosphoric acid etching or HF etching plus silanization was preferred to surface treatment of MTA before composite resin bonding.

A comparative evaluation of shear bond strength of composite resin to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin: An in vitro study.

Aim:Based on the importance of coronal sealing right after endodontic treatment, this in vitro study aimed to evaluate the difference of shear bond strength to pulp chamber dentin treated with sodium thiosulfate and proanthocyanidin (PA).Materials and Methods:Fifteen extracted mandibular molar teeth were decoronated at the level of cementoenamel junction horizontally. The individual teeth were then sectioned mesiodistally to expose the pulp chamber dentin using a diamond disc. The specimens were randomly divided into three groups (n = 10). Group A: control group, treated with 5.25% sodium hypochlorite (NaOCl) for 30 min followed by a final rinse with 17% ethylenediaminetetraacetic acid (EDTA) solution for 3 min; Group B: after pretreatment with NaOCl and EDTA, it is further treated with 5% sodium thiosulfate (Na2S2O3) for 10 min; and Group C: after pretreatment with NaOCl and EDTA, it is further treated with 6.5% PA for 10 min. After drying the specimens, a bonding agent namely One Coat Bond SL (SwissTEC, Coltene) was applied to the pulp chamber dentin followed by a composite restoration (SwissTEC, Coltene). Each specimen was then tested under a universal testing machine at the dentin/resin interface to determine the shear bond strength.Results:Both the groups in which 5% Na2S2O3 and 6.5% PA were used for 10 min showed bond strength that was found to be statistically higher than the positive control (P < 0.05).Conclusion:The use of Na2S2O3 and PA can significantly increase the bond strength of composite resin to NaOCl/EDTA-treated dentin, allowing adhesive restorations to be immediately applied after endodontic treatment.

Comparative evaluation of the effect of different disinfecting agents on bond strength of composite resin to dentin using two-step self-etch and etch and rinse bonding systems: An in-vitro study.

Objective:This study was carried out to examine the effect of the application of different disinfecting agents on the shear bond strength (SBS) of an etch-and-rinse system.Materials and Methods:A total of 120 dentin surfaces of human molars were taken. Sixty samples were taken for immediate (testing was done after 24 h) and delayed (testing was done after 6 months) each. Further, they were divided into three subgroups (n = 20) according to the disinfectant used: Group I: control (no disinfectant); Group II: chlorhexidine based; and Group III: Aloe barbadensis miller (Aloe vera) based. Dentine bonding agent was applied, and resin composite build-ups were done for SBS testing. Samples were examined under scanning electron microscope for observing the gap formation for dentin-restoration interface. SBS results were statistically analyzed.Results:The results of the study showed that both chlorhexidine and aloe vera had improved bond strength as compared to the control group both for immediate and delayed SBSs.Conclusion:Thus, aloe vera can be used as an alternative to chlorhexidine for cavity disinfection.

Evaluation of 5% proanthocyanidin and 30% alpha-tocopherol on shear bond strength of composite to bleached enamel: An In vitro study

Objective: The aim of this in vitro study is to evaluate and compare the effect of 5% proanthocyanidin and 30% alpha-tocopherol on the bond strength of composite resin to the bleached enamel. Materials and Methods: The labial enamel surface of sixty central incisors was flattened for the purpose of this study. Fifteen teeth served as control group which did not receive bleaching nor antioxidant treatment. The remaining 45 teeth then were randomly divided into three groups of 15 each. They are Group 1: bleaching with 38% hydrogen peroxide for 10 min without the use of antioxidant, Group 2: bleaching followed by treating with 5% proanthocyanidin, and Group 3: bleaching followed by treating with 30% alpha-tocopherol. The bonded specimens were stored in distilled water (37°C, 24 h) and tested for shear bond strength in a universal testing machine. The data were analyzed with one-way ANOVA and Tukey's post hoc test. Results: Higher bond strength values were seen in the control group followed by 5% proanthocyanidin group. Conclusion: Use of 5% proanthocyanidin can effectively reverse the bond strength of bleached enamel.

Effect of antioxidant on orthodontic bracket bond strength after vital bleaching.

: The objective of this study is to compare the neutralization effect of various antioxidant agents on the bond strength of composite resins on stainless steel and ceramic brackets immediately bonded to previously bleached teeth. One hundred and sixty human maxillary premolars were used for the study. Teeth were divided into four groups (n = 40): Group 1 (control), Group 2 (bleached), Group 3 (sodium ascorbate), and Group 4 (tocopherol acetate). Each group was divided into two subgroups, one was bonded with stainless steel and other with ceramic brackets using 3M Transbond XT. Universal testing machine was used to determine the shear bond strength (SBS). Among the metal brackets, Group 1A had the highest SBS (12.18 + 1.41 MPa) and Group 2A had the least SBS (6.18 + 1.49 MPa). Weibull analysis indicated that bond strength for a 90% probability of failure was highest for Group 1A (13.99 MPa) and lowest for Group 2A (8.49 MPa). For ceramic brackets, Group 1B had the highest SBS (13.80 + 1.69 MPa) and Group 2B had the least SBS (8.05 + 1.85 MPa). Weibull analysis indicated that bond strength for a 90% probability of failure was highest for Group 1B (14.61 MPa) and lowest for Group 2B (8.85MPa). The in vitro study showed that bleaching reduced the SBS significantly, and this could be effectively reversed by the application of antioxidants in both metal and ceramic brackets.

Micro-shear bond strength of composite resin to glass ionomer cement using an alternative method to build up test specimens.

Despite the relevance of the sandwich technique, there are still doubts about the best adhesive strategy and surface treatment for glass ionomer cements (GICs). The aim of this study is to evaluate the best surface treatment for GIC to ensure an effective and durable adhesion to resin, through micro-shear test, using an alternative method to build up test specimens. Eighty GIC samples were divided into eight groups (n = 10) according to five surface treatments (none, etching, air drying, grinding, and grinding plus etching) and according to the adhesive system (conventional or self-etch). Five starch tubes were positioned on each sample, and a flowable composite was inserted generating 50 resin test bodies per group and a total of 400 tested areas. All specimens were submitted to the micro-shear test: half immediately and half after thermal cycling (10,000 cycles of 20 s each/5° and 55°C). All samples were analyzed to evaluate fracture. Representative samples were also analyzed by scanning electron microscopy and energy dispersive spectroscopy. Data were analyzed with two-way ANOVA and Tukey's honest significant difference post hoc test (P <.05). The bond strengths in the thermal cycled specimens were lower and showed a statistically significant difference (P = 0). The "grinding" groups showed the highest bond strength. The alternative method to build up test specimens was effective and easy to execute. Grinding of the GIC surface, which is not normally performed before the use of the adhesive system, represented the best option of surface treatment.