Assessment of physical properties of bioactive glass-modified universal multimode adhesive and its bonding potential to artificially induced caries affected dentin.

BACKGROUND: To evaluate the physical properties of bioactive glass-modified universal multimode adhesive and its micro-tensile bond strength (µTBS) to artificially induced caries-affected dentin. METHODS: All bond universal adhesive was used in the study. Specimens were divided into 2 main groups: control unmodified adhesive and 5 wt% BAG modified adhesive. The degree of conversion, pH, bioactivity, and viscosity of the adhesives were tested with n = 5 for each test. Micro-tensile bond strength evaluation was done in etch & rinse (ER) and selective-etch (SE) modes, where 24 human molar teeth were used (n = 3), 12 teeth for immediate bond strength, and the other 12 were tested after 6 months of storage in simulated body fluid (SBF). RESULTS: No significant difference was found between the control and the 5wt% BAG groups regarding the degree of conversion (61.01 ± 0.43 and 60.44 ± 0.61 respectively) and the viscosity (109.77 ± 22.3 and 124.3 ± 9.92 respectively). The control group revealed significantly lower pH values than the 5wt% BAG group (3.16 ± 0.5 and 4.26 ± 0.09 respectively). Immediate bond strength results revealed that the 5wt% BAG in the ER mode had the highest bond strength followed by the control group in the ER mode (44.16 ± 7.53 and 44.00 ± 7.96 respectively). SE groups showed that the immediate strength of the 5wt% BAG group was higher than the control group (42.09 ± 6.02 and 39.29 ± 6.64 respectively). After 6 months of storage, bond strength results revealed a decrease in bond strength values for the control groups but not for the 5wt% BAG in both application modes. CONCLUSIONS: The incorporation of BAG (5wt%) improved the universal adhesive micro-tensile bond strength and bond durability for both adhesive application modes without affecting its degree of conversion or viscosity.

Use of marine occurrent extracts to enhance the stability of dentin extracellular matrix.

Chitosan (CS) and phloroglucinol (PhG), two extracts abundantly found in marine life, were investigated for their ability to biomodify demineralized dentin by enhancing collagen crosslinks and improving dentin extracellular matrix (ECM) mechanical and biochemical stability. Dentin obtained from non-carious extracted human molars were demineralized with phosphoric acid. Baseline Fourier-transform infrared (FTIR) spectra, apparent flexural elastic modulus (AE) and dry mass (DM) of each specimen were independently acquired. Specimens were randomly incubated for 5 min into either ultrapure water (no-treatment), 1% glutaraldehyde (GA), 1% CS or 1% PhG. Water and GA were used, respectively, as a negative and positive control for collagen crosslinks. Specimens' post-treatment FTIR spectra, AE, and DM were obtained and compared with correspondent baseline measurements. Additionally, the host-derived proteolytic activity of dentin ECM was assessed using hydroxyproline assay (HYP) and spectrofluorometric analysis of a fluorescent-quenched substrate specific for matrix metalloproteinases (MMPs). Finally, the bond strength of an etch-and-rinse adhesive was evaluated after application of marine compounds as non-rinsing dentin primers. Dentin specimens FTIR spectral profile changed remarkably, and their AE increased significantly after treatment with marine compounds. DM variation, HYP assay and fluorogenic substrate analysis concurrently indicated the biodegradation of CS- and PhG-treated specimens was significantly lesser in comparison with untreated specimens. CS and PhG treatments enhanced biomechanical/biochemical stability of demineralized dentin. These novel results show that PhG is a primer with the capacity to biomodify demineralized dentin, hence rendering it less susceptible to biodegradation by host-proteases.

Evaluation of Microbiological Susceptibility and Long-term Adhesive Properties to Dentin of Primers with Terminalia catappa Linn.

PURPOSE: To investigate the antibacterial effects of Terminalia catappa Linn (TCL) leaf extracts at different concentrations and the effects of these extracts used as primers on the long-term adhesive properties of two universal adhesives. MATERIALS AND METHODS: After extract preparation, the antimicrobial and antibacterial activities of TCL against Streptococcus mutans (UA 159) were assessed in microdilution assays to provide the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Additionally, to provide quantitative data on the ability of TCL extract to reduce cell viability, colony forming units (CFU) were counted. To examine adhesive properties, 288 human molars were randomly assigned to 32 experimental conditions (n = 9) according to the following variables: (1) treatment agent: negative control (untreated surface), and primers at concentrations of 1xMIC, 5xMIC, and 10xMIC; (2) adhesives: Scotchbond Universal (SBU) and Futurabond Universal (FBU); (3) adhesive strategy: etch-and-rinse (ER) or self-etch (SE); and (4) storage time: 24 h or after 2 years. Primers were applied for 60 s, upon which the teeth were incrementally restored and sectioned into adhesive-dentin bonded sticks. These were tested for microtensile bond strength (µTBS) and nanoleakage (NL) after 24-h and 2-year water storage, as well as in-situ degree of conversion (DC) at 24 h. The chemical profile of the hybrid layer was determined via micro-Raman spectroscopy. Biofilm assay data were analyzed using the Kruskal-Wallis test; the pH of culture media and the chemical profile were analyzed by one-way ANOVA. The adhesive properties (µTBS, NL, DC) were evaluated using a four-way ANOVA and Tukey's test. Significance was set at 5%. RESULTS: Similar values of MIC and MBC were observed (2 mg/ml), showing bactericidal potential. CFU analysis demonstrated that concentrations of 5xMIC and 10xMIC significantly inhibited biofilm formation (p < 0.001). The application of the TCL primer at all concentrations significantly increased the immediate µTBS and DC, and decreased the immediate NL values when compared to the control group (p < 0.05), regardless of the adhesive and adhesive strategies. Despite an increase in the NL values for all groups after 2 years (p > 0.05), in groups where the TCL primer was applied, the µTBS remained constant after 2 years for both adhesives, while a decrease in the µTBS was observed in the control groups (p < 0.05). Usually, 10xMIC showed better results than 1xMIC and 5xMIC (p < 0.05). The application of TCL promoted cross-linking; cross-linking rates increased proportionally to the concentration of TCL (p < 0.05). CONCLUSION: Primers containing TCL promoted bactericidal and bacteriostatic action, as well as cross-linking with dentin, while maintaining the adhesive properties of the adhesive-dentin interface after 2 years of water storage.

Effects of Nd:YAG laser irradiation at different energy densities on dentin bond durability under simulated pulpal pressure.

OBJECTIVES: To evaluate the effects of Nd:YAG laser irradiation on the microstructures of dentin surfaces and the long-term bond strength of dentin under simulated pulpal pressure. MATERIALS AND METHODS: Under simulated pulp pressure, 30 freshly extracted caries-free third molars were cut into 2-mm-thick dentin samples and then divided into five groups: the control and laser groups (93.3 J/cm2; 124.4 J/cm2; 155.5 J/cm2; 186.6 J/cm2). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and Vickers hardness were used to analyze the surface morphology, composition, and mechanical properties of the dentin before and after laser irradiation. Another 80 caries-free third molars were removed and treated as described above, and the resin was bonded to the dentin surface with Single Bond Universal (SBU) adhesive in self-etch mode to make stick specimens. Microtensile bond strength (µTBS), confocal laser scanning microscopy (CLSM), and interfacial silver nanoleakage tests before and after 10,000 times thermocycling were then performed to analyze the bonding properties and interfacial durability of each group. RESULTS: SEM observations revealed that the surfaces of all laser group specimens were rough with open dentin tubules. Laser irradiation altered the surface composition of dentin while removing some collagen fibers but did not affect its surface hardness or crystallographic characteristics. Furthermore, laser irradiation with an energy density of 124.4 J/cm2 significantly promoted the immediate and aging bond strengths and reduced nanoleakage compared to those of the control group. CONCLUSIONS: Under simulated pulp pressure, Nd:YAG laser pretreatment altered the chemical composition of dentin and improved the immediate and long-term bond strength. CLINICAL RELEVANCE: This study investigated the optimal parameters for Nd:YAG laser pretreatment of dentin, which has potential as a clinical method to strengthen bonding.

Comparative bonding performance of coronal dentin disks and CAD/CAM resin composite disks for biological restoration: The impact of resin-coating technique.

This study evaluated the bonding performance of coronal dentin disks, designed for biological restoration, and CAD/CAM resin composite disks when bonded to flat dentin surfaces using dual-cure resin cements, with and without a resin-coating (RC) technique. Three distinct groups were established within the non-RC group, each using one of the two types of resin cements in a self-adhesive mode: one-step self-etch adhesive (1-SEA) without light-cure, 1-SEA with light-cure, and a separate group using an alternate cement. Within the RC group, a subgroup was established for each cement. The microtensile bond strength (µTBS) of the disk-dentin beam was tested after 0 and 10,000 thermocycles in a 5°C/55°C. No significant µTBS difference was observed among the non-RC groups. However, when using RC, the µTBSs of coronal dentin disks significantly exceeded those of CAD/CAM resin composite disks. Thermocycle aging did not affect µTBS in any of the bonding methods, except in self-adhesive mode.

Adhesion of tooth fragment after trauma: effect of adhesion strategy and storage in the rescue box.

This study aims to investigate the impact of storage conditions for crown fragments (specifically, whether they were stored within a tooth rescue box or in tap water) on their adhesion to fractured teeth when subjected to two different adhesive systems (namely, total etch and self etch). Sixty maxillary premolars were sectioned to obtain tooth fragments. These fragments were stored briefly (2 hours) and reattached in the following groups: Group 1 (fragments stored in tooth rescue box and reattached with etch and rinse (E&R) technique), Group 2 (fragments stored in tap water and reattached with E&R technique), Group 3 (fragments stored in tooth rescue box and reattached with self-etch (SE) technique), and Group 4 (fragments stored in tap water and reattached SE technique). After reattachment, the bonded tooth fragments underwent thermal cycling (500 cycles, 5-55 °C) and bond strength testing using a universal testing machine. Two-way Analysis of Variance (ANOVA) and Tukey's tests were used for bond strength comparison (p ≤ 0.05). A two-parameter Weibull distribution was conducted to evaluate the reliability of the storage medium and adhesion modality on bond strength. The results showed that measured shear bond values (MPa ± Standard deviation (SD); arranged in descending order) for each group were: Group 2 (Tap water/E&R = 6.5 ± 2.1), Group 1 (Rescue box/E&R = 6.0 ± 2.5), Group 4 (Tap water/E&R = 5.1 ± 2.8), and Group 3 (Rescue box/SE = 3.6 ± 3.2). Significant differences were found only between Groups 2 and 3 (p = 0.002). In conclusion, storing crown fragments in a tooth rescue box did not significantly affect the shear bond strength of the restored tooth. However, fragments reattached using the self-etch technique showed comparable shear bond strength but a higher rate of adhesive failures compared to the E&R technique.

Exploring the role of flavonoids in caries-affected dentin adhesion: A comprehensive scoping review.

OBJECTIVES: The aim of this scoping review was to evaluate the available scientific evidence regarding the use of flavonoids in the treatment of caries-affected dentin focusing on bonding to dentin. METHODS: A comprehensive literature search was performed in five databases from March 2022 and updated in April 2023: PubMed, EMBASE, Scopus, Web of Science, and Scielo. Additionally, the references of included studies were manually searched. Gray literature was excluded from the review. STUDY SELECTION: Inclusion criteria included in vitro, in situ, and in vivo studies (animal or human) published in English. Abstracts, reviews, case reports, book chapters, doctoral dissertations, guidelines, and studies using pure plant extracts were excluded. Data collected from the selected studies were summarized and subjected to narrative and descriptive analysis. Out of the 91 studies identified, only 16 studies met the inclusion criteria. RESULTS: The review analyzed eight different flavonoids (hesperidin, galardin, proanthocyanidin, genipin, quercetin, naringin, epigallocatechin-3-gallate, and other catechins subtypes) used as pretreatment or loaded into adhesive systems, primers, and phosphoric acid. The use of flavonoids improved the mechanical properties of the materials and modified the biological properties of the dentin, reducing collagen loss by the inhibition of proteolytic activity of matrix metalloproteinases (MMPs). CONCLUSIONS: Based on the findings of this scoping review, it can be concluded that the use of flavonoids as pretreatment or incorporation into dental materials preserves collagen in the hybrid layer, inhibiting the MMPs activities, modifying the collagen fibrils of the dentin matrix and improving the mechanical properties of the dental adhesive systems. Therefore, it represents a promising approach for promoting dentin biomodification. This can result in more stable bonding of adhesive restorations to caries-affected dentin.

Promoting bond durability by a novel fabricated bioactive dentin adhesive.

OBJECTIVE: To prepare a bioactive dentin adhesive and investigate its effect on promoting bonding durability of dentin. METHODS: The mineralization of the bioactive glass with high phosphorus (10.8 mol% P2O5-54.2 mol% SiO2-35 mol% CaO, named PSC) and its ability to induce type I collagen mineralization were observed by SEM and TEM. The Control-Bond and the bioactive dentin adhesive containing 20 wt% PSC particles (PSC-Bond) were prepared, and their degree of conversion (DC), microtensile bond strength (µTBS), film thickness and mineralization performance were evaluated. To evaluate the bonding durability, dentin bonding samples were prepared by Control-Bond and PSC-Bond, and mineralizated in simulated body fluid for 24 h, 3 months, and 6 months. Then, the long-term bond strength and microleakage at the adhesive interface of dentin bonding samples were evaluated by microtensile testing and semiquantitative ELIASA respectively. RESULTS: The PSC showed superior mineralization at 24 h and induced type I collagen mineralization to some extent under weakly alkaline conditions. For PSC-Bond, DC was 62.65 ± 1.20%, µTBS was 39.25 ± 4.24 MPa and film thickness was 17.00 ± 2.61 µm. PSC-Bond also formed hydroxyapatite and maintained good mineralization at the bonding interface. At 24 h, no significant differences in µTBS and interface microleakage were observed between the Control-Bond and PSC-Bond groups. After 6 months of aging, the µTBS was significantly higher and the interface microleakage was significantly lower of PSC-Bond group than those of Control-Bond group. SIGNIFICANCE: PSC-Bond maintained bond strength stability and reduced interface microleakage to some extent, possibly reducing the occurrence of secondary caries, while maintaining long-term effectiveness of adhesive restorations.

Longitudinal bond strength of a universal adhesive and chemical dentin characterization under different acid etching protocols.

OBJECTIVE: This study aimed to analyze the longitudinal bond strength of a universal adhesive and chemically characterize the dentin substrate under different acid etching protocols. METHODOLOGY: Dentin samples were etched with polyacrylic acid 25% (PAA) for 10 seconds (n=3) and phosphoric acid 32% (PA) for 15 seconds (n=3) and analyzed by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) before and after treatment. For collagen degradation, samples (n=12) were divided into 3 groups: PAA, PA, and Deionized water (control), and analyzed by the quantity of solubilized type I collagen C-terminal cross-linked telopeptides and solubilized C-terminal peptide in relation to total protein concentration (ICTPtp and CTXtp) and by their ultimate tensile strength (UTS). For the adhesive interface analysis, dentin samples (n=72) were divided into 3 groups: PAA, PA, and Self-etch (SE), and subdivided into 2 groups: 24 h (baseline) and 1 year. The following tests were performed: microtensile bond strength (µTBS) (n=48), scanning electron microscopy (SEM) (n=12), and nanoleakage (n=12). RESULTS: The FTIR of PAA showed lower reduction of the peaks in the phosphate group when compared to PA. For ICTPtp, PA showed a significantly higher value. For CTXtp, PA and PAA groups failed to statically differ from each other. UTS was significantly lower for PA. For µTBS, storage time significantly affected bond strength. The results were unaffected by the etching protocol. For SEM, after 1 year, PA had little evidence of degradation in the upper third of the adhesive interface in comparison to the other groups. Nanoleakage showed no considerable silver impregnation after 1 year in the SE group. CONCLUSION: The use of PAA prior to a universal adhesive (when compared to PA) represents a less aggressive type of etching to dentin. However, self-etching still seems to be the best option for universal adhesive systems that have functional monomers in their composition.

Influence of airborne particle abrasion on dentin bonding effectiveness of a 2-step universal adhesive.

OBJECTIVE: To determine the effect of airborne particle abrasion (APA) on micro-tensile bond strength (µTBS) to dentin using different air-abrasion/polishing powders. METHODS: The bonding effectiveness of G2 Bond Universal (G2B), used in etch-and-rinse (E&R) and self-etch mode (SE), was tested on bur-cut dentin and dentin air abraded/polished using six different powders (aluminum oxide 29 µm (AO29) and 53 µm (AO53), aluminum trihydroxide (AT), sodium bicarbonate (SB), sodium bicarbonate soft (SBsoft) and bioactive glass (BG); Velopex). Adhesive-composite resin specimens were immersed in distilled water at 37 °C for one week and cut into microspecimens. Half of the specimens were subjected to 50,000 thermocycles (aged). Immediate and aged µTBS to dentin were measured. Statistical analysis was performed using linear mixed-effects (LME) modeling (p < 0.05). RESULTS: Comparing the aged bond strengths to air-abraded/polished dentin with bur-cut dentin, pretreatment with SB and SBsoft in combination with G2B used in E&R mode, and BG air polishing in combination with both application modes (E&R, SE), resulted in a significantly higher bond strength. Dentin bond strength was only significantly lower when air abraded with AO29 and using G2B in SE mode. Aging did not significantly influence bond strength for both application modes (E&R, SE), except for AO29 and AT-treated dentin, where bond strengths decrea sed significantly using G2B in SE mode. In general, G2B reached significantly higher bond strengths on air-abraded/polished dentin in E&R mode than in SE mode. CONCLUSION: Air-abrasion/polishing did not impair dentin bond strength using G2B, except when dentin was air abraded with AO29 and using G2B in SE mode. Air polishing positively influenced the bond strength to dentin in specific groups. CLINICAL SIGNIFICANCE: APA is safe concerning bonding to dentin. The E&R application mode is preferred using G2B as adhesive on air-abraded/polished dentin. Air polishing with BG positively influenced dentin bond strength for both application methods.

Effect of sodium hypochlorite, ethylenediaminetetraacetic acid, and dual-rinse irrigation on dentin adhesion using an etch-and-rinse or self-etch approach.

The aim was to investigate the influence of endodontic irrigation solutions and protocols on the micro-tensile bond strength (µTBS) to dentin using an etch-and-rinse (ER) or self-etch (SE) adhesive approach. Eighty extracted human molars were ground to dentin. After pretreating for 27 min (21 min-3 min-3 min) with five different endodontic irrigation protocols (Group 1: NaOCl-EDTA-NaOCl; Group 2: NaOCl-NaOCl-EDTA; Group 3: NaOCl-NaCl-NaOCl; Group 4: Dual Rinse-Dual Rinse-Dual Rinse; Group 5: NaCl-NaCl-NaCl), an ER (Optibond FL, Kerr) or a SE (Clearfil SE Bond, Kuraray) adhesive system was applied. After light-curing, composite build-ups were made and cut into dentin-composite sticks. µTBS and failure modes were analyzed. Nonparametric statistical analyses (α = 0.05) were performed for comparison of the five groups within each type of adhesive as well as between the two adhesive systems used. The use of an ER instead of a SE adhesive system resulted in significantly higher µTBS for all irrigation protocols except for group 1 (NaOCl-EDTA-NaOCl) and 2 (NaOCl-NaOCl-EDTA). A statistical difference between the five different endodontic irrigation protocols was only found within the SE adhesive group, where group 1 (NaOCl-EDTA-NaOCl) achieved highest values. The use of an ER adhesive system cancels out the effect of the endodontic irrigation solution. The highest µTBS was achieved when using a NaOCl-EDTA-NaOCl-irrigation protocol in combination with Clearfil SE Bond, which shows that the selection of the endodontic irrigation should match the corresponding SE adhesive system.

Marginal adaptation of two-step self-etch versus universal adhesives for Class V restorations: Effect of Er:YAG laser vs. bur prepared cavities.

PURPOSE: To compare the in vitro effect of laser and bur preparation on marginal adaptation of Class V cavities restored with a 2-step self-etch and distinct universal one-component universal adhesives used in self-etching mode. METHODS: 96 Class V cavities were prepared with conventional burs or with an Er:YAG laser. Four universal self-etch (Unibond Extra Low Shrinkage, All Bond Universal, SKB-100 and Prime&Bond active) and a 2-step self-etch adhesive (Clearfil SE Bond) that served as control were used to restore the cavities with direct composite. The percentages of continuous margins were evaluated by quantitative SEM analysis before and after a fatigue test consisting of 240,000 occlusal loads and 600 warm/cold thermal cycles. RESULTS: The marginal adaptation of bur prepared restorations was statistically superior to laser-prepared ones. Class V cavities restored with Clearfil SE Bond and the one-component self-etching universal adhesives All Bond Universal and Prime&Bond active presented the highest and statistically similar percentages of continuous margins before and after loading under both bur and laser cavity preparation. The lowest percentages of continuous margins were observed in the groups restored with the low shrinking adhesive (Unibond ELS), with medians of 49 and 21 for bur and laser prepared cavities after loading. CLINICAL SIGNIFICANCE: Class V cavities presented smoother and higher percentages of continuous margins when prepared by bur rather than by laser. The 2-step self-etch adhesive Clearfil SE Bond and 1-step self-etch universal adhesives All Bond Universal and Prime&Bond active showed a comparable marginal performance.

Effect of ultrasonic and sonic instrumentation on shear bond strength of resin composite to enamel: An in vitro study.

PURPOSE: To assess and compare the effects of sonic and ultrasonic instrumentation on shear bond strength (SBS) and investigate the influence of adhesive system application modes (etch&rinse/self-etch) on SBS. METHODS: In this experimental study, 45 extracted sound human molars were selected. Mesial and distal surfaces of the teeth were abraded until 90 smooth enamel surfaces were obtained. Specimens were divided into two groups, with half (N= 45) conditioned in etch&rinse mode and the remaining (N= 45) in self-etch mode using Tetric N Bond Universal. Composite resin discs were produced on these surfaces by filling Teflon molds. All specimens were aged via thermocycling. Each group was further divided into three more groups (n= 15) according to the type of periodontal instrumentation (ultrasonic, sonic or none). SBS values were recorded and analyzed using two-way ANOVA. Fracture sites were examined under a stereomicroscope. RESULTS: The type of periodontal instrumentation had no significant effect on SBS values, whether sonic, ultrasonic or their absence (P= 0.945). The type of adhesive system mode had a significant influence on the shear bond strength values. Etch&rinse groups had significantly higher shear bond strength values than self-etch groups (P< 0.001). CLINICAL SIGNIFICANCE: This study reassures practitioners that sonic and ultrasonic instruments are safe for enamel bonding and highlights the importance of selecting adhesive techniques for optimal restorative outcomes.

Shear bond strength of universal adhesives to human enamel and dentin.

OBJECTIVE: The composition of universal adhesives is highly diverse. The purpose of this in vitro study was to compare the shear bond strength of a composite with five different universal adhesives to human enamel and dentin. MATERIALS AND METHODS: The shear bond strength of a composite (G-aenial Universal Injectable) to human enamel and dentin was tested in selective enamel etching mode before and after thermocyclic aging (10,000 cycles) using five different universal adhesive systems (Adhese Universal VivaPen, Clearfil Universal Bond Quick, G-Premio Bond, Prime&Bond active, and Scotchbond Universal Plus). Two-bottle systems (OptiBond FL and G2-Bond Universal) were used as control. Scanning electron microscopy was conducted of the bonding interface. RESULTS: Significant differences in shear bond strength values were found among the five evaluated universal adhesives. Lowest shear bond strength values were observed for 2-hydroxyethylmethacrylate (HEMA)-free systems. Thermocyclic aging did not significantly reduce shear bond strength values indicating that the initial bond remains stable. CONCLUSIONS: The clinical use of universal adhesives Adhese Universal VivaPen, Clearfil Universal Bond Quick, and Scotchbond Universal Plus can be encouraged as they provided comparable or even better shear bond strength values than the two-bottle controls. CLINICAL SIGNIFICANCE: Universal adhesives that were developed for the same indication and approved for clinical use demonstrated variety in shear bond strength values. When applied in the selective enamel etching mode, a stable bond can be expected from adhesives containing HEMA and monomers with phosphate groups.

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

OBJECTIVES: 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). METHODS AND MATERIALS: 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. RESULTS: 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. CONCLUSIONS: 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.

Bond strength comparison of a fiber-reinforced composite resin: Different dentin conditions and preparation techniques.

This study aimed to compare the bond strength of a fiber-reinforced composite resin with traditional and bulk-fill composite resins under different dentin conditions and preparation techniques. Eighty molar teeth, excluding the mesio-distal half of the occlusal dentin surfaces of each teeth, were isolated with acid-resistant nail varnish and stored in a demineralisation solution (pH 4.5). After mechanical removal of the varnish, the teeth were buried in acrylic resin blocks. In every composite resin group, one-half of the specimens were prepared with a diamond bur and another half with Er: YAG laser. Then, the specimens were divided into four groups of composite resins (Filtek Z250, G-aenial Posterior, SonicFill 2, Ever X Posterior) (n = 10). Shear bond strengths were measured using a universal testing device, and failure types were determined with stereomicroscope images. SEM images were obtained at 1000× magnification. Data were analyzed using a three-way analysis of variance (ANOVA), and Bonferroni correction was used for multiple comparisons (p = .05). Differences in the dentin surface affected the bond strength results (p < .05), whereas there was no significant difference between cavity preparation methods (p > .05). EverX Posterior showed the highest bond strength results. Within the limitations of this study, fiber-reinforced composite resin exhibited successful bond strength results in addition to improved mechanical properties. RESEARCH HIGHLIGHTS: Fiber-reinforced composite had successful bond strength values. Bond strength values of sound dentin groups were higher than those of caries-affected dentin groups. The use of an Er: YAG laser for preparation did not lead to insufficient bond strength results.

Effect of experimental dentin etchants on dentin bond strength, metalloproteinase inhibition, and antibiofilm activity.

OBJECTIVE: this study evaluated dentin microtensile bond strength (µTBS) and failure modes (at 24 h and one year), bonding interface regarding hybridization, surface morphology regarding demineralization, in situ metalloproteinase (MMP) activity, and antibacterial effect of three dentin etchants compared to 35% phosphoric acid (PA). MATERIALS AND METHODS: The Adper Single Bond 2 adhesive (3 M Oral Care) was applied on moist dentin etched with PA (control) or on air-dried dentin etched with 3% aluminum nitrate + 2% oxalic acid (AN), 6.8% ferric oxalate + 10% citric acid (FO), or 10% citric acid (CA). The µTBS test used 40 human teeth (n = 10). Failure modes and surface morphology were analyzed by scanning electron microscopy (n = 3), while bonding interface morphology and MMP activity were evaluated by laser scanning confocal microscopy (n = 3). Antibacterial activity was evaluated against S. Mutans biofilm by means of viable cells count (CFU/mL). RESULTS: PA presented the highest bond strengths regardless of aging time. PA, AN, and CA showed stable bond strengths after one year of storage. Adhesive and mixed failures were predominant in all groups. Thin hybrid layers with short resin tags were observed for the experimental etchants. The AN-based etchant was able to inhibit MMP activity. All tested etchants presented antibacterial activity against S. Mutans biofilm. SIGNIFICANCE: This study suggests different dentin etchants capable of inhibiting MMP activity while also acting as cavity disinfectants.

Clinical evaluation of posterior restorations over wet and dry dentin using an etch-and-rinse adhesive: A 36-month randomized clinical trial.

OBJECTIVES: To evaluate the clinical performance of posterior restorations over wet and dry dentin with an etch-and-rinse adhesive after 36 months of clinical service. METHODS: Forty-five participants were recruited, each one had at least two posterior teeth that needed restoration. Ninety restorations were placed on Class I or Class II cavities. For the restoration protocol, a simplified etch-and-rinse adhesive (Adper Single Bond 2) was applied over wet (WD) or dry dentin (DD) and later restored with a bulk-fill composite (Filtek Bulk Fill) under rubber dam isolation. Each restoration was evaluated using the World Dental Federation (FDI) criteria after 6, 12, and 36 months of clinical service, regarding the following principal restoration characteristics: postoperative sensitivity, marginal discoloration, marginal adaptation, fracture of material and retention, and recurrence of caries. Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used for statistical analysis. RESULTS: After 36 months of clinical evaluation, no significant difference between groups was observed in each FDI criterion (p > 0.05). Twenty restorations (WD=10, DD=10) showed minor marginal staining, and twenty-two restorations (WD=11, DD=11) presented small marginal adaptation defects (p > 0.05). Four restorations were lost (WD = 2, DD = 2) and the fracture rates (95% confidence interval) were 94.9% for each one, without significant difference between wet and dry dentin (p > 0.05). SIGNIFICANCE: The degree of dentin moisture does not seem to affect the clinical performance of a simplified etch-and-rinse adhesive in posterior restorations when the adhesive is applied vigorously over the dentine surface.

Effect of Silver Diamine Fluoride on Bonding Performance and Ultra-morphological Characteristics to Sound Dentin.

OBJECTIVES: This study aimed to evaluate microtensile bond strength (µTBS) and ultra-morphological characteristic changes in sound dentin resulting from silver diamine fluoride (SDF) when using adhesives. METHODS: Ninety-six extracted human third molars were divided into the SDF-contaminated dentin group and the sound dentin group. In the SDF-contaminated dentin group, 38% SDF was agitated for 1 min, left undisturbed for 2 min, and rinsed with distilled water for 30 s. Then, each group was further subdivided into six subgroups (n = 8 / group) according to application modes: self-etch mode (SE) and etch-and-rinse mode (ER) followed by three adhesives: (1) Scothbond Universal Plus Adhesive (SUP); (2) G2-Bond Universal Adhesive (G2B); and (3) Clearfil Mega Bond 2 (MB2). All specimens were restored with resin composite and were stored in distilled water for 24 h before µTBS testing. Data from the µTBS test were analyzed using Three-way ANOVA and Duncan test (p < 0.05). The morphology of fractured surface and adhesive-dentin interfaces were evaluated by SEM, TEM, and STEM. Further elemental analysis was done by EDX. RESULTS: All SDF-contaminated dentin groups demonstrated significantly lower µTBS than sound dentin groups. All ER groups had higher µTBS than SE groups, except for G2B in the sound dentin group. STEM/EDX revealed an SDF-dentin-reacted layer in the SDF-contaminated dentin group. SIGNIFICANCE: SDF had an adverse effect on adhesives. Additionally, ER mode is preferable when bonded to SDF-contaminated dentin. A calcium and fluoride-contained layer was observed in all SDF-contaminated dentin.

Effect of phosphoric acid containing polyvinylpyrrolidone as protective etchant for dentin bonding.

STATEMENT OF PROBLEM: Phosphoric acid is commonly used in dentistry as an etchant but can result in excessive demineralization of dentin, a major contributor to the instability of dentin-bonded restorations. Nevertheless, research on the development of etchants that can reduce acid damage is sparse. PURPOSE: The purpose of this in vitro study was to investigate the effects of polyvinylpyrrolidone-modified phosphoric acid on the dentin bonding of an etch-and-rinse adhesive. MATERIAL AND METHODS: Protective etchants were prepared by adding polyvinylpyrrolidone to 35% phosphoric acid aqueous solutions: the 3 concentrations were 0.5% (P0.5% group), 1% (P1% group), and 2% (P2% group) w/v. The treatment agent of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), microhardness, microtensile bonding strength (µTBS), nanoleakage, and in situ zymography were used to evaluate the appearance of the protective etchant on dentin bonding. The results were analyzed with a 1-way ANOVA test (α=.05). RESULTS: SEM showed no obviously exposed collagen fiber in the P1% and P2% groups. FTIR showed less demineralization of the dentin surface, and microhardness was higher after treatment with the protective etchant (P<.05). The µTBS of P1% (70 ±9.2 MPa) was the highest, and group C (44 ±5.8 MPa) was the lowest in all groups (P<.05). Moreover, there was weaker MMP activity in the P1% and P2% groups (P<.05). CONCLUSIONS: This study demonstrated that the protective etchant effectively reduced demineralization, enhanced bond strength, and reduced nanoleakage and enzyme activity within the hybrid layer.