Application Of Silane Coupling Agent Research Articles

Major outcomes of clinical and experimental studies to highlight the importance of using silane in composite resin restorations in modern dentistry: a systematic review

Introduction: Dental restorations are often placed due to caries or fractures, and composite resin is often the material of choice to restore teeth. Several factors may play a role related to the application of silane coupling agents, such as the type of silane (hydrolyzed or non-hydrolyzed) and the service life of the defective composite resin restoration being repaired. Objective: It was to analyze the main outcomes of clinical and experimental studies to highlight the importance of using silane in composite resin restorations in modern dentistry. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from February to April 2024 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 111 articles were found, 36 articles were evaluated in full and 30 were included and developed in the present systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 30 studies with a high risk of bias and 22 studies that did not meet GRADE and AMSTAR-2. Most studies did not show homogeneity in their results, with X2=78.4%>50%. It was concluded that the previous application of silane reduced the bond strength values. The two-bottle adhesive showed better results than single-bottle or self-etching systems for composite resin repairs. Furthermore, the association of preheated hydrofluoric acid/silane applied or not with electric current promoted different values of micro shear resistance, types of fracture, and contact angles in the resin cement/ceramic connection. Silane application is essential for surfaces conditioned by hydrofluoric acid, but the use of adhesive is optional when silane is applied.

Silane coupling agent enhances recycle aggregate/asphalt interfacial properties: An experimental and molecular dynamics study

Incorporating recycled concrete aggregate (RCA) into hot mix asphalt mixtures is an effective means of reducing natural sand and gravel extraction and consuming construction solid waste. The surface cement mortar and micro-cracks are the essential differences between RCA and natural aggregates. Therefore, it reduces the adhesion energy between RCA and asphalt interface, resulting in the performance decline of RCA asphalt mixture. To address this issue, this study used a silane coupling agent (SCA) to enhance the adhesion performance at the RCA/asphalt interface. The enhancing mechanism of SCA on the interface was systematically explored in terms of macroscopic performance, micro-interface structure, and nano-interfacial interactions. The macro-experimental results indicated that the performance of RCA asphalt mixes was significantly improved after modification of RCA with SCA solution at 10% concentration. The microscopic test results showed that the hydrolysis products of SCA could chemically adsorb on the surface of RCA to form a dense coupling layer, thereby fixing the interface structural defects. The molecular dynamics results show that SCA can form strong binding energy with the RCA surface mortar through interaction such as Si-O-Si bonds, stable ionic bonds, and hydrogen bonds, and it also has good compatibility with the asphalt layer. In conclusion, SCA can effectively enhance the performance of RCA asphalt mixtures, especially addressing the issue of poor adhesion between RCA surface mortar and asphalt. This study provides theoretical and experimental support for the application of SCA in RCA asphalt mixtures.

Characteristic fatigue strength and reliability of dental glass-ceramics: Effect of distinct surface treatments – Hydrofluoric acid etching and silane treatment vs one-step self-etching ceramic primer

The aim of this study was to mechanically characterize through flexural fatigue test two CAD-CAM glass-ceramics according to distinct surface etching protocols. To do so, feldspathic (FELD) and lithium disilicate (LD) glass ceramics were subjected to different surface treatments: (1) control – no treatment (Ctrl); (2) conventional protocol etching with 5% hydrofluoric acid followed by silane coupling agent application (HF + SIL; Monobond N, Ivoclar); or (3) using a self-etching ceramic primer (E&P; Monobond Etch & Prime, Ivoclar). Ceramic discs (N = 120; Ø = 12 mm; thickness = 1.2 mm) were produced from CAD-CAM blocks, with 60 being from FELD (VITABLOCS Mark II, Vita Zahnfabrik) and 60 from LD (IPS e.max CAD, Ivoclar). Next, 20 disks of each ceramic were allocated into three groups: Ctrl, HF + SIL, or E&P. Surface roughness data were collected on all samples before and after surface treatments (except for Ctrl). Cyclic fatigue (n = 15) biaxial flexural strength tests were performed by the piston-on-three-balls geometry (ISO 6872) considering the test parameters established from a monotonic test (n = 5). The monotonic test was carried out at a 1 mm/min loading rate and 500 kgf loading cell until fracture to obtain the failure data. The cyclic fatigue test was executed underwater at a frequency up to 20 Hz, with the first stress being 25% of the monotonic test for 5000 cycles, followed by increments of 5% of the monotonic test at each step of 10,000 cycles until failure (fracture). Complementary fractography, topography and Atomic Force Microscopy (AFM) analyses were performed. Characteristic Fatigue Strength (CFS) and Weibull modulus were analyzed by Weibull analysis using the fatigue test data. Roughness and complementary analysis data were analyzed by one-way ANOVA. The statistical results exhibited similar CFS among Ctrl, HF + SIL and E&P for both glass-ceramics. The survival analysis corroborates the findings, however the Weibull modulus pointed out superior structural reliability of FELD treated with the E&P group compared to HF + SIL. According to the complementary analyses, HF + SIL exhibited a higher surface area than E&P and Ctrl for FELD (p = 0.001). Roughness showed statistically significant differences among conditions for FELD (E&P < Ctrl = HF + SIL; p < 0.05) and no difference for LD (p > 0.05). Therefore, the CFS were not influenced by any condition evaluated for FELD and LD glass-ceramics; however, superior structural reliability (higher Weibull modulus) for the feldspathic ceramic treated with the E&P was observed.

The Effect of Laser Irradiation to Surfaces of Computer-Aided Design/Computer-Aided Fabrication Resin Blocks Coated with a Silane Coupling Agent on Bond Strength between the Resin Blocks and Composite Resin.

The aim of this study was to investigate the effect of laser irradiation to computer-aided design/computer-aided fabrication (CAD/CAM) resin blocks coated with a silane coupling agent on the bond strength between resin blocks and composite resin. The CAD/CAM resin blocks used in this study were Cerasmart 300 (GC) and Vita Enamic (Vita); they were cut into plates and then subjected to a series of treatments. After processing with a silane coupling agent, treatment with a semiconductor laser was performed at 3.0, 5.0, and 7.0 W, followed by bonding procedures. The control group included those exposed to silane and bonded without laser application. After bonding, a mold with a simulated cavity was formed on the specimen and filled with flowable composite resin, and they were stored for 24 h or stressed by thermal cycling for subsequent testing that assessed the shear bond strength (n = 10). The results revealed that the bond strength was significantly enhanced by laser irradiation after applying a silane coupling agent (p < 0.03), whereas significant increase was not detected between the materials (p > 0.05). Particularly, 7 W laser irradiation had a significant increase on the bond strength between the composite resin and Cerasmart block after thermal cycling (p = 0.009). The SBS of the composite resin to CAD/CAM resin blocks was significantly enhanced by laser irradiation after silane coupling agent application.

The clinical success of repaired posterior composite restorations with and without silane application.

To evaluate the clinical success of posterior composite restorations repaired with and without silane application for up to 2 years. In this retrospective study, patient record files acquired from the 40 patients who were treated due to needing repair for two class II defective composite restorations and visited the clinical practice for regular check-up visits were used. In the experimental group, the defective restorations were repaired using a silane coupling agent (Porcelain Primer), a universal adhesive (G-Premio Bond), and a microhybrid resin composite (Charisma Smart). In the control group, the restorations were repaired using the universal adhesive and the resin composite without silane coupling agent application. The repaired restorations were blindly assessed by two calibrated examiners using modified USPHS criteria at baseline, 6 months, 1, and 2 years. The data were analyzed using non-parametric tests (p = 0.05). After 2 years, 80 repaired class II restorations were evaluated. No restoration of either the control or silane-treated group failed. After 2 years, there were no statistically significant differences between the experimental and control groups (p > 0.05). The differences in surface roughness were observed in each group over time (p < 0.05). There were no variations in other criteria over time (p > 0.05). There was no significant effect of the silane coupling agent on restoration repair survival. The repair of localized defects of the posterior composite restorations either with or without silane application is a conservative treatment option that may increase the clinical success of these restorations.

Comparative evaluation of adhesion of glass fiber post to the root dentin after surface treatment of post and using universal bonding agent: An in vitro study.

The purpose of the study is the evaluation and comparison of surface roughness and bond strength of glass fiber post (GFP) after different types of surface treatment and the application of a universal bonding agent. Forty GFPs were divided into four groups based on surface treatment: Group I, silane coupling agent application for 60 s; Group II, air abrasion with 30 μm silicon dioxide powder particles in 2.5 bar pressure from 2 cm distance for 10 s, followed by silane coupling agent application; Group III, 9% hydrofluoric acid application for 10 s, rinsed and air-dried, followed by silane coupling agent application; and Group IV, silane coupling agent application, followed by universal bonding agent application. Surface roughness evaluation is done by a profilometer. All posts were cemented in the root of the maxillary central incisor with resin cement. After that, root was placed in an acrylic mold, and the external end part of the post was mounted on another acrylic mold. Pull-out bond strength was measured by a universal testing machine. Highest surface roughness and bond strength values were found in Group II. Pretreatment of GFP increases the surface roughness of post as well as bond strength of post to root dentin. There is a correlation between surface roughness and bond strength. However, the use of only universal bonding agent also showed comparable pull-out bond strength of GFP, which means only use of universal bonding agent also a new alternative as pretreatment of GFP and helps in increase in bond strength.

Evaluation of Shear Bond Strength of Prepared Samples of Silorane Composite Repaired with Silorane

Aim: To evaluate shear bond strength of silorane based composite samples repaired with silorane composite with application of silane coupling agent and adhesive bond of silorane before and after thermal cycling. Study design: Experimental study Place and duration of study: Science of Dental Materials Department, de’Montmorency College of Dentistry Lahore from 1st January 2014 to 31st October 2014. Methodology: Sixty composite specimens equally divided into control and experimental groups. Control group was further prepared for repair procedure after polymerization without thermal cycling while experimental group was given with 5000 thermal cycles between temperature range of 5-55oC, dwell time of 20 seconds) before testing, all samples were surface roughened with 400 grit silicon carbide strip, followed by application of silorane coupling agent and adhesive bond of silorane over the substrate and cured for 20 seconds. Repair silane based composite was applied on all substrate silorane composite samples and polymerized, before testing samples were left in distilled water (24 hour at 37oC) and tested with universal testing machine (crosshead speed 0.5 mm/min) until fracture. Results: There is 12 (20%) adhesive, mixed 2 (3.3%) and cohesive is 46 (76.7%). The thermal cycling has no effect on bonding interface in experimental group on strength at bonding interface. Conclusion: Silorane based composite as repair composite gave better strength with silorane based composite and can be used for repair options. Keywords: Shear bond strength, Silorane based composite, Silorane adhesive bond

Study on volume change and scanning electron microscopy observation of silica-filled solution polymerized styrene-butadiene rubber/cis-1,4-polybutadiene rubber blends upon stretching.

Solution polymerized styrene-butadiene rubber/cis-1,4-polybutadiene rubber (SBR/BR) blends filled with silica is widely used system in tread compounds for passenger tires. The application of silane coupling agents greatly improves the interaction between polymer and filler through chemical bonds. By testing a series of SBR/BR blends filled with different specific surface area and content of silica, we measured the volume change data of the compounds upon stretching and plotted the corresponding ΔV/V-ε curves. In order to normalize for stress differences, ΔV/(Vσ)-ε curves were also plotted using stress-strain data. Scanning electron microscopy (SEM) was used to observe the microstructures in the vulcanizate in situ when stretched. The dispersion, agglomeration, and vacuole formation process can be visualized clearly in the SEM images.

Effect of repair systems on dentin bonding performance.

The purpose of this study was to investigate the influence of phosphoric acid etching, metal primer or silane coupling agent application on dentin bonding performance of a 2-step self-etch adhesive system. Human dentin surfaces were prepared and divided into four groups depending on the pre-treatment method: no pretreatment (Clearfil SE Bond 2, CONTROL); 40% phosphoric acid (K-Etchant GEL, K); metal primer (Alloy Primer, AP); or silane coupling agent (Porcelain Bond Activator, PB). The specimens were sectioned into beams, separated into 2 subgroups (n=20): no thermocyling or thermocycled (TC), and subjected to a µTBS test and an acid-base challenge for SEM observation. Statistically lower results were observed between K and AP groups, PB and CONTROL, and PB with/without TC (p<0.05). SEM images at the dentin-adhesive interface revealed that all groups produced an acid-base resistant zone (ABRZ), with a funnel-shaped erosion under the ABRZ for the K group.

Effect of various surface treatments on the bond strength of resin luting agent and the surface roughness and surface energy of CAD/CAM materials.

The aim of this study was to examine the effect of various surface treatments on the bond strength of a resin luting agent and the surface roughness and surface energy of computer-aided design and computer-aided manufacturing (CAD/CAM) materials. Four types of CAD/CAM blocks (Shofu Block HC: BHC; GC Cerasmart: CER; VITA Enamic: ENA; and Lava Ultimate: LAV) were used. All blocks were randomly divided into eight groups based on the surface treatment as follows: no surface treatment (C), airborne-particle abrasion (AA), hydrofluoric acid etching (HA), silane coupling agent application (SL), AA/SL, HA/SL, AA/HA, and AA/HA/SL. The microtensile bond strength (µTBS), surface roughness and surface energy were measured. Three-way ANOVA revealed that all surface treatments significantly influenced the µTBS between the resin luting agent and all types of CAD/CAM materials; however, the effect of each surface treatment on surface roughness and energy was dependent on the CAD/CAM materials.

A Comparative Evaluation of Shear Bond Strength of Orthodontic Brackets Bonded to Porcelain Fused Metal Crowns Treated with Different Surface Conditioning Techniques―An Invitro Study

With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests by scanning electron microscope study were used to examine the effect of 5 different surface conditioning methods: 37% phosphoric acid gel, 9% Hydrofluoric acid, sandblasting + 9% Hydrofluoric acid, Sandblasting + Silane, Fine diamond bur roughening + silane for bonding metal brackets to ceramic surfaces of feldspathic porcelain. A total of 60 human maxillary premolar teeth extracted for therapeutic purposes from patients seeking orthodontic treatment were collected, and 50 ceramic crowns were fabricated onto the premolar teeth following crown preparation. 10 natural teeth were used as controls, they were acid etched in conventional manner using 37% phosphoric acid. Metal brackets were bonded using a light-curing composite. The samples were stored in distilled water at physiological temperature (37oC) for 1 day, and thermocycled 500 times between 5°C and 55°C. Shear bond tests were performed with a universal testing device, and the results were statistically analysed. Ceramic surfaces conditioned with sand blasting followed by application of Silane produced maximum bond strength of 12.34 ± 0.95 MPa comparable or even better than the control group 11.03 ± 1.63 MPa followed by 9% Hydrofluoric acid 11.48 ± 0.98 MPa & Fine Diamond Bur roughening + Silane 9.28 ± 1.11 MPa. Ceramic surfaces conditioned with 37% Ortho Phosphoric acid produced least SBS of 5.51 ± 0.88 MPa and hence not suitable for bonding Orthodontic brackets in a clinical scenario. Statistical tests showed significant difference between and within the groups in shear bond strength and P value also was highly significant, i.e. ***p<0.001. The SEM photomicrographs of all the six different surface preparations revealed different surface morphologies & were corroborative of SBS values. Even though 9% Hydrofluoric acid and Fine diamond bur roughening produced clinically acceptable SBS values, because of their technique sensitivity and side effects, they have to be used with great care and caution. sand blasting followed by the application of Silane coupling agent was found to be the best porcelain surface conditioning method.

Mode I fracture evaluation of CFRP-to-concrete interfaces subject to aggressive environments agents: Freeze-thaw cycles, acid and alkaline solution

The long-term durability of the interface between FRP (fiber reinforced polymer) and concrete is crucial to the safety of FRP strengthened concrete structures. Some experimental works have been carried out to investigate the effect of environmental factors on model II fracture behavior of the FRP-to-concrete interface. However, fewer efforts have been made to estimate interfacial durability under mode I loading. This study evaluates the mode I fracture energy release rate of CFRP (carbon fiber reinforced polymer)-to-concrete interface subjected to freeze-thaw cycling, acid attack, and alkali attack. Significant decrease of fracture energy release rate is observed after environmental conditioning. With the increase of freeze-thaw cycles and soaking time, the failure mode of the specimen changes from tensile failure of concrete to adhesive failure along the interface. Test results also confirm that the durability of the CFRP-to-concrete interface can be improved by application of silane coupling agent under freeze-thaw cycling and alkaline condition.

Freeze–thaw resistance of epoxy/concrete interface evaluated by a novel wedge splitting test

Abstract Externally bonding using epoxy is one of major applying method for FRP strengthening technology. The long-term performance of the epoxy/concrete interface has been proven to be a key for practical application of FRP strengthening, especially when the strengthened structures are exposed to severe environmental conditions. In this study, an experimental program has been carried out to examine the effect of freeze–thaw cycles (soaked in tap water and 5% sodium sulfate solution) on the deterioration of the epoxy/concrete interface through a novel wedge splitting test, which can directly measure the traction-separation law of the interface under mode I loading. The effect of silane treatment on the freeze–thaw resistance of the interface was also examined. A simplified tri-linear constitutive model of the epoxy/concrete interface was obtained according to the test results. Results showed that both the ultimate bond strength and the fracture energy decrease exponentially with the number of freeze–thaw cycles. Under mode I loading, the failure mode of the reference specimen is the tensile failure of the concrete. With the increase of freeze–thaw cycles, the failure mode gradually turns into adhesive failure along the epoxy/concrete interface. Testing results also confirm that the freeze–thaw resistance of the epoxy/concrete interface can be improved by application of silane coupling agent.

Does acid etching morphologically and chemically affect lithium disilicate glass ceramic surfaces?

This study evaluated the surface morphology, chemical composition and adhesiveness of lithium disilicate glass ceramic after acid etching with hydrofluoric acid or phosphoric acid. Lithium disilicate glass ceramic specimens polished by 600-grit silicon carbide paper were subjected to one or a combination of these surface treatments: airborne particle abrasion with 50-μm alumina (AA), etching with 5% hydrofluoric acid (HF) or 36% phosphoric acid (Phos), and application of silane coupling agent (Si). Stainless steel rods of 3.6-mm diameter and 2.0-mm height were cemented onto treated ceramic surfaces with a self-adhesive resin cement (Clearfil SA Cement). Shear bond strengths between ceramic and cement were measured after 24-hour storage in 37°C distilled water. SEM images of AA revealed the formation of conventional microretentive grooves, but acid etching with HF or Phos produced a porous surface. Bond strengths of AA+HF+Si (28.1 ± 6.0 MPa), AA+Phos+Si (17.5 ± 4.1 MPa) and HF+Si (21.0 ± 3.0 MPa) were significantly greater than those of non-pretreated controls with Si (9.7 ± 3.7 MPa) and without Si (4.1 ± 2.4 MPa) (p&lt;0.05). In addition, HF etching alone (26.2 ± 7.5 MPa) had significantly higher bond strength than AA alone (11.5 ± 4.0 MPa) (p&lt;0.05). AA+HF, AA+Phos and HF showed cohesive failures. Etching with HF or Phos yielded higher bond strength between lithium disilicate glass ceramic and self-adhesive resin cement without microcrack formation.

Adhesive bonding to polymer infiltrated ceramic.

Aim of this study was to investigate the mechanism of adhesive bonding to the polymer-infiltrated ceramic VITA Enamic [VE]. Shear bond strength was measured with three resin composite cements: RelyX Unicem 2 Automix, Clearfil SA and Variolink II on polished surfaces of VE and its components silicate ceramic [SC] and polymer [PM] (n=12). Further, the effect of etching VE with 5% HF for 15-240 s and the application of silane coupling agents was analyzed in a screening test (n=6). Shear bond strength measurements were performed after 24 h of water storage at 37°C. Significant bonding to polished substrates could only be achieved on VE and SC when silane coupling agents were used. Etching of VE with 5% HF increased shear bond strength. Following silanization of etched VE, a further increase in shear bond strength could be established. Etching for more than 30 s did not improve shear bond strength.

Surface conditioning protocol for multiple substrates in repair of cervical recessions adjacent to ceramic.

Remove glaze of the ceramic surface at the margins using fine-grit diamond bur under water cooling. Undisturbed glaze layer will not react with HF and subsequent application of silane coupling agents. Removal of glaze layer increases the surface area on ceramic for mechanical retention and allows the reaction of silane with the glassy matrix.7 The presence of glass phase in ceramics is known to be expedient for better siloxane bonds.1

Effect of viscosity of dual-cure luting resin composite core materials on bond strength to fiber posts with various surface treatments

Background/purposeThe objective of this study was to evaluate the viscosity of two dual-cure resin composite core materials and their bond strength to fiber posts treated with various surface treatments. Materials and methodsViscosity at 60–90 seconds after mixing two resin composite core materials, Clearfil DC Core (DC) and Build-It FR (BI), was tested by a rheometer. Eighteen fiber posts (FibreKor) were divided into three groups according to the following post surface treatments: (1) no surface treatment; (2) application of silane coupling agent (Silane); and (3) application of silane followed by Bond-1 adhesive resin (Silane + Bond-1). Treated posts were cemented into artificial post spaces using DC or BI. After 24-hour storage, each specimen was serially sliced into 12 beams for a microtensile bond strength test. The data were divided into upper, middle, and bottom regions, and statistically analyzed (α = 0.05). Failure modes were observed using a scanning electron microscope. ResultsThe viscosity of BI at 60 seconds after mixing was lower than that of DC. Bond strengths were found to be affected by luting resin composites, surface treatment, and region. For DC, bond strength was significantly improved in the group of Silane + Bond-1 (P < 0.05). For BI, application of Silane significantly improved bond strength (P < 0.05), but application of Silane + Bond-1 had no advantageous effect on it. ConclusionBond strengths between luting resin composites and fiber posts were affected by post surface treatments, depending on the resin composite used. Application of a low-viscosity adhesive resin to the post surface seemed to be beneficial for a high-viscosity luting resin composite.

Effect of different surface treatments of luted fiber posts on push out bond strength to root dentin

PurposeThe purpose of this in vitro study was to evaluate the influence of different post surface treatments on the micro push out bond strength of a luting agent to a fiber post. Materials and methodsSixty freshly extracted single rooted upper central incisor teeth were selected, cut perpendicular to the long axis at the labial cemento-enamel junction. All root canals were instrumented, obturated, the post spaces were prepared to a depth of 11 mm. The specimens were classified into five groups according to the surface treatment performed to the post. Group 1:-no surface treatments (control group), Group 2:-surface treatment with chloroform, Group 3:-surface treatment as in group 2 in addition to the application of silane coupling agent (Calibra), Group 4:-surface treatment by sandblasting using 50 μm alumina particles, Group 5:-surface treatment as in group 4 in addition to the application of silane coupling agent (Calibra), A dual-polymerizing resin luting agent (Calibra) was used for cementation of posts. Three segments (1 mm each) from the cervical 1/3 of each root were obtained. Micro push out test was performed on a universal testing machine at a cross-head speed of 1.0 mm/min until bond failure occurred. Data were analyzed with 1-way ANOVA. ResultsMicro push out bond strength of the luting agent to the post was significantly affected by surface treatment (P < 0.05). Treating the surface of the post with airborne-particle abrasion followed by silanization resulted in the highest bond strength compared with other treatments. There was no significant difference in bond strength between the chloroform group before and after silanization. ConclusionsAirborne-particle abrasion in addition to silanization provided the highest increase in bond strength between the fiber post and the resin luting agent evaluated.

Shear Bond Strength of Acrylic Teeth to Acrylic Denture Base after Different Surface Conditioning Methods

Acrylic resin ruled the dental profession for 60 years, and this success is attributed to its aesthetics, handling properties, physical and biological compatibility, its stability in oral environment and its cost effectiveness. The objective of this study is to evaluate and compare the bond strength of acrylic resin teeth treated with various conditioning materials like monomer and silane coupling agent. METHDOLOGY: A study was carried out in which 96 samples were grouped into 3 groups with a sample size of 32 each (16 premolars, 16 molars). They were conditioned with different conditioning materials i,e monomer and silane coupling agent. Monomer, Silane coupling agent are coated on the ridge lap area before thermocycling and cured according to the manufacturer recommendations. The samples are retained from the fask; trimmed and polished. The samples are then subjected to shear bond strength using the Insteron Universal Testing Machine. In the present study it was found that application of monomer increased the bond strength between acrylic teeth and denture base, when compared to the conventionally processed samples. However it was found that application of silane coupling agent further increased the shear bond strength between acrylic teeth and denture base. Interprations and Within the confnes of this study it is found that there was a signifcant improvement in the bond strength between the acrylic teeth and denture base when silane coupling agent and monomer were used as surface conditioning material. The order of shear strength of samples is control > monomer > silane coupling agent.

Shear bond strength of stainless steel brackets bonded to porcelain surface treated with 1.23% acidulated phosphate fluoride gel compared to hydro fluoric acid with silane coupling agent (In vitro comparative study)

With the increasing demands for adult orthodontics, a growing need arises to bond attachments to porcelain surfaces. Optimal adhesion to porcelain surface should allow orthodontic treatment without bond failure but not jeopardize porcelain integrity after debonding.The present study was carried out to compare the shear bond strength of metal bracket bonded to porcelain surface prepared by two mechanical treatments and by using different etching systems (Hydrofluoric acid 9% and acidulated phosphate fluoride 1.23%). Materials and Methods: The samples were comprised of 60 models (28mm *15mm*28mm) of metal fused to porcelain (feldspathic porcelain). They were divided as the following: group I (control): the porcelain surface left untreated and glazed, group II (Diamond bur group): the porcelain surface was treated with fine diamond bur at speed of 350000 rpm for 20 seconds, group III (Red stone bur): the porcelain surface was treated with coarse red stone bur at speed of 8500 rpm for 20 seconds. Each group consists of 20 samples, then each group subdivided into two subgroups; one treated with acidulated phosphate fluoride 1.23% and the other subgroup treated with Hydrofluoric acid 9 % with silane coupling agent. Results: The result of this study revealed that there was very high significant difference among all tested groups and the highest shear bond strength was for diamond bur group with HFA and Silane (8.67 MPa), the 2nd highest strength was for control group with HFA and Silane (7.52 MPa), the 3rd was (7.38 MPa) in red stone bur with HFA and Silane, the least shear bond strength values were obtained for subgroups treated with acidulated phosphate fluoride gel 1.23%. Conclusions: The most reliable procedure for bonding orthodontic brackets to the porcelain surfaces is through the surface treatment combinations of mechanical roughening by using diamond bur, 9% Hydrofluoric acid and Silane coupling agent application.