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At least 505 records · Page 28Linked to original sources
PubMed2004

Bond strengths of repaired laboratory composites using three surface treatments and three primers.

PURPOSE: To determine the in vitro bond strength of three laboratory composites repaired with their corresponding direct repair composites using various combinations of surface treatments and primers. METHODS: The effects of three surface treatments (600-grit as a control, air abrasion with 50-microm Al2O3 particles and 8% hydrofluoric acid etching) and three primers with different formulations [Artglass Liquid (resin/silane), Sculpture Thinning Liquid (resin), and Targis Wetting Agent (silane)] were studied on three laboratory composites (Artglass, Targis and Sculpture). Specimens were stored for 24 hours at 37 degrees C and 100% relative humidity. Tensile bond strengths were determined on an Instron universal testing machine at a crosshead speed of 0.5 mm/minute at room temperature, keeping the specimens moist throughout the testing procedure. RESULTS: Three-way analysis of variance (SuperANOVA) indicated that in general, 8% hydrofluoric acid produced the highest bond strengths when used to prepare the three laboratory composites. Either 8% hydrofluoric acid or air abrasion with Al2O3 particles produced the strongest repair bond strengths for Tetric Ceram when used with the resin/silane primer (Artglass Liquid) with values ranging from 36.9 to 39.6 MPa., respectively, as did the combination of hydrofluoric acid and the silane primer (Targis Wetting Agent) 38.2 MPa. The 8% hydrofluoric acid produced the highest bond strengths when used to prepare Artglass and Sculpture and used with the resin/silane primer, 32.9 and 38.7 MPa, respectively. Most bond failures (65%) were adhesive between the laboratory and repair composites, followed by cohesive failures in the laboratory composite with Artglass/Charisma and Targis/Tetric Ceram; and cohesive in the repair composite with Sculpture/Sculpt-It. Overall, the resin/silane primer produced the highest repair bond strengths for Al2O3- and hydrofluoric acid-treated composites. CLINICAL SIGNIFICANCE: Air abrasion and hydrofluoric acid etching offer acceptable bond strengths for laboratory composites repaired with direct repair composites. Repair bond strengths are enhanced by the application of a resin/silane primer.

Adhesives↗
PubMed1974

Cement dermatitis.

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Aluminum Silicates↗
PubMed1972

[Cavity lining].

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Acrylic Resins↗
PubMedDate not supplied

Comparison of marginal integrity of ceramic and composite veneer restorations luted with two different resin agents: an in vitro study.

PURPOSE: The aim of the present study was to examine the marginal integrity of a composite veneer, Artglass, in comparison to a ceramic veneer, IPS Empress, by using two different luting agents. The study also aimed to evaluate the effect of grit blasting on marginal integrity of IPS Empress ceramic veneers. MATERIALS AND METHODS: A total of 42 human maxillary incisors were used to construct 14 veneers for each experimental group: (1) Artglass veneers, (2) IPS Empress veneers with grit blasting, and (3) IPS Empress veneers without grit blasting. Veneers were luted with Variolink II High Viscosity and Variolink Ultra. The restored teeth were sectioned buccolingually and mesiodistally, and marginal gap width measurements were made at 200x magnification. The data were statistically analyzed with analysis of variance. RESULTS: The mean marginal gap width varied from 105 to 182 microns. No significant differences were recorded between the marginal gap widths in relation to different types of veneers or luting agents. However, significantly higher marginal discrepancies were observed for the incisal margins of IPS Empress veneers without grit blasting. CONCLUSION: In view of the higher marginal discrepancy of IPS Empress veneers divested without grit blasting, the use of this alternative technique was not beneficial. The use of a highly filled resin luting agent (Variolink Ultra) did not cause an increase in marginal gap widths of the veneers.

Aluminum Silicates↗
PubMed2005

A comparison of three different methods for the quantification of the in vitro wear of dental materials.

OBJECTIVE: Different approaches are utilized to quantify the wear generated on flat specimens with a wear simulator. However, there are no systematic studies comparing different wear quantification methods with a series of materials that exhibit different wear rates. METHODS: Sixteen restorative materials, including 14 composites (BelleGlass, Chromasit, Estenia, Esthet-X, Four Seasons, Heliomolar RO, Heliomolar HB, Herculite XRV, InTen-S, Point 4, SureFil, Targis cured at 95 and 130 degrees C, Tetric Ceram) as well as an amalgam (Amalcap) and a ceramic (Empress) material, were subjected to attrition wear against standardized Empress antagonists in the Willytec wear simulator (120,000 cycles, 5 kg, 1.6 Hz). The volume and maximal vertical loss were quantified directly on the specimens with a profilometry device (Perthometer) and the FRT MicroProf optical sensor. After the fabrication of plaster replicas, the loss was also determined with a 3D laser scanning device. For the statistical analysis, the data were subjected to a logarithmic transformation. Intraclass correlation was calculated to measure the agreement among all three methods, while limits of agreement were used to compare one method against another. RESULTS: There was a very good agreement between all three quantification methods for both volume and vertical loss. The mechanical sensor measured consistently higher values compared to the optical sensors for the volume loss (correction factor 0.95), whereas for the vertical loss, consistently lower values were obtained (correction factor 1.17). However, the ranking of the materials was only marginally influenced by the quantification method. SIGNIFICANCE: All three sensors are suitable for the quantification of wear facets. Due to speed and simplicity, the laser sensor has greater advantages over the two other sensors.

Acrylic Resins↗
PubMed2001

Metal-free inlay-retained fixed partial dentures.

OBJECTIVE: The treatment procedures used in conjunction with two different metal-free restorative systems are illustrated on the basis of clinical examples. In addition, a report on the initial clinical findings is provided. METHOD AND MATERIALS: Metal-free restorative materials are opening doors to new preparation methods because of their close link to the adhesive cementation technique. As a result of the developments over the past few years, various metal-free systems that can be used to fabricate short-span fixed partial dentures (FPD) are now available. Certain guidelines, however, must be observed in the process. Because of their minimal invasiveness, inlay-retained FPDs offer an interesting solution in cases where the residual dentition exhibits low caries activity. Since the beginning of 1997, a total of 23 metal-free inlay-retained FPDs made of two different types of framework material (11 of high-strength pressed ceramic and 12 of fiber-reinforced composite) have been examined in a clinical study. RESULTS: One inlay-retained FPD made of pressed ceramic had to be replaced because of a fracture. Because the materials have only been on the market for a short time, long-term results are not yet available. CONCLUSION: This type of restoration provides excellent esthetics and reduced invasiveness compared with complete crown-retained FPDs, although indications are limited by the special mechanical properties of the material.

Acid Etching, Dental↗
PubMed1985

The dissolution mechanisms of silicate and glass-ionomer dental cements.

The mechanism of dissolution of two dental cements of the acid-base setting types (silicate and glass-ionomer) is considered. Dissolution is incongruent, probably because most of the leached species can derive both from the matrix (polysalt gel) and the partly reacted glass particles. The release occurs by means of three discrete mechanisms, surface wash-off, diffusion through pores and cracks or diffusion through the bulk. Such behaviour is shown to be capable of being modelled with extremely high goodness-of-fit values, using equations such as y = const + at1/2 + bt. Analogies with research from the fields of geochemistry and nuclear fuel storage are made and these systems obey similar relationships. The dental cement systems differ, however, in that their dissolution is to some extent reversible. This is explained in terms of formation of insoluble complexes, either by reaction of the constituent ions, or by replacement of OH-, for example, with F-.

Chemical Phenomena↗
PubMed1984

The fracture toughness of tooth coloured restorative materials.

A fracture mechanics approach has been used to quantify the failure of tooth coloured restorative materials which are subjected to tensile forces. The materials examined included silicates, glass ionomers, composites (both chemically and photo-initiated) and bonding resins for composites. The parameter chosen was the plane strain critical stress intensification factor, KIC. Silicate and glass ionomer are both brittle and have values for KIC inferior to those of composites. Composites have fracture toughnesses in a range from marginally higher than that of the bonding resin to almost three times that figure. The reason for this is discussed in terms of the dispersion toughening theories.

Chemical Phenomena↗
PubMed1991

Creep behavior of glass-ionomer restorative materials.

The creep of microspecimens of five glass-ionomer filling materials and one glass-ionomer-cermet cement was studied by means of a torsional creep apparatus. The glass-ionomer specimens were aged one week and conditioned in 37 degrees C water. Shear stress of 2.47 x 10(-4) N.m was maintained for three h, and recovery was followed for 50 h. Creep curves were obtained at 21, 37, and 50 degrees C. The effect of temperature increase was studied. All the glass ionomers exhibited linear visco-elastic behavior at low deformations. Their shear moduli and resistance to creep were similar to those of some composites measured by the same method. The increase of temperature influenced the creep behavior and moduli of the materials (i.e., increased creep and residual strains and decreased shear modulus). Although the applied torque was very small, there was permanent deformation, the result of viscous flow in all experiments which was more pronounced at 50 degrees C.

Cermet Cements↗