The effect of water immersion on the shear bond strength between chairside reline and denture base acrylic resins: Basic science research

Purpose: The effect of water immersion on the shear bond strength (SBS) between 1 heat-polymerizing acrylic resin (Lucitone 550-L) and 4 autopolymerizing reline resins (Kooliner-K, New Truliner-N, Tokuso Rebase Fast-T, Ufi Gel Hard-U) was investigated. Specimens relined with resin L were also evaluated. Materials and Methods: One hundred sixty cylinders (20 × 20 mm) of L denture base resin were processed, and the reline resins were packed on the prepared bonding surfaces using a split-mold (3.5 × 5.0 mm). Shear tests (0.5 mm/min) were performed on the specimens (n = 8) after polymerization (control), and after immersion in water at 37°C for 7, 90, and 180 days. All fractured surfaces were examined by scanning electron microscopy (SEM) to calculate the percentage of cohesive fracture (PCF). Shear data were analyzed with 2-way ANOVA and Tukey's test; Kruskall-Wallis test was used to analyze PCF data (α = 0.05). Results: After 90 days water immersion, an increase in the mean SBS was observed for U (11.13 to 16.53 MPa; p < 0.001) and T (9.08 to 13.24 MPa, p = 0.035), whereas resin L showed a decrease (21.74 MPa to 14.96 MPa; p < 0.001). The SBS of resins K (8.44 MPa) and N (7.98 MPa) remained unaffected. The mean PCF was lower than 32.6% for K, N, and T, and higher than 65.6% for U and L. Conclusions: Long-term water immersion did not adversely affect the bond of materials K, N, T, and U and decreased the values of resin L. Materials L and U failed cohesively, and K, N, and T failed adhesively. © 2007 by The American College of Prosthodontists.

Shear bond strength of orthodontic brackets bonded using halogen light and light-emitting diode at different debond times

The aim of this in vitro study was to compare the photoactivation effects of QTH (Quartz-Tungsten-Halogen) and LED (Light-Emitting Diode) on the SBS (Shear Bond Strength) of orthodontic brackets at different debond times. Seventy-two bovine lower incisors were randomly divided into two groups according to the photoactivation system used (QTH or LED). The enamel surfaces were conditioned with Transbond self-etching primer, and APC (Adhesive Pre-Coated) brackets were used in all specimens. Group I was cured with QTH for 20 s and Group II with LED for 10 s. Both groups were subdivided according to the different experimental times after bonding (immediately, 24 h and 7 days). The specimens were tested for SBS and the enamel surfaces were analyzed according to the Adhesive Remnant Index (ARI). The statistical analysis included the Tukey's test to evaluate the main effects of photoactivation and debond time on SBS. The Chi-square test was used to compare the ARI values found for each group, and no statistically significant difference was observed. The debond time of 7 days for QTH photoactivation showed statistically greater values of SBS when compared to the immediate and 24 h periods. There was no statistically significant difference between the QTH and LED groups immediately and after the 24 h period. In conclusion, bonding orthodontic brackets with LED photoactivation for 10 s is suggested because it requires a reduced clinical chair time.

Effect of toothbrushing with different manual toothbrushes on the shear bond strength of orthodontic brackets

The aim of this study was to evaluate the effect of brushing with a Colgate 360° or Oral B Indicator 35 toothbrush on the shear bond strength of orthodontic brackets bonded to extracted human teeth. The bristle wear and bristle tip morphology were also examined after simulated tooth-brushing. Orthodontic brackets (Roth-P/1 st and 2 nd pre-molar S/D- Slot 0.18) were bonded (Transbond XT ®) to the smoothest surface of each of 45 extracted human molar and premolar teeth. Test specimens were randomly divided into three groups: Group 1, control group with no brushing; Group 2, brushing with the Oral B Indicator 35; Group 3, brushing with the Colgate 360°. Samples were adapted to a machine that simulated tooth-brushing. The bond strength of each bracket to each tooth was assessed with a mechanical testing machine. The bristle wear and bristle tip morphology indices were also assessed. Statistically significant differences were defined for p ≤ 0.05. The average bond strengths (range: 90.18-90.89 kgf/cm 2) did not differ among the three groups. The Colgate 360° showed less bristle wear and a better bristle tip morphology than the Oral B Indicator 35 toothbrush. However, use of either toothbrush did not decrease the bond strength of the orthodontic brackets. Therefore, patients undergoing orthodontic therapy can safely use either toothbrush.

In vitro study of shear bond strength in direct bonding of orthodontic molar tubes

Objective: Although direct bonding takes up less clinical time and ensures increased preservation of gingival health, the banding of molar teeth is still widespread nowadays. It would therefore be convenient to devise methods capable of increasing the efficiency of this procedure, notably for teeth subjected to substantial masticatory impact, such as molars. This study was conducted with the purpose of evaluating whether direct bonding would benefit from the application of an additional layer of resin to the occlusal surfaces of the tube/tooth interface. Methods: A sample of 40 mandibular third molars was selected and randomly divided into two groups: Group 1 - Conventional direct bonding, followed by the application of a layer of resin to the occlusal surfaces of the tube/tooth interface, and Group 2 - Conventional direct bonding. Shear bond strength was tested 24 hours after bonding with the aid of a universal testing machine operating at a speed of 0.5mm/min. The results were analyzed using the independent t-test. Results: The shear bond strength tests yielded the following mean values: 17.08 MPa for Group 1 and 12.60 MPa for Group 2. Group 1 showed higher statistically significant shear bond strength than Group 2. Conclusions: The application of an additional layer of resin to the occlusal surfaces of the tube/tooth interface was found to enhance bond strength quality of orthodontic buccal tubes bonded directly to molar teeth.

Analysis of the effects of thermal cycling on the microtensile shear bond strength of a self-etching and a conventional pit and fissure sealants to dental enamel

Objective: To analyze the effects of thermal cycling on the microtensile shear bond strength of a self-etching and a conventional pit and fissure sealants to dental enamel. Material and Method: Twenty-four healthy human molars extracted for orthodontic reasons, were sectioned in the mesio-distal direction and divided into two groups (n=24) according to the sealant to be applied: GI - conventional sealant Climpro (3M/ESPE) and GII - self-etching sealant Enamel Loc (Premier Dental). The sealants were applied on flattened enamel in matrixes 1 mm in diameter, in accordance with the manufacturers' recommendations. The specimens were stored in distilled water at 37°C for 24 hours. After this, half the samples of both groups were submitted to 500 thermal cycles in 30s baths at temperatures between 5 and 55°C. Forty-eight hours after the samples were made, the microtensile shear test was performed in an Instron 4411 test machine, with a stainless steel wire with a cylindrical cross section of 0.2mm in diameter at a constant speed of 0.5mm/s. The bond strength values were submitted to ANOVA for 2 factors and the fracture patterns were examined under an optical microscope at 65X magnification. Results: Thermal cycling did not influence the bond strength of the two sealants. The conventional sealant Climpro presented a statistically higher microtensile shear bond strength (11.72MPa, 11.34MPa with and without cycling, respectively) than the self-etching sealant Enamel Loc (5.92MPa, 5.02MPa with and without cycling, respectively). Fracture pattern analysis showed the occurrence of 100% of adhesive failures for Enamel Loc, while the conventional sealant Climpro presented 95% of adhesive failures and 5% of mixed failures. Conclusion: The conventional sealant presented higher microtensile shear bond strength to dental enamel in comparison with the self-etching sealant. Thermal cycling did not affect the bond strength of the sealants used in this study. © 2011 Nova Science Publishers, Inc.

Shear bond strength of resin cement bonded to alumina ceramic after treatment by aluminum oxide sandblasting or silica coating

Purpose: To evaluate the shear bond strength and bond durability between a dual-cured resin cement (RC) and a high alumina ceramic (In-Ceram Alumina), subjected to two surface treatments. Materials and Methods: Forty disc-shaped specimens (sp) (4-mm diameter, 5-mm thick) were fabricated from In-Ceram Alumina and divided into two groups (n = 20) in accordance with surface treatment: (1) sandblasting by aluminum oxide particles (50 μm Al 2O 3) (SB) and (2) silica coating (30 μm SiO x) using the CoJet system (SC). After the 40 sp were bonded to the dual-cured RC, they were stored in distilled water at 37°C for 24 hours. After this period, the sp from each group were divided into two conditions of storage (n = 10): (a) 24 h-shear bond test 24 hours after cementation; (b) Aging-thermocycling (TC) (12,000 times, 5 to 55°C) and water storage (150 days). The shear test was performed in a universal test machine (1 mm/min). Results: ANOVA and Tukey (5%) tests noted no statistically significant difference in the bond strength values between the two surface treatments (p= 0.7897). The bond strengths (MPa) for both surface treatments reduced significantly after aging (SB-24: 8.2 ± 4.6; SB-Aging: 3.7 ± 2.5; SC-24: 8.6 ± 2.2; SC-Aging: 3.5 ± 3.1). Conclusion: Surface conditioning using airborne particle abrasion with either 50 μm alumina or 30 μm silica particles exhibited similar bond strength values and decreased after long-term TC and water storage for both methods. © 2011 by The American College of Prosthodontists.

Effect of ceramic surface treatment on the shear bond strength of a resin cement to different ceramic systems

This study evaluated three surface treatments and their effects on the shear bond strength between a resin cement and one of three ceramics. The ceramic surfaces were evaluated with scanning electron microscopy (SEM ) as well. Specimens were treated with 50 μm aluminum oxide airborne particles, 10% hydrofluoric acid etching, or a combination of the two. Using a matrix with a center hole (5.0 mm × 3.0 mm), the ceramic bonding areas were filled with resin cement following treatment. The specimens were submitted to thermal cycling (1,000 cycles) and the shear bond strength was tested (0.5 mm/minute). The failure mode and the effect of surface treatment were analyzed under SEM . Data were submitted to ANOVA and a Tukey test (α = 0.05). Duceram Plus and IPS Empress 2 composite specimens produced similar shear bond strength results (p > 0.05), regardless of the treatment method used. Hydrofluoric acid decreased the shear bond strength of In-Ceram Alumina specimens. For all materials, surface treatments changed the morphological surface. All treatments influenced the shear bond strength and failure mode of the ceramic/resin cement composites.

Effect of fluoride solutions on the shear bond strength of orthodontic brackets

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values.

Effects of extreme cooling methods on mechanical properties and shear bond strength of bilayered porcelain/3Y-TZP specimens

Objectives: This study investigated the effect of extreme cooling methods on the flexural strength, reliability and shear bond strength of veneer porcelain for zirconia. Methods: Vita VM9 porcelain was sintered on zirconia bar specimens and cooled by one of the following methods: inside a switched-off furnace (slow), at room temperature (normal) or immediately by compressed air (fast). Three-point flexural strength tests (FS) were performed on specimens with porcelain under tension (PT, n = 30) and zirconia under tension (ZT, n = 30). Shear bond strength tests (SBS, n = 15) were performed on cylindrical blocks of porcelain, which were applied on zirconia plates. Data were submitted to one-way ANOVA and Tukey's post hoc tests (p < 0.05). Weibull analysis was performed on the PT and ZT configurations. Results: One-way ANOVA for the PT configuration was significant, and Tukey's test revealed that fast cooling leads to significantly higher values (p < 0.01) than the other cooling methods. One-way ANOVA for the ZT configuration was not significant (p = 0.06). Weibull analysis showed that normal cooling had slightly higher reliability for both the PT and ZT configurations. Statistical tests showed that slow cooling decreased the SBS value (p < 0.01) and showed less adhesive fracture modes than the other cooling methods. Clinical Significance: Slow cooling seems to affect the veneer resistance and adhesion to the zirconia core; however, the reliability of fast cooling was slightly lower than that of the other methods. © 2013 Elsevier Ltd.

Comparison of shear bond strength of orthodontics brackets on composite resin restorations with different surface treatments

INTRODUÇÃO: frequentemente, os pacientes ortodônticos apresentam restaurações de resina composta; no entanto, existem poucos estudos que avaliam a melhor forma de colagem ortodôntica nessa situação. OBJETIVO: o objetivo do presente trabalho foi avaliar a força adesiva de braquetes ortodônticos em restaurações resinosas com tratamento de superfície. MÉTODOS: foram utilizados 51 incisivos inferiores bovinos divididos aleatoriamente em três grupos. No grupo controle (GC), os braquetes foram colados em esmalte dentário; nos grupos experimentais com tratamento (GCT) e sem tratamento (GST), os braquetes foram colados em restauração de resina previamente realizada, diferenciando-se pelo tratamento de superfície com broca diamantada. Os dentes foram incluídos em tubos de PVC com resina acrílica autopolimerizável. O ensaio de cisalhamento foi executado em máquina universal de ensaios Emic. Os grupos foram submetidos à ANOVA com pós-teste de Tukey para verificação da diferença estatística entre os grupos (α = 0,05). RESULTADOS: GC (6,62MPa) e GCT (6,82MPa) apresentaram resultados semelhantes, enquanto o GST (5,07MPa) obteve resultados estatisticamente menores (p < 0,05). CONCLUSÃO: conclui-se que a melhor técnica de colagem de braquetes ortodônticos em restaurações de resina composta é a de realização de desgaste sobre a superfície.

The effect of thermal cycling on the shear bond strength of porcelain/Ti-6Al-4V interfaces

The aim of the study was to evaluate the effect of thermal cycling on the shear bond strength of the porcelain/Ti-6Al-4V interfaces prepared by two different processing routes and metallic surface conditions. Polished and SiO2 particle abraded Ti-6Al-4V alloy and Triceram bonder porcelain were used to produce the interfaces. Porcelain-to-metal specimens were processed by conventional furnace firing and hot pressing. Thermal cycling was performed in Fusayama's artificial saliva for 5000 cycles between 5 +/- 1 and 60 +/- 2 degrees C. After thermal cycling, shear bond tests were carried out by using a custom-made stainless steel apparatus. The results were analyzed using t-Student test and non-parametric Kruskal-Wallis test (p<0.01). Most of the polished-fired specimens were fractured during thermal cycling; thus, it was not possible to obtain the shear bond strength results for this group. Sandblasted-fired, polished-hot pressed, and sandblasted-hot pressed specimens presented the shear bond strength values of 76.2 +/- 15.9, 52.2 +/- 23.6, and 59.9 +/- 22.0 MPa, respectively. Statistical analysis indicated that thermal cycling affected the polished specimens processed by firing, whereas a significant difference was not observed on the other groups. (C) 2015 Elsevier Ltd. All rights reserved.

Evaluation of the shear bond strength of the union between two CoCr-alloys and a dental ceramic

Introduction: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum) combined with Omega 900 ceramic (Vita Zahnfabrik). Material and Method: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer's recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC), with the aid of a device developed for such intention, and constant speed of 0.5mm/min. Results and Conclusions: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys.

Effect of surface area and air-drying distance on shear bond strength of etch-and-rinse adhesive

We evaluated the effects of air-drying distance and bond surface area on the shear bond strength of a 2-step etch-and-rinse adhesive. A total of 120 bovine anterior teeth were equally divided into 6 main groups based on bonding surface area. The main groups were divided into sub-groups (n = 5) according to air-drying distance. The shear strength was determined using a universal testing machine at a crosshead speed of 0.5 mm/min. The averaged results were subjected to two-way ANOVA and Tukey's test (alpha = 0.05). Two-way ANOVA testing identified no significant cross-product interactions (p > 0.05), but the main factors of area (p < 0.0001) and air-drying distance (p < 0.00001) significantly affected the mean bond strength. Shorter air-drying distances improved bond strength, and increased surface area decreased the bond strength.

Shear bond strength between Ni-Cr alloy bonded to a ceramic substrate

Shear bond strength between Ni-Cr alloy bonded to a ceramic substrate Introduction: The aim of this study was to evaluate the shear bond strength between a Ni-Cr alloy and a ceramic system submitted or not to thermocycling. Materials and methods: Forty-eight cylinder blocks of Ni-Cr with 3.0 mm diameter by 4.0 mm hight and 48 disc-shaped specimens (7.0 mm in diameter by 2.0 mm thick) composed of ceramic were prepared. The Ni-Cr cylinder blocks were randomised in two groups of 24 specimens each. One group was submitted to air-particle abrasion (sandblasting) with 50 mu m Al2O3 (0.4-0.7 MPa) during 20 s, and the other group was submitted to mechanical retentions with carbide burrs. Each group was subdivided into other two groups (n = 12), submitted or not to thermocycling (500 cycles, 5-55 degrees C). The cylinder blocks were bonded to the disc-shaped ceramic specimens under 10 N of load. The shear bond strengths (MPa) were measured using a universal testing machine at a cross head speed of 0.5 mm/min and 200 kgf of load. The data were submitted to statistical analysis (ANOVA and Tukey's test). Results: The air-particle abrasion group exhibited significantly higher shear bond strength when compared to drilled group (p < 0.05). Conclusions: Thermocycling decreased significantly the bond strengths for all groups tested.

Shear bond strength of nanofilled flowable resins used for indirect bracket bonding

AIM: To evaluate the bond strength of brackets fixed with different materials (two light-cured nanofilled resins - Transbond Supreme LV and Flow Tain LV, a light-cured resin - Transbond XT (control) and two chemically cured resins for indirect bonding - Sondhi Rapid- Set and Custom I.Q.) using the indirect bonding technique after 10 min and 24 h, and evaluate the type of failure. METHODS: One hundred premolars were selected and randomly divided into groups (n=10) according to the material and fixation period. The brackets were bonded through the indirect technique following the manufacturer's instructions and stored in deionized water at 37°C for 10 min or 24 h. After, the specimens were submitted to a shear bond strength (SBS) test (Instron) at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to ANOVA and Tukey's test (p<0.05) and the ARI scores were submitted to the chi-square test. RESULTS: It could be observed a significant difference among the materials (Flow Tain LV = Transbond Supreme LV = Transbond XT> Sondhi Rapid-Set > Custom I.Q.). There was no significant difference in resistance values between 10 min and 24 h, regardless of the materials. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistically significant difference (p>0.05). CONCLUSIONS: It was concluded that the light-cured nanofilled materials used in indirect bonding showed greater resistance than the chemically cured materials. The period of fixation had no influence on the resistance for different materials.