Microtensile bond strength analysis of adhesive systems to Er:YAG and Er,Cr:YSGG laser-treated dentin

The aim of this in vitro study was to evaluate the effect of different surface treatments (control, diamond bur, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser) on sound dentin surface morphology and on microtensile bond strength (μTBS). Sixteen dentin fragments were randomly divided into four groups (n?=?4), and different surface treatments were analyzed by scanning electron microscopy. Ninety-six third molars were randomly divided into eight groups (n?=?12) according to type of surface treatment and adhesive system: G1 = Control + Clearfil SE Bond (SE); G2 = Control + Single Bond (SB); G3 = diamond bur (DB) + SE; G4 = DB + SB, G5 = Er:YAG laser (2.94 μm, 60 mJ, 2 Hz, 0.12 W, 19.3 J/cm²) + SE; G6 = Er:YAG + SB, G7 = Er,Cr:YSGG laser (2.78 μm, 50 mJ, 30 Hz, 1.5 W, 4.5 J/cm²) + SE; and G8 = Er,Cr:YSGG + SB. Composite blocks were bonded to the samples, and after 24-h storage in distilled/deionized water (37 °C), stick-shaped samples were obtained and submitted to μTBS test. Bond strength values (in megapascal) were analyzed by two-way ANOVA and Tukey tests (α?=?0.05). G1 (54.69?±?7.8 MPa) showed the highest mean, which was statistically significantly higher than all the other groups (p?<?0.05). For all treatments, SE showed higher bond strength than SB, except only for Er,Cr:YSGG treatment, in which the systems did not differ statistically from each other. Based on the irradiation parameters considered in this study, it can be concluded that Er:YAG and Er,Cr:YSGG irradiation presented lower values than the control group; however, their association with self-etching adhesive does not have a significantly negative effect on sound dentin (μTBS values of >20 MPa).     

Microtensile bond strength of an etch-and-rinse adhesive to enamel and dentin after Er:YAG laser pretreatment with different pulse durations

The purpose of this study is to evaluate microtensile bond strength (μTBS) of an etch-and-rinse adhesive to enamel and dentin after treatment with Er:YAG laser using different pulse durations. Extracted human molars were flattened to obtain enamel or dentin surfaces. The enamel specimens (E) were divided into nine groups and the dentin (D) specimens were divided into seven groups according to the surface treatments (n = 6). E-C: acid was applied according to the manufacturer’s instructions and used as control, E-SSP: 120 mJ, 10 Hz, SSP (50 μs), E-SSP-A: 120 mJ,10 Hz, SSP+acid, E-VSP: 120 mJ, 10 Hz, VSP (100 μs), E-VSP-A: 120 mJ, 10 Hz, VSP+acid, E-SP: 120 mJ, 10 Hz, SP (150 μs), E-SP-A:120 mJ,10 Hz, SP+acid, E-LP:120 mJ,10 Hz, LP (300 μs), E-LP-A:120 mJ,10 Hz, LP+acid; D-C: acid was applied and used as control, D-SSP: 80 mJ, 10 Hz, SSP, D-SSP-A: 80 mJ, 10 Hz, SSP+acid, D-VSP: 80 mJ, 10 Hz, VSP, D-VSP-A: 80 mJ, 10 Hz, VSP+acid, D-SP: 80 mJ, 10 Hz, SP, D-SP-A: 80 mJ, 10 Hz, SP+acid. After application of etch-and-rinse adhesive, composite built-ups were created with a nanoceramic composite. Specimens were sectioned into serial 1-mm² sticks, and μTBS was measured in five sticks from each tooth randomly selected (n = 30). Failure modes were determined under a stereomicroscope. μTBS test data were analyzed by Welch-ANOVA followed by Dunnett's T3 tests and failure mode distributions were analyzed by Pearson Chi-square test (p = 0.05). μTBS was higher for enamel and dentin after additional acid etching than laser irradiation alone. E-SSP-A group exhibited the highest μTBS for enamel (p < 0.05). The D-SP-A group showed the highest value but the difference was not significant in comparison to D-C (p > 0.05). The μTBS of laser-irradiated but not acid-etched groups decreased when longer pulse durations were used. Laser treatment could enhance or impair the μTBS to enamel and dentin depending on the pulse duration used and additional acid application.     

Shear bond strength and ultrastructural interface analysis of different adhesive systems to Er:YAG laser-prepared dentin

Lasers in Medical Science - The aim of this study was to evaluate the shear bond strength (SBS) of a microhybrid composite resin bonded with three different adhesive systems to Er:YAG laser- (EL)...     

Microtensile bond strength of resin composite to dentin treated with Er:YAG laser of bleached teeth

The objective of this study was to evaluate the influence of Er:YAG laser (λ = 2.94 μm) on microtensile bond strength (μTBS) and superficial morphology of bovine dentin bleached with 16% carbamide peroxide. Forty bovine teeth blocks (7 × 3 × 3 mm³) were randomly assigned to four groups: G1- bleaching and Er:YAG irradiation with energy density of 25.56 J/cm² (focused mode); G2 - bleaching; G3 - no-bleaching and Er:YAG irradiation (25.56 J/cm²); G4 - control, non-treated. G1 and G2 were bleached with 16% carbamide peroxide for 6 h during 21 days. Afterwards, all blocks were abraded with 320 to 600-grit abrasive papers to obtain flat standardized dentin surfaces. G1 and G3 were Er:YAG irradiated. Blocks were immediately restored with 4-mm-high composite resin (Adper Single Bond 2, Z-250-3 M/ESPE). After 24 h, the restored blocks (n = 9) were serially sectioned and trimmed to an hour-glass shape of approximately 1 mm² at the bonded interface area, and tested in tension in a universal testing machine (1 mm/ min). Failure mode was determined at a magnification of 100× using a stereomicroscope. One block of each group was selected for scanning electron microscope (SEM) analysis. μTBS data was analyzed by two-way ANOVA and Tukey test (α = 0.05). Mean bond strengths (SD) in MPa were: G1- 32.7 (5.9)^A; G2- 31.1 (6.3)^A; G3- 25.2 (8.3)^B; G4- 36.7 (9.9).^A Groups with different uppercase letters were significantly different from each other (p < .05). Enamel bleaching procedure did not affect μTBS values for dentin adhesion. Er:YAG laser irradiation with 25.56 J/cm² prior to adhesive procedure of bleached teeth did not affect μTBS at dentin and promoted a dentin surface with no smear layer and opened dentin tubules observed under SEM. On the other hand, Er:YAG laser irradiation prior to adhesive procedure of non-bleached surface impaired μTBS compared to the control group.     

Effect of Er:YAG laser on bond strength to dentin of a self-etching primer and two single-bottle adhesive systems

BACKGROUND AND OBJECTIVES: To assess the effect of erbium:yttrium aluminium garnet (Er:YAG) laser on bond strength to dentin of a self-etching primer (Clearfil Liner Bond 2V, CL2V) and two single-bottle agents (Excite, EX; Gluma One Bond, GB). STUDY DESIGN/MATERIALS AND METHODS: Thirty human molars were selected, roots were removed and crowns were bisected, providing 60 halves. Specimens were included and ground to expose dentin. Bonding site was limited and samples were assigned to three groups: I, CL2V; II, EX; III, GB. Dentin was either conventionally treated or submitted to laser conditioning + conventional treatment. The adhesive protocol was performed, samples were stored for 24 hours and bond strength was tested to failure (0.5 mm/min). RESULTS: Statistical analysis showed a decrease in bond strength for lased subgroups and this drop was more evident for EX. CL2V provided the best overall results, regardless of the surface treatment. CONCLUSIONS: Er:YAG laser may adversely affect bond strength in higher or lesser degree, depending on the adhesive system used.     

Analysis of the interfacial micromorphology and bond strength of adhesive systems to Er:YAG laser-irradiated dentin

This study evaluated the effects of different parameters of dentin irradiation with erbium-doped yttrium aluminum garnet (Er:YAG) laser on bond strength to dentin and analyzed the ultramorphological characteristics of resin–laser-irradiated dentin interfaces using a transmission electron microscope (TEM). Dentin surfaces were abraded with SiC paper (600 grit) or Er:YAG laser-irradiated (120/4, 140/6, 180/4, or 200/6 mJ/Hz). Three adhesive systems were tested: Single Bond Plus (3M ESPE), Clearfil Protect Bond (Kuraray Med.), and Clearfil Tri-S Bond (Kuraray Med.). Treatments were performed over flat dentin surfaces of human third molars. Specimens were stored in distilled water for 1 week or 6 months and prepared for a microtensile bond strength test and interfacial ultrastructure for analysis. Microtensile bond strength data (n?=?5) were analyzed with three-way analysis of variance. Irradiation with Er:YAG laser did not reduce the bond strength values for self-etching adhesives even after 6 months of water storage. The hybrid layer formation was observed only when the adhesives were applied to non-irradiated dentin (control group). Nanoleakage occurred in all resin–dentin interfaces using Single Bond Plus for both periods. Nanoleakage pattern and bond strength of self-etching adhesives to dentin were less affected by Er:YAG laser irradiation and by the 6-month storage in water than was those of the etch-and-rinse adhesive. TEM analysis revealed no hybridization when dentin was laser-irradiated. Clinical significance: Minimally invasive caries removal has been proposed. Nevertheless, bonding mechanisms to lased dentin are not entirely described. Knowing the interaction between the treated dentin and bonding agents and its behavior over time is of utmost importance for new technologies. Regarding that, two-bottle self-etching adhesive system provided a more consistent evidence of its better behavior when bonding to lased substrate.     

Shear bond strength of self-etching adhesive systems to Er:YAG-laser-prepared dentin

This study was conducted to compare the shear bond strengths of composite resin bonded to Er:YAG laser or bur-prepared dentin surfaces using three self-etching adhesive systems. The occlusal surfaces of 120 human third molars were ground flat to expose dentin. The dentin was prepared using either a carbide bur or an Er:YAG laser at 350 mJ/pulse and 10 Hz (fluence, 44.5 J/cm²). Three different self-etching adhesive systems were applied: iBond™, Xeno III™ and Clearfil SE Bond™. Rods of composite resin were bonded to dentin surfaces and shear bond tests were carried out. Both dentin surfaces after debonding and resin rods were observed using a scanning electron microscope. When the Xeno III™ was used, no difference was observed on shear bond strength values when bur and Er:YAG laser were compared. When using iBond™ and Clearfil SE Bond™, bond strength values measured on Er:YAG-laser-prepared surfaces were lower than those observed on bur-prepared surfaces. The absence of smear layer formation during the preparation of the dentin by the Er:YAG laser did not improve the adhesion values of self-etching adhesive systems.     

Shear strength of the bond to primary dentin: influence of Er:YAG laser irradiation distance

The aim of this study was to assess in vitro the influence of Er:YAG laser irradiation distance on the shear strength of the bond between an adhesive restorative system and primary dentin. A total of 60 crowns of primary molars were embedded in acrylic resin and mechanically ground to expose a flat dentin surface and were randomly assigned to six groups (n = 10). The control group was etched with 37% phosphoric acid. The remaining five groups were irradiated (80 mJ, 2 Hz) at different irradiation distances (11, 12, 16, 17 and 20 mm), followed by acid etching. An adhesive agent (Single Bond) was applied to the bonding sites, and resin cylinders (Filtek Z250) were prepared. The shear bond strength tests were performed in a universal testing machine (0.5 mm/min). Data were submitted to statistical analysis using one-way ANOVA and the Kruskal-Wallis test (p<0.05). The mean shear bond strengths were: 7.32 ± 3.83, 5.07 ± 2.62, 6.49 ± 1.64, 7.71 ± 0.66, 7.33 ± 0.02, and 9.65 ± 2.41 MPa in the control group and the groups irradiated at 11, 12, 16, 17, and 20 mm, respectively. The differences between the bond strengths in groups II and IV and between the bond strengths in groups II and VI were statistically significant (p<0.05). Increasing the laser irradiation distance resulted in increasing shear strength of the bond to primary dentin.     

Comparative study of the dentin/adhesive systems interface after treatment with Er:YAG laser and acid etching using scanning electron microscope

BACKGROUND AND OBJECTIVES: To assess dentin/adhesive systems interface after dentin conditioning with Er:YAG laser. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four dentin half-disks were assigned to 3 groups: All Bond 2 (AB); Optibond Solo Plus (OP); and Clearfil Liner Bond 2V (CL), which were divided into three sub-groups, according to dentin surface treatment: Er:YAG laser; Er:YAG laser plus acid; acid solely. After the adhesive protocol, specimens were embedded in resin, sectioned, and prepared for SEM analysis. Each area was examined under 1,500x magnification to assess the hybrid layer. RESULTS: Acid conditioning provided to AB and OP thick and homogeneous hybrid layer, as well as conical and uniform tags. The same pattern was observed for CL. In general, dentin treatment with laser, even when associated to acid, promoted irregular and thin hybrid layer, as well as scarce and thin tags. CONCLUSIONS: Er:YAG laser influenced the adhesive systems interface, hampering hybrid layer formation.     

Er:YAG laser cavity preparation and composite resin bonding with a single-component adhesive system: relationship between shear bond strength and microleakage

BACKGROUND AND OBJECTIVES: The purpose of this study was to assess the performances of a single-component adhesive system when an Er:YAG laser was used to prepare cavities. STUDY DESIGN/MATERIALS AND METHODS: Shear bond strength tests were performed on composite rods bonded with a single-component adhesive system to dentin surfaces prepared using either bur+acid, Er:YAG laser (fluence = 44 J/cm2), or Er:YAG laser+acid. Class V cavities were prepared differently according to the molar surface: buccal surfaces were prepared using a diamond bur, and lingual surfaces using the Er:YAG laser. In group 1, cavity walls were not acid treated after Er:YAG laser preparation. In group 2, only the enamel walls were acid treated. In group 3, all the enamel and dentin walls were acid treated. Microleakage was assessed using a methylene blue dye penetration method. RESULTS: Bond strength values did not differ significantly between the three groups (P = 0.162). Better marginal adaptation was obtained between the composite resin and cavity walls when Er:YAG laser preparation was followed by a total acid etching (P = 0.008). CONCLUSIONS: Our results supported the use of single-component adhesive systems in cavities prepared using Er:YAG laser. The step of acid etching must be maintained for the whole cavity walls in regard of the microleakage values.     

Effect of low fluency dentin conditioning on tensile bond strength of composite bonded to Er:YAG laser-prepared dentin: a preliminary study

Several studies in the literature have previously shown that the bond strength of a composite bonded to dentin is almost equivalent as when dentin is prepared by either bur or Er:YAG laser. The aim of this preliminary study is to assess the hypothesis that dentin conditioning at low fluency by means of Er:YAG laser can improve the value of adhesion of composites resin to dentin. Sixty surfaces of caries-free human third molars extracted for orthodontic purposes were randomly divided into five groups of 12 teeth. The bur group was the control, prepared using bur, group L was prepared using Er:YAG 200 mJ, SSP (50 μs), 20 Hz, 15 seconds of sweeping, for groups L80, L100, L120, they were prepared first, with the same parameters of the group L 200, and then they received a conditioning, which is, respectively, 15 s of irradiations at: 80 mJ (SSP, 10 Hz), 100 mJ (SSP, 10 Hz), and 120 mJ (SSP, 10 Hz). All samples were restored in a single-component adhesive system: Xenon (DENTSPLY), and ceramX (DENTSPLY) as the resin composite. The specimens were submitted to tensile bond strength test using a universal testing machine. Data were submitted to statistical analysis using ANOVA coupled to a Tukey-Kramer test at the 95% level. The mean values in MPa were 33.3 for group B, 36.73 for group L 200, 41.7 for group L80, 37.9 for group L100, and 39.1 for group L120. Our results showed that dentin conditioning at a low fluency of 12.58 J/cm² per pulse, with 80 mJ output energy and 50-μs pulse duration can significantly improve tensile bond strength of a composite bonded to Er:YAG laser-prepared dentine.     

Micro-shear bond strength of Er:YAG-laser-treated dentin

This study tested if dentin adhesion is affected by Er:YAG laser. Ninety dentin disks were divided in groups (n = 10): G1, control; G2, Er:YAG laser 150 mJ, 90 degrees contact, 38.8 J/cm(2); G3, Er:YAG laser 70 mJ, 90 degrees contact, 18.1 J/cm(2); G4, Er:YAG laser 150 mJ, 90 degrees non-contact, 1.44 J/cm(2); G5, Er:YAG laser 70 mJ, 90 degrees non-contact, 0.67 J/cm(2); G6, Er:YAG laser 150 mJ, 45 degrees contact, 37.5 J/cm(2); G7, Er:YAG laser 70 mJ, 45 degrees contact, 17.5 J/cm(2); G8, Er:YAG laser 150 mJ, 45 degrees non-contact, 1.55 J/cm(2); and G9, Er:YAG laser 70 mJ, 45 degrees non-contact, 0.72 J/cm(2). Bonding procedures were carried out and the micro-shear-bond strength (MSBS) test was performed. The adhesive surfaces were analyzed under SEM. Two-way ANOVA and multiple comparison tests revealed that MSBS was significantly influenced by the laser irradiation (p < 0.05). Mean values (MPa) of the MSBS test were: G1 (44.97 +/- 6.36), G2 (23.83 +/- 2.46), G3 (30.26 +/- 2.57), G4 (35.29 +/- 3.74), G5 (41.90 +/- 4.95), G6 (27.48 +/- 2.11), G7 (34.61 +/- 2.91), G8 (37.16 +/- 1.96), and G9 (41.74 +/- 1.60). It was concluded that the Er:YAG laser can constitute an alternative tool for dentin treatment before bonding procedures.     

Influence of Er:YAG and Ti:sapphire laser irradiation on the microtensile bond strength of several adhesives to dentin

Lasers in Medical Science - The aim of the present study was to evaluate the influence of erbium:yttrium–aluminum–garnet (Er:YAG) and Ti:sapphire laser irradiation on the microtensile...     

Microleakage of Er:YAG laser and dental bur prepared cavities in primary teeth restored with different adhesive restorative materials

The purpose of this study was to evaluate and compare the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation and conventional dental bur cavity preparation on in vitro microleakage of class V cavities restored with different adhesive restorative materials and two types of self-etching adhesives in primary teeth. Standard class V cavities were prepared on 80 extracted primary, and the teeth were randomly divided into eight subgroups prepared either by dental bur or Er:YAG laser irradiation and then restored with self-cured glass ionomer (GI), resin-modified glass ionomer (RMGI), resin composite and Clearfil SE Bond (two-step self-etching adhesive), and resin composite and Clearfil S3 Bond (one-step self-etching adhesive). Restorations were finished and stored in distilled water at 37 °C for 24 h and then subjected to thermocycling. All the teeth were sealed with nail varnish, placed in a silver nitrate solution, and then vertically cut in a buccolingually direction. Subsequently, the specimens were evaluated for gingival and occlusal microleakage using a stereomicroscope. Data were analyzed using Kruskal–Wallis test followed by Mann–Whitney test. Wilcoxon test was used for comparing occlusal microleakage with gingival microleakage at p?<?0.05. A higher degree of occlusal and gingival microleakage values for the teeth restored with GI or RMGI was obtained by both preparation methods compared with that of resin composites and the two self-etching primers. Er:YAG laser irradiation resulted in a significantly higher degree of microleakage only at the gingival margins for teeth restored with GI or RMGI, or composite and Clearfil S3 Bond compared with the bur preparation. The Er:YAG laser-prepared teeth restored with composite and Clearfil SE Bond demonstrated a better marginal seal on occlusal and gingival margins compared with that of bur-prepared cavities. The degree of microleakage in class V cavities was affected by the type of adhesive restorative materials, type of self-etching adhesive, cavity margin location, and tooth preparation method either by Er:YAG laser or dental bur.     

The effect of Er:YAG laser irradiation on the bond stability of self-etch adhesives at different dentin depths

The aim of this study was to evaluate the effect of Er:YAG laser irradiation on the micro-shear bond strength of self-etch adhesives to the superficial dentin and the deep dentin before and after thermocycling. Superficial dentin and deep dentin surfaces were prepared by flattening of the occlusal surfaces of extracted human third molars. The deep or superficial dentin specimens were randomized into three groups according to the following surface treatments: group I (control group), group II (Er:YAG laser; 1.2 W), and group III (Er:YAG laser; 0.5 W). Clearfil SE Bond or Clearfil S³ Bond was applied to each group’s dentin surfaces. After construction of the composite blocks on the dentin surface, the micro-shear bond testing of each adhesive was performed at 24 h or after 15,000 thermal cycles. The data were analyzed using a univariate analysis of variance and Tukey’s test (p < 0.05). Laser irradiation in superficial dentin did not significantly affect bond strength after thermocycling (p > 0.05). However, deep-dentin specimens irradiated with laser showed significantly higher bond strengths than did control specimens after thermocycling (p < 0.05). Thermocycling led to significant deterioration in the bond strengths of all deep-dentin groups. The stable bond strength after thermocycling was measured for all of the superficial-dentin groups. No significant difference was found between the 0.5 and 1.2 W output power settings. In conclusion, the effect of laser irradiation on the bond strength of self-etch adhesives may be altered by the dentin depth. Regardless of the applied surface treatment, deep dentin showed significant bond degradation.     

Microtensile bond strength of composite resin to glass-infiltrated alumina composite conditioned with Er,Cr:YSGG laser

Tribochemical silica-coating is the recommended conditioning method for improving glass-infiltrated alumina composite adhesion to resin cement. High-intensity lasers have been considered as an alternative for this purpose. This study evaluated the morphological effects of Er,Cr:YSGG laser irradiation on aluminous ceramic, and verified the microtensile bond strength of composite resin to ceramic following silica coating or laser irradiation. In-Ceram Alumina ceramic blocks were polished, submitted to airborne particle abrasion (110 μm Al₂O₃), and conditioned with: (CG) tribochemical silica coating (110 μm SiO₂) + silanization (control group); (L1-L10) Er,Cr:YSGG laser (2.78 μm, 20 Hz, 0.5 to 5.0 W) + silanization. Composite resin blocks were cemented to the ceramic blocks with resin cement. These sets were stored in 37°C distilled water (24 h), embedded in acrylic resin, and sectioned to produce bar specimens that were submitted to microtensile testing. Bond strength values (MPa) were statistically analyzed (α ≤0.05), and failure modes were determined. Additional ceramic blocks were conditioned for qualitative analysis of the topography under SEM. There were no significant differences among silicatization and laser treatments (p > 0.05). Microtensile bond strength ranged from 19.2 to 27.9 MPa, and coefficients of variation ranged from 30 to 55%. Mixed failure of adhesive interface was predominant in all groups (75–96%). No chromatic alteration, cracks or melting were observed after laser irradiation with all parameters tested. Surface conditioning of glass-infiltrated alumina composite with Er,Cr:YSGG laser should be considered an innovative alternative for promoting adhesion of ceramics to resin cement, since it resulted in similar bond strength values compared to the tribochemical treatment.     

Composite resin's adhesive resistance to dentin: influence of Er:YAG laser focal distance variation

The aim of this study was to analyze in vitro the influence of Er:YAG laser focal distance variation on tensile bond strength of a composite resin to dentin. Although there are several studies using the Er:YAG laser for dentin treatment, there is a lack of available literature related to the Er:YAG laser focal distance variation. Sixty vestibular and lingual dentin surfaces from extracted human third molars, kept in a 0.4% azide sodium solution, were ground and assigned to six groups. The control group was conditioned with 35% phosphoric acid (CA). In the lased groups, the dentin surface treatment was performed by irradiation with Er:YAG laser (80 mJ/2 Hz), varying the focal distance (11, 12, 14, 16, and 17 mm), followed by acid etching. The Single Bond/Filtek Z250 (3M) resinous system was used for the specimen manufacture. The tensile bond strength tests were performed in a Universal Testing Machine with 50 kgf load cell and 0.5 mm/min cross head speed. The averages in MPa were: CA: 18.03 (+/-2.09); 11 mm; 9.92 (+/-3.34); 12 mm: 9.49 (+/-2.29); 14 mm: 10.99 (+/-3.45); 16 mm: 10.56 (+/-1.93); and 17 mm: 17.05 (+/-2.31). It was concluded that the application of Er:YAG laser in a defocused mode (17 mm) associated with acid etching was similar to the treatment of acid solely. Er:YAG laser irradiation in a focused (12 mm) and a defocused (11, 14, and 16 mm) mode coupled with acid conditioning produced the lowest values of adhesion.