Dental Adhesives Research Articles

Development and assessment offluorinated grapheme nanoparticles modified dental adhesives

Background: The success of adhesion to the tooth structure plays an important role in the dental restoration,which can effectively avoid the terrible clinical problems during the bonding process, including the secondarycaries and the loading of adhesive compositions with fillers and nanoparticles with antibacterial propertieshas led to a significant reinforcement effect of the adhesive.Objective: The current study is designed to investigate the effects of addition of 2% of fluorinated grapheneon the adhesive-dentin hybrid layer for two types of commercially available universal adhesive, guidedusing the etch and rinse technique as a bonding procedure.Method: Forty extracted premolar teeth will be divided into four groups of ten teeth. Group I: the nonincorporated (Prime & Bond Universal) bonding agent (Control group). Group II:using the 2% FGnanoparticles incorporated (Prime & Bond Universal) bonding agent. Group III: non-incorporated (AllBond Universal) bonding agent (Control group). Group IV: using the incorporated (All Bond Universal)bonding agent. The degree of conversion was also measured using Fourier transform infrared spectroscopy(FTIR). The antibacterial activity of the adhesives was evaluated using agar diffusion test against thefollowing bacteria: Streptococcus mutans and Lactobacillus salivarius obtained from saliva.Results: A significantly greater antibacterial activity was obtained with adhesives containing a 2% fluorinatedgrap hene nanoparticles than other groups (P<.01). Degree of conversion of tested adhesives was not changesignificantly after addition of 2% of fluorinated grap hene nanoparticles.Conclusion: The antibacterial effect of adhesives that incorporated with 2% of fluorinated graphenenanoparticles was higher than the non-incorporated etch- and rinse adhesive systems. The degree ofconversion of adhesives was not significantly different.

Heating and preheating of dental restorative materials-a systematic review.

To perform a review on the influence of preheating and/or heating of resinous and ionomeric materials on their physical and mechanical properties and to discuss the benefits and methods of preheating/heating that have been used. A search was performed in the Pubmed, Scopus, Scielo, and gray literature databases. In vitro studies published from 1980 until now were searched using the descriptors "composite resins OR glass ionomer cements OR resin cements OR adhesives AND heating OR preheating." Data extraction and quality of work evaluation were performed by two independent evaluators. At the end of reading the search titles and abstracts, 74 articles were selected. Preheating of composite resins reduces viscosity, facilitates adaptation to cavity preparation walls, increases the degree of conversion, and decreases the polymerization shrinkage. Preheating of resin cements improves strength, adhesion, and degree of conversion. Dental adhesives showed good results such as higher bond strength to dentin. However, unlike resinous materials, ionomeric materials have an increase in viscosity upon heating. Preheating improves the mechanical and physical properties. However, there is a lack of clinical studies to confirm the advantages of preheating technique. Preheating of dental restorative materials is a simple, safe, and successful technique. In order to achieve good results, agility and training are necessary so the material would not lose heat until the restorative procedure. Also, care is necessary to avoid bubbles and formation of gaps, which compromises the best restoration performance.

Effect of different self-etch adhesive application methods on the shear bond strengths of composite resin to dentin

Dental adhesion is a complex phenomenon that has challenged the conventional biomechanical principles applied to Dental Medicine. Many of the advances in aesthetic restorative dentistry are due to dental adhesion: bond of direct resin-based restorations, bond of all ceramic restorations, bond of orthodontic brackets, bond of indirect resin-based restorations and improving tooth shape and colour. An adhesive is a material that not only joins two substrates together, but also transfers loads from one surface to another. Therefore, the performance of dental adhesion is measured through adhesion strength. This paper aims at investigating the influence of application method and the optional preliminary acid etching on the shear bond strengths of a composite resin to dentin, using self-etch adhesives in single or double layer. Buccal surfaces of 40 extracted human teeth were prepared and dental adhesives were applied on the dentin surfaces. Microshear bond strength increased when double-layer application was used, but this improvement was adhesive dependent. The use of optional preliminary acid etching did not improve significantly the bond strength to dentin.

Reverse planning for making an occlusal splint before restorative treatment: case report of rehabilitation of a patient with bruxism

Recovery of worn tooth surfaces using composite resin has been increasingly accepted by clinicians, since rehabilitation through additive techniques aims at minimal or no intervention and preserves healthy dental structure, ensuring longevity to the treatment. Adhesive dentistry can afford promising results through a correct diagnosis and treatment plan. Planning can offer not only dental rehabilitation, but also controlling cause of the wear process. Strategies that seek to prevent the progression of muscle activities such as bruxism, should be established. This article aims to present a clinical case report of a rehabilitation treatment planned and executed through the digital flow, in which the patient presents wear and tear caused by the habit of bruxism. The rehabilitation of the anterior upper teeth was carried out in direct composite resin, associated with the preparation and installation of an occlusal splint, used before, during and after the restorative treatment, ensuring the reestablishment of the shape, function and dental aesthetics.

Recent advances in nanodentistry: a special focus on endodontics

Root canal ecosystem is a complex environment due to its anatomy and persistence of microorganisms; those may reside within the canal after therapeutic efforts and cause subsequent complications and treatment failure. Nanomaterials with unique physicochemical properties have high accessibility to untouched areas of the intracanal ecosystem. Therefore, they have attracted the attention of researchers on the efficacy of nanodentistry in endodontics. This Letter reviews the recent advances in nanodentistry, especially in root canal treatment. In addition, it focuses on the application of nanoparticles in treatment and prevention of a variety of post-treatment infections in endodontics, treatment of antibiotic resistance and bacterial biofilm structures. In addition, it points out applications of nanoparticles in endodontic materials, restorative materials, dental adhesives, implants, prostheses and dentures. At last, the Letter elaborates on how nanoparticles used for targeted endodontic drug delivery and their efficiently controlled releases.

Copper nanoparticles as nanofillers in an adhesive resin system: An in vitro study.

The incorporation of an antibacterial agent into an adhesive could improve its clinical performance. Some nanoparticles (NPs), including copper nanoparticles (Cu NPs), display an antibacterial effect. Therefore, Cu NPs could act as a nanofiller when added to an adhesive. The aim of this study was to evaluate the antibacterial activity, cytotoxicity and shear bond strength (SBS) of an experimental dental adhesive with Cu NPs. Different concentrations (0.0050 wt%, 0.0075 wt% and 0.0100 wt%) of Cu NPs were added to the adhesive. The distribution of Cu NPs in the polymer matrix was observed based on transmission electron microscope (TEM) images. The antimicrobial activity of the adhesive + Cu NPs was evaluated with the agar disk diffusion test against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli) and Streptococcus mutans (S. mutans). The cytotoxicity assay was performed by means of the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method with human pulp cells (HPC). Additionally, the SBS tests were carried out (n = 31) and the modes of fracture were registered. The vestibular and lingual surfaces of each tooth were randomly assigned to the study groups (group I - control adhesive; group II - adhesive + 0.0100 wt% Cu NPs). The samples were statistically analyzed (p ≤ 0.05). The adhesive + 0.0100 wt% Cu NPs showed inhibition zones against the strains under study that were similar to, or slightly smaller than, the halos produced by chlorhexidine (CHX) and specific drugs for each strain (30 μg of cefotaxime against S. mutans and S. aureus, and 1.25/3.75 μg of sulfamethoxazole/ trimethoprim against E. coli). The control adhesive was moderately cytotoxic (relative cell viability of 36.7 ±0.8%), being more cytotoxic than Cu NPs themselves (58.3 ±0.1%). A significantly higher SBS was obtained for the adhesive + 0.0100 wt% Cu NPs (6.038 ±2.95 MPa) than for the control group (3.278 ±1.75 MPa). The modes of fracture in group I were almost equally distributed between adhesive and cohesive failures whereas in group II, the failure was mainly cohesive. The results of this study suggest that incorporating Cu NPs into an adhesive improves its SBS and provides it with antibacterial properties, without increasing its inherent cytotoxicity - 2 desirable characteristics for the dental adhesives of composites.

Effects of Zn-Doped Mesoporous Bioactive Glass Nanoparticles in Etch-and-Rinse Adhesive on the Microtensile Bond Strength.

The purpose of this study was to assess the effects in the dentin bond strength of dental adhesives (DAs) and biological effects using zinc (Zn)-doped mesoporous bioactive glass nanoparticles (MBN-Zn). Synthesized MBN and MBN-Zn were characterized by scanning electron microscopy (SEM), X-ray diffraction and the Brunauer, Emmett and Teller (BET) method. The matrix metalloproteinases (MMP) inhibition effects of DA-MBN and DA-MBN-Zn were analyzed. The microtensile bond strength (MTBS) test was conducted before and after thermocycling to investigate the effects of MBN and MBN-Zn on the MTBS of DAs. The biological properties of DA-MBN and DA-MBN-Zn were analyzed with human dental pulp stem cells (hDPSCs). Compared with the DA, only the DA-1.0% MBN and DA-1.0% MBN-Zn exhibited a statistically significant decrease in MMP activity. The MTBS values after thermocycling were significantly increased in DA-1.0% MBN and DA-1.0% MBN-Zn compared with the DA (p < 0.05). It was confirmed via the MTT assay that there was no cytotoxicity for hDPSCs at 50% extract. In addition, significant increases in the alkaline phosphatase activity and Alizarin Red S staining were observed only in DA-1.0%MBN-Zn. These data suggest the 1.0% MBN and 1.0% MBN-Zn enhance the remineralization capability of DAs and stabilize the long-term MTBS of DAs by inhibiting MMPs.

Current perspectives on dental adhesion: (1) Dentin adhesion – not there yet

The essential goal of any adhesive restoration is to achieve a tight and long-lasting adaptation of the restorative material to enamel and dentin. The key challenge for new dental adhesives is to be simultaneously effective on two dental substrates of conflicting nature. Some barriers must be overcome to accomplish this objective. While bonding to enamel by micromechanical interlocking of resin tags within the array of microporosities in acid-etched enamel can be reliably achieved and can effectively seal the restoration margins against leakage, bonding effectively and durably to organic and humid dentin is the most puzzling task in adhesive dentistry.Much of the research and development of dental adhesives has focused on making the clinical procedure more user-friendly by reducing the number of bottles and/or steps. Although clinicians certainly prefer less complicated and more versatile adhesive materials, there is a trade-off between simplification of dental adhesives and clinical outcomes. Likewise, new materials are launched with claims of being novel and having special properties without much supporting evidence.This review article discusses dental adhesion acknowledging pioneer work in the field, highlights the substrate as a major challenge to obtain durable adhesive restorations, as well as analyzes the three adhesion strategies and their shortcomings. It also reviews the potential of chemical/ionic dental adhesion, discusses the issue of extensively published laboratory research that does not translate to clinical relevance, and leaves a few thoughts in regard to recent research that may have implications for future adhesive materials.

Current perspectives on dental adhesion: (2) Concepts for operatively managing carious lesions extending into dentine using bioactive and adhesive direct restorative materials.

This article reviews the current concepts for operatively managing carious lesions extending into dentine with minimal removal of tooth structure and restoring with dentine adhesives and direct composite resin. It looks sequentially at the operative steps involved including remineralisation with bioactive cements, bonding to caries-affected dentine including smear-layer modification using HOCl, creation of an acid-base resistance zone,steps to optimise the performance of all-in-one adhesives, and incremental placement of direct composite resin to improve bond strengths to cavity floor dentine. It explores how understanding the phenomenon of colour-shifting at the composite resin-enamel/dentine restoration borders can help in creating near “invisible” restoration margins through a “chameleon” effect. With the increased risks of transmission of Covid-19 when aerosol generating procedures are carried out in Dentistry, following a minimally invasive approach to managing dental caries should be given serious consideration.

Zinc-based particle with ionic liquid as a hybrid filler for dental adhesive resin

ObjectivesThe aim of this study was to evaluate the effect of a zinc-based particle with ionic liquid as filler for an experimental adhesive resin. MethodsThe ionic liquid 1-n-butyl-3-methylimidazolium chloride (BMI.Cl) and zinc chloride (ZnCl2) were used to synthesize 1-n-butyl-3-methylimidazolium trichlorozincate (BMI.ZnCl3), which was hydrolyzed under basic conditions to produce the simonkolleite (SKT) particles. SKT was analyzed by scanning electron microscopy and transmission electron microscopy. An experimental adhesive resin was formulated and SKT was incorporated at 1, 2.5, or 5 wt.% in the adhesive. One group without SKT was a control group. The antibacterial activity against Streptococcus mutans, cytotoxicity, degree of conversion (DC), ultimate tensile strength (UTS), softening in solvent, and microtensile bond strength (μ-TBS) were investigated. ResultsSKT prepared from the ionic liquid BMI.ZnCl3 presented a hexagonal shape in the micrometer scale. SKT addition provided antibacterial activity against biofilm formation of S.mutans and planktonic bacteria (p < 0.05). There were no differences in pulp cells’ viability (p > 0.05). The DC ranged from 62.18 (±0.83)% for control group to 64.44 (±1.55)% for 2.5 wt.% (p > 0.05). There was no statistically significant difference among groups for UTS (p > 0.05), softening in solvent (p > 0.05), and 24 h or 6 months μ-TBS (p > 0.05). ConclusionsThe physicochemical properties of adhesives were not affected by SKT incorporation, and the filler provided antibacterial activity against S. mutans without changes in the pulp cells' viability. This hybrid zinc-based particle with ionic liquid coating may be a promising filler to improve dental restorations. Clinical relevanceA filler based on a zinc-derived material coated with ionic liquid was synthesized and added in dental adhesives, showing antibacterial activity and maintaining the other properties analyzed. SKT may be a promising filler to decrease the biofilm formation around resin-based restorative materials.

Current perspectives on dental adhesion: (3) Adhesion to intraradicular dentin: Concepts and applications

Adhesion science is one of the greatest contributions to restorative dentistry. Adhesion not only established the current principles of tissue preservation, but also allowed for the production of more hermetic and long-lasting restorations. Although adhesive strategies are routinely used in most clinical situations, adhesion to root dentin is still a major challenge. The presence of humidity together with less intertubular dentin are factors that limit the adhesive potential of root dentin. This situation is more unfavorable in endodontically treated teeth prepared for prefabricated or custom-made intraradicular posts; these procedures may alter the mechanical properties of teeth by modifying the viable dentin surface for adhesion. Also, contaminants deposited on the dentin surface are difficult to remove through conventional techniques. Moreover, root canal morphology has a very unfavorable C-factor, bringing undesirable effects resulting from polymerization contraction of resin-based materials. However, the differences between coronal and root dentin are not a barrier for dentin adhesion. Standardization of procedures and care during clinical steps are fundamental to the success of adhesion to coronal or intraradicular dentin. Thus, it is essential to know the anatomy of the root structure, the factors that interfere with intraradicular adhesion, as well as the current adhesive materials and techniques.

In Vitro Analysis of Quality of Dental Adhesive Bond Systems Applied in Various Conditions

Introduction: There are several methods of reducing a microleakage, and one of them is choosing appropriate adhesive material. The aim of the work was the in vitro analysis of 4 bonds: 3M ESPE “Single bond”, Dentsply “Prime and Bond Active”, Coltene “One Coat 7 Universal”, and Kuraray “Clearfil Universal Bond Quick”. Material and methods: 136 healthy molar teeth were collected and randomly split into 4 groups and Vth Class cavities were prepared. Chosen adhesives were used in four groups of teeth with the same composite. Teeth were the thermocycled, sealed, covered with lacquer, and submerged in 1% methylene blue solution for 24 h. After the thermocycling, the vertices of each tooth were sealed using dental wax. Each tooth was then fully covered with lacquer. All teeth were then submerged into 1% methylene blue solution for 24 h in room temperature. In the next step they were transversely cut through a center of restoration. The Olympus BX43 microscope was used to photograph each cut tooth. With the usage of Olympus stream software, measurement of the dye’s leakage was performed. Results. The statistical analysis proved that the most effective material when applied to ideally prepared cavity surface was Dentsply “Prime and Bond Active”. The second material was 3M ESPE “Single Bond”, third—Coltene “One Coat 7 Universal” and fourth—Kuraray “Clearfil Universal Bond Quick”. The most effective material applied to a too-dry surface was Dentsply “Prime and Bond Active”, second—3M ESPE “Single Bond”, third—Coltene “One Coat 7 Universal” and fourth—Kuraray “Clearfil Universal Bond Quick”. When it comes to too damp surfaces the best results were obtained with Dentsply “Prime and Bond Active” then Coltene “One Coat 7 Universal”, 3M ESPE “Single Bond” and Kuraray “Clearfil Universal Bond Quick”. Conclusion: The level of cavity dampness influences the quality of adhesives. Better results are obtained with over-dried surfaces than over-damp, which is connected with the dilution of the material.

Evolution of Network Structure and Mechanical Properties in Autonomous-Strengthening Dental Adhesive

The inherent degradation property of most dental resins in the mouth leads to the long-term release of degradation by-products at the adhesive/tooth interface. The by-products increase the virulence of cariogenic bacteria, provoking a degradative positive-feedback loop that leads to physicochemical and mechanical failure. Photoinduced free-radical polymerization and sol‒gel reactions have been coupled to produce a novel autonomous-strengthening adhesive with enhanced hydrolytic stability. This paper investigates the effect of network structure on time-dependent mechanical properties in adhesives with and without autonomous strengthening. Stress relaxation was conducted under 0.2% strain for 8 h followed by 40 h recovery in water. The stress‒time relationship is analyzed by nonlinear least-squares data-fitting. The fitted Prony series predicts the sample’s history under monotonic loading. Results showed that the control failed after the first loading‒unloading‒recovery cycle with permanent deformation. While for the experimental sample, the displacement was almost completely recovered and the Young’s modulus increased significantly after the first test cycle. The experimental polymer exhibited higher degree of conversion, lower leachate, and time-dependent stiffening characteristics. The autonomous-strengthening reaction persists in the aqueous environment leading to a network with enhanced resistance to deformation. The results illustrate a rational approach for tuning the viscoelasticity of durable dental adhesives.

Wollastonite as filler of an experimental dental adhesive

ObjectiveThe aim of this study was to formulate experimental dental adhesives with wollastonite and evaluate the physical, chemical, and bioactivity properties of the resins. MethodsWollastonite was characterized by Fourier transform infrared spectroscopy, X-ray and laser diffraction analyses, and scanning electronic microscopy. An experimental adhesive resin was formulated, and wollastonite was used as filler at 0 (control group), 0.5, 1, or 2 wt.%. Radiopacity, degree of conversion (DC%), microhardness, softening in solvent, ultimate tensile strength (UTS), 24 h- and 1 year- microtensile bond strength (μTBS), mineral deposition, and color of the adhesives were evaluated. ResultsWollastonite particles showed a needle-like shape, a mean diameter of 70 (± 30) μm, characteristic chemical peaks, and pure crystalline β-CaSiO3 phase. There were no significant differences (p > 0.05) for radiopacity, softening in solvent, and color change. The group with 2 wt.% of wollastonite showed higher microhardness and UTS in comparison to the control group (p < 0.05). After one year, the control group showed reduced μTBS compared to the immediate value (p < 0.05). The groups with wollastonite presented stable μTBS after one year in comparison to the immediate μTBS (p > 0.05). Wollastonite induced mineral deposition on the adhesive surface over the time of storage in simulated body fluid. ConclusionThe addition of wollastonite improved the mechanical behavior of the adhesive without changing the analyzed chemical properties. The adhesives with this filler presented mineral deposition and acceptable clinical color. Moreover, dentin treated with wollastonite-doped adhesives showed higher bonding stability after one year of aging. Clinical significance: Wollastonite, a silicate-based material, provided bioactivity for the adhesives, which assists in producing therapeutic tooth-restoration interfaces. Moreover, the incorporation of this mineral improOfiller to improve the biological properties of adhesives and assist in dentin-restoration stability.

Small Extracellular Vesicles from Lipopolysaccharide-Preconditioned Dental Follicle Cells Promote Periodontal Regeneration in an Inflammatory Microenvironment.

Lipopolysaccharide (LPS)-induced inflammatory microenvironment can enhance the dental follicle cells (DFCs) proliferation, differentiation, and adhesion abilities beneficial to periodontal regeneration, which possibly attributes the success to exosomes according to recent studies. This study aimed to investigate the therapeutic efficacy and underlying mechanisms of LPS-preconditioned DFC-derived small extracellular vesicles (sEVs), which enriched exosomes for periodontal regeneration in an inflammatory microenvironment. LPS preconditioning could significantly increase the secretion of sEVs derived from DFCs. Both LPS-preconditioned dental follicle cell-derived sEV (L-D-sEV) and DFC-derived sEV (D-sEV) promoted the proliferation of periodontal ligament cells from periodontitis (p-PDLCs) with a dose-dependent and saturable manner and also enhanced the migration and differentiation of p-PDLCs. Furthermore, L-D-sEV showed a modest benefit than D-sEV to promote p-PDLCs differentiation. In vivo, an L-D-sEV-loaded hydrogel applied in the treatment of periodontitis was beneficial to repair lost alveolar bone in the early stage of treatment and to maintain the level of alveolar bone in the late stage of treatment in experimental periodontitis rats, which could partly decrease the expression of the RANKL/OPG ratio. In conclusion, L-D-sEV was beneficial to p-PDLCs forming an integrity periodontal tissue. The biological injectable L-D-sEV-loaded hydrogel could be used as a treatment method for experimental periodontitis in rats, promoting periodontal tissue regeneration and providing a new alternative cell therapy method for periodontal tissue regeneration.

Microwave assisted urethane grafted nano-apatites for dental adhesives

The objectives were to synthesize urethane grafted nano-apatite in shortest possible time duration using the microwave irradiation method and to utilize them for synthesis of experimental dental adhesives. The structural, morphological, thermal, and mechanical behavior of synthesized grafted nano-apatite were investigated. Then, these grafted nano-apatite particles were incorporated in various concentrations that is, 5wt.%, 10wt.%, and 15wt.% into dimethacrylate resins to develop bioactive adhesives. The weight measurement analysis in deionized water and phosphate buffer saline, Knoop micro-hardness, and degree of conversion were evaluated. The bacterial adhesion was investigated with Streptococcus mutans at 6h, 24h, and 48h. Statistical analysis was conducted using one-way ANOVA. The urethane dimethacrylate was successfully grafted on the nano-apatite surface and spectroscopic analysis confirmed the presence of urethane and phosphate peaks. An inverse relationship was found in both media between the concentration of grafted fillers and weight loss. No significant difference was observed in the micro-hardness and degree of conversion among the groups, whereby the degree of conversion for all groups was in the range of 83% to 86%. The mean number of bacterial colonies was significantly lower in the 15wt.% group compared to 5wt.% and 10wt.%. The grafted nano-apatite presented favorable results for adhesive resin incorporation, where 15wt.% group comparatively showed superior results than other groups.

Dental Adhesive Interfaces Reinforced with Magnetic Nanoparticles: Evaluation and Modeling with Micro-CT versus Optical Microscopy.

Dental adhesives are used in a wide range of applications, including to place direct composite restorations in frontal or posterior teeth. One of the most frequent causes for the failure of composite resin restorations is microleakages. The first aim of this work is to introduce a new type of self-etched dental adhesive doped with magnetic nanoparticles (MPs) synthetized in the laboratory. The scope is to produce adhesives with a minimized width/thickness to decrease the risk of microleakages. The second aim is to assess the width/thickness of the adhesive layer in all the characteristic areas of the teeth using both the less precise but most common optical microscopy and the more accurate and volumetric micro-Computed Tomography (CT) investigations. Twenty extracted teeth have been divided into four groups: Group 1 includes ‘blank’ samples with adhesives that are not doped with MPs; Group 2 includes samples with adhesives doped with MPs; Groups 3 and 4 include samples with adhesives doped with MPs that are subjected to an active magnetic field for 5 and 10 min, respectively. Microscopy investigations followed by micro-CT and EDAX are performed on the adhesive. While a rather good agreement is obtained between the microscopy and micro-CT results, the capability of the latter to offer a full volumetric reconstruction of the layer is exploited to analyze the adhesion of the four considered dental materials. Thus, from micro-CT results the graphs of the surface areas as functions of the adhesive layer width are modeled mathematically, as well as the volume of sealants, for each of the four groups. To our knowledge, it is the first time that such a methodology is used. Characteristic parameters are extracted and the ascertainment of the optimal parameter that should be utilized for such assessments is discussed. The study demonstrates the adhesion improvement produced for Groups 3 and 4, where MPs are used. It also concludes that the magnetic field should be applied to the adhesive material for the longest possible exposure time (with a trade-off with the clinical duration of the treatment).

Efficacy of Polyacrylic Acid as a Conditioning Agent on the Bond Strength of Self-adhesive Resin Cements to Dental Enamel.

This in vitro study evaluated the effectiveness of polyacrylic acid as an acid etchant similar to phosphoric acid and its effect on the microtensile bond strength of self-adhesive resin cement to enamel. Ninety Te-Econom Plus resin blocks (11 x 4 mm) were cemented onto bovine enamel and distributed into 10 groups according to the surface treatments (no surface treatment; etching with 37% phosphoric acid; etching with 20% polyacrylic acid; etching with 37% phosphoric acid + dental adhesive, and etching with 20% polyacrylic acid + dental adhesive) and the self-adhesive resin cements used (RelyX U200 and MaxCem Elite) (n = 9). After bonding, the specimens were sectioned into sticks, subjected to thermocycling (5760 cycles, 5°C and 55°C) and microtensile bond strength testing (n = 6). Images of representative specimens were obtained using a scanning electron microscope. Enamel penetration evaluation of different surface treatments was analysed by confocal laser scanning microscopy (n = 3). Data on bond strength were subjected to 2-way ANOVA and Tukey's least significant difference test (α = 0.05). Both 37% phosphoric acid and 20% polyacrylic acid yielded the same microtensile bond strength between self-adhesive resin cement and enamel, independent of the application of dental adhesives (p > 0.05). MaxCem Elite showed higher bond strength values than RelyX U200 just for the 20% polyacrylic acid group (p = 0.001). Acid pre-conditioning of dental enamel may influence the bond strength of self-adhesive resin cement to enamel, and 20% polyacrylic acid showed efficacy similar to that of 37% phosphoric acid.

Shear Bond Strength of a Contemporary Dental Adhesive System to Two Types of Zirconia

Aim: to evaluate the shear bond strength of an adhesive system (Single bond universal adhesive+ RelyX Ultimate cement) and Panavia F2.0 to two types of zirconia (conventional ZI zirconia and translucent TZI zirconia) after thermocycling. Materials & Methods: 10 square shaped large samples from Incoris ZI blocks , and 10 from Incoris TZI blocks were prepared with larger dimensions (12x12x2mm). Another 10 square shaped small samples from each type of zirconia blocks were with small dimensions (6x6x2mm). The surfaces of the large and small samples were air abraded with 110 µm AL2O3 particles, then each small sample was bonded to the large sample using two types of cements (RelyX Ultimate cement in combination with Single bond universal adhesive and Panavia F2.0 cement) under 3Kg load and light cured. After bonding, all specimens were thermocycled for 5000 cycles. The cement/zirconia interface for each subgroup was detected under scanning electron microscope and the shear bond strength was tested using a computerized universal testing machine. Results: No significant difference between shear bond strength of all subgroups tested. Conclusion: The shear bond strength of RelyX Ultimate+ Single bond universal adhesive to two types of zirconia was comparable to Panavia F2.0 , and the shear bond strength of translucent zirconia bonded with two types of cements was comparable to conventional zirconia. Keywords: Panavia F2.0, RelyX Ultimate, Sandblasting , Single Bond Universal Adhesive, Zirconia.

Characteristics of 10-Methacryloyloxidecyl Dihydrogen Phosphate Monomer in Self-Etching Two-Bottled Dental Adhesive System: Comparison with Commercial Products.

Dentin bonding is a key in restorative dentistry. Here, we developed a self-etching two-bottle adhesive system containing 10-methacryloyloxidecyl dihydrogen phosphate monomer (MDP) and the physical, mechanical, and biocompatible properties were evaluated. The characteristics of MDP were analyzed using nuclear magnetic resonance (NMR). Tests for water sorption and solubility, the shear-bond strengths to dentin and enamel, and cytotoxicity were performed. The newly-blended experimental group showed the lowest thickness and water sorption and solubility values. The shear bond strength of enamel and dentin were comparable to control groups (the three other products were ClearfilTM, UniFil®, and AdheSE®). All test groups showed 60% of cell viability. In this study, the properties of the newly-synthesized adhesive are comparable with the others. The fundamental goal of this study is to get the MDP patent released, as it is intended for domestic production. For this purpose, this dentin adhesive was developed and compared with the commercial product.