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PubMed1996

Adhesive bonding to dentin with ferrous chloride primers and tri-n-butylborane-initiated luting agents.

A variety of surface modifications with metal chlorides has been used to enhance the bond of resins to dentin. This study investigated the effectiveness of ferrous chloride in terms of the initiation of polymerization in dentin bonding. The efficacy of experimental dentin primers was evaluated via the bonding of two luting agents to dentin. The 16 primers evaluated were ferrous chloride (FeCl2) aqueous solutions, eight with and eight without 35% 2-hydroxyethyl methacrylate (HEMA). The concentrations of FeCl2 in the primers ranged from 2.0 x 10(-6) to 5.0 x 10(-4) mol/g. One luting agent (Super-Bond C&B) consisted of methyl methacrylate (MMA), 4-methacryloyloxyethyl trimellitate anhydride (4-META), and tri-n-butylborane (TBB) initiator. The other luting agent was prepared with MMA and TBB, but without 4-META. Bovine dentin surfaces were flattened, etched with an aqueous solution of 10% phosphoric acid, primed, and then bonded with stainless steel rods. Tensile strengths of the bonded specimens were measured after one-day immersion in water. Tensile testing revealed that the bond strength was influenced by the application of FeCl2 and/or HEMA. The maximum bond strength of 33.0 MPa was recorded with the use of primer containing FeCl2 and HEMA in MMA-TBB resin. In the case of Super-Bond, only surface treatment of dentin with aqueous primers containing 5.0 x 10(-5) to 2.0 x 10(-4) mol/g ferrous chloride resulted in bond strength values above 22.0 MPa. This bonding technique, combining the use of ferrous chloride primer with Super-Bond resin, may potentially be applied for seating resin-bonded restorations.

Analysis of Variance↗

PubMed2005

Silica encapsulation and magnetic properties of FePt nanoparticles.

Core-shell nanoparticles have emerged as an important class of functional nanostructures with potential applications in many diverse fields, especially in health sciences. We have used a modified aqueous sol-gel route for the synthesis of size-selective FePt@SiO2 core-shell nanoparticles. In this approach, oleic acid and olyel amine stabilized FePt nanoparticles are first encapsulated through an aminopropoxysilane (APS) monolayer and then subsequent condensation of triethoxysilane (TEOS) on FePt particle surface. These well-defined FePt@SiO2 core-shell nanoparticles with narrow size distribution become colloidal in aqueous media, and can thus be used as carrier fluid for biomolecular complexes. In comparison, the scarce hydrophilic nature of oleic acid monolayers on FePt particle surface yields an edgy partial coating of silica when only TEOS is applied for the surface modification. The synthesized core-shell nanoparticles were characterized by direct techniques of high resolution transmission electron microscopy (HRTEM), EDS and indirectly via UV-vis absorption and FTIR studies. The FePt@SiO2 nanoparticles exhibit essential characteristics of superparamagnetic behavior, as investigated by SQUID magnetometry. The blocking temperatures (T(B)) of FePt and FePt@SiO2 (135 and 80 K) were studied using zero field cooled (ZFC)/field cooled (FC) curves.

Adsorption↗

PubMed1996

Stability of trypsin immobilized on inorganic orthopedic biomaterials.

Biochemical surface modification of biomaterials utilizes immobilized biomolecules to induce preferred tissue responses. Although several techniques are available for immobilizing biomolecules on organic substrates, comparatively few are available for use with inorganic materials, such as those used in many orthopedic applications. The present study investigated the stability/elutability of a model enzyme immobilized on Co-Cr-Mo and Ti-6Al-4V alloys using p-nitrophenyl chloroformate (p-NPC). Trypsin-conjugated biomaterials were incubated in cell culture medium at 37 degrees C for up to 96 hr, and the residual immobilized activity was measured. Although all samples initially bound enzymatically active trypsin, significant decreases were observed within the first 2 hr of incubation. Immobilization of trypsin on Co-Cr-Mo treated with 0.65 mg p-NPC/cm2 of nominal surface area gave significantly higher residual activity than on untreated samples at 24-96 hr of incubation and prevented the nearly complete loss of enzymatic activity that was observed with free (not immobilized) enzyme. Derivatization of Ti-6Al-4V with p-NPC was not beneficial to the level of immobilized enzymatic activity after incubation in medium for longer than 6 hr.

Alloys↗

PubMed2000

Impression cytology of the conjunctival epithelium in patients with chronic renal failure.

AIMS: To assess ocular surface changes in patients with chronic renal failure (CRF), to compare the results with the degree of corneo-conjunctival calcium deposits, and to determine whether precipitation of calcium salts predisposes ocular surface modifications. METHODS: Impression cytology from 50 CRF patients on regular haemodialysis and 22 age and sex matched control subjects were studied. Specimens were obtained from the temporal bulbar conjunctiva using cellulose acetate filter paper. The samples were fixed in 95% ethanol, stained with the periodic acid Schiff (PAS) stain, and evaluated by light microscopy and were graded by a masked observer. Corneo-conjunctival calcification was graded by the Porter and Crombie classification. RESULTS: In the study group, three patients (6%) disclosed grade 0, 14 patients (28%) grade 1, and 33 patients (66%) grade 2-3 cytological changes. There was a statistically significant difference between the patient and the control groups (p= 0.0007), but no correlation could be found between the impression cytology grades and the calcium deposit grades (p=0.62). CONCLUSION: The ocular surfaces of CRF patients differ significantly from those of normal individuals, and it can be detected using impression cytology. These data suggest that the severity of conjunctival changes are not related to the presence or extent of calcium deposition.

Adolescent↗

PubMed2004

Protecting nanoscaled non-oxidic particles from oxygen uptake by coating with nitrogen-containing surfactants.

To suppress the reactivity of nanoscaled non-oxidic powders of titanium nitride (TiN) and silicon carbonitride (SiCN) against hydrolysis and oxidation, chemical surface modification with nitrogen-containing surfactants was investigated. Among these surfactants, long-chain primary amines, ethylenediamines, guanidines, nitriles, isocyanates, and succinimides were examined. Thermogravimetry, elemental analysis, and behavior against the water-vapor adsorption of the modified particles were used as methods to estimate the protective capacity of the organic coating material. The best results were obtained by using the long-chain amines and octadecylisocyanate, which were indicated by a significant shift of the powder oxidation toward the higher temperatures and an increase of the particle hydrophobicity. A long-chain succinimide was found to be the most effective in dispersing nanoscaled TiN in organic media. Preparation of a stable aqueous dispersion without significant changes in the elemental composition of the powder was achieved by the application of an ionic surfactant to the surface-modified particles.

Hydrolysis↗

PubMed2001

Development of systems for targeting the regional lymph nodes for diagnostic imaging: in vivo behaviour of colloidal PEG-coated magnetite nanospheres in the rat following interstitial administration.

PURPOSE: Nanoparticles can be utilised for targeting drugs to the regional lymph nodes or as diagnostic agents. The surface modification of magnetite nanospheres with poly(ethylene glycol) (PEG) has been assessed by in vitro characterisation and in vivo studies following subcutaneous administration to the rat. METHODS: Magnetite nanospheres were prepared with a grafted PEG layer using various PEG lengths from 350 to 1,000 Da. Thermogravimetric analysis was utilised to measure the adsorbed amount of PEG. Colloid stability was confirmed by measurement of the particle size and electrophoretic mobility. The kinetics of injection site drainage and lymph node retention were determined 2 hours after subcutaneous administration, for nanospheres coated with PEG lengths of 350, 550. 750, and 1,000 Da. For the 750 PEG coated nanospheres, the kinetics of distribution was determined over a 48-hour time course. RESULTS: The distribution of the nanospheres was modified and the lymph node localisation enhanced by altering the surface coverage of PEG on the magnetic surface. CONCLUSIONS: PEG-coated magnetite nanospheres with different surface characteristics can be utilised to target a diagnostic agent to regional lymph nodes.

Animals↗

PubMed2006

Fabrication of non-biofouling polyethylene glycol micro- and nanochannels by ultraviolet-assisted irreversible sealing.

We present a simple and widely applicable method to fabricate micro- and nanochannels comprised entirely of crosslinked polyethylene glycol (PEG) by using UV-assisted irreversible sealing to bond partially crosslinked PEG surfaces. The method developed here can be used to form channels as small as approximately 50 nm in diameter without using a sophisticated experimental setup. The manufactured channel is a homogeneous conduit made completely from non-biofouling PEG, exhibits robust sealing with minimal swelling and can be used without additional surface modification chemistries, thus significantly enhancing reliability and durability of microfluidic devices. Furthermore, we demonstrate simple analytical assays using PEG microchannels combined with patterned arrays of supported lipid bilayers (SLBs) to detect ligand (biotin)-receptor (streptavidin) interactions.

Acrylates↗

PubMedDate not supplied

[Biomechanics of cement-free endoprostheses].

At present only about 20 per cent of endoprosthetic stems and 30 per cent cups are implanted without cement. Nevertheless, the number of modifications and new developments in cementless endoprosthetics is continuously growing. Years ago bone cement was made responsible for all failures, but meanwhile the approach to it got more differentiated. The advantages of cement fixation in case of elderly patients as well as those of cementless implantation for patients where revision operation could be expected were recognized. Whereas sufficient primary stability can be generally achieved without any problem in case of cement implantation, the cementless one needs more intensified planning as well as a different surgical technique. Today not only torsional stability and stiffness of stem and bone implant are discussed more intensively than before but also new anchorage concepts as for example tubular stems or custom made systems. Obviously, the existing screw cups and clamp/clip systems are more in demand than cementless stem systems. The results of different coatings and surface modifications are rather inhomogeneous and there is a need of more basic research in this respect.

Acetabulum↗

PubMed2000

The transport activity of the Na+-Ca2+ exchanger NCX1 expressed in HEK 293 cells is sensitive to covalent modification of intracellular cysteine residues by sulfhydryl reagents.

Membrane permeable N-ethylmaleimide (NEM) and (2-aminoethyl)methanethiosulfonatehydrobromide (MTSEA) inhibited the rat brain Na(+)-Ca(2+) exchanger RBE-2 (NCX1.5) expressed in HEK 293 cells in a dose dependent manner. 50% inhibition was obtained at 1 mm MTSEA and 1.65 mm NEM. External application of membrane impermeable [2-(trimethylammonium) ethyl]methanethiosulfonatebromide (MTSET) and sodium(2-sulfonatoethyl)methanethiosulfonate (MTSES) did not inhibit the transport activity in whole cells. Following reconstitution, however, of RBE-2 transfected cell proteins into proteoliposomes, external application of MTSET and MTSES led to a decrease in transport activity to 42.7 (S.D. = 9.1) and 51% (S.D. = 10.14), respectively. Similar results were obtained also when the rat heart isoform RHE-1 (NCX1.1) or the rat brain isoform RBE-1 (NCX1.4) was expressed. NEM and MTSEA inhibited Na(+) gradient-dependent Ca(2+) uptake also in HEK 293 cells expressing RBE-2/C14A/C20S/ C122S/C780S (numbering corresponds to RBE-2), a mutant in which all putative extracellular cysteines were exchanged. To study the accessibility of different cysteines to covalent modification, surface biotinylation of cells expressing the wild type exchanger and its mutants was carried out using 3-(N-maleimidylpropionyl)biocytin. Surface biotinylation revealed immunoreactive protein derived from the wild type Na(+)-Ca(2+) exchanger only if the transfected cells were exposed to the reducing agent Tris(2-carboxyethyl)phosphine. No reduction was needed when the single cysteine mutants of RBE-2, C14A, C20S, and C780S, were expressed. Treatment of the cells expressing these mutants with MTSET before biotinylation, led to a decrease in the amount of exchanger protein that was revealed. No immunoreactive protein was detected when the quadruple mutant RBE-2, C14A/C20S/C122S/C780S, was biotinylated, suggesting that no additional cysteines are accessible directly from the extracellular face of the membrane. Permeabilizing the cells expressing RBE-2/C14A/C20S/ C122S/C780S with streptolysin O resulted in biotinylation of the exchanger protein. Its amount decreased if exposure to NEM preceded streptolysin O treatment. Our results suggest that Na(+)-Ca(2+) exchange activity is inhibited by covalent modification with sulfhydryl reagents of cysteine residues that are accessible from the cytoplasmic face of the membrane.

Animals↗

PubMed2005

Interventions for replacing missing teeth: different types of dental implants.

BACKGROUND: Dental implants are available in different materials, shapes and with different surface characteristics. In particular, numerous implant surface modifications have been developed for enhancing clinical performances. OBJECTIVES: To test the null hypothesis of no difference in clinical performance between various root-formed osseointegrated dental implant types. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Handsearching included several dental journals. We checked the bibliographies of relevant clinical trials and review articles for studies outside the handsearched journals. We wrote to authors of the identified randomised controlled trials (RCTs), to more than 55 oral implant manufacturers; we used personal contacts and we asked on an internet discussion group in an attempt to identify unpublished or ongoing RCTs. No language restriction was applied. The last electronic search was conducted on 28 June 2004. SELECTION CRITERIA: All RCTs of oral implants comparing osseointegrated implants with different materials, shapes and surface properties having a follow up of at least 1 year. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Results were expressed as random effects models using weighted mean differences for continuous outcomes and relative risk for dichotomous outcomes with 95% confidence intervals. MAIN RESULTS: Thirty-one different RCTs were identified. Twelve of these RCTs, reporting results from a total of 512 patients, were suitable for inclusion in the review. Twelve different implant types were compared with a follow up ranging from 1 to 5 years. All implants were made in commercially pure titanium and had different shapes and surface preparations. On a 'per patient ' rather than 'per implant' basis no significant differences were observed between various implant types for implant failures. There were statistically significant differences for peri-implant bone level changes on intraoral radiographs in three comparisons in two trials. In one trial there was more bone loss only at 1 year for IMZ implants compared to Branemark (mean difference 0.60 mm; 95% CI 0.01 to 1.10) and to ITI implants (mean difference 0.50 mm; 95% CI 0.01 to 0.99). In the other trial Southern implants displayed more bone loss at 5 years than Steri-Oss implants (mean difference -0.35 mm; 95% CI -0.70 to -0.01). However this difference disappeared in the meta-analysis. More implants with rough surfaces were affected by perimplantitis (RR 0.80; 95% CI 0.67 to 0.96) meaning that turned implant surfaces had a 20% reduction in risk of being affected by perimplantitis over a 3-year period. AUTHORS' CONCLUSIONS: Based on the available results of RCTs, there is limited evidence showing that implants with relatively smooth (turned) surfaces are less prone to loose bone due to chronic infection (perimplantitis) than implants with rougher surfaces. On the other hand, there is no evidence showing that any particular type of dental implant has superior long-term success. These findings are based on a few RCTs, often at high risk of bias, with few participants and relatively short follow-up periods. More RCTs should be conducted, with follow up of at least 5 years including a sufficient number of patients to detect a true difference if any exists. Such trials should be reported according to the CONSORT recommendations (http://www.consort-statement.org/).

Dental Implantation, Endosseous↗

PubMed2001

In vivo evaluation of ammonia plasma modified ePTFE grafts for small diameter blood vessels replacement. A preliminary report.

BACKGROUND: Today, saphenous veins are most frequently used to reconstruct occluded or diseased small diameter vessels (< or =6 mm in diameter). However, these veins are unavailable in 30-40% of patients. In such a situation, prosthetic grafts provide the only alternative. Since an endothelial cell (EC) lining, important for maintaining a haemostatic-thrombotic balance, does not develop onto the intima of implanted grafts in humans, these grafts occlude within a short period of time. The failure of vascular grafts is attributed to their characteristics which are nonconducive towards endothelial cell adhesion, spreading and growth. In order to examine whether the patency of vascular grafts can be improved by the surface modification of grafts' intima, small diameter grafts were modified by a novel ammonia plasma treatment to enhance their interactions with EC. METHODS: Through laparotomy, ammonia plasma treated ePTFE (4 mm in diameter) grafts (n=3) and control untreated grafts (n=6) were implanted into the distal infrarenal aorta of rabbits. At appropriate time, grafts and adherent tissue were removed, fixed, stained and embedded in Poly/Bed 812. Light microscopic examination of thin sections cut from the proximal and distal anastomatic and midportion segments of explanted grafts was carried out. RESULTS: In control group studies, all animals developed lower limb paraplegia within seven days of implantation. Light microscopic examination of explanted control grafts showed that control grafts were obstructed by thrombosis/intimal hyperplasia. However, ammonia plasma modified explanted grafts, after one month of transplantation, revealed an endothelial cell-like lining that covered the grafts' inner surfaces. Accordingly, these grafts remained patent in animals. CONCLUSIONS: The grafts' surfaces that are made conducive to EC adhesion and proliferation and host response may influence endothelial regeneration. It is hoped that the combination of angiogenic molecules (i.e. endothelial cell specific growth factors such as VEGF) with ammonia plasma modified grafts may provide further insight into the development of ideal small diameter prosthesis.

Ammonia↗

PubMed2005

A sexual dimorphism in intrathymic sialylation survey is revealed by the trans-sialidase from Trypanosoma cruzi.

Sialylation is emerging as an important issue in developing thymocytes and is considered among the most significant cell surface modifications, although its physiologic relevance is far from being completely understood. It is regulated by the concerted expression of sialyl transferases along thymocyte development. After in vivo administration of trans-sialidase, a virulence factor from the American trypanosomatid Trypanosoma cruzi that directly transfers the sialyl residue among macromolecules, we found that the alteration of the sialylation pattern induces thymocyte apoptosis inside the "nurse cell complex." This suggests a glycosylation survey in the development of the T cell compartment. In this study, we report that this thymocyte apoptosis mechanism requires the presence of androgens. No increment in apoptosis was recorded after trans-sialidase administration in females or in antiandrogen-treated, gonadectomized, or androgen receptor mutant male mice. The androgen receptor presence was required only in the thymic epithelial cells as determined by bone marrow chimeric mouse approaches. The presence of the CD43 surface mucin, a molecule with a still undefined function in thymocytes, was another absolute requirement. The trans-sialidase-induced apoptosis proceeds through the TNF-alpha receptor 1 deathly signaling leading to the activation of the caspase 3. Accordingly, the production of the cytokine was increased in thymocytes. The ability of males to delete thymocytes altered in their sialylation pattern reveals a sexual dimorphism in the glycosylation survey during the development of the T cell compartment that might be related to the known differences in the immune response among sexes.

Animals↗

PubMed2002

Organic-inorganic nanostructured colloids.

The synthesis and applications of organic-inorganic nanostructured colloids and colloidal-based materials are reviewed here. Emphasis is placed on the strategies and synthetic methods developed to organize organic-inorganic architectures. The article begins with a description and a general hierarchical classification of different systems, from inorganic particle synthesis and surface modification to more elaborate nanostructured colloids obtained through in situ encapsulation and/or self-assembly techniques. Ordering of colloids into two- and three-dimensional arrays and their use as templates is also considered. For every system, typical examples are given that highlight the advantages and limitations of the techniques, as are more recent developments. Some properties and applicability of organic-inorganic colloids in catalysis, medicine, and coating technologies are also cited.

Colloids↗

PubMed1997

Biocompatibility in cardiopulmonary bypass.

Recent advances in surgical techniques and perfusion technology allow cardiac operations to be performed routinely with low mortality rates. However, patients undergoing cardiac operations with cardiopulmonary bypass (CPB) are still associated with bleeding disorders, thrombotic complications, massive fluid shifts, and the activation of blood components that are collectively known as the whole body inflammatory response. In this review, the effect of cardiopulmonary bypass on various humoral and cellular components of blood is examined. Blood activation caused by interaction with artificial materials of extracorporeal circuit and by material-independent stimuli is discussed. Methods to control blood activation during and after cardiopulmonary bypass are described. These include surface modification of extracorporeal circuit, control of flow dynamics in the circuit, pharmacological intervention, and the use of extracorporeal devices to remove inflammatory mediators. Recent findings on the effects of heparin-coated circuits on inflammatory response and clinical outcome are reviewed. It appears that the causes of inflammatory response to cardiopulmonary bypass are multifactorial and that an integrated strategy is needed to control and eliminate the negative effects of CPB.

Antibody Formation↗

PubMed2004

Ultra-sensitive fully automated immunoassay for detection of propanil in aqueous samples: steps of progress toward sub-nanogram per liter detection.

The widely-used pesticide propanil is a selective post-emergent general-use acetanilide herbicide registered for control of broadleaf and grass weeds in rice, small grain, and turf. Because broad application and quite heavy use of this herbicide lead to contaminated sites and, consequently, contaminated water, immunoanalytical methods with very low limits of detection (LOD) and low limits of quantification (LOQ) are becoming increasingly important for environmental analysis and, especially, for monitoring drinking-water quality. Environmental monitoring of pesticides, hormones, endocrine-disrupting chemicals, and antibiotics in aqueous samples (e.g. surface, ground, waste, or drinking water) with quite difficult matrices places large demands on chemical analysis. Biosensors have suitable characteristics such as efficiency in enabling very fast, sensitive, and cost-effective detection. Here we describe the steps of progress toward sub-nanogram per liter detection of propanil with a fully automated immunoassay. In contrast with common analytical methods such as GC-MS or HPLC-MS the biosensor used requires no sample pre-treatment and pre-concentration. The basis of our sensitive assay is an antibody with a high affinity constant toward propanil. During the optimization process, we compared different surface modifications (four different immobilized derivatives) and reduced the amount of antibody per sample. In fact, optimization of the assay resulted in an LOD of 0.6 ng L(-1) and an LOQ of 4.5 ng L(-1) without any sample pre-treatment and without pre-concentration. These results for propanil with the RIANA instrument, and its improved sensitivity for detection of a single pesticide at the low nanogram per liter range, show that biosensors can compete with common analytical methods in the field of water analysis.

Autoanalysis↗

PubMed2005

Surface engineering of stainless steel materials by covalent collagen immobilization to improve implant biocompatibility.

It was shown recently that the deposition of thin films of tantalum and tantalum oxide enhanced the long-term biocompatibility of stainless steel biomaterials due to an increase in their corrosion resistance. In this study, we used this tantalum oxide coating as a basis for covalent immobilization of a collagen layer, which should result in a further improvement of implant tissue integration. Because of the high degradation rate of natural collagen in vivo, covalent immobilization as well as carbodiimide induced cross-linking of the protein was performed. It was found that the combination of the silane-coupling agent aminopropyl triethoxysilane and the linker molecule N,N'-disulphosuccinimidyl suberate was a very effective system for collagen immobilizing. Mechanical and enzymatic stability testing revealed a higher stability of covalent bound collagen layers compared to physically adsorbed collagen layers. The biological response induced by the surface modifications was evaluated by in vitro cell culture with human mesenchymal stem cells as well as by in vivo subcutaneous implantation into nude mice. The presence of collagen clearly improved the cytocompatibility of the stainless steel implants which, nevertheless, significantly depended on the cross-linking degree of the collagen layer.

Adsorption↗

PubMed2006

Protein nanopatterns and biosensors using gold binding polypeptide as a fusion partner.

An efficient strategy for immobilizing proteins on a gold surface was developed by employing the gold binding polypeptide (GBP) as a fusion partner. Using the enhanced green fluorescent protein (EGFP), severe acute respiratory syndrome coronavirus (SARS-CoV) envelope protein (SCVme), and core streptavidin (cSA) of Streptomyces avidinii as model proteins, specific immobilization of the GBP-fusion proteins onto the gold nanoparticles and generation of protein nanopatterns on the bare gold surface were demonstrated. The GBP-fused SCVme bound to gold nanoparticles successfully interacted with its antibody and showed changes in absorbance and color, allowing efficient diagnosis of SARS-CoV. The fusion proteins could be successfully immobilized on the gold surface by nanopatterning and microcontact printing as examined by atomic force microscopy and surface plasmon resonance analysis. The poly(dimethylsiloxane) microfluidic channels were created on the gold surface and were used for antigen-antibody and DNA-DNA interaction studies. Specific immobilization of GBP-EGFP fusion protein and its interaction with the antibody in the microchannels could be demonstrated. By immobilizing the DNA probe through the use of GBP-fused cSA, specific hybridization of the target DNA prepared from Salmonella could also be achieved. The GBP-fusion method allows immobilization of proteins onto the gold surface without surface modification and in bioactive forms suitable for studying protein-protein, DNA-DNA, and other biomolecular interaction studies. Furthermore, these studies can be carried out in a microfluidic system, which allows high-throughput analysis of biomolecular interactions.

Biological Assay↗

PubMedDate not supplied

Surface roughness in ceramics with different finishing techniques using atomic force microscope and profilometer.

This study assessed the finishing and polishing of 3 ceramic materials: Vitadur Alpha, IPS Empress 2 and AllCeram. Surface modification techniques were selected to simulate dental practice. Forty-five specimens of each ceramic were divided into 5 groups of 9 specimens, which were finished using the following procedures: Group 1--glaze; Group 2--glaze, grinding and subsequent polishing with the Eve system; Group 3--glaze, grinding and subsequent polished with the Identoflex system; Group 4--glaze followed by polishing with Identoflex; Group 5--glaze, grinding and subsequent polishing with Shofu kit. Two roughness-measuring instruments were used: a stylus profilometer and an atomic force microscope (AFM). The 135 specimens were evaluated quantitatively with respect to Ra (average roughness) and Ry (maximum roughness height), and the results were examined statistically by ANOVA and Tukey's test, with a significance level of 0.05. The roughness parameter (Ra), measured by the profilometer, and AFM showed that some of the commercial intraoral polishing kits tested achieved a finish equal in smoothness to the glazed surface. According to Pearson's test, no correlation was found between the parameter Ry, measured with the profilometer, and AFM. The profilometer results for Ry demonstrated no significant differences between the final polished surfaces and the initial glazed ones. On the other hand, the Ry values obtained by AFM indicated the tested polishing kits incapability of producing smoothness comparable to the glazed surfaces.

Aluminum Oxide↗