heliosit and prisma-fil

The authors studied the superficial hardness of composite resins cured for two different times: 20 and 40 seconds of light exposure. The hardness values were read immediately and 24 hours after polymerization. A significant increase in hardness was observed with 40 s exposure as compared to 20 s. Hardness values were significantly higher at 24 h than immediately after polymerization.

Topics: Bisphenol A-Glycidyl Methacrylate; Composite Resins; Hardness; Light; Materials Testing; Polymethacrylic Acids; Polyurethanes; Resin Cements; Surface Properties; Time Factors

The shear/peel and tensile/peel bond strengths of the original Transcend and the new Transcend series 2000 bracket were determined using two different light-cured composites, Prismafil (high filler) and Heliosit (low filler). Predominant sites of failure were recorded for each bracket with each cement in each mode of testing. Transcend series 2000 produced higher bond strengths than Transcend in shear/peel, but were significantly weaker in tensile/peel testing. Heliosit generally produced higher bond strengths than Prismafil. Enamel fractures were observed with Transcend in both modes of testing when bonded with Heliosit, but not with Transcend series 2000 when bonded with Heliosit. The new Transcend series 2000 brackets should only be removed in tensile/peel mode as suggested by the manufacturers, due to their very high bond strengths in shear.

Topics: Ceramics; Composite Resins; Dental Bonding; Dental Cements; Dental Debonding; Dental Enamel; Dental Stress Analysis; Equipment Failure; Humans; Materials Testing; Orthodontic Appliance Design; Orthodontic Brackets; Resin Cements; Stress, Mechanical; Surface Properties; Tensile Strength

After the gross reduction and fine finishing of a composite resin restoration, selecting a system to create the smoothest polish is difficult because high magnification is necessary to compare the surface roughness. The surfaces of four anterior and posterior composite resins were compared using a Mylar strip, an unfilled resin as a glaze, polishing with three rubber polishers, and three different manufacturers' series of disks. This study suggested that pairing a specific composite resin with a matching polishing system produced the smoothest surface. Because of the differences in the size, shape, number of filler particles, and the type of resin, one system was incapable of creating the smoothest surface for all composite resins.

Topics: Acrylic Resins; Aluminum Oxide; Analysis of Variance; Bisphenol A-Glycidyl Methacrylate; Carbon; Carbon Compounds, Inorganic; Composite Resins; Dental Materials; Dental Polishing; Equipment Design; Evaluation Studies as Topic; Methacrylates; Polymethacrylic Acids; Polyurethanes; Resin Cements; Rubber; Silicon; Silicon Compounds; Surface Properties

The purpose of this investigation was to compare the bond strengths to enamel obtained in shear/peel and tensile/peel modes of testing using five different ceramic brackets and two different light-cured composites. The site of failure was also examined. Shear/peel bond strength was significantly affected by adhesive type, with Heliosit having higher mean bond strengths than Prismafil. Bond strength was significantly affected by bracket type; the highest mean bond strength in both tests being attained using Transcend with Heliosit. All brackets resisted shear/peel forces better than tensile/peel forces. High bond strengths are associated with an increased incidence of bracket and enamel fractures with Transcend and Starfire.

Topics: Adhesives; Ceramics; Composite Resins; Dental Bonding; Dental Debonding; Dental Enamel; Dental Stress Analysis; Equipment Design; Equipment Failure; Humans; Materials Testing; Orthodontic Brackets; Resin Cements; Stress, Mechanical; Surface Properties; Tensile Strength; Zirconium

A pre-production sample of zirconium oxide (ceramic) brackets was examined in this study. A laboratory investigation of the tensile/peel bond strength of the brackets was carried out using two light-cured adhesives (Prismafil and Heliosit) and one chemically-cured adhesive (Delphic). The mode of failure was also investigated using optical and scanning electron microscopy. The bond strengths achieved with Prismafil were statistically significantly (P less than 0.05) lower than Heliosit and Delphic between which no significant differences were found. All samples failed at the bracket-adhesive interface. A clinical test demonstrated the extreme ease of sliding along stainless steel and nickel-titanium archwires, and revealed a low plaque adhesion. The principal disadvantage of these brackets appears to be their off-white highly opaque appearance which in addition to giving poor aesthetics may adversely affect bond strength with light-cured adhesives.

Topics: Adhesives; Adolescent; Ceramics; Composite Resins; Dental Bonding; Dental Debonding; Dental Stress Analysis; Equipment Failure; Evaluation Studies as Topic; Female; Humans; Materials Testing; Orthodontic Appliance Design; Orthodontic Brackets; Orthodontic Wires; Resin Cements; Stress, Mechanical; Surface Properties; Tensile Strength; Zirconium

Six different dental composite materials were investigated regarding leaching of filler elements such as silicon, barium, and zinc. The leaching was conducted by storing the samples in distilled water at 60 degrees C for half a year. The results could not prove that the leaching behavior of filler elements in most of the investigated cases decreases with time. The practical implications of this study could be important. If other elements follow the same leaching pattern, therapeutic elements such as fluoride could be incorporated in filler particles. The tendency of composites to leach filler elements almost linearly with time, could be used to generate a constant release rate of such therapeutic elements over time. Such an application could have a major impact on controlling caries adjacent to composite restorations and sealants.

Topics: Barium; Bisphenol A-Glycidyl Methacrylate; Chemical Phenomena; Chemistry, Physical; Composite Resins; Electron Probe Microanalysis; Materials Testing; Methylmethacrylates; Resin Cements; Silicon Dioxide; Spectrophotometry, Atomic; Time Factors; Water; Zinc

The shear strength of a commercial dentin bonding agent was studied using human dentin in vitro. The agent was tested for compatibility with three proprietary composite resins. In addition, some samples were subjected to prolonged water immersion and thermocycling to determine effects on bond strength. There was no statistically significant difference in shear strengths when the three composite resins were used. In addition, there was no difference in shear strengths among those samples thermocycled or immersed for up to one year. The implications of this study are that the dentin bonding agent may be used with several composite resins with no significant difference in bond strengths, and that the bond seems stable when subjected to immersion or simulated intra-oral thermal stresses.

Topics: Adhesives; Biocompatible Materials; Bisphenol A-Glycidyl Methacrylate; Composite Resins; Dental Bonding; Dentin; Humans; Resin Cements; Stress, Mechanical; Tensile Strength; Thermodynamics; Time Factors; Water