Analysis of camphorquinone in composite resins as a function of shade

Objective. To identify and quantify the camphorquinone (CQ) used in different brands of composite resins as a function of the shade analyzed.Materials and methods. Filtek Z250 A3 (FZA3), Filtek Z-250 Incisal (FZI), Pyramid Enamel A1 (PEA1), Pyramid Enamel Translucent (PET), Filtek Supreme A3E (FSA3) and Filtek Supreme GT (FSGT) were used. Five hundred milligrams of each resin were weighed and then dissolved in 1.0 ml of methanol. The samples were centrifuged to accelerate the sedimentation of the inorganic particles. 0.8 ml of the supernatant solution was collected with a pipette and assessed under gas chromatography coupled to the mass spectrometer (GC-MS). The results were compared to pure CQ solutions, used as a standard. Student's t-test, (p = 0.05) significant at the level of 5%, compared the results of each brand shade.Results. A smaller amount of camphorquinone was found in Filtek Z-250 (FZI) resin incisal shade when compared to (FZA3) A3 shade. on the other hand, Filtek Supreme resin featured a statistically larger camphorquinone amount in the incisal shade. in Pyramid Enamel resin camphorquinone was found only in shade Al, while the photoinitiator used in the Translucent shade was not identified.Significance. Based on the data obtained, it is possible to conclude that a single composite resin brand may feature differences in amount and type of photoinitiator used. (C) 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Development of new standard procedures for the evaluation of dental composite abrasive wear

This article discusses the development of a test bench and a methodology for the study of composite resin abrasive wear. To evaluate the operation of the test bench and to compare the proposed methodology with other existing ones, a study was made of the five composites most commonly used by dentists.The one-way ANOVA method and the Tukey test were used to statistically analyze the results by multiple comparisons of the groups of resins tested. Using the proposed methodology, these resins were classified in an increasing order of abrasive wear strength, as follows: Charisma (the lowest abrasive wear strength), Tetric, TPH, Herculite and Z-100 (the highest abrasive wear strength) (P < 0.05). In comparison to other methodologies, the results of the proposed methodology presented the lowest coefficient of variation. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Polymerization shrinkage evaluation of three packable composite resins using a gas pycnometer.

Modern restorative dentistry has been playing an outstanding role lately since composite resins, allied to adhesive systems, have been widely applied on anterior and posterior teeth restorations. The evolution of composite resins has mostly been verified due to the improvement of their aesthetic behavior and the increase in their compressive and abrasive strengths. In spite of these developments, the polymerization shrinkage inherent to the material has been a major deficiency that, so far, has been impossible to avoid. Using a gas pycnometry, this research investigated the polymerization shrinkage of three packable composite resins: Filtek P60 (3M), Prodigy Condensable (Kerr), and SureFil (Dentsply/Caulk), varying the distance from the light source to the surface of the resins (2 mm or 10 mm). The pycnometer Accupyc 1330 (Micromeritics, USA) precisely records helium displacement, allowing fast and reliable measurements of the volume of composite resin immediately before and after polymerization, without interference of temperature or humidity. Results were not found to be statistically different for the three tested resins, either for 2 mm or 10 mm-distance from the light source to the composite surface.

Surface roughness of packable composite resins polished with various systems

Purpose: The aim of this study was to evaluate the surface roughness of four packable composite resins, SureFil™ (Dentsply, Petrópolis, Rio de Janeiro, Brazil), Prodigy Condensable™ (Kerr Co., Orange, CA, USA), Filtek P60™ (3M do Brasil, São Paulo, Brazil), and ALERT® (Jeneric/Pentron, Inc., Wallingford, CT, USA) and one microhybrid composite resin (Filtek Z250™, 3M do Brasil) after polishing with four finishing systems. Materials and Methods: Twenty specimens were made of each material (5 mm in diameter and 4 mm high) and were analyzed with a profilometer (Perthometer® S8P, Perthen, Mahr, Germany) to measure the mean surface roughness (Ra). The specimens were then divided into four groups according to the polishing system: group 1 - Sof-Lex™ (3M do Brasil), group 2 - Enhance™ (Dentsply), group 3 - Composite Finishing Kit (KG Sorensen, Barueri, São Paulo, Brazil), and group 4 - Jiffy Polisher Cups® (Ultradent Products, Inc., South Jordan, UT, USA). The specimens were polished and then evaluated for Ra, and the data were subjected to analysis of variance, analysis of covariance, and Tukey's test (p = .05). Results: The mean Ra of SureFil polished with Sof-Lex was significantly lower than that of KG points. Prodigy Condensable polished with Enhance showed a significantly less rough surface than when polished with Sof-Lex. Filtek P60 did not exhibit a significant difference with the various polishing systems. For ALERT the lowest mean Ra was obtained with Sof-Lex and the highest mean Ra with KG points. Regarding Filtek Z250, polishing with KG and Jiffy points resulted in a significantly lower mean Ra than when polished with Enhance. Conclusions: Packable composite resins display variable roughness depending on the polishing system used; the Sof-Lex disks and Jiffy points resulted in the best Ra values for the majority of the materials tested.

Background interference on the color of dental composite materials with different thickness by digital contrast

In this work the color dependence of resin composites with the background color was evaluated. The objective was to measure since what thickness the color of the sample stops being influenced by the color of the background over which the resin is placed and the methodology used in experiment was based in analyzing the contrast of digital images of the sample over a black background. The results shown that since 0.8 mm the images contrast becomes almost constant; it prove that since this thickness the color of resin composite depends on the optical resin properties only. The experiment was repeated under three conditions of luminosity to evaluate the influence of it on the image contrast and the results obtained were identical.

Changes on transmittance mode of different composite resins

The purpose of this study was to evaluate the transmittance of seven different composite resins. Ten specimens were prepared (10 mm diameter, 2 mm thickness) for each experimental group, as follows: G1- Charisma® A 2 (Heraeus-Kulzer); G2- Filtek™ Supreme A 2E (3M/ESPE); G3- Filtek™ Supreme A2B (3M/ESPE); G4-Filtek™ Supreme YT (3M/ESPE); G5- Esthet-X® A2 (Dentsply); G6- Esthet-X® YE (Dentsply); G7- Durafill® A 2 (Heraeus-Kulzer) and G8- Filtek™ Z-100 A2 (3M/ESPE). The transmittance mode was measured using a UV-visible spectrophotometer (Cary Instruments) at 400-760 nm. The specimens were evaluated at three different times: zero hour (initial), 24 hours and 10 days after immersion in artificial saliva. The differences in transmittance were determined by two-way analysis of variance (ANOVA) and Tukey's test. The various composite resins showed significant differences in the wavelength dependence of transmittance. The mean values of transmittance increased significantly, with wavelengths increasing from 400 to 760 nm. The performance of the experimental groups was similar in terms of immersion time, considering that at time zero and after 10 days, all the groups showed similar results, which were statistically higher than the values obtained after 24 hours of immersion. The Filtek™ Supreme YT composite resin presented the highest mean transmittance values along the wavelengths at the three measured times. Esthet-X® YE and Durafill® yielded similar mean transmittance values, which were higher than those of the other groups. This study shows that the transmittance values of composite resins are directly related with the type, size and amount of inorganic filler particles.

Assessment of color fidelity of several composite resins compared to their Vita Classical shade registration

This study compared the color fidelity of different composite resins with their registration in the Vita Classical Shade Guide. Using a prefabricated Teflon mold, 120 specimens were divided into four groups fn - 30), according to the resin tested. Three subgroups (a = 10) were prepared for each resin group; these subgroups tested enamel shade, dentin shade, and enamel and dentin shade. Three measurements were performed to verily whether the tooth shade matched that of the Vita Classical Shade Guide. The color was evaluated and the shade variations were calculated. The data were submitted to a three-way AN OVA test (time, color match, and composite type), followed by Tukey's test. It was concluded that all composite resins showed color differences in relation to the Vita Classical Shade Guide.

Esthetic and function improvement by direct composite resins and biomimetic concept

Aim: This case report describe a resin layering restorative technique based on biomimetic concept to improve esthetics in a patient with dental defects that affected both enamel and dentin in anterior teeth. Background: Severe structural defect in anterior teeth compromises esthetics and it is a high challenge to become the defect imperceptible after the restoration. Case description: A clinical sequence of applying different composite resin layers allowed the reproduction of the interaction between hard dental tissues and the restorative material. Conclusion: This technique achieved a satisfactory final esthetic outcome, preserving sound teeth structure and at same time, improved the quality of life of the young patient. Clinical significance: The utilization of the biomimetic concept to increase a disharmonic smile with dental defects is based in a conservative approach, which reached a satisfactory and esthetic outcome.

Thermal and structural properties of commercial dental resins light-cured with blue emitting diodes (LEDs)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Degree of conversion of nanofilled and microhybrid composite resins photo-activated by different generations of LEDs

Objective: This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs). Material and methods: Filtek (TM) Z350 nanofilled composite resins and Amelogen (R) Plus, Vit-l-escence (TM) and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free Light (TM) 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm(-1)) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1). Results: The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (p<0.001). The Tukey's test showed that the nanofilled resin (Filtek (TM) Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (Filtek (TM) Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free Light (TM) 2). Conclusions: The nanofilled resin showed the lowest DC, and the Vit-l-escence (TM) microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second-generation LED Radii-cal provided the lowest DC.

Toughening of Fibre Composite Resins through Modification of Plant Oils

Extract from the executive summary: A collaborative scoping research project to identify plant oil species with potential value in the production of fibre composite resins and assess their suitability to Queensland’s regions has been conducted by QDPI&F, USQ and Loc Composites Pty Ltd. The use of plant-oil based resins in the production of fibre composites will contribute to the Queensland economy through establishing sustainable high technology building products from renewable sources while decreasing the reliance of resin production on fossil fuels. The main objective of this project was to indentify a suite of plant oil species that show agronomic adaptability to the Australian environment (e.g. climate, soils) and economic viability of extracting plant oils for resin production within a highly competitive supply and demand production market.