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PubMed2003

Physical and biological evaluations of sintered hydroxyapatite/silicone composite with covalent bonding for a percutaneous implant material.

A composite (HA/silicone) of hydroxyapatite (HA) microparticles with an average diameter of 2.0 micro m covalently linked to a silicone substrate has been developed, and its physical and biological properties as a percutaneous soft-tissue-compatible material have been evaluated. In tensile property measurement, samples of HA/silicone and the original silicone were similar in tensile strength, ca. 7.8 MPa, and elongation at break, ca. 570%. It was found that chemical surface modification with HA particles presented no mechanical disadvantage. In an adhesive-tape peeling test, scanning electron microscopic (SEM) observation showed that HA particles coupled directly to the substrate were not removed. HA particles may bond strongly with the substrate. In human periodontal ligament fibroblast attachment and proliferation experiments, the number of cells attached to HA/silicone was 14 times greater than that attached to the original silicone after 24 h of incubation. The value on HA/silicone was ca. 80% versus that on a tissue-culture plastic used as a positive control. After 72 h of incubation, the number of cells grown on HA/silicone increased to the level of the positive control. In observation of fluorescence microscopy stained by Hoechst 33342, cells appeared to tightly adhere to HA particles coupled to the silicone sheet due to intact nuclear morphology. Observation of cells by fluorescence dye with rhodamin phalloidin showed an extensive F-actin cytoskeleton on HA/silicone. In a 4-week animal implant test, force required to pull out the HA/silicone sheet was 15 times that of the original silicone. HA-particle coating on silicone with covalent linkage gave the inert surface bioactivity. The HA composite thus effectively prevents germ infection percutaneously.

Animals↗

PubMed2006

Fabrication of a three-dimensional nanostructured biomaterial for tissue engineering of bone.

A plasma process for the surface modification of HA powders has been developed. Acrylic acid and acrylic acid/octadiene plasma deposited films onto HA particles have demonstrated to interact with SBF allowing the calcium dissolution-precipitation mechanism. Therefore, a nanostructured composite between HA and a self-assembling peptide scaffold (RAD16-I) has been developed. The differentiation of mESC in this scaffold has been studied, in order to test the osteogenic capacity of the new composite material. We have observed that the mESC can be induced to produce Ca salts (mineralization) in a 3D-microenvironment and moreover, this activity can be enhanced by the presence of HA particles into the nanofiber scaffold.

Animals↗

PubMed2006

Pulmonary toxicity study in rats with three forms of ultrafine-TiO2 particles: differential responses related to surface properties.

Surface properties are critical to assess effects of ultrafine-TiO(2) particles. The aim of this study was to assess lung toxicity in rats of newly developed, well characterized, ultrafine-TiO(2) particles and compare them to TiO(2) samples in two different size ranges and surface modifications. Groups of rats were intratracheally instilled with doses of 1 or 5mg/kg of either two ultrafine rutile TiO(2) particles (uf-1 or uf-2); rutile R-100 fine-TiO(2) (F-1); 80/20 anatase/rutile P25 ultrafine-TiO(2) (uf-3); or alpha-quartz particles. Phosphate-buffered saline (PBS) solution instilled rats served as vehicle controls. Following exposures, the lungs of PBS and particle-exposed rats were evaluated for bronchoalveolar lavage (BAL) fluid inflammatory markers, cell proliferation, and by histopathology at post-instillation time points of 24h, 1 week, 1 and 3 months. The ranking of lung inflammation/cytotoxicity/cell proliferation and histopathological responses was quartz>uf-3>F-1=uf-1=uf-2. Exposures to quartz and to a lesser degree, uf-3 anatase/rutile TiO(2) particles produced pulmonary inflammation, cytotoxicity and adverse lung tissue effects. In contrast, exposures to F-1 fine-TiO(2) particles or to uf-1/uf-2 ultrafine-TiO(2) particle-types produced transient inflammation. We conclude that differences in responses to anatase/rutile uf-3 TiO(2) particles versus the rutile uf-1 and uf-2 TiO(2) particles could be related to crystal structure, inherent pH of the particles, or surface chemical reactivity. Thus, based on these results, inhaled rutile ultrafine-TiO(2) particles are expected to have a low risk potential for producing adverse pulmonary health effects. Finally, the results demonstrate that exposures to ultrafine-TiO(2) particle-types can produce differential pulmonary effects, based upon their composition, and crystal structure. Thus, the lung toxicity of anatase/rutile uf-3 should not be viewed as representative for all ultrafine-TiO(2) particle-types.

Animals↗

PubMed2005

Immobilisation of oligo-peptidic probes for microarray implementation: characterisation by FTIR, atomic force microscopy and 2D fluorescence.

Proteomic microarrays show a wide range of applications for the investigation of DNA-protein, enzyme-substrate as well as protein-protein interactions. Among many challenges to build a viable "protein microarray", the surface chemistry that will allow to immobilised various proteins to retain their biological activity is of paramount importance. Here we report a chemical functionalisation method allowing immobilisation of oligo-peptides onto silica surface (porous silica, glass, thermal silicon dioxide). Substrates were first derivatised with a monofunctional silane allowing the elaboration of dense and uniform monolayers in highly reproducible way. Prior to the oligo-peptides grafting, this organic layer was functionalised with an amino-polyethyleneglycol. The coupling step of oligo-peptides onto functionalised supports is achieved through activation of the C-terminal function of the oligo-peptides. Chemical surface modifications were followed by FTIR spectroscopy, AFM measurements and fluorescence scanning microscopy. A systematic study of the oligo-peptide grafting conditions (time, concentration, solvent) was carried out to optimise this step. The oligo-peptides grafting strategy implemented in this work ensure a covalent and oriented grafting of the oligo-peptides. This orientation is ensured through the use of fully protected peptide except the terminal primary amine. The immobilized peptides will be then deprotected before biological recognition. This strategy is crucial to retain the biological activity of thousands of oligo-probes assessed on a microarray.

Biotinylation↗

PubMed2001

The ex vivo wettability of soft contact lenses.

PURPOSE: To investigate the ex vivo wettability of Etafilcon A contact lenses over an eight hour period of wear and observe the influence of surfactant pre-treatment. METHODS: Etafilcon A hydrogel lenses, comprising poly[2-hydroxyethyl methacrylate-co-methacrylic acid] and 58% water, were soaked for 12 hours in either 0.9% saline (control) or a 1% aqueous solution of poloxamine 1107 (treated). The advancing and receding contact angles were subsequently determined ex vivo after various periods of wear in six adapted contact lens wearers using a single-blind, randomised protocol. Contact angles were measured with a dynamic contact angle tensiometer, using the Wilhelmy plate technique. Patient comfort scores were recorded and the static surface tensions of the probe fluids assessed. RESULTS: Control lenses exhibited no change in wetting angles over time, indicating a lack of surface modification by components within the tear film. Treated lenses exhibited a significantly reduced advancing angle (p < 0.001) and hysteresis angle (p < 0.001) when compared with control lenses. In addition, treated lenses were consistently rated as being more comfortable than control lenses (p = 0.04). CONCLUSIONS: This study has shown clearly that new Etafilcon A lenses do not exhibit significant changes in wettability during the initial four hour wearing period. Pre-treatment of such lenses with a polymeric surfactant results in wetting of the lenses due to the adsorption of surfactant. The surfactant is retained by the lens for at least eight hours of wear, resulting in significant improvements in subjective comfort, especially over the first 30 minutes of wear.

Adolescent↗

PubMed2002

Adhesive bonding of composite material to cast titanium with varying surface preparations.

The purpose of the present study was to evaluate the surface preparation effects of eight metal conditioners and an adhesive system on bonding between a prosthodontic composite material and cast titanium. Eight primers designed for conditioning base metal alloys (Acryl Bond, All-Bond 2 Primer B, Alloy Primer, Cesead II Opaque Primer, Eye Sight Opaque Primer, Metafast Bonding Liner, Metal Primer II, and MR Bond) as well as a surface modification technique (Siloc) were assessed. Disk specimens cast from titanium (T-Alloy H) were either primed with one of the eight primers or treated with the Siloc system, and then bonded with a light-activated composite material (Artglass). Bond durability was evaluated by thermocycling (4 and 60 degrees C, 1 min each, 20, 000 cycles). After thermocycling, two groups either primed with the Cesead II Opaque Primer material or treated with the Siloc system exhibited significantly greater bond strength (20.0 and 19.0 MPa) than the other groups (0.2-12.6 MPa, P < 0.05). These two systems are considered to be useful for improving bonding between the titanium and the composite material tested.

Adhesives↗

PubMed2005

Characterization of human atherosclerotic plaques by intravascular magnetic resonance imaging.

BACKGROUND: Development and validation of novel imaging modalities to assess the composition of human atherosclerotic plaques will improve the understanding of atheroma evolution and could facilitate evaluation of therapeutic strategies for plaque modification. Surface MRI can characterize tissue content of carotid but not deeper arteries. This study evaluated the usefulness of intravascular MRI (IVMRI) to discern the composition of human iliac arteries in vivo. METHODS AND RESULTS: Initial studies validated IVMRI against histopathology of human atherosclerotic arteries ex vivo. A 0.030-inch-diameter IVMRI detector coil was advanced into isolated human aortoiliac arteries and coupled to a 1.5-T scanner. Information from combined T1-, moderate T2-, and proton-density-weighted images differentiated lipid, fibrous, and calcified components with favorable sensitivity and specificity and allowed accurate quantification of plaque size. The validated approach was then applied to image iliac arteries of 25 human subjects in vivo, and results were compared with those of intravascular ultrasound (IVUS). IVMRI readily visualized inner and outer plaque boundaries in all arteries, even those with extensive calcification that precluded IVUS interpretation. It also revealed the expected heterogeneity of atherosclerotic plaque content that was noted during ex vivo validation. Again, IVUS did not disclose this heterogeneity. The level of interobserver and intraobserver agreement in the interpretation of plaque composition was high for IVMRI but poor for IVUS. CONCLUSIONS: IVMRI can reliably identify plaque composition and size in arteries deep within the body. Identification of plaque components by IVMRI in vivo has important implications for the understanding and modification of human atherosclerosis.

Adult↗

PubMed2005

Novel surface modified molecularly imprinted polymer focused on the removal of interference in environmental water samples for chromatographic determination.

Uniformly sized molecularly imprinted polymers (MIPs) for bisphenol A (BPA) with surface modification and immobilized intervals of functional monomers afforded by utilizing 4,4'-methylenebisphenol as a pseudo component have been prepared. MIPs for BPA were prepared using 4-vinyl pyridine immobilized in the most effective interval and ethylene glycol dimethacrylate as a functional monomer and cross-linking agent, respectively. Prepared MIPs showed significant selectivity for BPA retention and removal performance for interference in actual samples as the HPLC stationary phase compared to those of ordinary MIPs. These MIPs were employed as pretreatment media of column switching HPLC and the HPLC system provided a detection limit of 0.36 ppt when electrochemical detection was used. Actual samples, including Suwannee River natural organic matter (NOM), were applied and BPA was detected in the NOM even if widely used UV detection was employed.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

New nanocomposite materials reinforced with cellulose whiskers in atactic polypropylene: effect of surface and dispersion characteristics.

New nanocomposite films were prepared with atactic polypropylene as the matrix and either of three types of cellulose whiskers, with various surface and dispersion characteristics, as the reinforcing phase: aggregated without surface modification, aggregated and grafted with maleated polypropylene or individualized and finely dispersed with a surfactant. Films obtained by solvent casting from toluene were investigated by means of scanning electron microscopy, dynamic mechanical analysis, and tensile testing. In the linear region, the mechanical properties above the glass-rubber transition were found to be drastically enhanced for the nanocomposites as compared to the neat polypropylene matrix. These effects were ascribed to the formation of a rigid network with filler/filler interactions. In addition, interactions between the filler and the matrix as well as the dispersion quality were found to play a major role on the mechanical properties of the composites when investigation of the films was performed in the nonlinear region.

Biocompatible Materials↗

PubMed2026

Targeted Nanoparticle Delivery CRISPR/Cas9: overcoming biological barriers, enhancing stability, and improving therapeutic precision.

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) has emerged as a promising gene-editing platform for genetic disorders; however, its in vivo application remains limited by low delivery efficiency and biological barriers. Many CRISPR payloads fail to reach target sites due to extracellular degradation, immune clearance, and intracellular trafficking limitations. This review examines the interplay between biological barriers and nanoparticle engineering strategies for CRISPR/Cas9 delivery. A barrier-oriented engineering approach is proposed as a central framework, encompassing ligand-based surface modification for enhanced targeting and uptake, improved circulation stability via PEGylation and biomimetic coatings, and optimized payload release through endosomal escape strategies. Stimulus-responsive nanoparticle systems further enable spatiotemporal control over payload release. Nuclear targeting strategies, including optimization of nuclear localization signals (NLS) and exploitation of endogenous trafficking pathways, are highlighted as key factors for improving genome-level editing efficiency. Despite these advances, major challenges-including limited intracellular delivery efficiency, insufficient targeting precision, and safety concerns-continue to hinder clinical translation. Future directions highlight artificial intelligence-driven nanoparticle design, personalized delivery systems, and next-generation CRISPR platforms. Overall, an integrated, barrier-oriented engineering strategy is essential for advancing CRISPR/Cas9 delivery toward clinical applications, ultimately advancing global good health and well-being.

CRISPR/Cas9↗

PubMed2006

Differential inflammatory macrophage response to rutile and titanium particles.

Titanium and its alloys are widely used as implant materials for dental and orthopaedic applications due to their advantageous bulk mechanical properties and biocompatibility, compared to other metallic biomaterials. In order to improve their wear and corrosion resistance, several surface modifications that give rise to an outer ceramic layer of rutile have been developed. The ability of rutile wear debris to stimulate the release of inflammatory cytokines from macrophages has not been addressed to date. We have compared the in vitro biocompatibility of sub-cytotoxic doses of rutile and titanium particles in THP-1 cells driven to the monocyte/macrophage differentiation pathway as well as in primary cultures of human macrophages. Confocal microscopy experiments indicated that differentiated THP-1 cells and primary macrophages efficiently internalised rutile and titanium particles. Treatment of THP-1 cells with rutile particles stimulated the release of TNF-alpha, IL-6 and IL-1beta to a lesser extent than titanium. The influence of osteoblasts on the particle-induced stimulation of TNF-alpha and IL-1beta was analysed by co-culturing differentiated THP-1 cells with human primary osteoblasts. Under these conditions, secretion levels of both cytokines after treatment of THP-1 cells with rutile particles were lower than after exposure to titanium. Finally, we observed that primary macrophages released higher amounts of TNF-alpha, IL-6 and IL-1beta after incubation with titanium particles than with rutile. Taken together, these data indicate that rutile particles are less bioreactive than titanium particles and, therefore, a higher biocompatibility of titanium-based implants modified with an outer surface layer of rutile is expected.

Biocompatible Materials↗

PubMed1992

In vitro evaluation of biocompatibility of surface-modified poly(methyl methacrylate) plate with rabbit lens epithelial cells.

Collagen type I was immobilized onto a poly(methyl methacrylate) (PMMA) plate by covalent bonding following surface modification by two methods. One method introduced amino groups by aminolysis with N-lithioethylenediamine (PMMA-NH2) and the other introduced carboxyl groups by graft copolymerization of acrylic acid (AAc) and acrylamide (AAm) (PMMA-COOH). Lens epithelial rabbit cells were cultured on the PMMA plate which was immobilized with collagen. Polygonal cells with a mosaic appearance were observed on the PMMA-COOH plate immobilized with collagen type I, whereas pleomorphic cells were present on the virgin PMMA and on the PMMA-NH2 plate immobilized with collagen type I. We concluded the PMMA-COOH plate immobilized with collagen type I provided a more comfortable atmosphere for lens epithelial cells, causing no metaplasia, than the other plates used in this cell culture model experiment.

Animals↗

PubMed1999

Apatite formation on ethylene-vinyl alcohol copolymer modified with silanol groups.

The surfaces of ethylene-vinyl alcohol copolymer (EVOH) substrates were modified with silanol (Si-OH) groups, and their apatite forming ability was examined in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma or in a solution with ion concentrations 1.5 times those of SBF (1.5SBF). The surface modification of EVOH was carried out by reacting 3-isocyanatopropyltriethoxysilane, followed by hydrolysis of the ethoxysilyl groups into Si-OH groups. However, no apatite formation was observed on the EVOH substrate thus modified, even after 3 weeks in SBF and 1.5SBF. The Si-OH modified EVOH substrate was further modified by hydrolysis and polycondensation of tetraethyoxysilane (TEOS). It was found that the apatite forms on the TEOS-modified substrate within 3 weeks in 1.5SBF. These results suggest that the presence of a large amount of Si-OH groups (i.e., a cluster of Si-OH groups) on the substrate is prerequisite to apatite formation in the body environment. Apatite-EVOH composites prepared by this process might be useful as hard tissues substitutes.

Apatites↗

PubMedDate not supplied

Assessment of the acrosomal status of ram spermatozoa by RCA lectin-binding and partition in an aqueous two-phase system.

The acrosome reaction is an important marker for sperm function. Because different laboratory techniques may be used to detect this exocytotic process, the objective of this study was to investigate the use of fluoresceinated lectins to assess the acrosomal status of nonpermeabilized ram spermatozoa. In addition, we used centrifugal countercurrent distribution (CCCD) in an aqueous 2-phase system to assess the sperm surface modifications associated with the acrosome reaction by observing changes in their partition behavior. We analyzed the binding of 5-fluorescein isothiocyanate (FITC)-conjugated lectins to ram sperm to select a lectin that bound preferentially to the acrosomal region, which would allow differentiation of acrosome-intact from acrosome-damaged ram spermatozoa. Ricinus communis agglutinin (RCA) bound intensely to the anterior and weakly to the equatorial acrosomal regions. Acrosomal labeling changed when spermatozoa were induced to acrosome-react with calcium ionophore A23187. RCA acrosomal labeling significantly increased (P < .0001) after incubation (84% versus 28% in control samples). To determine if RCA lectin labeling could be used to assess the acrosomal status of fresh ram spermatozoa in suspension, we compared the percentage of acrosome-reacted sperm detected by the carboxyfluorescein diacetate/propidium iodide (CFDA/PI) double-fluorescent staining with the percentage detected by FITC-RCA labeling. The incidence of acrosome-reacted spermatozoa detected by CFDA/PI was not significantly different (P = .704; 13 comparisons in 6 different experiments) from the incidence of spermatozoa detected by FITC-RCA staining. The evaluation of the spontaneous acrosome reaction by RCA labeling (5.83%) was not significantly different (P = .644) from that assessed by CFDA/PI (6.88%). The percentage of induced acrosome reactions detected by CFDA/PI staining (56%) significantly correlated (P < .0001; r = 0.876) with that detected by RCA labeling (56.67%). We simultaneously carried out a comparative CCCD in an aqueous 2-phase system to analyze sperm surface changes associated with the acrosome reaction. Results revealed that sperm surface hydrophobicity decreased in samples that had been incubated with ionophore compared with the untreated-control samples. Likewise, RCA binding after CCCD showed that all acrosome-reacted cells were stained, whereas only 42% of cells were lectin-labeled in the untreated semen sample. This change in lectin reactivity of acrosome-reacted spermatozoa signals the presence of some deep membrane or intracellular residues that would affect partitioning. Therefore, the FITC-RCA-labeling procedure can be used to accurately assess the acrosomal status of ram spermatozoa in suspension.

Acrosome Reaction↗

PubMed2005

Adsorption of Acid Red 57 from aqueous solutions onto surfactant-modified sepiolite.

The adsorption of Acid Red 57 (AR57) onto surfactant-modified sepiolite was investigated in aqueous solution in a batch system with respect to contact time, pH and temperature. The surface modification of surfactant-modified sepiolite was controlled using the FTIR technique. The pseudo-first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 90 min, whereas diffusion is not only the rate controlling step. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Freundlich model agrees with experimental data well. The activation energy, change of free energy, enthalpy and entropy of adsorption were also evaluated for the adsorption of AR57 onto surfactant-modified sepiolite. The results indicate that surfactant-modified sepiolite could be employed as low-cost material for the removal of textile dyes from effluents.

Adsorption↗

PubMed2005

Preparation and colloidal stability of monodisperse magnetic polymer particles.

A previously proposed method was examined for producing monodisperse, submicrometer-sized magnetic polymer particles. The method applies soap-free emulsion polymerization during which Fe3O4 magnetic nanoparticles are heterocoagulated onto precipitated polymer nuclei. To chemically fix the magnetic particles to the polymer nuclei, vinyl groups were introduced on the Fe3O4 particles in a preliminary surface modification reaction with methacryloxypropyltrimethoxysilane, and methacryloxypropyldimethoxysilane (MPDMS) was added to reaction systems of the soap-free emulsion polymerization. The colloidal dispersion stability of magnetic polymer particles was improved by the addition of an ionic monomer, sodium p-styrenesulfonate (NaSS), during the polymerization. The polymerizations were carried out with styrene monomer and potassium persulfate initiator in ranges of NaSS concentrations (0-2.4 x 10(-3) M), NaSS addition times (60-80 min), and monomer concentrations (0.3-0.6 M) at fixed concentrations of 1.6 x 10(-2) M initiator and 1.3 x 10(-2) M MPDMS for pH 4.5 adjusted with a buffer system of [CH3COOH]/[NaOH]. The addition of NaSS during the polymerization could maintain the dispersion stability of magnetic polymer particles during the polymerization. Selection of the reaction conditions enabled the preparation of colloidally stable, submicrometer-sized magnetic polymer particles that had coefficients of variation of distribution smaller than the standard criterion for monodispersity, 10%.

Colloids↗

PubMed2006

Surface treatment of flexor tendon autografts with carbodiimide-derivatized hyaluronic Acid. An in vivo canine model.

BACKGROUND: Clinical and experimental studies have demonstrated that restrictive adhesions and poor digital motion are common complications after extrasynovial tendon grafting in an intrasynovial environment. The purpose of this study was to test the hypothesis that surface modification of an extrasynovial tendon with use of a carbodiimide-derivatized hyaluronic acid-gelatin polymer (cd-HA) improves gliding ability and digital function after tendon grafting in a canine model in vivo. METHODS: The peroneus longus tendons from both hindpaws of twenty-four dogs were harvested and transplanted to replace the flexor digitorum profundus tendons in the second and fifth digits of one forepaw. Prior to grafting, one of the peroneus longus tendons was coated with cd-HA, which consists of 1% hyaluronic acid, 10% gelatin, 0.25% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), and 0.25% N-hydroxysuccinimide (NHS), while the other was immersed in saline solution only. Eight dogs were killed at one, three, and six weeks. Digital normalized work of flexion, tendon gliding resistance, and hyaluronic acid quantification (with the hyaluronic acid-binding-protein staining technique) were the outcome measures. RESULTS: The normalized work of flexion of the tendons treated with cd-HA was significantly lower than that of the saline-solution-treated controls at each time-point (p < 0.05). The gliding resistance of the cd-HA group was significantly lower than that of the saline-solution group at three and six weeks (p < 0.05). The ratio between the intensity of staining of the cd-HA-treated tendons with that of the saline-solution-treated controls was significantly greater at time-0 than at three or six weeks (p < 0.05), but there was no significant difference between time-0 and one-week values. CONCLUSIONS: Treating the surface of an extrasynovial tendon autograft with a carbodiimide-derivatized hyaluronic acid-gelatin polymer decreases digital work of flexion and tendon gliding resistance in this flexor tendon graft model in vivo. CLINICAL RELEVANCE: cd-HA gelatin may provide surgeons with a new and useful method to improve the quality of tendon graft surgery.

Animals↗

PubMed2001

Shear bond strength of resin composite veneering material to gold alloy with varying metal surface preparations.

STATEMENT OF PROBLEM: Although adequate surface preparation is indispensable to achieve a consistent and durable bond between resin composite materials and the metal substructures of veneered restorations, information on the bonding performance of current metal adhesive systems is limited. PURPOSE: The purpose of this study was to evaluate the surface preparation effects of 4 metal conditioners and 1 adhesive system on bonding between a prosthetic resin composite veneering material and a gold casting alloy. MATERIAL AND METHODS: Four primers containing sulfur derivative monomer and designed for conditioning noble metal alloys (Alloy Primer, Infis Opaque Primer, Metal Primer II, and Metaltite) and a surface modification technique (Siloc) were assessed. Cast disk specimens made of gold alloy (Pontor LFC) were either primed with 1 of the 4 primers or treated with the Siloc system and bonded with a light-activated prosthetic resin composite material (New Metacolor Infis). Control specimens were also prepared without the use of a bonding agent. Shear bond strengths were determined before and after thermocycling (20,000 cycles) for evaluation of bond durability. RESULTS: All of the primed and Siloc-treated groups showed improved 24-hour shear bond strengths compared with the control group. After thermocycling, the groups either primed with the Metaltite conditioner or treated with the Siloc system exhibited the highest mean shear bond strengths. CONCLUSION: The Metaltite conditioner and Siloc system each represent a useful method for improving the bond between the gold alloy and resin composite material tested.

Adhesives↗