Dentin Adhesives Research Articles

Effect of bioactive glass-containing dentin adhesives on microshear bond strength of composite restorations

Effect of bioactive glass-containing dentin adhesives on microshear bond strength of composite restorations

Efeito do tempo e do substrato dental na resistência de união de um sistema adesivo universal: estudo in vitro

Abstract Introduction Dentin adhesives provide union between the dental substrate and composite resin, but this union can be influenced by the cleaning agent. Objective Evaluate the use of ozonated water as a cavity cleaning solution. Material and method 40 bovine dental crowns were selected, divided into four groups: AD (dentin cleaning with distilled water) and AO (dentin cleaning with ozonized distilled water). Each group was divided into two storage periods (24h and 30 days) kept at 37 °C. The selected universal system adhesive was employed according to the manufacturer's instructions and light cured for 20 seconds. At that time, three cylinders were made (Tygon matrix with an internal diameter of 2 mm and a height of 2 mm) of composite resin in the crowns in the cervical, médium, and incisal regions and light cured for 30 seconds. After storage, the bonding strength was tested by micro-shear, and fracture type analysis was performed. The data were submitted to statistical analysis using the Shapiro-Wilk test with a significance level of 95%, ANOVA, and Turkey. Result There was a statistically significant difference between the bond strength values, only in the intergroup analysis for the time of 24 hours, between the middle third of the groups (LDAO24 = 2.70 (± 2.39); LDAO30 = 3.82 (± 2.31)). The predominant fracture type for both groups was an adhesive fracture, except in the medium and incisal thirds of the AD, which was a cohesive dentin fracture. Conclusion The utilization of ozone did not change the bond strength adhesive.

Oxidized Dopamine Acrylamide Primer to Achieve Durable Resin-Dentin Bonding.

The durability of the resin-dentin bonding interface is a key issue in clinical esthetic dentistry. Inspired by the extraordinary bioadhesive properties of marine mussels in a wet environment, we designed and synthetized N-2-(3,4-dihydroxylphenyl) acrylamide (DAA) according to the functional domain of mussel adhesive proteins. DAA's properties of collagen cross-linking, collagenase inhibition, inducing collagen mineralization in vitro, and as a novel prime monomer for clinical dentin adhesion use, its optimal parameters, and effect on the adhesive longevity and the bonding interface's integrity and mineralization, were evaluated in vitro and in vivo. The results showed that oxide DAA can inhibit the activity of collagenase and cross collagen fibers to improve the anti-enzymatic hydrolysis of collagen fibers and induce intrafibrillar and interfibrillar collagen mineralization. As a primer used in the etch-rinse tooth adhesive system, oxide DAA can improve the durability and integrity of the bonding interface by anti-degradation and mineralization of the exposed collagen matrix. Oxidized DAA (OX-DAA) is a promising primer for improving dentin durability; using 5% OX-DAA ethanol solution and treating the etched dentin surface for 30 s is the optimal choice when used as a primer in the etch-rinse tooth adhesive system.

Influence of calcium-based desensitizing toothpastes on the bonding performance of universal adhesive.

The study evaluated the effect of calcium-based desensitizing toothpastes on the dentinal tubule occlusion and its influence on the dentin bond strength of universal adhesive. Mid-coronal dentin samples were prepared for hypersensitivity model and treated by the following calcium-based desensitizing toothpastes: no treatment (Control), Clinpro (fTCP), Pro-Relief (Pro-Argin), and Repair & Protect (Novamin). Single Bond Universal adhesive was applied in self-etch or etch-and-rinse mode. The dentinal tubule occlusion and adhesion interface were evaluated under scanning electron microscope (SEM). A double-fluorescence technique was used to examine interfacial permeability under confocal laser scanning microscopy (CLSM). The micro-tensile bond strength (μTBS) was employed, followed by the fracture interface observation. SEM showed the toothpastes occluded dentinal tubules, and the occlusion exhibited stability against acid and abrasion. Hindered resin infiltration was observed in the adhesion interface after desensitization. CLSM showed more water permeation within or under the adhesion interface in etch-and-rinse mode than self-etch mode. Desensitization decreased the μTBS in self-etch mode. When using etch-and-rinse mode, the desensitized samples presented similar μTBS to the control group. No difference in μTBS was found between the two bonding modes, except for the control group. Calcium-based desensitizing toothpastes can effectively occlude the exposed dentinal tubules with acid-resistant and abrasion-resistant stability. The desensitization reduced the dentin bond strength of the universal adhesive system in self-etch mode but did not affect the bond strength of etch-and-rinse mode.

Microtensile Bond Strength of Total-Etch and Self-Etch Universal Adhesives Containing 10-MDP: A Systematic Review

A systematic review was performed to compare the human dentin microtensile bond strength of universal adhesives with 10-MDP when used as total-etch and self-etch strategies. Literature search was done on October 2019 without limitations on the language of publication, in four databases: PubMed, Web of Science, Scopus, and EBSCO. Additional manual search was done for the grey literature articles: OpenGrey and OpenThesis. Studies that evaluated the dentin bond strength of universal adhesives with 10-MDP using total-etch and self-etch strategy from the year 2000 up till October 2019 were included. The initial search resulted in 5121 references: 2234 from PubMed, 1814 from Scopus, 516 from Web of Science, 553 from EBSCO and 4 from OpenThesis. After full text analysis, 30 references were included in this systematic review. Seven different universal adhesives with 10-MDP were evaluated for dentin microtensile bond strength comparing total-etch and self-etch strategies: Single Bond Universal/Scotchbond Universal (3M ESPE), All Bond Universal (Bisco), Clearfil Universal Bond (Kuraray), G-Premio Bond (GC Corp), Tetric Bond Universal (Ivoclar Vivadent), Ambar Universal (FGM) and One Coat 7 Universal (Coltene). The total-etch strategy improved the dentine microtensile bond strength compared to self-etch strategy for all universal adhesives when stored in all three conditions: 24h, thermocycling and long-term immersion according to ISO (TS 11405:2015(E)). The evidence suggests that microtensile bond strength of universal adhesives containing 10-MDP may be improved utilizing total-etch strategy compared to self-etch strategy. This study provides valuable information on the importance of appropriate dentin adhesives strategy that affect success rate of restorations, which helps clinicians to make informed decisions on the strategy to be used during restorations in practice.

Effect of Cumulative Ionizing Radiation on Flexural Strength, Flexural Modulus, and Elasticity Modulus of Dentin in Unerupted Human Third Molars

PurposeThis in vitro study aimed to investigate the changes in mechanical properties in dentin of third molars after radiation therapy using variable doses and frequencies. Methods and MaterialsRectangular cross sectioned dentin hemisections (N = 60, n = 15 per group; >7 × 4 × 1.2 mm) were prepared using extracted third molars. After cleansing and storage in artificial saliva, random distribution was performed to 2 irradiation settings, namely AB or CD (A, 30 single doses of irradiation [2 Gy each] for 6 weeks; B, control group of A; C, 3 single doses of irradiation [9 Gy each]; and D, control group of C). Various parameters (fracture strength/maximal force, flexural strength, and elasticity modulus) were assessed using a universal Testing Machine (ZwickRoell). The effect of irradiation on dentin morphology was evaluated by histology, scanning electron microscopy, and immunohistochemistry. Statistical analysis was performed using 2-way analysis of variance and paired and unpaired t tests at a significance level of 5%. ResultsSignificance could be found considering the maximal force applied to failure when the irradiated groups were compared with their control groups (A/B, P < .0001; C/D, P = .008). Flexural strength was significantly higher in the irradiated group A compared with control group B (P < .001) and for the irradiated groups A and C (P = .022) compared with each other. Cumulative radiation with low irradiation doses (30 single doses; 2 Gy) and single irradiation with high doses (3 single doses; 9 Gy) make the tooth substance more prone to fracture, lowering the maximal force. The flexural strength decreases when cumulative irradiation is applied, but not after single irradiation. The elasticity modulus showed no alteration after irradiation treatment. ConclusionsIrradiation therapy affects the prospective adhesion of dentin and the bond strength of future restorations, potentially leading to an increased risk of tooth fracture and retention loss in dental reconstructions.

ЭФФЕКТИВНОСТЬ ИМПРЕГНАЦИИ ДЕНТИНА ЗУБОВ НАНОЧАСТИЦАМИ ГИДРОКСИДА МЕДИ-КАЛЬЦИЯ ПРИ ЭКСПЕРИМЕНТАЛЬНОМ ЛЕЧЕНИИ КАРИЕСА

For the prevention of recurrent and secondary caries of teeth, as well as bullets, antiseptic treatment of the carious cavity, dentine adhesives, laser radiation, etc. are used. However, these methods do not allow achieving effective decontamination and obturation of dentine tubules, in which pathogenic microflora can continue to persist. In the experimental treatment of dentin caries using electron microscopy, the effectiveness of a new technique of galvanophoretic nanoimpregnation of dentin with nanoparticles of a complex preparation of copper-calcium hydroxide was studied. Galvanophoresies was performed using an aluminum foil in contact with a copper-containing preparation. After instrumental treatment of the cavity, it is advisable to carry out nanoimpregnation of dentin for 14 days. During this period, 85-90% of the dentine tubules are obturated to an average depth of 800 microns and the dentine is saturated with calcium, which contributes to the restoration of its mineral composition, disturbed as a result of microbial demineralization. The effectiveness of nanoimpregnation of dentin with copper-calcium hydroxide decreases with age of the teeth, as well as with existing carious cavity.

Dentinhaftung bioaktiver Füllungsmaterialien für die Kinderzahnheilkunde

Aim: Bioactive materials are of interest for dental restoration in children with high caries risk. An important parameter for clinical success is durable adhesion to tooth hard tissues. Therefore, the present study evaluated dentin bonding behavior of two bioactive materials (ACTIVA BioACTIVE-RESTORATIVE [Acti, Pulpdent, Watertown, MA, USA] using All Bond Universal [BISCO, Schaumburg, IL, USA], and Cention N bonded with Adhese Universal [Cent, Ivoclar Vivadent, Schaan, Liechtenstein]) compared to a bonded resin composite (Filtek Z250 [FZ250, 3M Oral Care Dental Products, St. Paul, MN, USA] with OptiBond FL [Kerr, Biberach, Deutschland]) and a conventional glass ionomer cement (Fuji Triage pink [FTp, GC Corporation, Tokyo, Japan]) using Cavity Conditioner (GC Europe, Löwen, Belgien).Materials and methods: Twenty-eight caries-free third molars were randomly assigned to four groups (n = 7). Crowns were ground flat to expose dentin. Specimens were pretreated according to the manufacturers' instructions and built-up in 0.5-2 mm layers with composite. After storage (24 h at 37 °C in distilled water), specimens were cut into resin-dentin beams (0.36 mm2 for Acti, Cent, and FZ250; 1 mm2 for FTp) and subjected to microtensile bond strength testing. Additional micromorphological analyses were done using both light and scanning electron microscopy. Statistical appraisal was carried out using one-way analysis of variance (ANOVA; modified least significant difference [LSD] test; p <0.05). Results: Dentin bond strengths were (in MPa, numbers I-III indicate significant differences between groups): FZ250: 63.9 ± 8.3 (I); Acti: 52.1 ± 8.2 (II); Cent: 51.4 ± 10.9 (II); FTp: 3.7 ± 0.9 (III). A pronounced hybrid layer was only found in FZ250. The investigated bioactive restorative materials showed lower dentin adhesion compared to the bonded resin composite, but 13-fold higher values than the GIC (FTp).Conclusion: When adhesively bonded, the bioactive materials under investigation exhibited good dentin bonding behavior. In minimally invasive restorations, we recommend using them with a separate bonding step. However, further studies must show whether this impairs the caries-inhibiting, bioactive effect of the materials.

Assessment of the Physical Properties of an Experimental Adhesive Dentin Bonding Agent with Carbon Nanoparticles

The present study was aimed at reinforcing the control adhesive (CA) with two concentrations (2.5% &amp; 5%) of carbon nanoparticles (CNPs) and evaluating the impact of these additions on the adhesive’s properties. Scanning electron microscopy (SEM) and energy dispersive X-Ray (EDX) spectroscopy were utilized to examine the morphological characteristics and elemental mapping of the filler CNPs. To investigate the adhesive’s properties, rheological assessment, shear bond strength (SBS) testing, analysis of the adhesive–dentin interface, degree of conversion (DC) analysis, and failure mode investigations were carried out. The SEM micrographs of CNPs verified roughly hexagonal-shaped cylindrical particles. The EDX plotting established the presence of carbon (C), oxygen (O), and zirconia (Zr). Upon rheological assessment, a gradual reduction in the viscosity was observed for all the adhesives at higher angular frequencies. The SBS testing revealed the highest values for 2.5% CNP adhesive group (25.15 ± 3.08 MPa) followed by 5% CNP adhesive group (24.25 ± 3.05 MPa). Adhesive type interfacial failures were most commonly found in this study. The 5% CNP containing adhesive revealed thicker resin tags and a uniform hybrid layer without any gaps (compared with 2.5% CNP adhesive and CA). The reinforcement of the CA with 2.5% and 5% CNPs augmented the adhesive’s bond strength. Nevertheless, a diminished viscosity (at higher angular frequencies) and reduced DC were observed for the two CNP reinforced adhesives. CNP reinforced dentin adhesives are effective in enhancing the adhesive bond integrity of resin to dentin.

Evaluation of Bond Durability, Surface Morphology, and Remineralization at the Adhesive Interface with Dentin Bonding Agents Modified with Silica-doped Nanohydroxyapatite.

To compare and evaluate the bond durability, surface morphology, and remineralization of the adhesive layer with newer adhesive systems modified with novel bioactive nanoparticles. Bonding agents evaluated in this study include (a) Conventional dentin bonding agent (CN-DBA) (b) Nanohydroxyapatite (nanoHAP) incorporated dentin bonding agent (NH DBA); (c) Silica doped nanohydroxyapatite (Si nanoHAP) incorporated dentin bonding agent (Si NH DBA). A total of 104 human dentin discs (5 mm × 5 mm × 2 mm) were sectioned. Elemental analysis (Ca/P ratio) and surface morphology of the adhesive layer with different dentin adhesives were evaluated under scanning electron microscopy with energy-dispersive X-ray analysis after speculated storage time of 1 day and 6 months. Microshear bond strength of adhesive restorations with different dentin adhesives was evaluated under universal testing machine and fractographic analysis under scanning electron microscope after speculated storage time of 1 day and 6 months. The results were analyzed using analysis of variance and post hoc analysis. Si-NH-DBA showed highest mean microshear bond strength for both 1 day and 6 months, which was significantly higher compared to conventional nanofilled dentin bonding agent (CN-DBA) and NH-DBA. Si-NH-DBA group showed only 10% reduction in bond strength after 6 months, which was less compared to that of other groups. Similarly, Si-NH-DBA showed higher remineralization with stellate-shaped crystals at the adhesive layer after 6 months with hydrolytic resistant hybrid layer, compared to CN-DBA and NH-DBA. Silica-doped nanohydroxyapatite proved its efficiency on bond stability, remineralization, and hydrolytic resistance when incorporated into dentin bonding agents because of its bioactivity and carbonate-containing apatite-forming ability.

Primer application technique and remaining dentin thickness affected microtensile bond strength of contemporary dentin adhesives under simulated pulp pressure.

To evaluate the effect of application techniques, type of adhesives and remaining dentin thicknesses on microtensile bond strength (µTBS) of 3 adhesive systems. 112 flat occlusal dentinal surfaces of third molar were randomly allocated into 16 groups based on 2 remaining dentin thicknesses (RDT), 2 application techniques, and 3 adhesive systems (Optibond FL, OFL; Clearfil SE Bond, CSE; and Single Bond Universal, SB); SB was applied in either etch-and-rinse (ER) or self-etch (SE) mode. Simulated pulpal pressure was performed during restorative procedure and water storage. The stick-shaped specimens from each tooth underwent µTBS testing. The data were evaluated using a paired t test and ANOVA followed by a post hoc test. The fractured specimens were evaluated for mode of failure using a stereomicroscope. The mean µTBS values were significantly affected by RDT, application technique, and types of adhesives. Neither RDT nor application technique affected µTBS of SB in ER mode, whereas application technique affected both conventional and universal self-etch adhesives. RDT also influenced µTBS of OFL. RDT and application technique differently affected the µTBS of dentin bonding which was product-related. Etch-and-rinse systems had higher bond strength to superficial than to deep dentin, whereas self-etch systems were more sensitive to both RDT and application technique. The universal adhesive is less sensitive to intrinsic wetness and can be used according to manufacturer's instructions.

Enhancing adhesive–dentin interface stability of primary teeth: From ethanol wet-bonding to plant-derived polyphenol application

ObjectivesTo investigate whether the adhesive–dentin interface stability of primary teeth would be enhanced by epigallocatechin-3-gallate (EGCG) with ethanol wet-bonding. MethodsNon-caries primary molars were sliced to achieve a flat dentin surface and etched then randomly distributed into five groups in accordance with different treatments: group 1, no treatment; group 2, applying absolute ethanol wet-bonding for 60 s; groups 3–5, applying 0.1%, 0.5%, and 1% (w/v) EGCG-incorporating ethanol wet-bonding (0.1%, 0.5%, and 1% EGCG) for 60 s. Singlebond universal adhesive was then applied followed by resin composite construction. Microtensile bond strength, fracture mode, and nanoleakage at adhesive–dentin interface were evaluated after 24 h of water storage or 10,000 times of thermocycling. Zymography of hybrid layer, biofilm formation of Streptococcus mutans by CLSM, FESEM, and MTT test, and cytotoxicity by CCK-8 assay were respectively assessed. ResultsIrrespective of thermocycling, the dentin bond strength was preserved with reduced nanoleakage in the 0.5% and 1% EGCG groups. Furthermore, the activity of endogenous proteases and the growth of Streptococcus mutans biofilm were inhibited after treatment with 0.5% and 1% EGCG/ethanol solutions (groups 4 and 5). CCK-8 results of the 0.1% and 0.5% EGCG groups showed acceptable biocompatibility. ConclusionsTreatment by EGCG/ethanol solutions effectively enhanced the bond stability of primary teeth at the adhesive–dentin interface. Clinical significanceSynergistic application of EGCG and ethanol wet-bonding suggesting a promising strategy to improve dentin bonding durability with bacterial biofilm inhibition, thus increasing resin-based restorations’ service life in primary dentition.

Assessment of Caries-Affected Dentin Adhesive Interface Treated with Contemporary Conditioning Techniques.

Objective: The aim of this study was to assess shear bond strength (SBS) and failure analysis of adhesion of composite resin (CR) to caries-affected dentin (CAD) pretreated with the Er,Cr:YSGG (ECY) laser, photodynamic therapy (PDT), and etch and rinse (ER) used for cavity disinfection. Materials and methods: Methods used in this study included scanning electron microscopy (SEM), SBS analysis, failure analysis, and digital microscopy. The methods were adopted to assess bond integrity, CAD interface, smear layer, and hybridization. Thirty human third molars assessed clinically and having scores of 4 and 5 based on International Caries Detection and Assessment System (ICDAS) criteria were inspected. Infected dentin was removed. Dentin that was hard and stained pink was categorized as CAD. Ten samples were used in each group for pretreatment of CAD. Ten samples of healthy dentin [sound dentin (SD)] were collected separately and taken as controls. Samples were divided into the following groups: group 1: SD+ER; group 2: CAD+ER; group 3: CAD+ECY; and group 4: CAD+PDT after the pretreatment bonding agent was applied and the restorative procedure was performed using CR. Results: CAD conditioned with PDT before bonding to CR demonstrated the lowest SBS values (11.22 ± 0.77 MPa), whereas the highest SBS values were observed in the SD surface treated with ER (18.25 ± 1.22 MPa). In CAD and SD pretreated with ER, majority of failure modes were cohesive failure and admixed failure, whereas in CAD pretreated with PDT and the ECY laser, the adhesive failure mode was pertinent. Conclusions: The use of the ECY laser and PDT on CAD for cavity disinfection does not have potential for application in clinical settings as it decreases bond integrity of CR. Moreover, the ER pretreatment method for CAD and SD remains the gold standard.

Methacrylic monomer derived from cardanol incorporated in dental adhesive as a polymerizable collagen crosslinker

ObjectivesThe aim of this study was to evaluate the influence on MMP inhibition, dentin adhesion and physicochemical properties of an adhesive system incorporated with polymerizable collagen crosslinker monomer derived from cardanol. MethodsThe intermediary cardanol epoxy (CNE) was synthesized through cardanol epoxidation, followed by synthesis of cardanol methacrylate through methacrylic acid solvent-free esterification. Zymographic analysis was performed to evaluate the substances’ ability to inhibit gelatinolytic enzymes. Collagen crosslinkers were added into adhesives systems according to the following groups: Ybond Universal® (Control), Ybond® + 2 % proanthocyanidin (PAC), Ybond® + 2 % unsaturated cardanol (Cardanol) and Ybond® + 2 % cardanol methacrylate (CNMA). Degree of conversion (DC) of the adhesives was assessed by FT-IR. Disk-shaped specimens were prepared for water sorption (WS) and solubility (SL) tests. Human third molars were sectioned to expose medium dentin and restored according to the different adhesives used (n = 5). Then, the specimens were cut into 1 mm2 sticks to evaluate, after 24 h and 6-month aging, microtensile bond strength (µTBS) and nanoleakage by scanning electron microscopy. Data were analysed with ANOVA and Tukey's post-test (α = 0.05). ResultsCNMA and PAC completely inhibited all forms of gelatinolytic enzymes. Cardanol achieved a significantly lowest DC, while the other groups did not differ from each other (p > 0.05). PAC achieved significantly higher water sorption, while CNMA solubility was significantly lower when compared to the other adhesives (p < 0.05). PAC provided a statistically higher 24 h and 6-month aging bond strength. Intermediary similar µTBS were presented by control and CNMA (p = 0.108). All adhesives applied attained significantly reduced bond strength after aging (p < 0.05). Interfaces created using CNMA were almost devoid of silver deposits initially, however all groups showed large amounts of silver deposits on resin-dentin interface subjected to water aging. SignificanceAlthough CNMA was effective in inhibiting gelatinolytic enzymes, when incorporated into a universal adhesive it could not promote less degradation of the adhesive interface after water aging. Since it is a hydrophobic monomer, CNMA did not interact well with dentin collagen, however it reduced the solubility of the adhesive system besides not interfering in its polymerization.

Cause-Effect Relationship of Varying Bonding Thicknesses in Dentin Adhesion of Universal Adhesives.

To evaluate whether varying thicknesses of universal adhesives utilizing the additional coating strategy would affect their microtensile bond strength (µTBS) to dentin, hardness, and elastic modulus (mechanical properties). Ninety-nine human maxillary premolars were cut to expose coronal dentin, ground with regular-grit diamond burs, and randomly distributed into 9 groups based on 1. adhesive: Scotchbond Universal Adhesive (SB; universal), G Premio Bond (GP; universal) and Clearfil Megabond 2 (MB; two-step self-etch; control); and 2. application strategy (one, two or three coats; each coat light cured). After adhesive application and resin composite buildup, the bonded teeth were stored in distilled water (37°C; 24 h). Resin-dentin sticks from eight premolars per group (each premolar yielded 3 sticks; n = 24 sticks altogether) were prepared for the µTBS test, followed by measurement of the adhesive thicknesses at their fractured ends using SEM. The mechanical properties of the adhesive layers produced by different coats were evaluated on separate resin-dentin slices (n = 3 teeth per group). Two coats significantly increased the µTBS (p < 0.001) of all the adhesives. The correlation between adhesive thickness and bond strength was positive for GP but negative for SB. MB did not show any correlation. Additional coating significantly increased the mechanical properties of GP (p < 0.05) but did not affect SB and MB (p < 0.05). An additional adhesive coating over the manufacturers' recommendations improved the bond strength of all the adhesives tested. However, the increased mechanical properties of the adhesives with additional curing was material dependent.

Strength of Fiber Posts with Experimental TiO2 and ZrO2 Particle Bonding—An SEM, EDX, Rheometric and Push-Out Strength Study

The present study aimed to prepare experimental adhesives (EAs): 5 wt.% titanium dioxide (TiO2) adhesive; and 5 wt.% zirconium oxide (ZrO2) adhesive; and analyze their impact on bond integrity of fiber posts to root dentin, and viscosity. The EA was composed of: bisphenol A glycol dimethacrylate (BisGMA); triethylene glycol dimethacrylate (TEGDMA); 2-hydroxyethyl methacrylate (HEMA); and ethyl 4-dimethylamino benzoate and camphorquinone. TiO2 and ZrO2 particles were individually incorporated into the EA at 5 wt.%, to form two groups (5% TiO2 and 5% ZrO2). The adhesives, with particles, were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The bonded interface was evaluated for adhesive–dentin penetration at the interface, using SEM. The study adhesive groups (EA, 5% TiO2 and 5% ZrO2) were analyzed for rheology and push-out bond strength of the fiber post to root dentin. Data were analyzed using analysis of variance and post hoc comparison. Both TiO2 and ZrO2 particles had irregular, non-uniform shapes. The EDX mapping showed the elemental presence of Ti (TiO2), Zr (ZrO2) and oxygen in formulated adhesives. The 5% TiO2 and 5% ZrO2 adhesives showed a decrease in viscosity, compared with the EA. Bond strength among the 5% TiO2 and 5% ZrO2 adhesives was statistically comparable (p &gt; 0.05), but higher than the control group (10.57 ± 1.45 MPa) (p &lt; 0.05). Reinforcement of the experimental dentin adhesive with 5% TiO2 or 5% ZrO2 increased the push-out bond strength of the fiber post to root dentin, in comparison with the EA. Particle-incorporated adhesives (5% TiO2 and 5% ZrO2) displayed decreased viscosity, compared with the EA (without particles).

The Effect of a 10-MDP-Based Dentin Adhesive as Alternative for Bonding to Implant Abutment Materials.

Bonding to different dental restorative materials is challenging. This study aimed to evaluate the effect of a 10-MDP-based dentin adhesive on the shear bond strength (SBS) of self-adhesive resin cement (RC) to implant abutment materials. One hundred and twenty specimens were obtained from zirconia (ZO), cobalt-chromium alloy (CoCr), and commercially pure titanium (Ti), which were treated as follows (n = 10): control group—non-treated (CG), 10-MDP-based dentin adhesive (SB), light-cured SB (SB-LC), and zirconia primer (ZP). Blocks of RC were buildup and, after 24 h, were tested for bond strength. Data of SBS (MPa) were submitted to two-way ANOVA and Tukey test (α = 0.05). There was no difference in SBS among materials for CG and ZP, higher SBS were recorded for Ti SB and Ti SB-LC compared to ZO upon the same surface treatments. For the comparisons among treatments, SB-LC showed the highest SBS for CoCr. For ZO and Ti, higher SBS were recorded with SB and SB-LC. No cohesive failures were observed. It was concluded that the surface treatment with 10-MDP-based materials increased the bond strength of the resin cement to abutment materials, which showed to be material dependent.

Polyphenol-Enriched Extract of Lacquer Sap Used as a Dentine Primer with Benefits of Improving Collagen Cross-Linking and Antibacterial Functions.

Commercial dentin adhesive systems are applied to restorations due to their resistant bonding properties, but they suffer from the lack of bioactivity and are prone to hydrolysis. Therefore, to overcome these limitations, an eco-friendly natural monomer, urushiol, was adopted to be a primer in dentin bonding due to its interaction with collagen and antibacterial activity, preventing further hydrolysis development. First, urushiol was determined to be capable of improving the biological stability of dentin collagen through cross-linking. Using high-fidelity analytical chemistry techniques, such as Fourier transform infrared spectroscopy, we quantified the effects of urushiol on collagen molecules. It could also effectively decrease weight loss after collagenase ingestion by improving the stability of dentin. Moreover, urushiol inhibited Streptococcus mutans growth as well as its biofilm formation. Finally, we demonstrated that the urushiol primer could improve the bonding strength, particularly after aging. The cross-linking and antibacterial functions of urushiol have provided promising developmental prospects for biomaterials in dentin adhesion.

Development of an Antibacterial Dentin Adhesive.

Nisin is a peptide that possesses potent antibacterial properties. This study evaluated the antibacterial activity of a nisin-doped adhesive against Streptococcus mutans, as well as its degree of conversion and microtensile bond strength (μTBS) to dentin. Nisin was added to the adhesive Adper Single Bond 2 (3M ESPE), resulting in four groups: Control Group (Single Bond 2); Group 1% (1 wt% nisin-incorporated), Group 3% (3 wt% nisin-incorporated) and Group 5% (5 wt% nisin-incorporated). Antibacterial activity against S. mutans was evaluated using colony-forming unit counts (CFU). The degree of conversion was tested using FTIR. Forty human teeth were restored for μTBS evaluation. Data were statistically analyzed with ANOVA and Tukey tests at α = 0.05. The nisin-doped adhesives, for all concentrations, exhibited a significant inhibition of the growth of S. mutans (p < 0.05); Incorporation of 5% and 3% nisin decreased the degree of conversion of the adhesive (p < 0.05). The μTBS (in MPa): Control Group—38.3 ± 2.3A, Group 1%—35.6 ± 2.1A, Group 3%—27.1 ± 1.6B and Group 5%—22.3 ± 1.0C. Nisin-doped adhesives exerted a bactericidal effect on S. mutans. The μTBS and degree of conversion of adhesive were not affected after incorporation of 1% nisin.

The roles of 10-methacryloyloxydecyl dihydrogen phosphate and its calcium salt in preserving the adhesive–dentin hybrid layer

Objectives10-Methacryloyloxydecyl dihydrogen phosphate (MDP) has been regarded as the most effective dentin-bonding monomer for more than 20 years. Although the dentin-bonding promoting effect of MDP has been well demonstrated, the mechanisms by which it benefits the stably of collagen within the adhesive–dentin hybrid layer are not currently fully understood. The objective of this study was to investigate the roles of MDP and its calcium salt in preserving the adhesive–dentin hybrid layer. MethodsMDP-conditioned collagen was investigated by Fourier-transform infrared spectroscopy, Ultraviolet–visible spectroscopy, and molecular docking. The structural changes to the dentin surface upon acid-etching and MDP-conditioning were observed by SEM. X-ray diffraction and nuclear magnetic resonance were used to investigate the chemical interactions between MDP and HAp. The collagen-protecting effects of MDP and its Ca salt were investigated using in-situ zymography, rhMMP-9 colorimetric assay, hydroxyproline assay, and molecular docking. ResultsMDP forms a stable collagen-phosphate complex through hydrogen bonding with the collagen in dentin. Furthermore, it generates MDP-Ca salts that are deposited on the dentin collagen scaffold, protecting it from degradation. Moreover, both free MDP and the MDP-Ca salt inhibit matrix metallopeptidase and exogenous proteases, with the inhibitory effect of the calcium salt being significantly stronger than that of the free form. SignificanceMDP-based adhesives preserve the collagen within the hybrid layer by simultaneously improving collagen’s resistance to exogenous enzymes and inhibiting MMP activity, both of which contribute to the longevity of dentin–resin bonding.