Sandra Kiss Moura

Evaluating resin-enamel bonds by microshear and microtensile bond strength tests: effects of composite resin

Objectives The aims of this study were to evaluate the effect of resin composite (Filtek Z250 and Filtek Flow Z350) and adhesive system [(Solobond Plus, Futurabond NR (VOCO) and Adper Single Bond (3M ESPE)] on the microtensile (µTBS) and microshear bond strength (µSBS) tests on enamel, and to correlate the bond strength means between them. Material and methods Thirty-six extracted human molars were sectioned to obtain two tooth halves: one for µTBS and the other one for µSBS. Adhesive systems and resin composites were applied to the enamel ground surfaces and light-cured. After storage (37ºC/24 h) specimens were stressed (0.5 mm/ min). Fracture modes were analyzed under scanning electron microscopy. The data were analyzed using two-way ANOVA and Tukeys test (α=0.05). Results The correlation between tests was estimated with Pearsons product-moment correlation statistics (α =0.05). For both tests only the main factor resin composite was statistically significant (p<0.05). The correlation test detected a positive (r=0.91) and significant (p=0.01) correlation between the tests. Conclusions The results were more influenced by the resin type than by the adhesives. Both microbond tests seem to be positive and linearly correlated and can therefore lead to similar conclusions.

Bond strength and morphology of enamel using self-etching adhesive systems with different acidities

Objectives: To assess the bond strength and the morphology of enamel after application of self-etching adhesive systems with different acidities. The tested hypothesis was that the performance of the self-etching adhesive systems does not vary for the studied parameters. Material and methods: Composite resin (Filtek Z250) buildups were bonded to untreated (prophylaxis) and treated (burcut or SiC-paper) enamel surfaces of third molars after application of four self-etching and two etch-and-rinse adhesive systems (n=6/condition): Clearfil SE Bond (CSE); OptiBond Solo Plus Self-Etch (OP); AdheSe (AD); Tyrian Self Priming Etching (TY), Adper Scotchbond Multi-Purpose Plus (SBMP) and Adper Single Bond (SB). After storage in water (24 h/37°C), the bonded specimens were sectioned into sticks with 0.8 mm2 cross-sectional area and the microtensile bond strength was tested at a crosshead speed of 0.5 mm/min. The mean bond strength values (MPa) were subjected to two-way ANOVA and Tukeys test (α=0.05). The etching patterns of the adhesive systems were also observed with a scanning electron microscope. Results: The main factor adhesive system was statistically significant (p<0.05). The mean bond strength values (MPa) and standard deviations were: CSE (20.5±3.5), OP (11.3±2.3), AD (11.2±2.8), TY (11.1±3.0), SBMP (21.9±4.0) and SB (24.9±3.0). Different etching patterns were observed for the self-etching primers depending on the enamel treatment and the pH of the adhesive system. Conclusion: Although there is a tendency towards using adhesive systems with simplified application procedures, this may compromise the bonding performance of some systems to enamel, even when the prismless enamel is removed.

Morphological characterization of the tooth/adhesive interface

The purpose of this study was to assess the morphological characteristics of the tooth/adhesive interface using different adhesive systems in MOD restorations under scanning electron microscopy (SEM). The tested hypothesis was that the morphology of the bonding interface would vary in different areas of MOD restorations for the three adhesive systems. MOD cavities were prepared in 12 sound extracted human third molars and restored with Filtek Z250 composite resin and one of the following adhesive systems: Experimental ABF (n=4), Clearfil SE Bond (n=4) self-etching primers and Single Bond etch-and-rinse adhesive system (n=4). After 24-h storage in distilled water at 37 degrees C, teeth were sectioned and prepared for SEM. The interfacial morphology varied depending on the adhesive system and also on the evaluated area. The null hypothesis was accepted because the morphology of the tooth/adhesive interface reflected the characteristics of both the dental substrate and the adhesive systems.

Bond strength of HEMA-containing versus HEMA-free self-etch adhesive systems to dentin

This study analyzed the bond strength (BS) of HEMA versus HEMA-free self-etch adhesive systems to dentin. The occlusal surface of 20 third molars was removed and the dentin was abraded with 600-grit silicon carbide paper. The teeth were randomly assigned to 4 groups (n = 5) and restored with GO, Adper SE Plus, OptiBond All-In-One, and Clearfil 3S Bond adhesive systems and Filtek Z350 composite. After light curing (600 mW/cm²), the teeth were stored in distilled water at 37 ºC for 24 h and were sectioned in the mesiodistal and buccolingual directions to obtain sticks (0.8 mm²). The sticks were subjected to tensile force using a universal testing machine (0.5 mm/min), and the modes of failure were analyzed by scanning electron microscopy and classified as adhesive, cohesive, or mixed. The BS data (in MPa) were treated using one-way ANOVA and Tukeys tests at 5% significance. GO presented the lowest mean bond strength value (10.57 ± 3.72) and differed significantly from the other materials (p = 0.001), which, in turn, presented statistically similar results (p>0.05) among themselves: Adper SE Plus (29.08 ± 8.93), OptiBond All-In-One (28.36 ± 6.49), and Clearfil 3S Bond (28.62 ± 6.97). Mixed fractures were the most prevalent. It was concluded that the influence of HEMA on BS to dentin was material dependent.

Long-term bond strength of adhesive systems applied to etched and deproteinized dentin

The aim of this study was to evaluate the early and 12-month bond strength of two adhesive systems (Single Bond-SB and One Step-OS) applied to demineralized dentin (WH) and demineralized/NaOCl-treated dentin (H). Twenty flat dentin surfaces were exposed, etched, rinsed and slightly dried. For the H groups, a solution of 10% NaOCl was applied for 60 s, rinsed (15 s) and slightly dried. The adhesives were applied according to the manufacturers instructions and composite resin crowns were incrementally constructed. After 24 h (water-37°C), the specimens was sectioned in order to obtain resin-dentin sticks (0.8 mm2). The specimens were tested in microtensile (0.5 mm/min) immediately (IM) or after 12 months of water storage (12M). The data (MPa) were subjected to ANOVA and Tukeys test (α=0.05). Only the main factors adhesive and time were significant (p=0.004 and p=0.003, respectively). SB (42.3±9.1) showed higher bond strengths than OS (33.6±11.6). The mean bond strength for IM-group (42.5±8.7) was statistically superior to 12M (33.3±11.8). The use of 10% NaOCl, after acid etching, did not improve the immediate and the long-term resin-dentin bond strength.

The influence of air temperature for solvent evaporation on bonding of self-etch adhesives to dentin

Objective: This study evaluated the effect of air temperature (warm or cold) for solvent evaporation on bonding and nanoleakage of self-etching adhesives to dentin. Materials and Methods: The adhesives Clearfil 3S Bond [S3], OptiBond All-In-One [OB], Adper SE Plus [AD], and Silorane adhesive [SI] were applied on dentin surfaces, and a warm (60 ± 2°C) or cold air (20 ± 1°C) was applied and light-cured. After water storage (24 h), the teeth were sectioned into sticks (0.8 mm 2 ) and tested in tensile. Then, they were immersed in a 50% solution of silver nitrate, photo-developed and the nanoleakage observed in a scanning electron microscope. The bond strength and nanoleakage pattern were analyzed by two-way analysis of variance and post hoc Tukeys test (α =0.05). Results: Higher bond strength and lower silver nitrate uptake were observed for the adhesives under warm condition (P < 0.05). AD and SI showed better adhesive results than S3 and OB (P < 0.05). Conclusion: The use of a warm air was useful to improve the bonding and diminish the nanoleakage of adhesive systems to dentin.

Do the Microshear Test Variables Affect the Bond Strength Values

Little is known about the effect of specimen preparation and testing protocols on the micro-shear bond strength (μSBS) results. To evaluate whether variations in polyethylene rod use affect (μSBS)). Human dentin disks were randomly distributed into six groups (n = 5): polyethylene tube (3 levels) and adhesive system (2 levels). In Group 1, polyethylene tubes filled with polymerized composite) were placed on adhesive covered surfaces. Tubes were removed 24 h after water storage, leaving the rods only. In Group 2, the same procedure was performed; however, tubes were kept in place during testing. In Group 3, composite rods without tubes were placed on adhesive covered dentin. In all groups, adhesives were photoactivated after positioning filled tubes/rods on adhesive covered surfaces. Specimens were tested under shear mode and the data subjected to a two-way ANOVA and Tukeys tests. Groups 1 and 2 resulted in statistically similar mean μSBS (P > 0.05); however, a greater number of pretest failures were observed for Group 1. Higher μSBS values were detected for Group 3, irrespective of adhesive system used (P < 0.05). Removing the polyethylene tube before composite rod is placed on dentin affects μSBS values.

Effect of different surface penetrating sealants on the roughness of a nanofiller composite resin

This study evaluated the effectiveness of different sealants applied to a nanofiller composite resin. Forty specimens of Filtek Z-350 were obtained after inserting the material in a 6x3 mm stainless steel mold followed by light activation for 20 s. The groups were divided (n=10) according to the surface treatment applied: Control group (no surface treatment), Fortify, Fortify Plus and Biscover LV. The specimens were subjected to simulated toothbrushing using a 200 g load and 250 strokes/min to simulate 1 week, 1, 3 and 6 months and 1 and 3 years in the mouth, considering 10,000 cycles equivalent to 1 year of toothbrushing. Oral-B soft-bristle-tip toothbrush heads and Colgate Total dentifrice at a 1:2 water-dilution were used. After each simulated time, surface roughness was assessed in random triplicate readings. The data were submitted to two-way ANOVA and Tukeys test at a 95% confidence level. The specimens were observed under scanning electron microscopy (SEM) after each toothbrushing cycle. The control group was not significantly different (p>0.05) from the other groups, except for Fortify Plus (p<0.05), which was rougher. No significant differences (p>0.05) were observed at the 1-month assessment between the experimental and control groups. Fortify and Fortify Plus presented a rougher surface over time, differing from the baseline (p<0.05). Biscover LV did not differ (p>0.05) from the baseline at any time. None of the experimental groups showed a significantly better performance (p>0.05) than the control group at any time. SEM confirmed the differences found during the roughness testing. Surface penetrating sealants did not improve the roughness of nanofiller composite resin.

The effect of long-term storage on the microleakage of composite resin restorations: qualitative and quantitative evaluation

The aim of this study was to evaluate the influence of storage periods of 24 hours and 3 months on the microleakage of class II cavities. Two methods of assessing microleakage were also compared. Class II cavities were prepared in sound human molars. MO cavities were restored using ABF experimental (Kuraray Medical Inc.) + Z250 composite resin (3M ESPE), and DO cavities were restored using Single Bond (3M ESPE) + Z250. After different storage periods, specimens were thermocycled, immersed in a dye (0.5% methylene blue solution for 4 h) and longitudinally sectioned. Dye penetration was scored according to a 0-4 scale. The extent of microleakage was measured using the ImageLab 2000 program. A statistically significant correlation was verified between both evaluation methods (r = 0.978, p < 0.001). ANOVA revealed a statistically significant difference between the tested adhesive systems regarding microleakage (p < 0.001), although it was not influenced by the different storage periods.

Six-month evaluation of a resin/dentin interface created by methacrylate and silorane-based materials

Objectives: This study aimed to compare the micro-tensile bond strength of methacrylate resin systems to a silorane-based restorative system on dentin after 24 hours and six months water storage. Material and Methods: The restorative systems Adper Single Bond 2/Filtek Z350 (ASB), Clearfil SE Bond/Z350 (CF), Adper SE Plus/Z350 (ASEP) and P90 Adhesive System/Filtek P90 (P90) were applied on flat dentin surfaces of 20 third molars (n=5). The restored teeth were sectioned perpendicularly to the bonding interface to obtain sticks (0.8 mm2) to be tested after 24 hours (24 h) and 6 months (6 m) of water storage, in a universal testing machine at 0.5 mm/min. The data was analyzed via two-way Analysis of Variance/Bonferroni post hoc tests at 5% global significance. Results: Overall outcomes did not indicate a statistical difference for the resin systems (p=0.26) nor time (p=0.62). No interaction between material x time was detected (p=0.28). Mean standard-deviation in MPa at 24 h and 6 m were: ASB 31.38 (4.53) and 30.06 (1.95), CF 34.26 (3.47) and 32.75 (4.18), ASEP 29.54 (4.14) and 33.47 (2.47), P90 30.27 (2.03) and 31.34 (2.19). Conclusions: The silorane-based system showed a similar performance to methacrylate-based materials on dentin. All systems were stable in terms of bond strength up to 6 month of water storage.