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At least 19 recordsLinked to original sources
PubMed2006

The effect of three silane coupling agents and their blends with a cross-linker silane on bonding a bis-GMA resin to silicatized titanium (a novel silane system).

OBJECTIVES: Three activated organofunctional silane coupling agents alone and blended with a non-functional cross-linker silane were evaluated as adhesion promoters in an experiment where a bis-GMA (bis-phenol-A-diglycidyldimethacrylate) resin was bonded to silicatized titanium. The adhesive performances of the silanes were assessed as shear bond strength values. MATERIALS AND METHODS: 3-Methacryloyloxypropyltrimethoxysilane, N-[3-(trimethoxysilyl)propyl]ethylenediamine and [3-(triethoxysilyl)propyl]urea were prepared as 1.0vol.% solutions in 95 vol.% ethanol. They were each also blended with 1.0 vol.% 1,2-bis-(triethoxysilyl)ethane solutions that were activated for 1 or 24 h. Titanium slides were cleaned, silicatized, distributed randomly to study groups and silanized with nine silane solutions. After silanization experimental bis-GMA resin stubs were photo-polymerized and post-polymerized in a light-curing unit. The shear bond strength was measured as 'dry samples' and after thermo-cycling (6000 cycles at 5-55 degrees C). RESULTS: The type of silane affected significantly the shear bond strength (p<0.001) and the use of cross-linker silane (p<0.005) according to the statistical analysis (ANOVA). It showed that the highest shear bond strength for thermo-cycled resin stub samples (n=8/group) was obtained with a blend of 1.0vol.% 3-methacryloyloxypropyltrimethoxysilane+1.0 vol.% 1,2-bis-(triethoxysilyl)ethane blend (10.4+/-3.5 MPa). The lowest results were obtained with 1.0 vol.% [3-(triethoxysilyl)propyl]urea (4.5+/-1.0 MPa), and with 1.0 vol.% N-[3-(trimethoxysilyl)propyl]ethylenediamine (4.5+/-1.4 MPa). CONCLUSIONS: Silanization with a blend of a functional silane and a cross-linker silane (a novel silane system) might improve the hydrolytic stability of a siloxane film between silicatized titanium and a bis-GMA resin.

Analysis of Variance↗
PubMed2000

To silanate or not to silanate: making a clinical decision.

Etched porcelain-bonded restorations have become the treatment of choice for the esthetic restoration of anterior teeth. The bond strength of composite resin to properly etched and silanated porcelain exceeds the cohesive strength of porcelain. Although bonding to enamel is accomplished by only etching the surface to create micromechanical retention, bonding to porcelain is achieved both mechanically through etching porcelain and chemically through the use of a silane coupling agent. Literature supports silanization of porcelain, which provides a more reliable bond than etching with hydrofluoric acid only, although the combination of both are recommended. This article discusses the importance of proper silanization of porcelain in obtaining a durable and reliable resin composite bond with porcelain.

Acid Etching, Dental↗
PubMed1997

(Phosphinoalkyl)silanes. 4.(1) Hydrozirconation as a Non-Photochemical Route to (Phosphinopropyl)silanes: Facile Assembly of the Bis(3-(diphenylphosphino)propyl)silyl ("biPSi") Ligand Framework. Access to the Related Poly(3-(dimethylsilyl)propyl)phosphines R(n)()P(CH(2)CH(2)CH(2)SiMe(2)H)(3)(-)(n)() (n = 1, R = Ph; n = 0).

Treatment of SiEt(3)(CH=CH(2)) with ZrCp(2)HCl (Schwartz's reagent) followed by reaction with PPh(2)Cl provides a high-yield (75%) route to Ph(2)PCH(2)CH(2)SiEt(3), and accordingly hydrozirconation of CH(2)=CHCH(2)SiHMe(2) affords the intermediate ZrCp(2)(CH(2)CH(2)CH(2)SiHMe(2))Cl (2). The latter, which is very sensitive to hydrolysis and reacts with HCl forming SiHMe(2)Pr(n)() and with NBS or I(2) affording SiHMe(2)CH(2)CH(2)CH(2)X (X = Br (3), I (4)), behaves similarly with PPh(2)Cl, PPhCl(2), or PBr(3) undergoing cleavage to the known Ph(2)PCH(2)CH(2)CH(2)SiMe(2)H (i.e. chelH, A) and the novel bis- and tris(silylpropyl)phosphines PhP(CH(2)CH(2)CH(2)SiMe(2)H)(2) (5) and P(CH(2)CH(2)CH(2)SiMe(2)H)(3) (6), respectively, with concomitant formation of ZrCp(2)Cl(2). Corresponding hydroboration of allylsilanes is facile, but subsequent phosphine halide cleavage yields (phosphinoalkyl)silanes only as constituents of intractable mixtures. Hydrozirconation followed by phosphination with PPh(2)Cl also converts SiHMe(CH(2)CH=CH(2))(2) to SiHMe(CH(2)CH(2)CH(2)PPh(2))(2) (i.e. biPSiH, B) together with a propyl analogue Ph(2)PCH(2)CH(2)CH(2)SiMe(Pr(n)())H (7) of A (ca. 2:1 ratio), as well as SiH(CH(2)CH=CH(2))(3) to a mixture (ca. 5:2:1 ratio) of SiH(CH(2)CH(2)CH(2)PPh(2))(3) (i.e. triPSiH, C), a new analogue SiH(Pr(n)())(CH(2)CH(2)CH(2)PPh(2))(2) (8) of B, and a further analogue Ph(2)PCH(2)CH(2)CH(2)SiHPr(n)()(2) (9) of A. A further analogue SiH(2)(CH(2)CH(2)CH(2)PPh(2))(2) (10) of biPSiH (B) is obtained similarly starting from SiH(2)(CH(2)CH=CH(2))(2). Steric control of silylalkyl cleavage from 2 is indicated by the fact that, like PPh(2)Cl (which forms B), two further biPSiH analogues SiH(Me)[CH(2)CH(2)CH(2)P(n-hex)(2)](2) (11) and SiH(Me)(CH(2)CH(2)CH(2)PPhBz)(2) (12) were obtained using P(n-hex)(2)Cl (i.e. n-hex = CH(3)(CH(2))(4)CH(2)-) or PPhBzCl (i.e. Bz = -CH(2)C(6)H(5)), respectively, whereas neither PPr(i)(2)Cl nor PBu(t)(2)Cl led to (phosphinoalkyl)silane formation. The surface-substrate linking reagent Ph(2)PCH(2)CH(2)CH(2)Si(OEt)(3) (D) is formed efficiently by similar means from Si(OEt)(3)(CH(2)CH=CH(2)). NMR data ((1)H, (13)C, (29)Si, (31)P) for 2-12 have been measured and are discussed.

Journal Article↗
PubMed2004

Photochemical reactions of (eta 5-cyclopentadienyl)bis(t-butylacrylate) rhodium with silanes: dynamics of isomer interconversion via Rh(eta 2-silane) species.

The compound CpRh(C(2)H(3)CO(2)(t)Bu)(2) 1 has been synthesised as a mixture of two pairs of interconverting isomers which differ in the relative orientations of the alkene substituents. The four isomers have been fully characterised by NMR spectroscopy. When complex 1 is photolysed in the presence of a silane, HSiR(2)R'R(2)R'= Et(3), Me(3), HEt(2), (OMe)(3) and Me(2)Cl] the corresponding Si-H oxidative addition products CpRh(SiR(2)R')(H)(C(2)H(3)CO(2)(t)Bu) and CpRh(H)(2)(SiR(2)R')(2) are formed. The Rh(III) complexes CpRh(SiR(2)R')(H)(C(2)H(3)CO(2)(t)Bu) exist in two isomeric forms of comparable energy which interconvert in an intramolecular process that does not involve a reversible [1,3] hydride or [1,3] silyl migration. The hydride (1)H NMR resonances for these species consequently broaden before coalescing into a single peak. For R(2)R'= Et(3), the activation parameters for interchange from the major to minor isomer were Delta H++= 60.2 +/- 2 kJ mol(-1) and Delta S++= 8 +/- 9 J mol(-1) K(-1), while for R(2)R'= Me(3) and Et(2)H, Delta H++= 61.5 +/- 1 kJ mol(-1), Delta S++= 6 +/- 5 J mol(-1) K(-1), and Delta H++= 61.8 +/- 3 kJ mol(-1), Delta S++= 12 +/- 9 J mol(-1) K(-1) respectively for conversion from the major isomer to the minor. For these complexes an eta(2)-Rh-H-Si transition state or intermediate is consistent with the evidence. When R(2)R'=(OMe)(3) and Me(2)Cl the change in appearance of the hydride resonances is more complex, with the activation parameters for interchange from the major to minor isomer for the former species being Delta H++= 78.3 +/- 2 kJ mol(-1) and Delta S++= 30 +/- 7 J mol(-1) K(-1) while for Me(2)Cl the barrier proved too high to measure before decomposition occurred. The complex spectral changes could be simulated when a discrete eta(2)-Rh-H-Si intermediate was involved in the isomer interconversion process and hence silane rotation in all these systems is proposed to involve two isomers of CpRh(eta(2)-HSiR(2)R')(C(2)H(3)CO(2)(t)Bu).

Journal Article↗
PubMed2004

Oxidative addition of silanes R3SiH to the unsaturated cluster [Os3(micro-H)[micro3-Ph2PCH2PPh(C6H4)](CO)8]: evidence for reversible silane formation in the dynamic behaviour of [Os3(micro-H)(SiR3)(CO)9(micro-dppm)].

Oxidative addition of the silanes R(3)SiH (R(3)= Ph(3), Et(3), EtMe(2)) to the unsaturated cluster [Os(3)(micro-H)[micro(3)-Ph(2)PCH(2)PPh(C(6)H(4))](CO)(8)] leads to the saturated clusters [Os(3)(micro-H)(SiR(3))(CO)(9)(micro-dppm)](SiR(3)= SiPh(3) 1, SiEt(3) 2 and SiEtMe(2)3) and the unsaturated clusters [Os(3)(micro -H)(2)(SiR(3))[micro(3)-Ph(2)PCH(2)PPh(C(6)H(4))](CO)(7)](SiR(3)= SiPh(3) 4, SiEt(3) 5 and SiEtMe(2)6). Structures are based on spectroscopic evidence and a XRD structure of [Os(3)(micro-H)(SiPh(3))(CO)(9)(micro-dppm)] 1 in which all non-CO ligands are coordinated equatorially and the hydride and the silyl groups are mutually cis. From variable-temperature (1)H NMR spectra of the SiEt(3) compound 2, exchange of the P nuclei is clearly apparent. Simultaneous migrations of the SiEt(3) group and of the hydride from one Os-Os edge to another generate a time-averaged mirror plane in the molecule. VT (1)H NMR spectra of the somewhat less bulky compound [Os(3)(micro-H)(SiMe(2)Et)(CO)(9)(micro-dppm)] 3 have been analysed. Two isomers 3a and 3b are observed with the hydride ligand located on different Os-Os edges. Synchronous migration of the hydride and SiMe(2)Et groups is faster than the observed interconversion of isomers which occurs by hydride migration alone. The synchronous motion of H and SiR(3)only occurs when these ligands are mutually cis as in the major isomer 3a and we propose that this process requires the formation of a transient silane complex of the type [Os(3)(eta(2)-HSiR(3))(CO)(9)(micro-dppm)]. Turnstile rotation within an Os(CO)(3)(eta(2)-HSiR(3)) group leads to the observed exchange within the major isomer 3a without exchange with the minor isomer. This process is not observed for the minor isomer 3b because the hydride and the silyl group are mutually trans. Protonation to give [Os(3)(micro-H)(2)(SiR(3))(CO)(9)(micro-dppm)](+) totally suppresses the dynamic behaviour because there are no edge vacancies.

Journal Article↗
PubMed2003

Catalytic asymmetric silane alcoholysis: practical access to chiral silanes.

A new asymmetric synthesis of chiral silanes has been developed. Chiral phosphine-modified copper complexes catalyze the alcoholysis of prochiral dihydrosilanes with good to excellent stereoselectivity at silicon. The application of this methodology to the tandem silylformylation-allylsilylation of alkynes has been demonstrated.

Alcohols↗
PubMed1995

Effect of silanation of fillers on their dispersability by monomer systems.

The effect of silanation on the dispersion of quartz and zirconia-silica fillers by monomers used to formulate composites was studied. Sixteen silane coupling agents and three methods were used, and the amounts of the monomers needed to reach wet and flow point values were determined. The silanes were selected to have a variety of organofunctional and hydrolysable groups. Silanation was done from an ethanol-water solution of the silanes and by adding the silanes directly to the filler at room temperature (24 degrees C) and at the boiling temperature of the silanes. The amount of silane used was either that required to produce minimum uniform coverage on the fillers or three times the minimum coverage. All silanes and all methods of treatment decreased the flow values for both fillers compared to the unsilanated controls. Generalizations were that the effectiveness of silanation on the dispersion of the filler particles was greater (i) when silanation from ethanol solution was used compared to direct addition; (ii) when three times the minimum uniform coverage was used; (iii) when the silane contained methoxy rather than ethoxy groups; (iv) when the silanes were trialkoxy rather than dialkoxy compounds; (v) when the length and bulkiness of the organic functional group was smaller; and (vi) when the organic functional group was methacrylate rather than acrylic. The strength of composites prepared from one of the monomer systems and quartz silanated with methacryloxypropyltrimethoxysilane was higher than those silanated with acryloxypropyltrimethoxysilane, which supports the use of the wet and flow point values as screening tests for estimating the dispersability of fillers.

Adhesiveness↗
PubMed2006

Evaluation of five dental silanes on bonding a luting cement onto silica-coated titanium.

OBJECTIVES: Five commercial dental silanes were evaluated in vitro as adhesion promoters bonding a luting cement to silica-coated titanium surfaces. METHODS: Titanium slides (n=20) were cleaned with alumina sand and then silica-coated with a special sand consisting of alumina particles coated with silica. The bonding of a resin composite cement (3M ESPE, Seefeld, Germany) to silica-coated and silanized titanium was evaluated by using the dental silane (RelyX Ceramic Primer) that belongs to the RelyX ARC cementing kit, and comparing it to four other dental silanes (Bisco Porcelain Primer, Cimara, ESPE Sil, and Pulpdent Silane Bond Enhancer). The resin composite cement stubs (n=8) were light-polymerized onto a silanized silica-coated titanium surface. The shear bond strength of the cement stubs was measured after dry storage and thermo-cycling 6000 times between 5 and 55 degrees C. The silanes and their reactions were chemically monitored by using Fourier transform infrared analysis. RESULTS: Statistical analysis using ANOVA revealed that the brand of silanes and the types of storage condition differ significantly (p<0.005). The highest shear bond strength was obtained with RelyX ceramic silane in dry conditions (19.5+/-4.3 MPa), and after thermo-cycling (16.6+/-3.5 MPa). The lowest results were obtained using Pulpdent Silane Bond Enhancer, in dry conditions (7.8+/-2.2 MPa), and after thermocycling (5.3+/-2.4 MPa). The analysis showed that silanes had different pH values. Some differences were detected between the silanes and their reactions. CONCLUSIONS: Dental silanes provide different bonding strengths and have differences in their pH, solvent system and silane concentration.

Adhesiveness↗
PubMed2003

The effect of filler and silane content on conversion of resin-based composite.

OBJECTIVE: This study examines the influence of filler loading and silane content on the conversion of photoactivated, resin-based composites as determined using Fourier transform infrared spectroscopy (FTIR). METHOD: Zirconia/silica filler was processed with a silane coupling agent (gamma-methacryloxypropyltrimethoxysilane) to achieve a range of silane-to-filler compositions. Treated fillers were compounded with a photoactivated BisGMA/TEGDMA resin to yield a series of pastes all containing 72 wt% total solids. Diffuse reflectance FTIR was used to characterize methacrylate unsaturation of the silane on the filler particles while paste conversion was determined using transmission FTIR. A resin matrix conversion was determined by adjusting the paste conversion for silane unsaturation. Two additional series of pastes were compounded to achieve variable filler-to-resin ratios using non-treated filler and filler processed with 8 wt% silane. Paste conversion was determined using transmission FTIR. RESULTS: Pastes compounded from fillers containing variable percent silane demonstrated linearly decreasing conversion (R(2)=0.986) with increasing silane content and ranged from 52.7 to 62.8%. Adjusting paste conversion for silane unsaturation yielded similar resin matrix conversion for all cured pastes (65.1+/-0.8%). Pastes compounded with increasing filler-to-resin ratios had progressively decreasing conversion. Correcting for silane unsaturation suggests this effect was independent of whether the filler was silane-treated or not. SIGNIFICANCE: Composite resin matrix conversion as determined via FTIR can be underestimated by the presence of unreacted methacrylate from silane on the filler. A corrected resin matrix conversion can be estimated by adjusting for silane unsaturation. Additionally, increasing filler-to-resin ratio progressively decreases conversion independent of the presence of silane on the filler.

Composite Resins↗
PubMedDate not supplied

Influence of surface conditions and silane agent on the bond of resin to IPS Empress 2 ceramic.

PURPOSE: The aim of this study was to evaluate the effect of different ceramic surface treatments on the tensile bond strength between IPS Empress 2 ceramic framework and Rely X adhesive resin cement, with or without the application of a silane coupling agent. MATERIALS AND METHODS: One hundred twenty disks were made, embedded in resin, and randomly divided into six groups: group 1 = sandblasting (100 microm), no silanation; group 2 = sandblasting (100 microm), silane treatment; group 3 = sandblasting (50 microm), no silanation; group 4 = sandblasting (50 microm), silane treatment; group 5 = hydrofluoric acid etching, no silanation; and group 6 = hydrofluoric acid etching, silane treatment. The disks were bonded into pairs with adhesive resin cement. All samples were stored in distilled water at 37 degrees C for 24 hours and then thermocycled. The samples were submitted to tensile testing. RESULTS: The use of silane improved the bond strength in relation to the groups in which silane was not applied (P < .05). The most effective surface treatment was etching with 10% hydrofluoric acid, both with (25.6 MPa) and without silane application (16.4 MPa); these values showed a statistically significant difference compared to sandblasting with 50- and 100-microm Al2O3. Sandblasting with 50-microm Al2O3, with (11.8 MPa) and without silane (5.4 MPa), demonstrated significantly higher tensile bond strength than sandblasting with 100-microm Al2O3, with (8.3 MPa) and without silane (3.8 MPa). CONCLUSION: Combined application of 10% hydrofluoric acid and silane enhanced the bond strength between the IPS Empress 2 ceramic framework and resin agent.

Acid Etching, Dental↗
PubMed2001

Aqueous Amino Silane Modification of E-glass Surfaces.

The majority of work available in the literature examines the effect of epoxy silane, gamma-aminopropyltrimethoxy silane, and methacrylate silane on E-glass surfaces. As alternatives to the most commonly used silanes, we investigated two novel silanes: gamma-ureidopropyltriethoxy silane and Nbeta(aminoethyl) gamma-aminotrimethoxy silane and additionally an amino-functional polysiloxane. The ureido silane-treated E-glass fibers demonstrated a zeta potential similar to that of the untreated E-glass fibers, which was independent of deposition solution pH over the pH range investigated. A moderately hydrophobic E-glass surface, which was silane concentration dependent, was noted as being due to condensed Si-O-Si bonds at the surface. The diamino silane demonstrated an extremely basic surface at the higher silane concentrations investigated. These outer surface layers were modified by changing the pH and the concentration of the deposition solution. The polysiloxane produced an increase in the hydrophobicity of the E-glass fiber, especially when deposited from extremely basic solutions. At the higher solution concentrations investigated, the silanes and the siloxane was initially deposited in patches and an outer surface or "skin" was formed over these patches, giving the appearance of fully coated fibers. Copyright 2001 Academic Press.

Journal Article↗
PubMed2004

[Characterizing methods of structure and character for silane film on metal surface].

Surface analysis methods for structure and characters of silane film on metal surface were reviewed in this paper. Many instrumental methods, such as XPS, ATR-FTIR, RA-FTIR, SIMS, ellipsometry, EIS and so on, were applied to characterizing different silane films on different metal base surfaces. According to the research on silane film formation mechanism, silane film state, silane film structure, silane film thickness, silane film corrosion resistance and so on, factors which affect silane film properties were discussed. Various parameters were proposed for characterizing silane film. Merits and defects of various surface analysis methods were expressed. In order to acquire more chemical information, different surface analysis methods can be combined for detection at the same time. Regarding the results from these detection and analysis, new silane treatment technique for metal surface can be optimized and improved greatly. Some other kinds of surface analysis methods were also mentioned in this paper. More advanced researches in the field of silane film analysis on metal surface were prospected.

English Abstract↗
PubMed2004

Stabilization of immobilized glucose oxidase against thermal inactivation by silanization for biosensor applications.

An important requirement of immobilized enzyme based biosensors is the thermal stability of the enzyme. Studies were carried out to increase thermal stability of glucose oxidase (GOD) for biosensor applications. Immobilization of the enzyme was carried out using glass beads as support and the effect of silane concentration (in the range 1-10%) during the silanization step on the thermal stability of GOD has been investigated. Upon incubation at 70 degrees C for 3h, the activity retention with 1% silane was only 23%, which increased with silane concentration to reach a maximum up to 250% of the initial activity with 4% silane. Above this concentration the activity decreased. The increased stability of the enzyme in the presence of high silane concentrations may be attributed to the increase in the surface hydrophobicity of the support. The decrease in the enzyme stability for silane concentrations above 4% was apparently due to the uneven deposition of the silane layer on the glass bead support. Further work on thermal stability above 70 degrees C was carried out by using 4% silane and it was found that the enzyme was stable up to 75 degrees C with an increased activity of 180% after 3-h incubation. Although silanization has been used for the modification of the supports for immobilization of enzymes, the use of higher concentrations to stabilize immobilized enzymes is being reported for the first time.

Biosensing Techniques↗
PubMed2006

Microtensile bond strength of a resin cement to feldpathic ceramic after different etching and silanization regimens in dry and aged conditions.

OBJECTIVES: This study evaluated the durability of bond strength between resin cement and a feldspathic ceramic submitted to different etching regimens with and without silane coupling agent application. METHODS: Thirty-two blocks (6.4 mm x 6.4 mm x 4.8 mm) were fabricated using a microparticulate feldspathic ceramic (Vita VM7), ultrasonically cleaned with water for 5 min and randomly divided into four groups, according to the type of etching agent and silanization method: method 1, etching with 10% hydrofluoric (HF) acid gel for 1 min + silanization; method 2, HF only; method 3, etching with 1.23% acidulated phosphate fluoride (APF) for 5 min + silanization; method 4, APF only. Conditioned blocks were positioned in their individual silicone molds and resin cement (Panavia F) was applied on the treated surfaces. Specimens were stored in distilled water (37 degrees C) for 24h prior to sectioning. After sectioning the ceramic-cement blocks in x- and y-axis with a bonded area of approximately 0.6mm(2), the microsticks of each block were randomly divided into two storage conditions: Dry, immediate testing; TC, thermal cycling (12,000 times)+water storage for 150 d, yielding to eight experimental groups. Microtensile bond strength tests were performed in universal testing machine (cross-head speed: 1mm/min) and failure types were noted. Data obtained (MPa) were analyzed with three-way ANOVA and Tukey's test (alpha=0.05). RESULTS: Significant influence of the use of silane (p<0.0001), storage conditions (p=0.0013) and surface treatment were observed (p=0.0014). The highest bond strengths were achieved in both dry and thermocycled conditions when the ceramics were etched with HF acid gel and silanized (17.4 +/- 5.8 and 17.4 +/- 4.8 MPa, respectively). Silanization after HF acid gel and APF treatment increased the results dramatically (14.5+/-4.2-17.4+/-4.8 MPa) compared to non-silanized groups (2.6 +/- 0.8-8.9 +/- 3.1 MPa) where the failure type was exclusively (100%) adhesive between the cement and the ceramic. SIGNIFICANCE: Silanization of the feldspathic ceramic surface after APF or HF acid etching increased the microtensile bond strength results significantly, with the latter providing higher results. Long-term thermocycling and water storage did not decrease the results in silanized groups.

Aluminum Silicates↗
PubMed1994

Silane treatment of filler and composite blending in a one-step procedure for dental restoratives.

The aim of this study was to investigate whether a one-step procedure of silane treatment of filler and composite blending could also produce the strong resin-filler integrity, as can be obtained for dental composites in two steps by pretreating the filler with a silane coupling agent before blending. Resin mixtures containing either a silane-functional methacrylate or a non-silane-functional methacrylate were blended with silane pretreated or non-treated filler particles. The resin-filler integrity of the composites was determined from the wear performance in three-body wear tests. For composites with the non-silane-functional methacrylate the wear rates dramatically decreased when the silane pretreated filler was used instead of untreated filler, showing the efficacy of the silane treatment. For composites with the silane-functional methacrylate the decrease was small, indicating comparable resin-filler integrity for the one-step and the two-step procedures.

Analysis of Variance↗
PubMedDate not supplied

An introduction to silanes and their clinical applications in dentistry.

PURPOSE: This overview presents a description of organofunctional trialkoxysilane coupling agents (silanes), their chemistry, properties, use, and some of the main clinical experiences in dentistry. MATERIALS AND METHODS: The main emphasis was on major dental journals that have been reviewed from 1958 up to the latest research news from 2002. A MEDLINE search with the key words "dental silanes" was used. Special silane literature and journals outside dentistry were also cited. RESULTS: The main emphasis is on the use of silanes in prosthetic and restorative dentistry. Clinical relevance was based mainly on either short- or long-term tests. The interpretation of various results is not given, mainly because of controversial observations that may be very difficult to explain. Nevertheless, the majority of the clinical results pointed to silanes playing a significant role in the adhesion process. Silane reaction mechanisms were not entirely understood, and there exist several theories for bonding mechanisms for silanes and substrates. CONCLUSION: Dental materials offer a continuously challenging forum for silanes, and silanes will play an essential role in material development.

Composite Resins↗
PubMed2000

Surface modification using silanated poly(ethylene glycol)s.

Surface-grafted poly(ethylene glycol) (PEG) molecules are known to prevent protein adsorption to the surface. The protein-repulsive property of PEG molecules are maximized by covalent grafting. We have synthesized silanated monomethoxy-PEG (m-PEG) for covalent grafting of PEG to surfaces with oxide layers. Two different trialkoxysilylated PEGs were synthesized and characterized. The first trialkoxysilylated PEG was prepared by direct coupling of m-PEG with 3-isocyanatopropyltriethoxysilane through a urethane bond (silanated PEG I). The other silanated PEG (silanated PEG II) containing a long hydrophobic domain between PEG and a silane domain was prepared by reacting m-PEG with 1,6-diisocyanatohexane and 10-undecen-1-ol in sequence before silylation with 3-mercaptopropyl trimethoxysilane. Silanated PEGs I and II were grafted onto glass, a model surface used in our study. The PEG-grafted glass surfaces were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Although contact angle did not change much as the bulk concentration of silanated PEG used for grafting increased from 0.1 to 20 mg/ml for both PEGs I and II, the surface atomic concentrations from XPS measurements showed successful PEG grafting. Surface PEG grafting increased concentration of surface carbon but decreased silicone concentration. The high resolution C1s spectra showed higher ether carbon with lower hydrocarbon compositions for the PEG-grafted surfaces compared to the control surface. AFM images showed that more PEG molecules were grafted onto the surface as the bulk concentration used for grafting was increased. AFM images of the dried surfaces showed that the surfaces were not completely covered by PEG molecules. After hydration, however, the surface appears to be covered completely probably due to the hydration of the grafted PEG chains. Glass surfaces modified with silanated PEGs reduced fibrinogen adsorption by more than 95% as compared with the control surface. Silanated PEGs provides a simple method for PEG grafting to the surface containing oxide layers.

Adsorption↗