Scotchbond Universal Adhesive Research Articles

Effect of Silane-Containing Adhesives on Repair Bond Strength between Fresh and Aged Composite Materials-A Pilot Study.

This study investigated the effects of different surface treatments and a silane-containing adhesive on the repair bond strength between fresh and aged resin composites. A total of 140 composite specimens were prepared and aged for 24 h or 4 months. Each group was subdivided into seven subgroups (n = 10) depending on the surface treatment (no surface treatment (NT), sandblasting (SAND), or Sof-lex coarse disc (DISC)) in combination with the use of the silane-containing adhesive ScotchBond Universal Plus (SBU) or an adhesive without silane Prime&Bond Universal (P&B). The same composite was used for the repair as for the primary specimen. Specimens were dark stored in distilled water at 37 °C for 28 days. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. The Kruskal-Wallis test with Bonferroni's post-hoc adjustment (α = 0.05) and the Mann-Whitney U-test were used for the statistical analysis. The results are shown as the median with the interquartile range. The highest bond strength (MPa) was achieved after 24 h in the DISC+P&B (20.39(16.85-28.83)). In the fresh 24 h group, the SAND+P&B (12.25(8.28-15.05)) and DISC+SBU (18.37(15.16-21.29)) were statistically similar. In the 4-month groups, both adhesives and surface treatments performed similarly. The NT, SAND, and DISC groups without adhesives had the lowest bond strength. In the repair of fresh or aged composite, the silane-containing adhesive SBU was not superior to the adhesive without the silane (P&B).

The effect of combining primers and cements from different cement systems on the bond strength between zirconia and dentin

ObjectiveThe aim of this study was to evaluate the influence of combining primers and cements from two different resin cement systems on the microtensile bond strength (μTBS) between zirconia and human dentin.Materials and methodsA total of 120 specimens of zirconia cemented to dentin were allocated into eight groups based on cement type (RelyX Ultimate or Panavia V5) and primers (Tooth Primer, Clearfil Ceramic Primer and Scotchbond Universal Adhesive) combinations, applied to dentin or ceramic surfaces. Following artificial aging with 5000 thermocycles, μTBS tests were conducted. Statistical analysis was performed using One-way ANOVA and Tukey’s post hoc tests (p ≤ 0.05), and failure modes were assessed.ResultsThe Panavia V5 cement system demonstrated the highest bond strength (19.4 ± 4.4 MPa), significantly higher than the other groups except when RelyX cement was used with Panavia primers (16.9 ± 3.7 MPa). Cohesive fractures within the cement layer were the predominant failure mode.ConclusionsThe combination of primers from different adhesive cement system brands may significantly affect the bonding effectiveness. Therefore, using products from a single product line of the same adhesive cement system, and following the manufacturer’s recommendations for indications and use, is crucial for a more predictable clinical outcome.

Effect of thiol compound on the dentin bond strength when using experimental one-bottle self-etch adhesive system

This study evaluated improvements in the micro-tensile bond strength of a one-bottle adhesive to dentin upon incorporating a thiol compound. Formulations containing 0, 0.1, 0.3 or 0.5% of the thiol were prepared (TH78-0, TH78-0.1, TH78-0.3 and TH78-0.5). Flat dentin surfaces were produced on non-carious extracted human molars using a diamond saw and 600 grit SiC paper. Each surface was subsequently treated with one of the four experimental adhesives or a commercially available adhesive (Scotchbond Universal Adhesive), following the manufacturers’ instructions. A resin composite was then incrementally built on the adhesive-treated surfaces and light-cured, after which the bonded specimens were sectioned and subjected to micro-tensile bond strength tests. Bond strengths ranging from 28.7 MPa (for the TH78-0.5) to 45.9 MPa (for the TH78-0.1) were obtained from the experimental specimens, whereas the commercial adhesive showed a strength of 36.9 MPa. A 0.1% thiol concentration therefore increased the baseline bonding of the adhesive and gave the highest strength, with significantly decreased values in the cases of 0.3% and 0.5% concentrations.

Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features.

This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM). The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM. Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC. The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.

Comparative Analysis of Techniques for Pit and Fissure Sealant Application to Reduce Microleakage.

Introduction In modern dentistry, the focus is more on preventing caries than on treating it, which helps preserve the tooth structure. Pit and fissure sealants (PFS) are the most effective methods for providing a mechanical barrier and avoiding the accumulation of dental plaque in deep pits and fissures, thereby preventing occlusal caries. The present study was conducted to compare the efficiency of dentin bonding agents (DBA) with or without fissurotomy in reducing microleakage before PFS placement. Materials and methods A total of 48 freshly extracted premolars were randomly divided into four groups as follows: Group 1, the conventional technique of PFS (Clinpro, 3M ESPE sealant); Group 2, fissurotomy performed before PFS placement; Group 3, Scotchbond Universal Adhesive (3M ESPE DBA) applied before PFS placement; and Group 4, fissurotomy along with DBA was used before PFS placement. The teeth were subjected to thermocycling followed by dye penetration using a 1% solution of methylene blue for 24 hours. All teeth were then assessed for microleakage by a qualitative method using a stereomicroscope at 40X and depth of dye penetration by image analysis. The Kruskal-Wallis test followed by Dunn's test was used for intergroup comparisons of microleakage scores, and ANOVAfollowed by Tukey's test was used for intergroup comparisons of the depth of dye penetration. These analyses were conducted using statistical software (SPSS version 22, Chicago, IL, USA). Results Statistically significant differences were observed between the groups in terms of the microleakage scores and depth of dye penetration (p<0.05). The group 4 showed a minimum microleakage score (0.50±0.52), and maximum scores were observed in Group 1 (2.16±0.71). Group 2 showed insignificant differences with groups 3 and 4 for depth of dye penetration (p>0.05). Statistically significant differences were observed between groups 1 and 2, groups 1 and 4, and groups 3 and 4 for the microleakage score (p<0.05). Conclusion Fissurotomy with or without DBA significantly reduced microleakage before the PFS placement. Prior use of fourth-generation DBA significantly reduced microleakage compared with PFS placement without the use of DBA.

Restoration-repair potential of resin-modified glass ionomer cement.

This in vitro study aimed to evaluate the repair bond strength of resin-modified glass ionomer cement using either the same material or a universal adhesive in the etch-and-rinse and self-etch modes plus resin composite. Twenty-four resin-modified glass ionomer cement blocks were stored in distilled water for 14 d and thermocycled. Sandpaper ground specimens were randomly assigned to three experimental groups according to the repair protocol: resin-modified glass ionomer cement (Riva Light Cure, SDI) and universal adhesive (Scotchbond Universal Adhesive, 3M Oral Care) in etch-and-rinse or self-etch modes and nanohybrid resin composite (Z350 XT, 3M Oral Care). After 24 h of water storage, the blocks were sectioned, and bonded sticks were subjected to the microtensile bond strength (μTBS) test. One-way ANOVA and Tukey's test were used to analyze the data. The failure mode was descriptively analyzed. The highest μTBS values were obtained when the resin-modified glass ionomer cement was repaired using the same material (p < 0.01). In addition, the mode of application of the universal adhesive system did not influence the repair bond strength of the resin-modified glass ionomer cement. Adhesive/mixed failures prevailed in all groups. Repair of resin-modified glass ionomers with the same material appears to be the preferred option to improve bond strength.

Effect of Er,Cr:YSGG and Nd:YAG Lasers on Microleakage of Composite Resin Restorations Using Universal Adhesives

Background: Clinical long-term success of bonded restorations is depended to reduce marginal microleakage and the laser application with combination of new bonding systems may play positive role. The aim of this study was comparative evaluation of Er,Cr:YSGG and Nd:YAG lasers effect on microleakage of class V composite resin restorations using several universal adhesives. Methods: In this in vitro study, standard class V cavities were prepared on both lingual and buccal surfaces of 72 intact premolar teeth. For evaluation of microleakage, the cavities were divided into 9 groups according to conditioning method (n=15): G1: G-Premio Bond [GP]; G2: Scotchbond Universal Adhesive [SU]; G3: All-Bond Universal [AB]; G4: GP+Nd:YAG Laser; G5: SU+Nd:YAG Laser; G6: AB+Nd:YAG Laser; G7: GP+Er,Cr:YSGG Laser; G8: SU+Er,Cr:YSGG Laser; and G9: AB+Er,Cr:YSGG Laser. The cavities were filled with composite resin and then subjected to thermocycling, placed in methylene blue solutions, embedded in resin blocks and vertically cut in the bucco­lingual direction. The microleakage in occlusal and gingival margins was defined as linear penetration of methylene blue and determined with a stereomicroscope to assign microleakage scores using a four­point scale. Data were analyzed by using SPSS software and Kruskal-wallis and Mann-Whitney U tests. Results: Microleakage scores had statistically significant different before and after laser irradiation in dependent to the adhesive used (P&lt;0.05) but there were no significant different between Nd:YAG and ER,Cr:YSGG laser, also between different universal adhesives (GP, SU, AB). The results showed that total microleakage scores of occlusal margins had significant statistical different in comparison with gingival margins (P&lt;0.001). Conclusion: The results indicate that Nd:YAG and Er,Cr:YSGG lasers irradiation, after using the investigated universal adhesives, had a positive effect on reducing the microleakage of composite Class V restorations. The microleakage rate was shown to be independent of adhesives and lasers type used in this study.

Effect of irradiance and exposure time on the adhesive properties of universal adhesives after 2years of storage.

This study aims to evaluate the effects of exposure time and irradiance on the dentin bonding properties (microtensile bond strength (μTBS) and nanoleakage (NL)) of the Clearfil Universal Bond Quick (CUQ) adhesive and Scotchbond Universal Adhesive (SBU) immediately and after 2years of water storage. Hence, 128 human molars were randomly assigned to 16 groups based on adhesive strategy, irradiance/exposure times, and storage time for each universal adhesive tested. The adhesives were applied using the etch-and-rinse and self-etch strategies and were light-cured using four different irradiance/exposure times: 1400 mW/cm2 for 5s (1400 × 5), 1400 mW/cm2 for 10s (1400 × 10), 3200 mW/cm2 for 5s (3200 × 5), and 3200 mW/cm2 for 10s (3200 × 10). Then, each sample was restored and sectioned into a resin-dentin bonded stick to be tested for μTBS and NL (immediately and after 2years of water storage). The mean μTBS and NL of all resin-dentin bonded sticks from the same hemi-tooth (factor time) were statistically analyzed using a three-way ANOVA and Tukey's test (a = 0.05). Despite a significant decrease in the μTBS values for all groups after 2years of water storage, the 3200 × 5 group showed higher μTBS values, whereas the 3200 × 10 group showed lower μTBS values for both universal adhesives tested. Although a significant increase in the NL values was observed for all groups after 2years of water storage, the 3200 × 10 group showed higher NL values than the other groups (p < 0.001). Results indicate that light-curing the adhesive layer with 14-16J/cm2 led to an improvement in the stability of the resin-dentin adhesive interface. A longer exposure time (10s) coupled with a higher irradiance (3200 mW/cm2) resulted in a greater degree of degradation of the adhesive interface. To guarantee better stability of the adhesive interface, clinicians could be preferred a light-cured universal adhesive layer with 14-16J/cm2. Higher irradiances should be avoided.

LETTER TO EDITOR.

Dear Editor,This letter is regarding an article published in your journal titled “Comparison of the Mechanical Properties and Push-out Bond Strength of Self-adhesive and Conventional Resin Cements on Fiber Post Cementation” (http://doi:10.2341/21-015-L).We would like to compliment the authors on the detailed comparative study of the mechanical properties and push-out bond strengths, which result when glass fiber posts are cemented with self-adhesive resin cements and conventional resin cements.In this correspondence, we would like to draw attention to the property of the RelyX Ultimate cement, which has an integrated dark cure activator (Sodium Toluene 4- sulfinate) for Scotchbond Universal Adhesive rendering it less dependent on light curing.1Because of this, we feel that the requirement for light to reach the deeper thirds of the root canal spaces and its subsequent impact on the bond strength may not be as critical as reported by the authors. We would appreciate it if the authors could enlighten us on our observation.Dear Dr Grover and Dr Shetty,On behalf of all authors, I am pleased to respond your letter.First, I would like to state that your comments are deeply appreciated. Second, the authors would like to point to the importance of performing scientific research that confirms the commercial claims of materials manufacturers. In that regard, although dual-cured resin cements were developed to benefit from the self- and light-curing mechanisms, previous studies show that the self-cure mechanisms on dual-cure cements, do not necessarily result in mechanical characteristics that are as good as those obtained whether by dual- or light-curing of the cements.1–8 These results are confirmed by a recent study, which included the Rely X Ultimate cement, finding that despite the presence of a dark-cure activator, self-curing produced a lower degree of conversion and hardness compared to the light-cure mode.8 In general, regarding dual-curing cements, previous studies showed that the polymerization of dual cure resin cements is not optimal in the absence of light.1–8Thus, the authors consider that the argument regarding the importance of light-curing the Rely X Ultimate remains valid, especially in the apical third of the root, because self-curing mechanical properties still benefit greatly from light-curing.State University of CampinasUniversidade Estadual de CampinasOperative DentistryAv Limeria 901Piracicaba, São Paulo 13414-903 Brazilemail: mrs.santi@hotmail.com

Long-Term In Vitro Adhesive Properties of Two Universal Adhesives to Dentin.

The composition of universal adhesives, as well as the adhesive strategy, may influence bonding effectiveness and durability. This study aimed to evaluate the microtensile bond strength (µTBS) and nanoleakage (NL), immediately and after 6-month aging, and in situ degree of conversion (DC), of two universal adhesives (Scotchbond Universal Adhesive, SBU; Xeno Select, XEN) applied with etch-and-rinse (ER) and self-etch (SE) strategies, in comparison with a two-step SE adhesive (Clearfil SE Bond, CSE). Dentin surfaces of fifty human third molars were randomly assigned to the following adhesives: two universal adhesives, SBU and XEN, applied in ER or SE mode and CSE, used as control. Teeth were sectioned into beams to be tested under µTBS, half of them after 24 h, and the rest after 6 months of water aging. Selected beams from each tooth were used for NL evaluation and in situ DC quantification. SBU and CSE showed significantly higher mean µTBS and lower nanoleakage than XEN, regardless of the evaluation time and adhesion strategy. XEN-SE yielded the lowest degree of conversion. Therefore, adhesive properties of universal adhesives to dentin are material dependent, regardless of the adhesion strategy, exhibiting XEN a significantly worse performance than SBU.

Can area delimitation and tube type impact microshear bond strength of adhesives to dental substrates?

Background he need of delimiting the bonding area on microshear bond strength (µSBS) test remains an unclear issue. In addition, there are different types of tube to perform the resin composite cylinders on µSBS test. The aim of this study was to evaluate the influence of the adhesive area delimitation and type of tube used to build up specimens for µSBS testing of adhesive systems, to enamel and dentin. Methods 120 bovine incisors were ground to achieve flat buccal enamel (n=60) and dentin (n=60) surfaces. Specimens of each substrate were randomly allocated into 6 groups (n=10) according to the adhesive system-a two-step self-etch (Clearfil SE Bond) and a universal adhesive (Scotchbond Universal Adhesive) applied in the self-etch and etch-and-rinse modes– and type of tube used to build up the specimens: starch and polyethylene. 4 resin composite cylinders (Filtek Z250) were made on each surface; in 2 of them the area delimitation was performed. The specimens were subjected to µSBS test after 24 h of water storage at 37°C. Data were submitted to three-way ANOVA and Tukey’s post hoc tests (α=0.05). Results The delimitation of the adhesive area did not influence on the bond strength to dentin (p=0.349) nor to enamel (p=0.158). The type of tube differently affected the ranking of adhesives in both substrates. Conclusions The delimitation of the adhesive area does not influence on the µSBS to enamel and dentin, irrespective of the tube type used to build up the resin composite specimens. The tube type’s impact on the bond strength depends on the dental substrate and adhesive system.

FT-IR analysis of the Interface between Universal Scotchbond and Oral Mucosa: a preliminary in-vitro study.

The long-term success of implant therapy depends not only on proper osseointegration, but also on the healing of the epithelium and the quality of the biological seal on the abutment and on the implant neck. This study aims to evaluate the possible use of dentinal adhesives on the surface of the transmucosal path of dental implants in order to create a hermetic seal between keratinized epithelium and abutment. Four sections of 12 µm thickness were obtained from a sample of the oral mucosa. Scotchbond TM Universal Adhesive (3M ESPE, Seefeld, Germany) was carefully applied both to the samples and to the transmucosal path of titanium abutment (Win-Six, BioSAFin, Italy). The adhesives were polymerized. FT-IR analysis was performed on: 1) polymerized Scotchbond Universal Adhesive (3M ESPE, Seefeld, Germany); 2) the interface between the titanium abutment and the adhesive; 3) the interface between the adhesive and the mucosa; 4) the mucosa samples. Comparing the spectra, it emerged that the adhesive has established chemical bonds both on titanium and on the keratinized mucosa, involving different types of chemical interactions. The results of this in-vitro study are encouraging. In the future biocompatibility and comparative study with other adhesives will be required.

Long-term Evaluation of Bonding Performance of Universal Adhesives based on Different Dentinal Moisture Levels.

To evaluate the microtensile bond strength (μTBS) and silver nitrate uptake (SNU) of three universal adhesives used in etch-and-rinse (ER) and self-etch (SE) modes on dry, wet, and oversaturated dentin surfaces after 24 h and 1 year of water storage. The morphology of the hybrid layer (MHL) and the degree of conversion (DC) were also evaluated. Human molars were divided into 36 groups according to combinations of the following variables: (i) universal adhesives (Ambar Universal APS [AMB], Prime&Bond Active [PBA], Scotchbond Universal Adhesive [SBU]), (ii) adhesive strategies (ER or SE), (iii) moisture level (dry, wet, or oversaturated dentin surface), and (iv) storage time (24 h or 1 year). After restoration, the specimens were sectioned into resin-dentin sticks and tested for μTBS and SNU according to storage time. For MHL, the specimens were sectioned and evaluated after 24 h using SEM. DC was evaluated using FTIR. ANOVA and Tukey's test were used for statistical analyses (5%). When 24-h vs 1-year data were compared, there was a significant decrease in μTBS and an increase in SNU values for the majority of experimental groups (p < 0.0001). On dry (ER) and oversaturated (ER and SE) dentin, AMB showed higher μTBS than did PBA (p < 0.00001). No significant decrease in μTBS was observed when universal adhesives were applied in the SE mode to dry dentin (p > 0.05). Regarding SNU, at all moisture levels, AMB showed lower SNU values than SBU (p < 0.001). Regarding MHL, SBU showed several imperfections when applied to oversaturated dentin in comparison with AMB and PBA. Regarding DC, when dentin was kept dry or was oversaturated, AMB showed a higher DC than PBA (p < 0.0001). The behavior of the different universal adhesives evaluated did not vary when applied to wet or dry dentin. However, the results with oversaturated dentin were dependent on the universal adhesive. Independent of the moisture level and the universal adhesive evaluated, significant degradation of the bonding properties occurred after 1 year of water storage, with the exception of universal adhesives applied to dry dentin in the SE strategy.

Effect of Universal Adhesives on Long-term Bond Strength to Zirconia.

To evaluate the effect of universal adhesives on the long-term bond strength to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). Polyethylene tubes filled with composite cement containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) were adhesively luted to 60 fully sintered Y-TZP slabs (7 x 7 x 2 mm) with or without (control) previous application of a 10-MDP-based adhesive (All Bond Universal, Bisco) - ABU; Clearfil Universal Bond Quick, Kuraray Noritake - CUB; Scotchbond Universal Adhesive, 3M Oral Care - SUA) on the zirconia surface. The bonded specimens were stored in water for 24 h, 6 months, or 1 year and subjected to microshear bond strength testing. The data were analyzed by one-way ANOVA and Tukey's test (p < 0.05). The contact angle was measured after adhesive application to evaluate surface wettability. The adhesive-treated specimens were analyzed with x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) for chemical characterization. The application of a 10-MDP-based adhesive significantly improved bond strength of composite cement to zirconia when compared to the control group (no adhesive application) (p < 0.05). One-year water storage significantly decreased bond strength for ABU- and CUB-bonded specimens, but not for SUA-bonded specimens. The analysis by XPS and ToF-SIMS showed peaks of carbon, phosphorus, and silicon in all adhesive-treated specimens. One-year water storage affected the bond strength of composite cement to zirconia when All Bond Universal or Clearfil Universal Bond Quick were used.

Contamination of Dentin with Hemostatic Agents - Is EDTA a Valuable Decontaminant before Using a Self-etch Universal Adhesive?

To investigate the effects of dentin decontamination procedures with ethylenediaminetetraacetic acid (EDTA) after contamination with two hemostatic agents, ViscoStat (VS) and ViscoStat Clear (VSC), on the microtensile bond strength (μTBS) of two different universal adhesives, before and after thermocycling (TC). Dentin surfaces of 100 human caries-free molars were either contaminated with one of the hemostatic agents or contaminated and then decontaminated with EDTA before the universal adhesives Scotchbond Universal Adhesive (SBU) or Prime & Bond Active (PBA) were applied in self-etch mode. Composite buildups were made and the teeth were sectioned into sticks (n = 90). Half of them immediately underwent the μTBS test, the other half after aging via TC. The data were statistically analyzed using Welch's ANOVA and the Games-Howell post-hoc test (p < 0.05). Significant differences were observed between the groups (p < 0.001). When the dentin surface was contaminated with VSC, TC significantly reduced the mean bond strength, regardless of the universal adhesive. Decontamination with EDTA showed a significant decrease in bond strength after VS contamination and SBU application. The fracture analysis showed mainly adhesive fractures (78.8%) in all test groups. As EDTA application did not significantly increase the μTBS of either universal adhesive in self-etch mode in-vitro, it cannot be recommended as a decontaminant.

Cause-Effect Relationship of Varying Bonding Thicknesses in Dentin Adhesion of Universal Adhesives.

To evaluate whether varying thicknesses of universal adhesives utilizing the additional coating strategy would affect their microtensile bond strength (µTBS) to dentin, hardness, and elastic modulus (mechanical properties). Ninety-nine human maxillary premolars were cut to expose coronal dentin, ground with regular-grit diamond burs, and randomly distributed into 9 groups based on 1. adhesive: Scotchbond Universal Adhesive (SB; universal), G Premio Bond (GP; universal) and Clearfil Megabond 2 (MB; two-step self-etch; control); and 2. application strategy (one, two or three coats; each coat light cured). After adhesive application and resin composite buildup, the bonded teeth were stored in distilled water (37°C; 24 h). Resin-dentin sticks from eight premolars per group (each premolar yielded 3 sticks; n = 24 sticks altogether) were prepared for the µTBS test, followed by measurement of the adhesive thicknesses at their fractured ends using SEM. The mechanical properties of the adhesive layers produced by different coats were evaluated on separate resin-dentin slices (n = 3 teeth per group). Two coats significantly increased the µTBS (p < 0.001) of all the adhesives. The correlation between adhesive thickness and bond strength was positive for GP but negative for SB. MB did not show any correlation. Additional coating significantly increased the mechanical properties of GP (p < 0.05) but did not affect SB and MB (p < 0.05). An additional adhesive coating over the manufacturers' recommendations improved the bond strength of all the adhesives tested. However, the increased mechanical properties of the adhesives with additional curing was material dependent.

Influence of Irradiance and Exposure Times on the Mechanical and Adhesive Properties of Universal Adhesives with Dentin

This study evaluated the influence of irradiance/exposure time on the Knoop hardness (KHN) and polymer cross-linking density (PCLD), as well as microtensile bond strength (μTBS), nanoleakage (NL), and in situ degree of conversion (DC) of universal adhesives. Two universal adhesive systems, Clearfil Universal Bond Quick (CUQ) and Scotchbond Universal Adhesive (SBU), were light-cured using various irradiance/exposure times: 1400 mW/cm2 for 5 s (1400*5); 1400 mW/cm2 for 10 s (1400*10); 3200 mW/cm2 for 5 s (3200*5); and 3200 mW/cm2 for 10 s (3200*10). Adhesive disks from each group were used to measure PCLD by KHN. One hundred and twenty-eight human molars were randomly assigned to 16 groups according to the following variables: adhesive system vs adhesive strategies vs radiance/exposure times. After restoration, specimens were sectioned into resin-dentin sticks and tested for μTBS, NL, and DC. The data from PCLD (%), KHN, μTBS (MPa), NL (%), and DC (%) data were subjected to ANOVA and Tukey's test (α=0.05). Significant reductions in KHN, μTBS, and DC (p=0.00001) values and an increase in NL and PCLD (p=0.00001) values were observed for 3200*10 when compared with other groups. Higher KHN, μTBS, and DC (p=0.000001) values were observed for 3200*5 in comparison with the other groups. The 1400*5 (7 J/cm2) and 1400*10 (14 J/cm2) groups showed intermediate values (p=0.000001). Although similar results in terms of hardness, polymer cross-linking density and nanoleakage were observed when 5 seconds at 3200 mW/cm2 and 10 seconds at 1400 mW/cm2 groups were compared, the use of higher irradiance (3200 mW/cm2) for only 5 seconds showed better results in terms of bond strength and degree of conversion for both universal adhesives to dentin. The prolonged exposure time (10 seconds) at the higher irradiance (3200 mW/cm2) showed the worst results.

Alternative surface treatments strategies for bonding to CAD/CAM resin-matrix ceramics

This study evaluated the shear bond strength (µSBS) and failure mode of CAD/CAM polymer-infiltrated ceramic network (PICN – Vita Enamic) and nanoceramic resin (NCR – Lava Ultimate) submitted to alternative surface treatments. 40 plates of each material were submitted to (n = 10) conventional (manufacturer’s indications): Sandblasting with Al2O3 (SAND) and 5% hydrofluoric acid etching (5% HF), or alternative treatments: 10% HF (10% HF) and Sandblasting + silanization (SAND/SIL). A self-etching adhesive system (Scotchbond Universal Adhesive, 3M Oral Care) was applied, and resin cement cylinders were built on the specimen’s treated surface and tested in µSBS after 24 h, or after water storage for 1 year. Data were evaluated by three-way repeated-measures ANOVA and Tukey test (α = 0.05). Failure mode was evaluated under scanning electron microscopy (SEM). At 24 h, HF etching (5% or 10%) promoted higher µSBS for PICN, while SAND and 5% HF promoted higher µSBS for NCR than SAND/SIL (p > 0.05). After storage for 1 year, all treatments decreased PICN’s bond strength, but 10% HF exhibited higher µSBS than 5% HF (p < 0.05). Also, 5% HF and SAND/SIL maintained µSBS of NCR, and in general, NCR exhibited higher µSBS than PICN. Failure mode was predominantly mixed after 24 h and mostly adhesive after 1-year storage. In conclusion, the surface treatments influenced the bond strength of PICN and NCR and 1-year storage decreased the bond strength for most groups. 10% HF is the treatment option for PICN while 5% HF-etching is an alternative to sandblasting for NCR.

Influence of pretreatments on microtensile bond strength to eroded dentin using a universal adhesive in self-etch mode

To evaluate the influence of pretreatments on microtensile bond strength (μTBS) to eroded dentin when using a universal adhesive in self-etch mode. Forty-eight human molars were randomly assigned to six groups (G1–G6, n = 8) and ground down until dentin exposure. G2–G6 were eroded with citric acid (pH 2.6) for 10 × 2 min (within 12 h) on 5 consecutive days. G1 and G2 served as uneroded and eroded controls and were not pretreated. G3 and G4 were pretreated for 60 s with NaOCl (10% and 5%, respectively). G5 was airborne-particle abraded using Al 2 O 3 for 15 s, and G6 was roughened with a diamond bur. The universal adhesive Scotchbond Universal was applied in self-etch mode. After composite build-up, μTBS was determined. Control group G1 (uneroded) showed higher μTBS than G2 (eroded). The μTBS (mean MPa ±SD) of G5 (airborne-particle abrasion; 11.6 ± 4.6) and G6 (bur-roughening; 11.0 ± 3.3) did not differ significantly from the μTBS of G1 (12.4 ± 4.2). Significantly higher μTBS compared to all other groups was observed in G3 (NaOCl 10%; 17.6 ± 7.6). Pretreatment with NaOCl 5% (G4) achieved significantly lower μTBS (3.5 ± 2.6) than the other groups, except for G2 (8.8 ± 2.0). Pretreatment with 10% NaOCl, diamond bur roughening or airborne-particle abrasion can increase bond strength of the tested adhesive to eroded dentine. Pre-treatment with 5% NaOCl is not recommended.

Push-out Bond Strength of Two Fiber Posts in Composite Resin Using Different Types of Silanization.

The aim of this study was to evaluate the effect of different surface treatments and thermocycling (TC) on the push-out bond strength of two brands of glass fiber posts (GFPs) to composite resin. White Post DC (WP) (FGM Dental Group International, Joinville, Santa Catarina, BR) and Exacto (EC) (Angelus, Clinical Research Dental, Londrina, PR, Brazil). GFPs were cleaned with 70% alcohol and divided into five groups, according to the surface treatment (n=15): control (C), without treatment; prehydrolyzed silane (S-pre) (Prosil, FGM Dental Group International); 37% phosphoric acid + prehydrolyzed silane (AcS-pre); Scotchbond Universal Adhesive System (AdU), 3M Oral Care; two-bottle silane (S2B) (Dentsply Sirona Inc). The composite resin was inserted around the posts by using a split matrix. The samples were cut into 1-mm slices. Half of the samples were subjected to the push-out test immediately, and the other half underwent TC before the test. After failure analysis, the data were submitted to three-way analysis of variance (ANOVA) (α=0.05). EC achieved higher bond strength than WP, regardless of TC (p<0.05). Regarding WP, surface treatments (p<0.001) and TC (p<0.001) influenced bonding strength. As for EC without TC, the highest bond strength (p<0.05) was found for C, then AcSpre, S-pre, AdU, and S2B. Application of TC resulted in a statistically higher bond strength values for the EC AcS-pre group (p<0.05), followed by S2B, S-pre, C, and AdU. The WP failures were predominantly cohesive, similar to the EC AdU and EC S2B groups. The other EC groups showed mostly mixed failures. Surface treatment and TC affected the bond strength to composite resin, depending on which post was used. It is important for dentists to understand the effects of different types of silanization on their chosen post.