Resin-dentin Bond Strength Research Articles

Effects of lactic acid etching on immediate and aged bond strength of resin-dentin bonding interface.

To investigate the effects of lactic acid etching on the immediate and aged bond strength of the resin-dentin bonding interface, the resin-dentin bonding interface was evaluated 24 hours and 6 months later. A total of 42 isolated third molars were randomly divided into 6 experimental groups according to different lactate concentration (35%, 40%, 45%) and acid etching time (30 s, 45 s), with 37% phosphoric acid etching 15 s as a control. In each group, dentin samples were etched under different acidic conditions and bonded with Adper Single Bond 2 (3M ESPE) as directed. The immediate group was immediately stored in deionized water at 37 °C for 24 h, and the aging group was stored in artificial saliva at 37 °C for 6 months. Immediate and aged bond strengths were measured by a micro-tensile tester, and the specimen fracture surface was observed under a microscope. 14 isolated third molars were randomly divided into 7 groups, and each group was etched with acid. Collagen fibers morphology in dentin was examined after gradient dehydration with ethanol by scanning electron microscopy (SEM). Statistically, there was no difference between the resin-dentin immediate bonding strength of 35% lactic acid for 30 s and 37% phosphoric acid for 15 s, but the aged bond strength was greater than that of the phosphoric acid group. According to scanning electron microscope observations, the collagen fiber morphology in 35% and 40% lactate etching dentin 30 s groups was relatively intact compared with other groups. In conclusion, 35% lactic acid etching of dentin 30 s ensures both immediate and aged resin-dentin bond strength.

Comparison of a self-adhesive resin cement, a conventional and a bulk-fill resin composite for luting of indirect restorative materials; the effect of thickness and material factors on translucence, monomer conversion and resin-dentin bond strength

Introduction: With developing technology, the search for the most ideal material to be used in the cementation of indirect restorations continues. To determine the effect of thickness and material factors on monomer conversion, translucency, and resin-dentin bond strength in luting indirect restorative materials (IRM) of different thicknesses using a resin cement, a conventional and a bulk-fill resin composite. Materials and methods: Samples of lithium disilicate glass-ceramic material (IPS e.max) and ceramic-resin hybrid material (Lava Ultimate) in 2 and 4 mm thicknesses, were luted using RelyX U200 (a self-adhesive resin cement), X-tra fil (a bulk-fill resin composite) and Z250 (a conventional microhybride resin composite) to the dentin surface and subjected to bond strength test after thermal cycle. In addition, the translucency parameter (TP) of the prepared blocks and the degree of conversion (DC) of the luting materials were investigated. The data was statistically analyzed. Results: The bond strength of X-tra fil and Z250 was statistically higher than RelyX U200 (p0.05). The increase in thickness decreased the TP of IRMs and the DC of resins underlying Lava (p0.05). Conclusion: Conventional and bulk-fill resin composites can be alternative luting materials to resin cements. Thickness increase did not change bond strength, while decreased TP, and DC only for Lava Ultimate.

Investigating the antibacterial activity of Thyme Oil/TiO2 modified resins against oral pathogenic bacteria

Dental composites lack inherent antimicrobial activity, leading to secondary caries and restoration failure. This study developed a novel thyme oil/TiO2 nanoparticle filler to impart sustainable antibacterial functions to dental resins. TiO2 nanoparticles were synthesized via a sol-gel method and characterized as 20–30 nm crystalline anatase particles. Functionalization with thyme oil was confirmed by FTIR, with 5.8% thyme oil content measured by TGA. Resin disks containing 0.5–2 wt% thyme-TiO2 exhibited significant inhibition zones against S. mutans, L. acidophilus and C. albicans (8–12 mm) compared to thyme oil-free controls (0 mm) (p < 0.05). Thyme-TiO2 at 1–2 wt% showed sustained release of thyme oil over 15 days with bacterial viability reduction of 68–99% compared to unmodified resin (p < 0.05). Resin-dentin microtensile bond strengths were 45–50 MPa for 0.5–2 wt% thyme-TiO2 and not significantly different from control (p > 0.05). Likewise, flexural strength, elastic modulus and surface microhardness values were unchanged with thyme-TiO2 incorporation ≤ 2 wt% (p > 0.05). DPSC viability was > 90% for all resins, indicating good cytocompatibility. Overall, the thyme-TiO2 nanocomposite successfully endowed the dental resin with potent, long-lasting antibacterial effects without compromising key mechanical properties.

Effect of Nisin-based pretreatment solution on dentin bond strength, antibacterial property, and MMP activity of the adhesive interface

ObjectiveTo evaluate the effect of a Nisin-based dentin pretreatment solution on microtensile bond strength, antibacterial activity, and matrix metalloproteinase (MMP) activity of the adhesive interface. Materials and methods100 human molars were sectioned to expose dentin. The teeth were assigned to five groups (n = 20), according to the dentin pretreatment: 0.5%, 1.0%, or 1.5% Nisin; 0.12% chlorhexidine (positive control), and no solution (negative control), and divided into 2 subgroups: no aging, and thermomechanical aging. Specimens were etched with 37% H3PO4 for 15 s and submitted to the dentin pretreatment. Then, they were bonded with an adhesive (Adper Single Bond 2) and a resin composite for microtensile bond strength (μTBS) evaluation. Antibacterial activity against Streptococcus mutans was qualitatively examined using an agar diffusion test. Anti-MMP activity within hybrid layers was examined using in-situ zymography. Data were analyzed with two-factor ANOVA and post-hoc Tukey’s test (α = 0.050). ResultsFor μTBS, significant differences were identified for the factors “solutions” (p = 0.002), “aging” (p = 0.017), and interaction of the two factors (p = 0.002). In the absence of aging, higher μTBS was observed for the group 0.5% Nisin. In the presence of aging, all groups showed similar μTBS values. All Nisin concentrations were effective in inhibiting the growth of S. mutans. Endogenous MMP activity was more significantly inhibited using 0.5% and 1.0% Nisin (p < 0.050). Conclusion0.5% and 1.0% Nisin solutions do not adversely affect resin-dentin bond strength and exhibit a potential bactericidal effect against S. mutans. Both concentrations effectively reduce endogenous gelatinolytic activity within the hybrid layer. Clinical relevanceThe use of 0.5% and 1.0% Nisin solutions for dentin pretreatment potentially contributes to preserving the adhesive interface, increasing the longevity of composite restorations.

Comparison of Adhesion Performance of a Self-curing and a Light-curing Universal Adhesive to Various Dental Substrates and CAD/CAM Materials.

To compare the adhesion of a self-curing (Tokuyama Universal Bond, TUB) and a light-curing (Scotchbond Universal, SBU) universal adhesive to CAD/CAM materials, enamel, and dentin. This study also assessed differences in enamel adhesion between self-etch vs selective etching modes, as well as immediate and long-term adhesion to dentin for both adhesives. Shear bond strength (SBS) testing was used to assess adhesion to enamel, dentin, Lava Ultimate (LU), Vita Enamic (VE), IPS e.max CAD (LD), IPS e.max ZirCAD (3Y-Zir), and Lava Esthetic (5Y-Zir) (n = 10). Moreover, bonding to enamel in self-etch and selective etching modes (n = 10) as well as immediate and aged resin-dentin bond strength (24 h after bonding, after 100,000 thermal cycles [TC] and long-term storage) was evaluated using the microtensile bond-strength test (n = 30). Failure mode was also determined for the bonding to dentin. Statistical analyses consisted of one-way and two-way ANOVA with appropriate post-hoc Tukey-Kramer or two-sample t-tests, as well as the chi-squared or Fisher's exact test (α = 0.05). TUB and SBU universal adhesives presented similar bonding to LU, VE, 3Y-Zir, and 5Y-Zir. However, SBS for TUB was superior to SBU when bonding to lithium-disilicate glass-ceramic (IPS e.max CAD). SBU showed better adhesion to dentin and enamel when used in the self-etch mode, while TUB promoted strong bond strength to enamel in the selective etching mode. TUB after TC was the only aging condition that yielded a significant reduction in resin-dentin bond strength. In-vitro adhesion performance of the self-curing and light-curing universal adhesives varies depending on the dental substrate or CAD/CAM restorative material used for bonding.

Chemical analysis of n-propyl gallate used as pre-treatment for resin-dentin bond strength: In vitro study.

This study aimed to evaluate the effect of n-propyl gallate as pre-treatment for resin-dentin bond strength. The dentin pre-treatments evaluated included propyl gallate of concentrations 0.1% (w/v), 1.0% (w/v), and 10.0% (w/v), as well as glutaraldehyde 5.0% (v/v), and distilled water as a control treatment. Dentin specimens were prepared for Fourier Transformed Infrared Spectroscopy (FT-IR) (n=3/pre-treatment). Pre-treatments were actively applied to dentin blocks before performing the adhesive procedure to composite resin. Microtensile bond strength to dentin (μTBS) (n=8/pre-treatment) was determined after 24h and 6 months of storage. Data were submitted to a two-way ANOVA, followed by Tukey's post hoc test. As for FT-IR, propyl gallate 1%-treated specimens presented higher water, carbonate, collagen, and amide absorbance rates compared to other tested groups, while specimens pre-treated with glutaraldehyde and distilled water presented similar absorbance curves. Regarding μTBS, all concentrations of propyl gallate resulted in statistically significant higher bond strength values than distilled water at 24h. After 6 months of storage, propyl gallate 0.1% was the only group that maintained μTBS over time. Propyl gallate 0.1% might be a suitable dentinal pre-treatment due to being able to present chemical bonds with demineralized dentin and providing resin-dentin bond stability after 6 months of storage.

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.

Effect of Dentin Biomodification on Resin Dentin Bond Strength

Effect of Dentin Biomodification on Resin Dentin Bond Strength

Novel hydrolytic resistant antibacterial monomers for dental resin adhesive

ObjectivesTo evaluate the properties of novel hydrolytic resistant antibacterial monomers and to determine the properties of resin adhesives containing these monomers. MethodsMethacrylamide-based QAC (Quaternary Ammonium Compound) monomers, 1-(11-Methacryla-midoundecyl)pyridine-1-ium bromide (MAUPB) and 1-(12-Methacryl-amidododecyl)pyridine-1-ium bromide (MADPB), and their methacrylate-derivatives, N-(1-Methacryloylundecanyl)pyridinium bromide (MUPB) and N-(1-Methacryloyldodecanyl)pyridinium bromide (MDPB), were synthesized and characterized. The minimum inhibitory (MIC) and bactericidal (MBC) concentrations were determined against S.mutans and E.faecalis. Cytotoxicity of unpolymerized monomers were evaluated using L-929 and MDPC-23. Each monomer was incorporated into experimental resins (BisGMA/TEGDMA/CQ/EDMAB or BisGMA/HEMA/CQ/EDMAB) at 10wt%. FTIR Spectra were collected for degree of conversion (DC%) measurement. Bacterial attachment on resin disks were determined by fluorescent microscope. Mechanical properties of experimental resins were evaluated by flexural strength & modulus and shear bond strength testing. ResultsThe antibacterial activity of MDPB≥MUPB>MADPB>MAUPB. The TC50 of MAUPB> MADPB>MUPB >MDPB. Incorporation of MAUPB in BisGMA/TEGDMA-based resin, had no significant effect on DC%, while significantly increase DC% in BisGMA/HEMA-based Resin. MUPB and MAUPB containing resins showed less viable bacterial attachment than pure resins. After 3-month storage, resins containing MAUPB illustrated higher flexural strength than their corresponding resins containing MUPB. BisGMA/HEMA-based resin containing MAUPB illustrated significantly higher resin-dentin shear bond strength than that of MUPB and pure resin. ConclusionsMethacrylamide monomer containing QAC, MAUPB, possessed antibacterial properties and superior physical and mechanical properties when incorporated in resin adhesives as compared to their corresponding methacrylate monomer, MUPB. Clinical significanceMethacrylamide-based QAC monomers are potentially used to formulate antibacterial hydrolytic resistant resin adhesives and enhance resin-dentin bond strength.

Effect of Chlorhexidine on Immediate and Delayed Bond Strength between Resin and Dentin of Primary Teeth: A Systematic Review and Meta-Analysis.

Objectives: The purpose of this study was to systematically review the literature and use meta-analysis to investigate whether chlorhexidine (CHX) application after acid etching as an adjunct treatment has any influence on the immediate and delayed bond strength to primary dentin. Materials and Methods: In this review, PubMed, ISI (all data bases), Scopus and Cochrane were searched according to the selected keywords up to April 30, 2018. The full texts of all published articles that met our primary inclusion criteria were obtained. The studies were analyzed in two parts: in vitro studies that evaluated the effect of CHX application during the bonding procedures (application after acid etching) on immediate and delay dentin bond strength of resin-dentin interface. Results: The initial search yielded 214 publications, of which 8 were selected after thorough methodological assessment. None of the clinical studies fulfilled the eligibility criteria. Our results indicated that in comparison to the control group, CHX significantly reduced immediate resin-dentin bond strength (P=0.043). These values were increased after aging (P<0.001). Conclusion: Based on this invitroMeta-analysisCHX application, improveresin-dentin bond strength durability in primary teeth.

Influence of silver nanoparticles on the resin-dentin bond strength and antibacterial activity of a self-etch adhesive system

Statement of problemThe influence of silver nanoparticles on adhesive properties of Single Bond Universal (3M ESPE) and the antibacterial activity of silver nanoparticles-modified adhesives against Streptococcus mutans is unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of silver nanoparticles on the dentin bond strength of modified adhesives and the antibacterial activity against the cariogenic pathogen S. mutans. Material and methodsSingle Bond Universal adhesive was used as the control. Silver nanoparticles were added to adhesives at 0.05% and 0.1% (by weight) (experimental groups), and scanning electron microscopy was used to observe the uniformity of the modified adhesives. The Single Bond Universal adhesive and the modified adhesives were then used to prepare dentin-composite resin blocks. The microtensile bond strength and microleakage of the prepared dentin-composite resin blocks were determined with or without thermocycling. The colony-forming units (CFU) of S. mutans cultured with the adhesives were evaluated, and the microtensile bond strength and microleakage of each group were tested after treatment with S. mutans. The differences in the microtensile bond strength or CFU were analyzed by using the 2-way analysis of variance and independent sample t test. The differences in microleakage between the groups were evaluated by using the Mann-Whitney test (α=.05). ResultsSilver nanoparticle-modified adhesives exhibited uniform morphologies without agglomeration and exhibited a homogeneous adhesive layer in dentin-composite resin blocks. The microtensile bond strength and microleakage of the modified adhesives were similar to those of the control group, with or without thermocycling (P>.05). However, thermocycling reduced the bond strength significantly (P<.001). Self-etch adhesives incorporated with silver nanoparticles showed significant antibacterial activities after less than 6 months of aging treatment. The modified adhesives did not exhibit a decreased bond strength after S. mutans exposure (P>.05), while the control group exhibited a markedly decreased bond strength after S. mutans exposure (P<.05). ConclusionsSilver nanoparticle-modified adhesives showed excellent antibacterial activities against S. mutans and resisted the destruction of dentin bond strength caused by S. mutans while not compromising the bonding properties of Single Bond Universal self-etch adhesives.

Effect of the Viscosity and Application Time of Different Phosphoric Acids on the Bond Strength and Nanoleakage of Fiber Posts to Root Dentin.

To evaluate the effect of application time and viscosity of meta-phosphoric acid (MPA) and ortho-phosphoric acid (OPA) on the push-out resin-dentin bond strength (PBS) and nanoleakage (NL) at the adhesive-root dentin interface. Ninety-six roots of premolars were endodontically prepared and randomly assigned into groups according to the (i) acid (OPA and MPA), (ii) viscosity (gel and liquid), and (iii) application time (7 and 15 seconds). Fiber posts were cemented to the roots, which were then transversally sectioned into serial slices. The slices (cervical, medium, and apical) were subjected to PBS or NL. Analysis of the dentin etching pattern was performed using scanning electron microscopy (SEM). The PBS (MPa) and NL (%) data were subjected to three-way repeated-measures analysis of variance (ANOVA) and Tukey's test (α=0.05). The cross-product interaction was significant for both PBS and NL (p<0.001). No significant difference in the PBS was observed with the use of OPA compared to MPA (p>0.05). Higher PBS values were observed in the groups etched for 15 seconds compared to 7 seconds, regardless of the acid, viscosity, or root third (p<0.05). Lower NL was observed for MPA etching when compared to OPA etching (p<0.05), and these values were not affected by increasing the application time or acid viscosity (p>0.05). A more pronounced etching pattern was observed with OPA than MPA regardless of the acid viscosity. The use of 40% meta-phosphoric acid promoted adequate bond strength without increasing dentin demineralization or void spaces in the hybrid layer.

Evaluation of six different one-step universal adhesive systems in terms of dentin bond strength, adhesive interface characterization, surface tension, contact angle, degree of conversion and solvent evaporation after immediate and delayed use.

In this study, it was aimed to investigate the effects of different waiting periods on resin-dentin bond strength (BS), degree of conversion (DC), contact angle (CA), surface tension (ST), solvent evaporation (weight loss) and the characteristics of adhesive interfaces of the current six universal adhesive resins (ARs). A total of 216 caries-free human lower third molar teeth were used. Composite resin restorations were performed by applying six universal ARs in etch-and-rinse and self-etch mode on standardized dentin surfaces after 0, 5, and 30 min waiting time. Then, a micro-shear BS test, SEM examination and characterization of the adhesive interface were performed. In addition, DC, CA, ST, solvent evaporation of all tested ARs were evaluated. The obtained data were statistically anaIyzed. The tested ARs did not show any statistical difference between 0 and 5min evaluations in all parameters evaluated except for weight loss (p > 0.05). While the weight loss, ST and CA of all ARs increased in 30 min (p < 0.05), the BS, DC, thickness of the adhesive layer and the hybrid layer, resin tag length and number of resin tags varied according to the ARs used. When the ARs were used in etch-and-rinse mode, all the parameters evaluated also varied according to the AR used. Higher adhesive layer thickness and lower hybrid layer thickness were found in the self-etch mode (p < 0.05). All of the adhesives tested can be safely used up to 30 min. This could also prevent economical loss caused by waste adhesive material. It is important to know how the bond strength, degree of conversion, adhesion, contact angle and surface tension properties of the adhesive resin waiting in the dispensing cup for a long time during clinical use are affected to make ideal restorations.

Adhesive sonic agitation improves bonding durability to class-II cavity preparation.

The purpose of this study was to evaluate the effect of adhesive sonic agitation on resin-dentin micro-tensile bond strength (µTBS) and interfacial morphology at the gingival wall of class-II cavity preparation. Seventy-two molars with prepared class-II cavities were divided into six groups (n = 12) according to the bonding mode; etch-and-rinse (E&R) or self-etch (SE) and application protocol of the universal adhesive (UA) employed (Clearfil Universal Bond Quick, Kuraray Noritake); following the manufacturer instructions (MI), manual agitation for 20s (20s), or sonic agitation for 20s using a modified sonic micro-brush mounted on EndoActivator device, Dentsply Sirona, (sonic). Restored teeth were sectioned into resin-dentin beams and slaps and µTBS was evaluated at 1week (1w) and after thermocycling (10k). µTBS data were analyzed using the linear mixed-effects modeling with specific contrast (p < 0.05). The resin-dentin interfacial morphology was evaluated using ascanning electron microscope. Adhesive sonic agitation resulted in significantly higher µTBS means in both E&R and SE modes, compared to MI group. The µTBS of MI group showed significant reduction upon aging when applied in SE mode. Sonic agitation was associated with enhanced adhesive infiltration into dentin specially in E&R mode. Sonic agitation of UA using modified sonic micro-brush attached to EndoActivator device significantly improved the resin-dentin µTBS and interfacial morphology at the gingival wall of class-II cavity preparation.

Four-year effects of copper-nanoparticles on durability of resin-dentin interfaces

ObjectiveTo evaluate the effect of the addition of copper nanoparticles (CuNp) at different concentrations in an etch-and-rinse (ER) adhesive on the resin-dentin bond strength (μTBS), nanoleakage (NL) and presence of copper nanoparticles within the hybrid layer, in the immediate time (IM) and after 4 years of water storage (4 y). Material and methodsSeven experimental adhesive systems were formulated according to the concentration of CuNp (0 [control], 0.0075, 0.015, 0.06, 0.1, 0.5 and 1 wt%) added into the ER adhesive Ambar (FGM). The adhesives were applied to flat occlusal dentin surfaces after acid etching, and then a resin restoration was build-up. Specimens were longitudinally sectioned to obtain resin-dentin beam-like, which were used for evaluation of μTBS, NL and identification of presence of CuNp within the hybrid layer, at the IM and 4 y periods. ANOVA and Tukey's test were applied (α = 0.05). ResultsAddition of CuNp up to 0.5% in the adhesive system significantly increased the μTBS at IM (p < 0.05). After 4 y, copper-containing adhesives showed higher values of μTBS compare to control (p < 0.05). All adhesives showed a significant decrease in μTBS over time (p < 0.05). Significant decreases in the NL values were observed in the copper-containing adhesives in IM in comparison with control group (p < 0.05). After 4 y, all copper-containing adhesives showed significantly decreased NL values compare to control group. All adhesives showed a significant increase in NL over time (p < 0.05). Presence of copper within the hybrid layer was identified from 0.06% concentration even after 4 y of water storage. ConclusionThe addition of copper nanoparticles from 0.06% to 0.5% concentrations in an adhesive decreased the degradation of the adhesive interface, mainly because it is still present in the hybrid layer even after 4 years of water storage.

Effect of Collagen Crosslinkers on Dentin Bond Strength of Adhesive Systems: A Systematic Review and Meta-Analysis.

This study aimed to identify the role of crosslinking agents in the resin–dentin bond strength (BS) when used as modifiers in adhesives or pretreatments to the dentin surface through a systematic review and meta-analysis. This paper was conducted according to the directions of the PRISMA 2020 statement. The research question of this review was: “Would the use of crosslinkers agents improve the BS of resin-based materials to dentin?” The literature search was conducted in the following databases: Embase, PubMed, Scielo, Scopus, and Web of Science. Manuscripts that reported the effect on the BS after the use of crosslinking agents were included. The meta-analyses were performed using Review Manager v5.4.1. The comparisons were performed by comparing the standardized mean difference between the BS values obtained using the crosslinker agent or the control group. The subgroup comparisons were performed based on the adhesive strategy used (total-etch or self-etch). The immediate and long-term data were analyzed separately. A total of 50 articles were included in the qualitative analysis, while 45 articles were considered for the quantitative analysis. The meta-analysis suggested that pretreatment with epigallocatechin-3-gallate (EGCG), carbodiimide, ethylenediaminetetraacetic acid (EDTA), glutaraldehyde, and riboflavin crosslinking agents improved the long-term BS of resin composites to dentin (p ≤ 0.02). On the other hand, the use of proanthocyanidins as a pretreatment improved both the immediate and long-term BS values (p ≤ 0.02). When incorporated within the adhesive formulation, only glutaraldehyde, riboflavin, and EGCG improved the long-term BS to dentin. It could be concluded that the application of different crosslinking agents such as carbodiimide, EDTA, glutaraldehyde, riboflavin, and EGCG improved the long-term BS of adhesive systems to dentin. This effect was observed when these crosslinkers were used as a separate step and when incorporated within the formulation of the adhesive system.

Phosphoric acid containing proanthocyanidin enhances bond stability of resin/dentin interface.

Proanthocyanidin (PA) is a promising dentin biomodifier due to its ability to stabilize collagen fibrils against degradation by matrix metalloproteinases (MMPs); however, the most effective protocol to incorporate PA into bonding procedures is still unclear. This study evaluated the effect of dentin biomodification with a PA acid etchant on MMP activity, adhesive interface morphology and resin-dentin microtensile bond strength. Sound extracted human molars were flattened to expose dentin and acid-etched for 15 s according to the groups: EXP - experimental phosphoric acid; EXP+PA - experimental phosphoric acid 10% PA; TE - total-etching system; SE - self-etching system. Samples were restored with composite resin and stored in distilled water (37ºC). MMP activity and interface morphology were analyzed after 24 h by in situ zymography (n=6) and scanning electron microscopy (n=3), respectively. The resin-dentin microtensile bond strength (μTBS) was evaluated after 24 h and 6 months storage (n=6). Significantly higher MMP activity was detected in etched dentin compared with untreated dentin (p<0.05), but no difference among acid groups was found. Resin tags and microtags, indicative of proper adhesive system penetration in dentinal tubules and microtubules, were observed along the hybrid layer in all groups. There was no difference in μTBS between 24 h and 6 months for EXP+PA; moreover, it showed higher long-term μTBS compared with TE and EXP (p<0.05). The results suggest that 15 s of biomodification was not sufficient to significantly reduce MMP activity; nonetheless, EXP+PA was still able to improve resin-dentin bond stability compared with total- and self-etching commercial systems.

Degradation and Stabilization of Resin-Dentine Interfaces in Polymeric Dental Adhesives: An Updated Review

Instability of the dentine-resin interface is owed to the partial/incomplete penetration of the resin adhesives in the collagen fibrils. However, interfacial hydrolysis of the resin-matrix hybrid layer complex activates the collagenolytic and esterase enzymes that cause the degradation of the hybrid layer. Adequate hybridization is often prevented due to the water trapped between the interfibrillar spaces of the collagen network. Cyclic fatigue rupture and denaturation of the exposed collagen fibrils have been observed on repeated application of masticatory forces. To prevent interfacial microstructure, various approaches have been explored. Techniques that stabilize the resin–dentine bond have utilized endogenous proteases inhibitors, cross linking agents’ incorporation in the exposed collagen fibrils, an adhesive system free of water, and methods to increase the monomer penetration into the adhesives interface. Therefore, it is important to discover and analyze the causes of interfacial degradation and discover methods to stabilize the hybrid layer to execute new technique and materials. To achieve a predictable and durable adhesive resin, restoration is a solution to the many clinical problems arising due to microleakage, loss of integrity of the restoration, secondary caries, and postoperative sensitivity. To enhance the longevity of the resin-dentine bond strength, several experimental strategies have been carried out to improve the resistance to enzymatic degradation by inhibiting intrinsic collagenolytic activity. In addition, biomimetic remineralization research has advanced considerably to contemporary approaches of both intrafibrillar and extrafibrillar remineralization of dental hard tissues. Thus, in the presence of biomimetic analog complete remineralization of collagen, fibers are identified.

Disinfection of caries affected dentin using rose bengal, titanium sapphire laser; ammonium hexa-fluorosilicate, and ozonated water on resin dentin bond strength

AimThe present study intended to evaluate the shear bond strength (SBS) of resin cement bonded to caries affected dentin (CAD) after disinfection with rose Bengal (RB), Ti-Sapphire Laser, Ammonium Hexafluorosilicate (NH4)2[SiF6], and ozonated water (O3). Material and MethodsA total of 100 extracted human mandibular molars were acquired using caries severity code, 6 of the ICDAS criteria. To achieve homogeneity and prevent size-biased distributions, the average cavity preparation of all specimens had a depth of 2 mm and a breadth of 3 mm. Specimens were divided into five groups (n = 20) at random according to type of disinfection. Group 1: control group, Group 2: RB, Group 3: O3, Group 4: Ti-sapphire laser, and Group 5: (NH4)2[SiF6]. All specimens were etch and rinsed, bonding agent was applied and restored with resin cement. Estimation of SBS was performed by placing samples (10/group) in universal testing machine. Stereomicroscope under 40 × magnification was employed for failure mode analysis (FMA). Statistical analysis was executed using the ANOVA and the Tukey multiple test (p<0.05). ResultsThe highest SBS was demonstrated in the control group when CAD bonded to resin cement without disinfection (18.22±1.14 MPa). Likewise, the lowest SBS values were unveiled by CAD disinfection with O3 (12.44±1.36 MPa). Similarly, CAD when disinfected with RB (16.25±1.01 MPa) and Ti-sapphire laser (16.25±1.22 MPa) bonded to resin cement exhibited comparable bond results (p>0.05). ConclusionCaries affected dentin when treated with etch and rinse technique without the use of disinfectant displayed the highest SBS. However, it was seen that utilization of various disinfectants altered the adhesion capacity or bonding efficacy of caries-affected dentin.

In vitro biological and adhesive properties of universal adhesive systems on sound and caries-affected dentine: 18 months

The present study aims to evaluate antimicrobial activity, cytotoxicity, as well as resin-dentine microtensile bond strength, nanoleakage and degree of conversion of six universal adhesives, on sound and caries-affected dentine after 18 months. The adhesives Prime&Bond Active (PBA), Scotchbond Universal (SBU), Tetric N-Bond Universal (TNU), Ambar Universal (AMU), Clearfil Universal Bond Quick (CUQ) and One Coat 7 Universal (OCU) were used. Antimicrobial activity was evaluated against Streptococcus mutans. For cytotoxicity, methyltetrazolium assay was used, after 24 h exposure of osteoblast-like cells line to the adhesive's dilution of 1, 0.1, and 0.01 v/v%. After, the adhesives were applied in etch-and-rinse or self-etch strategies on sound or caries-affected dentine surfaces, resin composites restorations were constructed. Then, the specimens were sectioned to obtain sticks to be evaluated in microtensile bond strength and nanoleakage after 24 h and 18 months, and degree of conversion after 24 h. ANOVA and Tukey's test were applied (α = 0.05). For antimicrobial activity, CUQ showed higher values than all adhesives. For cytotoxicity, the PBA, AMU, CUQ and OCU adhesives presented cytotoxicity in different dilutions. For microtensile bond strength, OCU presented the lowest values, regardless of time, dentine or strategy. For nanoleakage, differences were observed among adhesives depending on time, dentine or strategy. For degree of conversion, TNU presented the highest values, while PBA and OCU presented the lowest values. Worst values of microtensile bond strength and nanoleakage were always obtained in caries-affected dentine after 18 months. Thus, not all universal adhesives behave the same in terms of antimicrobial activity and cytotoxicity. However, the majority showed worst results when applied in caries-affected dentine, mainly after 18 months. Clinical relevance. Universal adhesive systems may have differences in their biological and adhesive properties, both on sound, but mainly in caries-affected dentine after 18 months.