Microtensile Bond Strength Research Articles

Surface mineral deposition and mechanical properties of one-step bonding agent with copper-modified niobium nanoparticles – An in vitro study

This study aimed to investigate the incorporation of copper-modified niobium (Nb/Cu) nanoparticles at concentrations of 0.1 % and 0.3 wt% in a one-step adhesive (PacBond Adhesive). Thirty sound human third molars were randomly divided into three groups: control, 0.1NbCu, and 0.3NbCu. Specimens were restored with PacBond and resin composite OptiComp, Composite LC. Stick specimens (0.64 mm2) were obtained and subjected to microtensile bond strength (MTBS) testing (n = 10) using a universal testing machine at a rate of 0.5 mm/min after 24 h and 6 months. Scanning electron microscope (SEM) analysis, microhardness after 24 h and immersion in ethanol (HK) (n = 7), degree of conversion (DC) (n = 6), and surface mineral deposition (n = 3) were also conducted. Data were analyzed using two-way ANOVA for MTBS and HK, and one-way ANOVA for %SHL and DC, all of them were followed by Tukey's test (p < 0.05). For MTBS, statistical difference in storage times was observed for 0.1NbCu after 24 h (p = 0.007). There was no statistical difference between the control and 0.3NbCu regarding time and materials after 24 h and 6 months (p = 0.065). There was no statistical difference among the groups for DC (p = 0.278), but there was a significant difference among the groups for the factor of time in HK measurements (p = 0.047). The 0.1NbCu and 0.3NbCu groups exhibited absorbance Bands indicative of surface mineral deposition after 14 and 21 days, and the 0.3NbCu interface showed better preservation in SEM analysis. The concentration of 0.3 % NbCu in a one-step adhesive appears promising and may offer enhanced longevity for the tooth/restoration interface.

Effect of silver diamine fluoride application on the microtensile bond strength of three commonly used restorative materials in primary teeth: An ultrastructural study.

Caries in primary teeth rapidly advances owing to its thin structure, thereby requiring restoration. However, restorations often fail due to various causes such as secondary caries and reduced microtensile bond strength (μTBS), which calls for the use of antimicrobial agents such as silver diamine fluoride (SDF). This study aims to measure and analyse the effect of SDF application on the μTBS of three regularly used restorative materials to dentin of primary teeth as well as compare the types of bond failure interfaces under SEM. The study comprised 60 samples equally divided into six groups among three restorative materials, namely, glass ionomer cement (GIC, Groups I and II), resin-modified glass ionomer cement (RMGIC, Groups III and IV), and composite resin (Groups V and VI) with subdivisions of A and B, where A represented samples with SDF application and B represented samples without SDF application. It was observed that μTBS of RMGIC to sound and carious dentin irrespective of SDF application was found to be statistically significant (P < 0.05), and when GIC, RMGIC, and composite resins were compared to both sound and carious dentin irrespective of SDF application, it was statistically significant (P < 0.05). SEM analysis revealed predominantly cohesive failures among all the groups. Based on the results, it was concluded that SDF has no adverse effect on the μTBS of GIC, RMGIC, and composite resin to both carious and sound dentin of primary teeth.

Comparison of microtensile bond strength of prepared teeth treated with proanthocyanidin, Camellia sinensis - Polyphenols, and metal crowns luted with resin-modified glass ionomer cement: An in vitro study.

The aim of this study was to evaluate the effect of proanthocyanidin and C. sinensis-polyphenols on microtensile bonding properties of prepared teeth with resin-modified glass ionomer cement (GIC). This was an in vitro study. Seventy-eight maxillary premolars were selected and mounted into auto-polymerizing acrylic resin blocks. The samples were prepared and metal crowns were fabricated. The samples were randomly divided into three groups. Samples under Group 1 were not treated with any of the extracts and followed conventional bonding protocol. Samples under Group 2 and Group 3 were treated with proanthocyanidin and C. sinensis-polyphenols, respectively. After dentin treatment, these samples were luted to metal crowns using resin-modified GIC. Universal testing machine was used to measure the load at which the crowns were debonded and microtensile bond strength in MPa was calculated. The results were statistically analyzed using one-way ANOVA and post hoc Tukey HSD. Samples treated with C. sinensis polyphenols (Group 3) had maximum bond strength followed by Group 2, where the samples were treated with proanthocyanidin. C. sinensis polyphenols due to their anti-proteolytic and antioxidant properties showed improved bond strength compared to proanthocyanidin, a cross-linking agent, followed by conventional bonding protocol.

Effect of Simulated Intrapulpal Pressure on Microtensile Bond Strength of Self-adhesive Resin Composite to Dentin

Effect of Simulated Intrapulpal Pressure on Microtensile Bond Strength of Self-adhesive Resin Composite to Dentin

Effect of trialkoxysilane/aminosilane-containing universal adhesive on resin-ceramic microtensile bond strength and ceramic wettability: An in-vitro study

BackgroundThe dual-silane (trialkoxysilane/aminosilane) universal adhesive (UA) is claimed for its enhanced priming capacity of glass-ceramics. ObjectiveThis study evaluated the effect of organofunctional trialkoxysilane- and organofunctional trialkoxysilane/aminosilane-containing UAs on the long-term resin–ceramic microtensile bond strength (μTBS) and wettability of ceramic. MethodsHydrofluoric acid-etched lithium disilicate discs were distributed into four groups as follows: (control), no priming was performed; (MBN), primed using a silane-based primer (Monobond N); (SBU), primed using a trialkoxysilane-containing UA (Single Bond Universal Adhesive) and (SBP), primed using a trialkoxysilane/aminosilane-containing UA (Scotchbond Universal Plus Adhesive). Ceramic discs were cemented into blocks then sectioned into microbeams stored in distilled water at 37° for 1 year. The μTBS was evaluated followed by assessment of the failure modes. The contact angle of the two UAs was measured with a goniometer using the sessile drop technique. ResultsMBN significantly improved the resin-ceramic μTBS (31.71 ± 6.33 MPa) compared to the control group. The resin-ceramic μTBS obtained after priming using SBP (22.83 ± 3.42 MPa) was comparable to those of MBN. SBU showed significantly inferior resin-ceramic μTBS (16.02 ± 6.28 MPa) compared with MBN. Mixed failures mode patterns were the most frequent in the groups. The ceramic wettability of both UAs did not significantly differ. ConclusionCeramic priming using a UA with dual-silane monomers (organofunctional trialkoxysilane/aminosilane) resulted in long-term adhesion comparable to a silane-containing primer. Incorporating aminosilane monomer in UA formulation did not affect the wetting of characteristics of the UA solution and enhanced its glass-ceramic priming capacity. Clinical significanceThe use of UA with optimized silane content as a primer for glass-ceramics simplifies clinical adhesive procedures including resin cementation and repair of ceramic restorations.

The Effect of Carbamide Peroxide Bleaching Gel with and without Remineralizing Agents on Microtensile Bond Strength of Resin Composites to Enamel

Introduction: Carbamide peroxide bleaching gel, along with remineralizing agents, can induce changes in the structure and mineral content of enamel, potentially leading to a decrease in the bond strength of resin composite to the enamel. Therefore, this laboratory study aimed to determine the effect of carbamide peroxide bleaching gel with and without remineralizing agents on the microtensile bond strength (µTBS) of resin composites with microhybrid and nanofill structures to enamel. Materials and Methods: Thirty extracted third molar teeth were randomly divided into five groups, each group subdivided into two equal subgroups: Group 1: Control group, Group 2: Bleaching gel without fluoride, Group 3: Bleaching gel containing fluoride, Group 4: Bleaching gel containing CPP-ACP, and Group 5: Bleaching gel containing fluoride and CPP-ACP. In the first subgroups, nanofilled resin composite Filtek Z350, while in the second subgroups, microhybrid resin composite Filtek Z250 were bonded to enamel surface. After specimen preparation, µTBS was measured using a universal testing machine. Data were analyzed using parametric tests (P value&lt;0.05). Results: The highest µTBS of resin composite to enamel was observed in the control group, while the lowest bond strength was seen in the fluoride-containing bleaching group. Comparisons of µTBS between the study groups pairwise, except for the comparison between the control group and the bleaching group, the bleaching group with (CPP-ACP+Fluoride), and the (CPP-ACP) group with the fluoride group, showed significant differences in bond strength. Although, the mean µTBS of the Filtek Z250 composite was higher than the Filtek Z350 composite in all groups, but this difference was not statistically significant. Conclusion: The use of carbamide peroxide bleaching gel with remineralizing agents leads to a decrease in µTBS of the resin composite to the enamel.

Effect of photodynamic therapy with two photosensitizers on the microtensile bond strength of a universal adhesive to affected dentin

BackgroundThis study aimed to evaluate the impact of photodynamic therapy (PDT) using two photosensitizers, methylene blue and indocyanine green, on the microtensile bond strength of a universal adhesive to caries-affected dentin. MethodsThe occlusal enamel of 60 third molars was cut to expose the inner one-third of the dentin. Artificial caries were induced through a pH cycling process. The samples were divided into three groups: M (Methylene blue+ diode laser), I (Indocyanine green agents+ diode laser irradiation), and control. Each group was further divided into two subgroups according to the adhesive protocol (self-etch, total-etch). After restoring with Gradia composite resin, teeth were sectioned and exposed to 5000 thermal cycles. Microtensile bond strength was measured using a universal testing machine. The data were subjected to two- and one-way ANOVA and paired comparisons were performed by the Tamhane and Tukey tests. ResultsThe study found significant effects of the photosensitizer, etching pattern, and their interactions on the microtensile bond strength of composite resin to caries-affected dentin (P < 0.001). In the self-etching mode, PDT with indocyanine green exhibited significantly higher bond strength values compared to PDT with methylene blue (P = 0.001) and the control groups (P < 0.001). However, no significant differences were observed in the total-etch mode. (P = 0.54). ConclusionsThe etching mode played a more significant role in the bond strength when using the universal adhesive alongside PDT with methylene blue and indocyanine green. Employing two photosensitizers in PDT during the self-etch mode significantly increased the bond strength values.

Effects of Internal Bleaching on Microtensile Bond Strength of a Former Veneer Composite to Tooth Enamel

Background: At present, combined provision of direct composite restorations and dental bleaching has become increasingly popular to meet the esthetic demands of patients. This study aimed to assess the effect of internal bleaching on microtensile bond strength of composite to freshly veneered enamel. Methods: In this in vitro experimental study, 50 sound extracted human premolars were randomly divided into five groups (n=10). All teeth received composite veneers. Two groups underwent no further intervention and were subjected to measurement of microtensile bond strength of composite to enamel 24 hr and one week after the veneering. The remaining three groups underwent internal bleaching. Group 3 underwent bleaching one month after the veneering, and microtensile bond strength was measured after 24 hr. In groups 4 and 5, bleaching was performed immediately after the veneering. Microtensile bond strength was measured after 24 hr in group 4 and after one month in group 5. Data were analyzed using one-way ANOVA. Results: All the groups were not significantly different regarding the mean bond strength (p=0.110), but they were significantly different in terms of the mode of failure (p=0.01) such that the mode of failure was mainly adhesive in the three bleached groups. Conclusion: Internal bleaching after composite veneering has no significant effect on microtensile bond strength of composite to the enamel.

Prodelphinidins enhance dentin matrix properties and promote adhesion to methacrylate resin

ObjectiveInvestigate the bioactivity and stability of Rhodiola rosea (RR) fractions as a natural source of prodelphinidin gallate (PDg) on dentin collagen via analysis of the viscoelastic and resin-dentin adhesive properties of the dentin matrix. MethodsThe biomimicry and stability of RR subfractions (F1, F2, F3 and F4) with collagen were determined by dynamic mechanical analysis (DMA). DMA used a strain sweep method to assess the dentin matrix viscoelastic properties [storage (E’), loss (E”), and complex (E*) moduli and tan δ] after treatment, 7-, 30- and 90-days of storage in simulated body fluids (SBF). Resin-dentin interface properties were assessed after 1 and 90-days in SBF by microtensile bond strength test and confocal laser scanning microscopy. Data were analyzed using two and one-way ANOVA and post-hoc tests (α = 0.05). ResultsRR fractions increased dentin matrix complex (96 - 69 MPa) and storage (95 - 68 MPa) moduli, compared to the control (∼9 MPa) in the ranking order: F2 ≥ F3 = F1 = F4 > control (p < 0.001). Treatment did not affect tan δ values. After 30- and 90-days, RR-treated dentin E*, E’ and tan δ decreased (p < 0.001). F2 fraction yielded the highest microtensile bond strength (43.9 MPa), compared to F1, F4 (35.9 - 31.7 MPa), and control (29 MPa). RR-treated interfaces mediated stable surface modifications and enhanced collagen-methacrylate resin interactions at the bioadhesive interface. SignificanceProdelphinidin gallates from RR are potent and reasonably stable biomimetic agents to dentin. Higher potency of F2 fraction with the dentin matrix and the adhesive interface is associated with a degree of polymerization of 2–3 and gallo(yl) motifs.

Is there a correlation between physical properties and film thickness of dual- and photo-polymerized resin cements and CAD/CAM-dentin micro-tensile bond strength?

To correlate µTBS of different resin cements with their film thickness (FT), Vickers hardness (HV), and ultimate tensile strength (UTS). Human molars (N = 30) were divided into six-groups according to 1: Resin cement: Bifix QM, (BF), GrandioSo Heavy Flow (GHF) and VisCalor Bulk (VB), and 2: Adhesive mode (Optibond Universal): Etch-and-rinse (E&R) or self-etching (SE). CAD/CAM blocks (7 × 7 × 4 mm3) were air-abraded using 50 μm Al2O3 and silane was applied (60 s), and air dried (10 s). For E&R, dentin was etched (15 s), rinsed (30 s), and blot-dried. For both modes, adhesive was applied (20 s), air-dried (5 s), and photo-polymerized (10 s). Sticks (1 × 1 mm2) were stored for 24-h or 6-months. Sticks were pulled in tension (1 mm/min). Debonded sticks were evaluated for failure mode analysis. For FT, nine-bonded slabs from each cement was prepared and evaluated. For UTS, eight-hourglass specimens from each cement were prepared and tested in tension. For HV, five-discs from each cement was prepared and evaluated using a HV tester. Data were analyzed using ANOVA/Pearson’s correlation tests (α = 0.05). No correlation between µTBS/HV was revealed (p > 0.05). A positive correlation between µTBS/FT and µTBS/UTS (p < 0.05) was observed. Three-way ANOVA revealed all experimental factors had a significant effect on µTBS (p < 0.05). The VB showed significantly lower µTBS (20.8 ± 9.3 MPa). The E&R mode showed higher µTBS (26.0 ± 10.9 MPa), and 24-h revealed a higher µTBS (27.4 ± 10.0 MPa). Mixed failure was the predominant type (42.51%). The VB showed the highest FT (122.2 ± 11.9 µm), with GHF revealed higher UTS and HV (112.5 ± 19.7 MPa and 91.6 ± 0.4 Kgf, respectively). Photo-polymerized flowable composite can substitute dual-polymerized cement for CAD/CAM composite bonding.

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

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

Influence of resin-coating techniques on the marginal adaptation and the bond strengths of CAD/CAM-fabricated hybrid ceramic inlays.

This study aimed to evaluate the effects of different resin-coating technique strategies and dual-cure resin luting materials on proximal marginal adaptation and the microtensile bond strengths (μTBSs) of CAD/CAM hybrid ceramic inlays. Extracted human molars were classified into four groups, depending on the coating technique: No coating (None), single coating (1-coating), double coating (2-coating), and flowable resin-coating (Combination). The inlays were bonded with one of the three materials: Panavia V5 (V5), Rely X Ultimate (RXU), and Calibra Ceram (CC). The differences with regard to adaptation were not significant. In the case of μTBS data for V5, no significant differences were observed, whereas for RXU, μTBS values for Combination statistically exceeded those for None and 1-coating. For CC, μTBS values for Combination statistically exceeded those for None, 1-coating, and 2-coating. The coating techniques did not influence the adaptation but influenced the bond strength, and Combination performed the best.

Assessment of the Micro-Tensile Bond Strength of a Novel Bioactive Dental Restorative Material (Surefil One).

The aim of this study is to assess the micro-tensile bond strength and the mode of failure of a bioactive hybrid self-adhesive composite (Surefil one) under various dentin conditions. Thirty-two extracted human molar teeth were used to test the micro-tensile bond strength of Surefil one under different dentine conditions (no treatment, 37% phosphoric acid etching, and universal adhesive) in comparison with a resin-modified glass ionomer (RIVA). All restorations were light cure-bonded onto flat dentine and then sectioned into beams. Then, fractured specimens were observed under a light microscope to evaluate the mode of failure. The Surefil one no-treatment group (NTG) exhibited the highest micro-tensile bond strength. Furthermore, there was no statistically significant difference observed between the Surefil one adhesive group (EAG) and the Surefil one acid etch group (EG). However, compared to other groups, the resin-modified glass ionomer (RIVA) produced the lowest results, which are statistically significant. Surefil one offers superior bond strength values when compared to resin-modified glass ionomers. Furthermore, Surefil one requires no dentin condition and has more straightforward clinical steps.

Microtensile bond strength and nanoleakage of self-etching adhesives containing different concentrations of 45S5 bioactive glass in caries-affected dentin

ObjectiveTo evaluate microtensile bond strength (μTBS) and nanoleakage (NL%) of self-etching adhesive systems containing different concentrations of bioactive particles when applied to caries-affected dentin: immediately and after 1 year of storage. Materials and methodsThree experimental self-etching adhesive systems were developed: (1) Experimental control adhesive (without glass), (2) adhesive containing 5 % 45S5 glass (45S5 5 %), and (3) adhesive containing 20 % 45S5 glass (45S5 20 %). Sound human molars were used (n = 7). The dentin surface was exposed, and half of the specimens were subjected to artificial caries induction, followed by partial removal of the carious tissue. Adhesives were applied to the dentin surface, and teeth were restored with composite resin and sectioned. Specimens undertook microtensile bond strength tests in a universal testing machine (Instron 3342) at 24-h and 1-year. Interfaces of the sectioned specimens were observed under a stereomicroscope to obtain the fracture mode. For nanoleakage test, specimens were infiltrated with silver nitrate and the interface was analyzed using a Scanning Electron Microscope (SEM) at 24-h and 1-year. Data were subjected to ANOVA test (three-way) and Holm-Sidak post-hoc (α = 0.05). ResultsFor μTBS (p = 0.574) and NL (p = 0.334) tests, there was no interaction between the 3 main factors (Material vs. Substrate vs. Time). There was an interaction between dentin and material for μTBS (p < 0.001) and NL (p = 0.005) tests. Bioactive adhesives with 5 % and 20 % concentration were not influenced by the type of dentin (p < 0.05). There was a reduction in μTBS values and an increase in NL values for the adhesive without bioactive glass in dentin affected by caries (p > 0.05). ConclusionBioactive glasses had therapeutic action on dentin. The bond strength values of bioactive adhesives were maintained in caries-affected dentin and had low nanoleakage values. Clinical significanceSelf-etching adhesives containing 45S5 bioactive glass have the potential to preserve the dentin substrate and improve the longevity of restorations with composite resins.

Extrafibrillar demineralization: Yes or no?

ObjectiveExtrafibrillar demineralization is considered to be an ideal solution for addressing the durability of resin-dentin bonding interfaces. However, its theoretical basis is contradictory to ionization equilibrium of hydroxyapatite dissolution. In this study, various calcium chelators were selected as dentin conditioners to explore the essence of dentin demineralization with chelators and its effect on resin-dentin adhesion. MethodsPolyethyleneimine grafted with EDTA and polyacrylic acid sodium (PAAN450k) larger than 40 kDa, as well as PAAN (PAAN3k) and EDTA smaller than 6 kDa, were prepared as dentin conditioners. The dentin powder was designed to characterize whether it would demineralize without contact with PAAN450k. Dentin demineralization effect with four conditioners was evaluated with field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy and quantification of hydroxyproline concentration after enzymatic degradation. Micro-tensile bond strength (µTBS) test and failure mode analysis were employed to assess the bonding effect of the four chelators in both wet and dry bonding, with H3PO4 wet bonding serving as the control group. ResultsDemineralization occurs when PAAN450k was not in direct contact with the dentin powder. The extrafibrillar demineralization cannot be induced by any chelator regardless of its molecular weight. Complete demineralization including extrafibrillar and intrafibrillar demineralization would occur with sufficient interaction time. Moreover, chelators could not provide a reliable dentin bonding effect under a short interaction time. SignificanceFrom the perspective of theory and application, extrafibrillar demineralization is not a reliable strategy, which provides a reminder for exploring new strategies in the future.

Influence of residues from bioceramic sealer on the bond interface with universal adhesive in different application modes.

This study evaluated the effect on adhesive layer thickness, bond strength, and adhesive failure pattern of the application of universal adhesive (Scotchbond Universal) using either manual or rotary brush in dentin previously impregnated with bioceramic sealer (Sealer Plus BC) using a manual brush, at 24h and 1 year. Eighty-eight bovine crowns were divided into four groups (n=22) according to the intervention: (i) use of bioceramic sealer and adhesive application using manual brush, (ii) use of bioceramic sealer and adhesive application using rotary brush, (iii) use of resin sealer and adhesive application using manual brush, and (iv) use of resin sealer and adhesive application using rotary brush. Subsequently, specimens were restored with a composite resin (Filtek Z-250). Adhesive layer thickness was evaluated using confocal microscopy. Bond strength was assessed using the microtensile bond strength test, and adhesive failure pattern was evaluated under a stereomicroscope. Data were analyzed using two-way ANOVA/Tukey tests. Specimens where a rotary brush had been used exhibited lower adhesive layer thickness. Specimens treated with resin sealer and using a manual brush showed lower bond strength values and a higher occurrence of adhesive failures at 24h and 1 year than specimens treated with bioceramic sealer and using rotary brush for adhesive application.

Enhancing bonding of zirconia lithium silicate ceramics to dentin: The effect of surface treatment and resin cement

This laboratory study evaluated the influence of surface treatments on surface topography, and the bonding of CAD/CAM (computer-aided design computer-aided manufacturing) zirconia-containing lithium silicate (ZLS) surfaces to human dentin using various contemporary resin cements. Specimens from ZLS CAD/CAM blocks (Celtra™ Duo and Vita™ Suprinity) underwent three surface pretreatments: grinding only; 5 % hydrofluoric acid etching followed by application of a silane coupling agent, and a self-etching ceramic primer. The specimens were bonded to a flat exposed dentin surface using two etch-and-rinse and two self-adhesive resin cements, and then sectioned into microspecimens for microtensile bond strength (μTBS) testing. Failure modes of bonded surfaces, and ceramic surface roughness and topography were assessed. Results indicated that surface treatment was essential for ZLS-dentin bonding. Hydrofluoric acid and silane, along with the self-etching primer resulted in comparable strengths and outperformed the control group. Etch-and-rinse cements yielded significantly higher μTBS than self-adhesive cements. Significant differences in surface roughness and topography were observed among the treatment groups. Hydrofluoric acid exhibited the highest roughness parameters and most prominent surface changes. These findings highlight the importance of surface treatment for enhancing zirconia-containing lithium silicate bonding to dentin, and emphasize the critical role of the resin cement choice in optimizing dental restorative outcomes.

Multi-acrylamides improve bond stability through collagen reinforcement under physiological conditions

ObjectivesAcrylamides were shown to significantly improve bonding stability in adhesive restorations, but the reinforcement mechanism has not been fully elucidated. We tested the hypothesis that hydrogen bonding reinforcement of the collagen network (with secondary or tertiary acrylamides), as well as degree of crosslinking of the polymer network (with di- or tri-functional acrylamides), can be two of the factors at play. MethodsTwo-step total etch adhesives comprising UDMA (60 wt%) and 40 wt% of: TAAEA, TMAAEA (secondary, tertiary tri-acrylamides), BAAP, DEBAAP (secondary, tertiary di-acrylamides) or HEMA (mono-methacrylate - control) were formulated. Simulated composite restorations (n = 5) were tested after cyclic mechanical and biological (S. mutans biofilm) challenges. Gap formation before and after aging was assessed with SEM imaging. Micro-tensile bond strength (μTBS, n = 6) was assessed after seven-day incubation in water or S. mutans-containing culture medium. Collagen reinforcement was assessed with hydroxyproline assay (n = 10) and rheology (n = 3). Data were analyzed with one-way/two-way ANOVA/Tukey’s test (alpha=5%). ResultsGap formation increased and bond strength decreased for all monomers after biofilm incubation (p < 0.001). Except for DEBAAP, secondary and tertiary di/tri-acrylamides showed lower occlusal gap width values, but no significant differences overall gap length compared to HEMA. μTBS increased for tri-acrylamides compared with HEMA. Samples treated with multi-acrylamides had lower concentration of hydroxyproline (by-product of collagen degradation) (p < 0.001), except for DEBAAP, which showed values close to HEMA (p > 0.05). Dentin shear modulus increased for all acrylamides after 72 h, especially TMAAEA. SignificanceIn general, multi-acrylamides promote collagen reinforcement, leading to reduced gap formation, and stabilize the bond strength under physiological conditions.

Bond Strength of Resin Cement Following Biomimetic Remineralization: An in vitro Study

Objectives This research assessed the efficacy of self-assembling peptide P11-4 (Curodont protect) in promoting biomimetic remineralization of dentin, thereby stabilizing the hybrid layer and enhancing the long-lasting of the resin-dentin bond. Methods Five premolar teeth were longitudinally sectioned to assess dentin microhardness before and after demineralization, as well as after the application of P11-4 (Curodont protect). For the microtensile test, ten premolar teeth were sectioned perpendicular to their long axes. The teeth were assigned to different groups. Following acid etching and rinsing, samples in control group I received no pretreatment, while the prepared dentin surface of group II was treated with 0.1 mL of P11-4 before the placement of the adhesive restoration. All specimens were stored in distilled water at 37 ± 2 °C for 24 hours and then underwent thermocycling. The microtensile test was measured, and the type of bond failure was evaluated. The obtained information, expressed in megapascals, was analyzed using a one-way analysis of variance (ANOVA), followed by Tukey’s multiple post hoc test. Results There was a statistically significant difference in hardness values after demineralization, followed by a significant increase in hardness after the application of P11-4 (Curodont protect) (p &lt; 0.001, effect size = 0.985). No statistically significant difference was found in the microtensile bond strength between the two groups (p = 0.384, effect size = 0.582). Adhesive-type failure was more commonly observed. Conclusion The use of self-assembling peptide P11-4 (Curodont protect) on dentin resulted in higher microhardness than the control group without adversely affecting resin cement bond strength.

Antibacterial Effect of Ozone on Cariogenic Bacteria and Its Potential Prejudicial Effect on Dentin Bond Strength-An In Vitro Study.

Ozone is increasingly utilized in dental caries treatment due to its antibacterial properties. In a context of limited studies and no consensus on protocols, this research aims to assess ozone's antibacterial efficacy on cariogenic bacteria and its potential adverse impact on dentin bond strength. Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei, and Actinomyces naeslundii suspensions were exposed to 40 μg/mL of ozone gas and 60 μg/mL of ozonated water (80 s) via a medical ozone generator. Negative and positive control groups (chlorhexidine 2%) were included, and UFC/mL counts were recorded. To examine microtensile bond strength (µTBS), 20 human molars were divided into four groups, and class I cavities were created. After ozone application, samples were restored using an etch-and-rinse and resin composite, then sectioned for testing. The SPSS v. 28 program was used with a significance level of 5%. The µTBS results were evaluated using one-way ANOVA, Tukey HSD, and Games-Howell. Bacterial counts reduced from 106 to 101, but dentin µTBS was significantly impacted by ozone (ANOVA, p < 0.001). Despite ozone's attractive antibacterial activity, this study emphasizes its detrimental effect on dentin adhesion, cautioning against its use before restorative treatments.