Rok research
Rok - a posterior light cured hybrid composite.
Performance
The aim of this study was to evaluate the resistance to corrosive wear of ICE and ROK and data were compared those of three popular brands, POINT 4 (Kerr-Sybron), Esthet (Caulk) and Supreme (3M/Espe). The corrosive wear had been simulated in two steps: A. CORROSION - Samples were exposed to 0.1 N NaOH (Sodium hydroxide) solution enriched with OH- at 60oC for two weeks. They were then washed and dried at 60oC. Each was measured for (i) Mass-loss (gravimetrically) (ii) Si-loss (ICP-AE) and (iii) Degradation depth (microscopically). The degrade surface of each brand was also characterised by scanning electron microscopy (SEM).
B. WEAR – Test composites were filled into ceramic discs and polished to a flat surface. Samples were then corroded as above. Corroded specimens were abraded in a tooth-brushing machine. The wear depth was measured relative to the ceramic disc.
Performance Rok, The Dental Advisor, Volume 21, 2004. Rok is a light-cured, radiopaque, hybrid composite for use in direct posterior restorations. The material is designed to have a high compressive strength and filler level, while maintaining low polymerisation shrinkage. The packable nature of Rok was rated very good, enhancing firm interproximal contacts. The composite is not sticky, but slightly dry, making the syringe material difficult to transfer from the pad to the tooth. Several consultants noted that before curing, the composite appeared to not blend with the tooth, but following light curing, shade blending with the tooth was rated very good – a four stars rating.
Performance
Seabra B.G.M., Seabra F.R.G.; Machado C.T., Oertli, D.C.B.;Braz, R.; Abreu A.D.J; Performance of two different types of light units on the composed resin cure depth; Abstract #0102, 1st Meeting of Latin Federation, 2005.
The difficulty in getting a composed resin with good mechanical properties must, in part, to its depth of polymerization, being necessary to know the source of used light and its capacity to polymerize. Of this form, the objective of this study was to evaluate the Vicker hardness of two composite in relation to the uniformity polymerization. Two light curing devices had been used, one of halogen light, Ultralux, and a LED, the Radii. Five samples had been prepared for each light unit and hybrid composed resin, Rok and Glacier (SDI), using cylindrical PVC matrix (4 mm of diameter and 2 mm of depth). All the samples had been light-cured by 20 s, following the instructions of the manufacturer. The samples had been stored in exempt containers of light for 24 h. The hardness was measured in two depths (top and 2 mm) with three impressions for each depth. The Vickers microhardness test (Shimadzu) was carried out under a 300g load for 15 s. The data had been analyzed by “ t” test. To the composed resin Glacier, used as control, this it did not present statistically significant differences in the top hardness (60,04 ± 2,75, Radii and 58,26 ± 3,24, Ultralux), as well as for the hardness at 2mm (50,58 ± 2,38, Radii and 46,84 ± 3,44, Ultralux). However, had statistically significant differences when comparing these data, in relation to the hardness of top and 2mm depth, for both devices (p< 0,01). For the Rok composite, it did not significant difference statistic in the top hardness (82,2 ± 1,46, Radii and 79,44 ± 3,47, Ultralux), as well as for the hardness at 2mm (63,9 ± 2,39, Radii and 73,22 ± 2,47, Ultralux), but, it had statistically significant differences when comparing these data, in relation to the hardness of top and 2mm, for both the devices (p= 0,01). These results indicate that not having uniformity of polymerization to the depth of 2mm for two composed resins tested and between the two devices light-curing units, however, Rok composite resin presented better resulted that the Glacier composed resin, in the evaluated situations. Key-words: composite resin, photopolymerization.
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Media Research Abstracts Research Abstracts - Rok
Media Research Abstracts Research Abstracts - Rok
