Microtensile Bond Strength Research Articles

Silver diamine fluoride and resin-dentin bonding: Optimization of application protocols

ObjectiveTo evaluate the effect of SDF-based treatments following delayed bonding and surface treatment approaches on resin-dentin bonding efficiency of a universal adhesive under different application modes. MethodsMid-coronal dentin surfaces from sound third molars were randomly treated with 38% silver diamine fluoride (SDF) and/or additionally with potassium iodide (SDF/KI). Untreated dentin served as control. SDF-treated teeth were assigned to groups according to surface treatment approaches (air-abrasion and water rinsing), the application mode of a mild universal adhesive (etch-and-rinse or self-etch) and delayed bonding (immediate, 7, 15 or 30 days). Microtensile bond strength (n = 5), SEM analyses of hybrid layer formation and dentin etching patterns and dentin permeability were evaluated. Data were analyzed with factorial ANOVA. ResultsSDF-based treatments affected dentin bonding depending on application mode and surface treatment approaches (p<0.001). Etch-and-rinse bonding was not affected by SDF-based treatments (p<0.05), producing more homogenous hybrid layers. While dentin etching patterns of etch-and-rinse application were not affected by SDF-based treatments, self-etching presented limitations. Bond strength reductions of self-etched dentin were restored by silver-removal strategies containing a water-rinsing step (p<0.05). Delayed bonding additionally reduced dentin permeability (p<0.05), further decreasing with longer periods (p<0.05). ConclusionAlthough the negative effect of SDF-based treatments on resin-dentin bonding can be avoided by strategies incorporating water-rinsing before hybridization, delayed bonding brings additional advantages due to higher mineral deposition. Clinical significanceWhile the etch-and-rinse technique avoids major bonding drawbacks to SDF-treated dentin, self-etch bonding requires removal of excess silver deposits before hybridization. Performing SDF-based treatments and dentin hybridization in separate sessions (>15 days apart) potentialize mineral deposition improving caries control and service life of composite restorations.

Comparative Evaluation of the Repair Bond Strength of Dental Resin Composite after Sodium Bicarbonate or Aluminum Oxide Air-Abrasion.

The dental prophylactic cleaning of a damaged resin-based composite (RBC) restoration with sodium bicarbonate can change the surface characteristics and influence the repair bond strength. The purpose of this study was to compare the effect of sodium bicarbonate (SB) and aluminum oxide (AO) surface treatments on the microtensile bond strength (µTBS) of repaired, aged RBC. Bar specimens were prepared from microhybrid RBC and aged in deionized water for 8 weeks. Different surface treatments (AO air-abrasion; SB air-polishing), as well as cleaning (phosphoric acid, PA; ethylene-diamine-tetraacetic-acid, EDTA) and adhesive applications (single bottle etch-and-rinse, ER; universal adhesive, UA), were used prior to the application of the repair RBC. Not aged and aged but not surface treated RBCs were used as positive and negative controls, respectively. The repaired blocks were cut into sticks using a precision grinding machine. The specimens were tested for tensile fracture and the µTBS values were calculated. Surface characteristics were assessed using scanning electron microscopy. AO-PA-UA (62.6 MPa) showed a 20% increase in µTBS compared to the NC (50.2 MPa), which proved to be the most significant. This was followed by SB-EDTA-UA (58.9 MPa) with an increase of 15%. In addition to AO-PA-UA, SB-EDTA-UA could also be a viable alternative in the RBC repair protocol.

Microtensile bond strength of resin cements to 3-D printed and milled temporary restorative resins

To evaluate the microtensile bond strength (µTBS) of two resin cements to 3D printed and milled CAD/CAM resins used for provisional fixed partial dentures. Blocks (5 x 5 x 5 mm) of three 3D-printed resins (Cosmos3DTemp / Yller; Resilab3D Temp / Wilcos and SmartPrint BioTemp, / MMTech) were printed (Photon, Anycubic Technology Co.). A milled material (VitaCAD-Temp, VITA) was used as control. Half the specimens were sandblasted and the rest were untreated. Two blocks were bonded with the corresponding resin cement: PanaviaV5 (Kuraray Noritake) and RelyX Ultimate (3M Oral Care). After 24 hours, the bonded blocks were sectioned into 1 x 1 mm side sticks. Half the beams were tested for µTBS and the other half was thermocycled (5000 cycles, 30s dwell-time, 5s transfer time) before µTBS testing. A four way Generalized Linear Model (material*sandblasting*cement*aging) analysis was applied. VITA exhibited the lowest µTBS, regardless of the cement, sandblasting and thermocycling. Sandblasting significantly improved the µTBS of VIT, especially after aging, but did not improve the µTBS of 3D printed resins. Sandblasting was not beneficial for 3D printed resins, although is crucial for adhesive cementation of milled temporary resins. Airborne particle abrasion affects the integrity of 3D-printed resins, without producing a benefit on the microtensile bond strength of these materials. However, sandblasting is crucial to achieve a high bond strength on milled temporary resins.

Evaluation of the antibacterial activity of dental adhesive containing biogenic silver nanoparticles decorated nanographene oxide nanocomposites (Ag@nGO NCs) and effect on bond strength to dentine.

Our study aimed to evaluate the antibacterial activities and dentin bond strengths of silver nanoparticles (Ag NPs) and silver nano-graphene oxide nanocomposites (Ag@nGO NCs) produced by green and chemical synthesis methods added to the dental adhesive. Ag NPs were produced by green synthesis (biogenic) (B-Ag NPs) and chemical synthesis methods (C-Ag NPs) and deposited on nGO (nano-graphene oxide). Ag NPs and Ag@nGO NCs (0.05% w/w) were added to the primer and bond (Clearfil SE Bond). Group 1: control, Group 2: nGO, Group 3: B-Ag NPs, Group 4: B-Ag@nGO NCs, Group 5: C-Ag NPs, Group 6: C-Ag@nGO NCs. Streptococcus mutans (S. mutans) live/dead assay analysis, MTT metabolic activity test, agar disc diffusion test, lactic acid production, and colony forming units (CFUs) tests were performed. Bond strength values were determined by the microtensile bond strength test (μTBS). Failure types were determined by evaluating with SEM. Statistical analysis was performed using one-way ANOVA and two-way ANOVA (p < 0.05). There was a difference between the groups in the viable bacteria ratio and lactic acid production tests (p < 0.05). When the inhibition zone and S. mutans CFUs were evaluated, there was no difference between Group 3 and Group 4 (p > 0.05), but there was a difference between the other groups (p < 0.05). When the metabolic activity of S. mutans was evaluated, there was a difference between Group 1 and other groups, and between Group 2 and Group 5, and Group 6 (p < 0.05). There was no difference between the groups in the μTBS values (p > 0.05). As a result, although the antibacterial activity of B-Ag NPs and B-Ag@nGO Ag NPs obtained by green synthesis is lower than that of chemically synthesis obtained C-Ag NPs and C-Ag@nGO NCs, they provided higher antibacterial activity compared to the control group and did not reduce μTBS. The addition of biogenic Ag NPs to the adhesive system increased the antibacterial effect by maintaining the bond strength of the adhesive. Antibacterial adhesives can increase the restoration life by protecting the tooth-adhesive interface.

Impact of Preceded Tumor Therapeutic Irradiation on the Microtensile Bond Strength of Universal Adhesives Applied in Self-Etch Mode to Human Dentin In Vitro

The aim of this study was to investigate the effect of preceded tumor therapeutic irradiation on the tensile bond strength of three modern universal adhesives applied in self-etch mode on dentin. Specimens prepared from 135 extracted human third molars were divided into three superior groups. These received either no radiation, 5 Gy, or a total dose of 60 Gy in vitro irradiation, fractionally applied. The samples of each group were further randomly assigned to six subgroups to test three adhesives (Futurabond® U, Voco; AdheSE® Universal Ivoclar Vivadent; Xeno® Select, Dentsply Sirona) in the self-etch application mode (n = 15). Tensile bond strength was determined using a universal testing machine (1.0 mm/min). Data were analyzed with ANOVA (p &lt; 0.01) and Tukey’s test (p &lt; 0.05). The influence of irradiation on the microtensile bond strength of the used dentin adhesives proved to be significant. For each material, a decrease in adhesion value was registered after irradiation. However, only for the material Xeno® Select were significantly reduced adhesion values determined after irradiation with 60 Gy compared to 0 Gy. Within the limitations of an in vitro study, some effects of tumor therapeutic irradiation of human dentin on the tensile bond strength of universal adhesives used in self-etch mode could be observed. Those decreases were only partly significant, depending on the material and the radiation dose. Whether the tensile bond strength on irradiated dentin depends on the particular application mode (etch-and-rinse vs. self-etch) of the universal adhesives remains to be investigated.

Theobromine versus casein phospho-peptides/Amorphous calcium phosphate with fluoride as remineralizing agents: effect on resin-dentine bond strength, microhardness, and morphology of dentine

BackgroundThis study aimed to assess the impact of theobromine and casein phospho-peptides/amorphous calcium phosphate with fluoride (CPP-ACPF) on the resin-dentine bond strength, microhardness, and dentine morphology.MethodsA total of 18 sound human molars for micro-tensile bond strength (µTBS), 20 sound human premolars for microhardness, and 30 premolars for Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) were used. Based on the pre-treatment used, teeth were split into six groups; sound dentine, demineralized dentine, and demineralized dentine treated with theobromine (Sigma Aldrich) and MI paste plus (GC International, USA) for two-time intervals; 5 min and 1 month. The bonded teeth were sectioned to produce 1 mm2 resin-dentine sticks which were evaluated for µTBS using a universal testing device (Instron 3365, USA). The dentine microhardness was tested by using the Vickers microhardness tester (Nexus 4000 TM, Netherlands). The pre-treated dentine surface was examined using SEM/EDX (Neoscope JCM-6000 plus Joel benchtop SEM, Japan). µTBS results were analysed with two-way ANOVA. Microhardness and EDX results were analysed with two-way mixed model ANOVA. The significance level was set at (p ≤ 0.05).ResultsWhile both remineralizing materials at the two-time intervals demonstrated µTBS comparable to sound dentine (46.38 ± 12.18), the demineralized group demonstrated statistically the lowest µTBS (p < 0.001). Whether used for 5 min or 1 month, theobromine significantly increased the microhardness (50.18 ± 3.43) and (54.12 ± 2.66) respectively (p < 0.001), whereas MI paste only increased the hardness (51.12 ± 1.45) after 1 month (p < 0.001).ConclusionsThe pre-treatment of demineralized dentine with theobromine for 5 min or 1 month could enhance its bond strength and microhardness while for MI paste plus, only 1-month application was efficient to ensure remineralization.

Microtensile Bond Strength of CAD-CAM Restorative Dental Material Blocks to Resin Cement: An In Vitro Study

Introduction: Today’s dentistry frequently employs bonded partial restorations, which are usually fabricated in ceramic materials. In the last decade, hybrid materials have emerged that attempt to combine the properties of composites and ceramics. Objectives: To evaluate in vitro, by means of a microtensile test, the bond strength between CAD-CAM restorative materials and the cement recommended by their manufacturer. Material and Method: From blocks of CAD-CAM restorative material bonded to composite blocks (Filtek 500®), beams with a bonding area of approximately 1 mm2 were made and divided into four groups: EMAX (IPS e.max CAD® lithium disilicate), VE (VITA Enamic® polymer-infiltrated ceramic matrix), LUA (Lava Ultimate® nano-ceramic resin with sandblasting protocol) and LUS (Lava Ultimate® nano-ceramic resin with silica coating protocol). In each group, perimeter (external) or central (internal) beams were differentiated according to the position in the block. The samples were tested on the LMT 100® microtensile machine. Using optical microscopy, the fractures were categorized as adhesive or cohesive (of the restorative material or composite), and the data were analysed with parametric tests (ANOVA). Results: The LUS group had the highest results (42 ± 20 MPa), followed by the LUA group (38 ± 18 MPa). EMAX had a mean of 34 ± 16 MPa, and VE was the lowest in this study (30 ± 17 MPa). In all groups, the central beams performed better than the perimeter beams. Both EMAX and VE had the most adhesive fractures, while LUA and LUS had a predominance of cohesive fractures. Conclusions: Lava Ultimate® nanoceramic resin with the silica coating protocol obtains the best bond strength values.

Bonding Protocols to Reverse the Bond Strength of a Universal Adhesive to Hemostatic Agent-contaminated Dentin.

To evaluate the effect of different bonding protocols on the microtensile bond strength (μTBS) of a universal adhesive to dentin contaminated with a hemostatic agent. Ninety-five extracted premolars were used in this study. For the μTBS test, 80 teeth were cut to expose mid-coronal dentin and randomly divided into two groups (uncontaminated dentin and hemostatic agent-contaminated dentin). Each group was further divided into five subgroups (n=8/group): 1) SE: no additional treatment, 2) ER: etching with 32% phosphoric acid, 3) CHX: rinsing with 0.2% chlorhexidine, 4) EDTA: rinsing with 17% EDTA, and 5) T40: application of universal adhesive for 40 seconds. A universal adhesive was applied followed by resin composite build-up. μTBS test was performed after 24 hours of water storage. Two-way analysis of variance (ANOVA) was calculated followed by the Duncan testing (α=0.05). The failure mode was analyzed using light microscopy. Additional teeth were prepared for energy-dispersive X-ray (EDX) analysis (n=1/group) and resin-dentin interface observation (n=2/group) using scanning electron microscopy. Adverse effects of hemostatic agent contamination on the bonding performance of a universal adhesive was found in the SE, CHX, and T40 groups (p<0.05). Fewer and shorter resin tags were observed in the SE, CHX, and T40 groups. A higher percentage of adhesive failure and mixed failure was found in contaminated dentin. All bonding protocols revealed lower amounts of Al and Cl after dentin contamination, except for the SE group. Hemostatic agent contamination adversely affected dentin bond strength. However, this bond strength could be reversed using the etch-and-rinse technique or rinsing with EDTA prior to adhesive application.

In vitro analysis of durability of S-PRG filler-containing composite crowns for primary molar restoration.

To evaluate the reliability, maximum principal stress, shear stress, and crack initiation of a computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite (RC) incorporating surface pre-reacted glass (S-PRG) filler for primary molar teeth. Mandibular primary molar crowns fabricated by experimental (EB) or commercially available CAD/CAM RCs (HC) were prepared and cemented to a resinous abutment tooth using an adhesive resin cement (Cem) or a conventional glass-ionomer cement (CX). These specimens were subjected to a single compressive test (n=5/each) and the step-stress accelerated life testing (SSALT) (n=12/each). Data was evaluated using Weibull analyses and reliability was calculated. Afterwards, the maximum principal stress and crack initiation point of each crown was analyzed by finite element analysis. To evaluate bonding of EB and HC to dentin, microtensile bond strength (μTBS) testing was conducted using primary molar teeth (n=10/each). There was no significant difference between the fracture loads of EB and HC for either cement (p>0.05). The fracture loads of EB-CX and HC-CX were significantly lower than EB-Cem and HC-Cem (p<0.05). The reliability at 600N for EB-Cem was greater than that for EB-CX, HC-Cem, and HC-CX. The maximum principal stress concentrated on EB was lower than that on HC. The shear stress concentrated in the cement layer for EB-CX was higher than that for HC-CX. There was no significant difference among the μTBSs of EB-Cem, EB-CX, HC-Cem, and HC-CX (p>0.05). The crowns fabricated with the experimental CAD/CAM RC incorporating S-PRG filler yielded greater fracture loads and reliability than the crowns manufactured with commercially available CAD/CAM RC regardless of the luting materials. These findings suggest that the experimental CAD/CAM RC crown may be clinically useful for the restoration of primary molars.

Effects of Various Adhesive Systems with Cavity Cleaning Techniques on Microtensile Bond Strength of Endodontically Treated Teeth

Effects of Various Adhesive Systems with Cavity Cleaning Techniques on Microtensile Bond Strength of Endodontically Treated Teeth

Phosphoric Acid Etch Partially Restores the Initial Bond Strength of Composite to Silver Diamine Fluoride-Treated Enamel Using Universal Adhesives.

Restoring bonding composite to silver diamine fluoride (SDF)-treated enamel is challenging. This study investigates if phosphoric acid etch restores composite bond strength to SDF-treated enamel using universal adhesives. Twenty-four recently extracted permanent teeth were randomly divided into 4 (2 experimental (SDF) and 2 control (CTR)) groups: SDF+Water: SDF (1 min) then water rinse (15 mL); CTR+Water: no treatment and water rinse (15 mL); SDF+Etch+Water: SDF (1 min), 35% phosphoric acid (40 s) then water rinse (15 mL); CTR+Etch+Water no treatment, 35% phosphoric acid (40 s) then water rinse (15 mL). The enamel surface in all the groups was bonded (All-Bond Universal) to 4-5 mm composite blocks (Z-250). Each sample was sectioned, and 6-8 beams (1 mm × 1 mm) were selected. The micro-tensile bond strength was measured by dividing the micro-tensile force peak by the adhesive surface area. Univariate ANOVA and Chi-square were used for between-group comparisons with p < 0.05. SDF+Water had significantly lower tensile strength compared to all the groups (p < 0.05). Although no difference was found in the tensile strength between the SDF+Etch+Water and the CTR+Etch+Water, the SDF+Etch+Water had significantly more adhesive failures compared to the CTR+Etch+Water (p = 0.047). While phosphoric acid etch seems to restore the initial composite bond strength to SDF-treated enamel, the long-term success of composite restorations bonded to SDF-treated enamel may need further investigation.

Effect of cleaning materials on microtensile bond strength of resin composite to primary dentin contaminated with root canal sealers

BackgroundThere have been no studies on the bond strength of adhesives with dentin surfaces contaminated with root canal sealers in primary teeth without underlying permanent teeth germs. This study investigated the cleaning materials used for primary tooth dentin contaminated with root canal sealers. The aim was to increase the success rate of root canal treatment in pedodontics clinics and retain the teeth for longer.MethodsThe occlusal enamel layer was removed, followed by the application of root canal sealers (AH Plus or MTA Fillapex) to the dentin and cleaning using different irrigation solutions (saline, NaOCl, and ethanol). The specimens were restored using a self-etch adhesive and composite. Sticks with a thickness of approximately 1 mm were obtained from each sample, and the bond strengths were measured using a microtensile testing device. The interfacial morphology of the bonded space was evaluated using scanning electron microscopy.ResultsThe control and AH Plus saline groups had the highest bond strengths. The groups cleaned using ethanol had the lowest bond strengths (p < 0.01).ConclusionCleaning the dentin with saline-soaked cotton pellets provided the best bond strengths. Therefore, saline is the most effective material for removing both epoxy resin- and calcium silicate-based root canal sealers from the access cavity.

Bonding of chitosan and nanochitosan modified universal adhesive to dentin

ObjectivesTo evaluate Wettability, pH and Microtensile bond strength (immediate and after thermocycling) of a universal adhesive after incorporation of 0.5% and 1% bulk-chitosan or nanochitosan. MethodsAll-bond universal adhesive was used to obtain five groups according to the type of additive; CONTROL, CHITOSAN (0.5), CHITOSAN (1%), NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%). Contact angle and pH of the adhesives were tested with n = 7 for each test. for Microtensile bond strength testing, premolars teeth (N = 50) were used; twenty-five teeth for immediate bond strength and the other twenty-five were tested after thermocycling. ResultsCONTROL and CHITOSAN (0.5%) groups showed significantly higher contact angle measurements (30.78 ± 3.71 and 27.77 ± 4.63 respectively) compared to all other groups. CONTROL group showed significantly higher pH value (3.17 ± 0.05), followed by NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) and the least pH values were for 0.5% CHITOSAN group and CHITOSAN (1%). Bond strength results revealed that NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) had the highest bond strength (52.99 ± 16.14, 55.80 ± 16.11). CONTROL, CHITOSAN (0.5%) and CHITOSAN (1%) had no significant difference. After thermocycling, NANOCHITOSAN (0.5%) and NANOCHITOSAN (1%) had the highest bond strength values (38.58 ± 7.01 and 40.07 ± 11.40), followed by CHITOSAN (0.5%) and CHITOSAN (1%), and the least bond strength value was obtained by the control group. Hybrid layer micrographs showed that NANOCHITOSAN (1%) has intense resin infiltration before and after aging compared to all other groups. ConclusionIncorporation of nanochitosan (0.5% and 1%) improved the universal adhesive microtensile bond strength and bond durability.

The effect of an extra hydrophobic resin layer on the bond strength and durability of one-step universal adhesives used as a primer

ObjectivesTo determine the effect of an extra hydrophobic resin layer (EHL) on the bond strength and durability of three different pH one-step universal adhesives (UAs) utilized in self-etch (SE) mode, and to explore whether UAs can be used as a primer in two-step bonding system. MethodsThree different pH UAs were utilized: G-Premio Bond (GPB), Scotchbond Universal (SBU), All-Bond Universal (ABU), while the bonding agent of Clearfil SE Bond 2 (SE2) was selected as the EHL. For the EHL groups, EHL was applied after the air blow of each UA and before light curing. The microtensile bond strength (μTBS), fracture modes, interfacial structures and nanoleakage (NL) were evaluated after 24 h water storage and after 15,000 thermal cycling (TC). Elastic modulus (EM) and hardness (H) was tested by a nanoindenter after 24 h. ResultsSignificantly higher μTBS was achieved in the GPB+EHL group compared with GPB both at 24 h and after 15,000 TC, while the additional use of EHL did not improve the μTBS of SBU and ABU significantly both at 24 h and after 15,000 TC. GPB+EHL demonstrated lower NL than GPB. The mean EM and H of the adhesive layer in GPB+EHL was significantly decreased compared with GPB. ConclusionsThe results indicated that the bond strength and durability of low pH one-step UA (GPB) were significantly improved by additional application of EHL both at 24 h and after 15,000 TC, while no significant improvement was observed for ultra-mild one-step UAs (SBU and ABU). Clinical significanceThis study indicates that GPB can be used as a primer in a two-step bonding system, while SBU and ABU may not be as effective. These findings may help guide clinicians in selecting the appropriate UAs and bonding techniques for different clinical scenarios.

Bonding performance of experimental HEMA-free two-step universal adhesives to low C-factor flat dentin.

Experimental two-step universal adhesives (2-UAs) providing a particle-filled hydrophobic adhesive resin with a significant film thickness to hydrophobically seal the adhesive interface were designed and synthesized. This study aimed to characterize their interfacial interaction with dentin, to determine whether the 2-UA formulations achieve durable bonding to low C-factor flat dentin and to measure their water sorption. Bonding effectiveness of 2-UAs that combine a 10-MDP-based primer with hydrophobic adhesive resins differing only for filler (BZF-21, BZF-29, and BZF-29_hv) were comparatively investigated with the commercial adhesive Clearfil SE Bond 2 (C-SE2, Kuraray Noritake). Adhesive-dentin interfaces were characterized with TEM. Adhesive-resin disks were immersed in distilled water at 37°C for 1 week, 6 months and 1 year to measure water sorption and solubility. 'Immediate' and 'aged' micro-tensile bond strength (μTBS) of the adhesives applied in etch-and-rinse (E&R) and self-etch (SE) bonding mode to low C-factor flat dentin were measured. Statistical analyses involved linear mixed-effects (LME) modelling and Kruskal-Wallis testing (p<0.05). TEM revealed that E&R hybrid layers were more sensitive to aging than SE hybrid layers. Lower water sorption was recorded for all UAs compared with C-SE2. The immediate μTBS of BZF-21 and BZF-29 was not significantly different from that of C-SE2. The 1-year aged μTBS of all 2-UAs was significantly lower than that of C-SE2, except for BZF-29 applied in E&R mode. A significant reduction in μTBS upon 1-year aging was recorded for BZF-21 and BZF-29 applied in E&R mode. A significant difference in μTBS between E&R and SE bonding modes was recorded for all adhesives except BZF-21. Experimental 2-UAs with a hydrophobic adhesive-resin design produced±20-μm thick adhesive-resin layers, absorbed less water and resulted in bonding performance that was more aging-resistant when applied in SE than in E&R bonding mode. The silica-filled BZF-29 2-UA revealed the most comparable bonding performance with C-SE2 in a low C-factor condition (flat dentin).

Effect of viscosity of experimental universal adhesive on bond strength to dentin prepared with Er:YAG laser

The aim of this study was to clarify the effect of universal adhesive (UA) viscosity on the bond strength of resin composite to dentin prepared with Er:YAG laser. Four experimental UAs (SI-1, SI-2, SI-3, and SI-4) were developed by adding 1, 2, 3, and 4 wt/% nanosilica to BeautyBond Xtreme (Shofu), respectively. BeautyBond Xtreme was used as a control (SI-0). The viscosities of experimental UAs were measured using a B-type viscometer. After bovine mandibular anterior teeth were ground with #600 emery paper to obtain the flattened dentin surfaces, the dentin surfaces were cut thinly by irradiating the Er:YAG laser. Specimens were prepared using the respective UA and flowable resin composite and subjected to the microtensile bond strength (µTBS) test. The data from viscosity measurement and the μTBS test were statistically analyzed using the Kruskal–Wallis test. The mean values of viscosity significantly differed among the all experimental groups (p < 0.01). The μTBS of SI-1 and SI-2 was significantly higher than that of SI-0, SI-3, and SI-4 (p < 0.001). The μTBS of SI-0 was significantly lower than that of SI-4 (p < 0.001). The viscosities of the experimental universal adhesives significantly affected their bond strength to laser-cut dentin.

Efficacy of methylene blue and curcumin mediated antimicrobial photodynamic therapy in the treatment of indirect pulp capping in permanent molar teeth

PurposeThis study aimed to evaluate the adhesive bond strength and antibacterial efficacy of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and curcumin (CUR)-mediated aPDT versus the conventional disinfectants, such as chlorhexidine gluconate (CHX) gel and sodium hypochlorite (NaOCl), for indirect pulp capping (IPC) treatment of permanent molars. MethodsOne Hundred grossly carious human permanent molars were collected through non-traumatic extraction. All specimens were embedded in polyvinyl cross-sections to the cemento-enamel junction. The cavity preparation was conducted by grinding the samples using silicon carbide discs. After culturing Streptococcus mutans (S. mutans), a 10 µL of S. mutans suspension (106 colony forming units/mL) was transferred in each tooth cavity and anaerobically incubated for 48 h at 37 °C. All specimens were randomly divided into 5 groups: Group-I: samples treated IPC; Group-II: samples treated with 2% CHX gel; Group-III: samples treated with 6% NaOCl; Group-IV: irradiation of prepared cavity with MB-mediated aPDT; and Group-V: irradiation of prepared cavity with CUR-mediated aPDT. After disinfection methods, the universal adhesive was used, and all specimens were restored using giomer. Eventually, confocal laser scanning microscopy, shear bond strength (SBS), micro-tensile bond strength (μTBS), four-point bending strength (4P-BS) analyses were performed, and the data were analyzed statistically. ResultsAt baseline, the highest SBS (48.8 ± 6.5 MPa), μTBS (54.3 ± 3.9 MPa), and 4P-BS (123 ± 32 MPa) scores were demonstrated by the samples treated with MB-mediated aPDT. However, after 12 months of storage, the highest SBS (42.3 ± 3.9 MPa) and μTBS (45.2 ± 6.6 MPa) scores were shown by samples treated with MB-mediated aPDT, while CUR-mediated aPDT treated samples demonstrated the highest 4P-BS scores (70 ± 18 MPa). Moreover, the highest antibacterial activity against S. mutans was shown by the samples treated with MB-mediated aPDT. ConclusionsThe application of aPDT, especially MB-mediated, demonstrated superior SBS, μTBS, and 4P-BS values as well as antibacterial activity against S. mutans as compared to 2% CHX gel and 6% NaOCl as cavity disinfectants for IPC treatment of permanent molars.

Microtensile Bond Strength of Different Bonding Agents to Superficial and Deep Dentin in Etch-and-Rinse and Self-Etch Modes.

Objectives: This study aimed to assess the microtensile bond strength (µTBS) of etch-and-rinse (E&R), self-etch (SE), and universal adhesives to superficial and deep dentin. Materials and Methods: In this in vitro study, 40 sound third molars were randomly divided into two main groups of superficial and deep dentin. Based on our classification, superficial dentin was right beneath the deepest occlusal groove, and deep dentin was 2mm beneath the deepest occlusal groove. Each group was divided into 4 subgroups (n=20) for application of Adper Single Bond 2 (ASB), Clearfil SE Bond (CSE), and Scotchbond Universal (SBU) in E&R and SE modes along with Charisma Smart composite resin on dentin. The specimens were incubated in distilled water at 37°C for 24 hours and their µTBS was then measured. The mode of failure was determined under a stereomicroscope at ×40 magnification. Data were analyzed by one-way ANOVA (alpha=0.05). Results: The highest µTBS belonged to the superficial dentin/SBU/E&R group. The µTBS was significantly higher in superficial dentin than deep dentin for all adhesives (P=0.005). There was no significant difference in mode of failure among the groups. Conclusion: Based on the results obtained in the present study, type of bonding agent and application mode affected µTBS. In use of universal adhesive, E&R mode can improve µTBS.

Effect of flavonoid-based experimental primers on dentin microtensile bond strength and interface morphology

ObjectivesThis study evaluated the effect of four flavonoid-based experimental primers on the dentin bond strength (μTBS) and the bonding interface morphology of an adhesive. Materials and methodsFour experimental primer solutions containing two different flavonoids (Kaempferol and Naringin) in two concentrations (10 mM and 20 mM) were applied for 30 s or 60 s on dentin after phosphoric acid etching, followed by an etch-and-rinse adhesive system. A Negative Control (NC) consisting of dentin not treated with experimental primer solutions and Positive Controls (PC) that used 0.2% chlorhexidine solution for 30 and 60 s were also tested. Eighty-eight teeth were selected for dentin μTBS (n = 8). Dentin-adhesive interface morphology (n = 4) were analyzed by confocal laser scanning microscopy (CLSM). Data were analyzed by mixed three-way ANOVA (μTBS) and two-way ANOVA (CLSM) (α = 0.05). Dentin μTBS was analyzed at 24 h and one-year, while the bonding interface morphology was evaluated at 24 h. ResultsRegarding μTBS, no statistical difference was found between the experimental groups and NC at 24 h. However, most experimental primers applied for 60 s presented higher values compared to NC at one-year. Hybrid layer formation and adhesive infiltration was observed in all groups by CLSM. ConclusionsThe application of flavonoid-based experimental primers for 60 s was able to produce higher μTBS than those obtained with NC and PC after one-year of artificial aging, without interfering with interface morphology.

Solvation role of dimethyl sulfoxide on the interaction with dentin bonding systems after 30 months.

To determine whether DMSO could serve as an effective pretreatment to improve the mechanical properties and minimize the degradation of the adhesive interface, through the degree of conversion (DC) and bond strength to dentin of different categories of dentin bonding systems (DBSs) after 30 months. DMSO (0, 0.5, 1, 2, 5, 10vol%) were incorporated into four categories of DBSs: Adper Scotchbond Multipurpose (MP), Adper Single Bond 2 (SB), Clearfil SE Bond (CSE) and Adper Scotchbond Universal (SU). DC was evaluated by Fourier transform infrared spectroscopy (FTIR). For microtensile bond strength test (µTBS), 1 % DMSO were applied on dentin as pretreatment before DBSs. For SU, both strategies were tested. Specimens for µTBS were tested after 24h, 6 and 30 months. DC and µTBS data were subjected to two-way ANOVA and Tukey test (α<0.05). Incorporating 5 %/10 % DMSO increased the DC of CSE. Controversially, when combined with SU, 2 % and 10 % DMSO jeopardized the DC. Regarding µTBS, 1 % DMSO pre-treatment increased the bond strength for MP, SB, SU-ER and SU-SE. After 30 months, MP, SU-ER and SU-SE showed a decrease compared to baseline but remained higher than the control. DMSO pretreatment may be a useful strategy to improve the bond interface over time. Its incorporation seems to favor the non-solvated systems regarding DC while it seems to show long-term benefits for bond strength using 1 % DMSO for MP and SU systems.