Effect of surface conditioning methods on the bond strength of luting cement to ceramics

Objectives. This study evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA based luting cement to six commercial dental ceramics. Methods. Six disc shaped ceramic specimens (glass ceramics, glass infiltrated alumina, glass infiltrated zirconium dioxide reinforced alumina) were used for each test group yielding a total number of 216 specimens. The specimens in each group were randomly assigned to one of the each following treatment conditions: (1) hydrofluoric acid etching, (2) airborne particle abrasion, (3) tribochemical silica coating. The resin composite luting cement was bonded to the conditioned and silanized ceramics using polyethylene molds. All specimens were tested at dry and thermocycled (6.000, 5-55degreesC, 30 s) conditions. The shear bond strength of luting cement to ceramics was measured in a universal testing machine (2 mm/min). Results. In dry conditions, acid etched glass ceramics exhibited significantly higher results (26.4-29.4 MPa) than those of glass infiltrated alumina ceramics (5.3-18.1 MPa) or zirconium dioxide (8.1 MPa) (ANOVA, P <0.001). Silica coating with silanization increased the bond strength significantly for high-alumina ceramics (8.5-21.8 MPa) and glass infiltrated zirconium dioxide ceramic (17.4 MPa) compared to that of airborne particle abrasion (ANOVA, P <0.001). Thermocycling decreased the bond strengths significantly after all of the conditioning methods tested. Significance. Bond strengths of the luting cement tested on the dental ceramics following surface conditioning methods varied in accordance with the ceramic types. Hydrofluoric acid gel was effective mostly on the ceramics having glassy matrix in their structures. Roughening the ceramic surfaces with air particle abrasion provided higher bond strengths for high-alumina ceramics and the values increased more significantly after silica coating/silanization. 2003 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved

Measurement of Bioactivity of Immunomodulatory Treatment of Relapsing Multiple Sclerosis. With Emphasis on MxA Protein

Background Multiple sclerosis (MS) is a demyelinating disease of the central nervous system, which mainly affects young adults. In Finland, approximately 2500 out of 6000 MS patients have relapsing MS and are treated with disease modifying drugs (DMD): interferon- β (INF-β-1a or INF-β-1b) and glatiramer acetate (GA). Depending on the used IFN-β preparation, 2 % to 40 % of patients develop neutralizing antibodies (NAbs), which abolish the biological effects of IFN-β, leading to reduced clinical and MRI detected efficacy. According to the Finnish Current Care Guidelines and European Federation of Neurological Societis (EFNS) guidelines, it is suggested tomeasure the presence of NAbs during the first 24 months of IFN-β therapy. Aims The aim of this thesis was to measure the bioactivity of IFN-β therapy by focusing on the induction of MxA protein (myxovirus resistance protein A) and its correlation to neutralizing antibodies (NAb). A new MxA EIA assay was set up to offer an easier and rapid method for MxA protein detection in clinical practice. In addition, the tolerability and safety of GA were evaluated in patients who haddiscontinued IFN-β therapy due to side effects and lack of efficacy. Results NAbs developed towards the end of 12 months of treatment, and binding antibodies were detectable before or parallel with them. The titer of NAb correlated negatively with the amount of MxA protein and the mean values of preinjection MxA levels never returned to true baseline in NAb negative patients, but tended to drop in the NAb positive group. The test results between MxA EIA and flow cytometric analysis showed significant correlation. GA reduced the relapse rate and was a safe and well-tolerated therapy in IFN-β-intolerant MS patients. Conclusions NAbs inhibit the induction of MxA protein, which can be used as a surrogate marker of the bioactivity of IFN-β therapy. Compared to flow cytometricanalysis and NAb assay, MxA-EIA seemed to be a sensitive and more practical method in clinical use to measure the actual bioactivity of IFN-β treatment, which is of value also from a cost-effective perspective.Taustaa Multippeliskleroosi (MS) on nuorten aikuisten merkittävin demyelinoiva keskushermoston sairaus. Suomessa on 6000 MS potilasta, joista noin 2500 saa aaltomaisesti etenevään MS-tautiin taudinkulkua muuntavaa lääkehoitoa: beetainterferonia (INF-β-1a tai INF-β-1b) tai glatirameeriasetaattia (GA). Käytetystä IFN-β- valmisteesta riippuen 2-40 %:lle hoidetuista potilaista kehittyy IFN neutraloivia vastaaineita (NAb), joiden on todettu vähentävän hoidon tehoa sekä kliinisen oirekuvan että aivojen magneettitutkimuksessa todettujen muutosten perusteella. Suomalaisen Käypä Hoito ja eurooppalaisen EFNS suosituksen mukaisesti NAb tulisi mitata ensimmäisten 24 kk aikana IFN-β-hoidon aloituksesta. Tarkoitus Tämän väitöskirjatyön tarkoituksena oli mitata IFN-β-hoidon biologista vastetta mittaamalla IFN indusoimaa MxA proteiinia (myxovirus resistance protein A) ja arvioida sen korrelaatiota neutraloiviin vasta-aineisiin. Lisäksi kehitettiin aiempaa nopeampi ja yksinkertaisempi MxA proteiinia mittaava EIA-testi ja selvitettiin glatirameeriasetaatin siedettävyyttä ja turvallisuutta MS-potilailla, jotka olivat joutuneet keskeyttämään IFN-β-hoidon sivuvaikutusten ja tehon heikkenemisen vuoksi. Tulokset NAbs kehittyivät ensimmäisten 12 hoitokuukauden aikana ja sitoutuvat vasta-aineet ilmaantuivat joko edeltävästi tai samanaikaisesti NAb kanssa. NAb tiitterien ja MxA proteiinitason välillä oli negatiivinen korrelaatio. MxA proteiinin perustaso laski NAb positiivisilla, mutta ei NAb negatiivisilla potilailla. MxA-EIA testin ja virtaussytometrianalyysin tulosten välillä oli merkitsevä korrelaatio. GA vähensi relapsien määrää ja osoittautui turvalliseksi ja hyvin siedetyksi hoidoksi potilailla, jotka eivät kyenneet käyttämään IFN-β-hoitoa. Johtopäätökset NAb estävät MxA proteiini-induktiota, jota voidaan käyttää IFN-β- hoidon biologisen vasteen mittarina. Virtausytometrianalyysiin ja NAb testiin verrattuna MxA-EIA proteiinimääritys on helppokäyttöisempi ja kliiniseen käyttöön kustannus-vaikuttavuudellista merkitystä. neutraloivat vasta-aineet, sitoutuvat vasta-aineet, immunogeenisyys, MxA riittävän herkkä menetelmä mittaamaan IFN-β-hoidon biologista vastetta. Tällä on myös kustannus-vaikuttavuudellista merkitystä.Siirretty Doriast

Fiber-reinforced composites in fixed partial dentures

Fiber-reinforced composite resin (FRC) prostheses offer the advantages of good aesthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinforcement in the fabrication of laboratory or chairsidemade composite-fixed partial dentures of conventional preparation. Other applications of FRC in dentistry are briefly mentioned. The possibilities fiber reinforcement technology offers must be emphasized to the dental community. Rather than limiting discussion to whether FRC prostheses will replace metal-ceramic or full-ceramic prostheses, attention should be focused on the additional treatment options brought by the use of fibers. However, more clinical experience is needed

Experimental novel silane system in adhesion promotion between dental resin and pretreated titanium

Five silane blends were evaluated as experimental adhesion-promoter primers. First, five organosilane monomers (silicon esters), 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, tetrakis-(2-ethyloxyethoxy)silane and bis-[3-(triethoxysilyl)propyl]tetrasulfide, were diluted to 1% (v/v) and blended with a non-functional cross-linking silane, 1,2-bis-(triethoxysilyl)ethane (1%), in 95% ethanol. After activation, each blend was applied to silica-coated Ti coupons. A resin based on bis-phenol-A-diglycidyldimethacrylate was then bonded and photo-polymerized as stubs to the pretreated Ti coupons. Half of the specimens were stored in dry conditions and half were artificially aged by thermo-cycling. The primers containing 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane produced significantly higher shear bond strength values than the control silane, a standard pre-activated product used in clinical dentistry. © Springer Science+Business Media B.V. 2010.published_or_final_versionSpringer Open Choice, 01 Dec 201

Effects of different silane coupling agent monomers on flexural strength of an experimental filled resin composite

The hydrolytic stability of various silane combinations and their effects on biomechanical properties and water sorption of an experimental dental composite made of bis-GMA and TEGDMA and silane-treated fillers were evaluated. Four silane coupling agents and their blends with a cross-linker silane were used as coupling agents for the 0.7-μm BaSiO 3 fillers. The silanization was carried out in toluene containing 1% (v/v) of one of the four following organofunctional silane coupling agents: 3- acryloxypropyltrimethoxysilane, 3methacryloxypropyltrimethoxysilane, 3-styrylethyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane. Blends of these functional silanes with 1% (v/v) of a cross-linker silane, 1,2- bis -(triethoxysilyl)ethane were also used for silanization. Composites were prepared by mixing 5.00 g Ba-glass filler with 2.00 g of a resin mixture consisting of bis-GMA (58.8 wt%) and TEGDMA (39.2 wt%) in a high-speed mixer. Threepoint bending test specimens (2.0 mm × 2.0 mm × 25.0 mm) were fabricated (n= 8) in a mould and photo-polymerized. The degree of conversion was measured with FT-IR. Biomechanical testing was carried out according to the ISO 10477 standard. Specimens were tested (flexural strength) after 30 days of water storage (37° C, distilled water). Water sorption and solubility (in wt%) were also measured on 1, 2, 3, 5, 7, 14, 21 and 30 days in water storage. Statistical analysis with ANOVA showed that the highest flexural strength was obtained when 3-acryloxypropyltrimethoxysilane + 1,2- bis -(triethoxysilyl) ethane (100.5 MPa; SD, 25.7 MPa) was used in the silanization step, and the lowest was obtained when 3isocyanatopropyltriethoxysilane + 1,2- bis-(triethoxysilyl)ethane (28.9 MPa; SD, 8.8 MPa) was used. The three-point bending strength was significantly affected by the functionality of the main silane tested (p 0.05). The composite that had been silanized with 3- isocyanatopropyltriethoxysilane had the greatest amount of water uptake (1.75%), and the composite silanized with 3-methacryloxypropyltrimethoxysilane + 1,2- bis-(triethoxysilyl)ethane had the least (1.08%). In conclusion, selection of the functional silane monomer can be a significant factor in developing filled resin composites in dentistry. © 2011 VSP.postprin

A new approach to cure and reinforce cold-cured acrylics

Purpose: The low degree of polymerization of cold-cured acrylics has resulted in inferior mechanical properties and fracture vulnerability in orthodontics removable appliances. Methods: In this study, the effect of reinforcement by various concentrations of chopped E-glass fibers (0%, 1%, 2%, 3% and 5% by weight of resin powder) and post-curing microwave irradiation (800 W for 3 min) on the flexural strength of cold-cured acrylics was evaluated at various storage conditions (at room temperature for 1 day and 7 days; at water storage for 7, 14 and 30 days). Results: The data was analyzed by using 1-way and 2-way ANOVA, and a Tukey post hoc test (α = .05). The specimens with chopped E-glass fibers treated with post-curing microwave irradiation significantly increased the flexural strength of cold-cured PMMA. The optimal concentration might be 2% fibers under irradiation. Conclusions: The exhibited reinforcement effect lasted in a consistent trend for 14 days in water storage. A new fiber-acrylic mixing method was also developed. © 2012 The Author(s).published_or_final_versio

Chairside fabricated fiber-reinforced composite fixed partial denture

The advances in the materials and techniques for adhesive dentistry have allowed the development of non-invasive or minimally invasive approaches for replacing a missing tooth in those clinical situations when conservation of adjacent teeth is needed. Good mechanical and cosmetic/aesthetic properties of fiber-reinforced composite (FRC), with good bonding properties with composite resin cement and veneering composite are needed in FRC devices. Some recent studies have shown that adhesives of composite resins and luting cements allow diffusion of the adhesives to the FRC framework of the bridges. By this so-called interdiffusion bonding is formed [1]. FRC bridges can be made in dental laboratories or chairside. This article describes a clinical case of chairside (directly) made FRC Bridge, which was used according to the principles of minimal invasive approach. Treatment was performed by Professor Vallittu from the University of Turku, Finland

Resin-Bonded Fiber-Reinforced Composite for Direct Replacement of Missing Anterior Teeth: A Clinical Report

Missing anterior teeth is of serious concern in the social life of a patient in most of societies. While conventional fixed partial dentures and implant-supported restorations may often be the treatment of choice, fiber-reinforced composite (FRC) resins offer a conservative, fast, and cost-effective alternative for single and multiple teeth replacement. This paper presents two cases where FRC technology was successfully used to restore anterior edentulous areas in terms of esthetic values and functionality