Wear of polyetherketoneketone (PEKK) caused by different antagonists

Wear of polyetherketoneketone (PEKK) caused by different antagonists

d e n t a l m a t e r i a l s 3 0 S ( 2 0 1 4 ) e1–e180 Keywords: Infiltrant; Pre-heat; Properties 155 http://dx.doi.org/10.1016/j.dental.2014.08.15...

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d e n t a l m a t e r i a l s 3 0 S ( 2 0 1 4 ) e1–e180

Keywords: Infiltrant; Pre-heat; Properties

155

http://dx.doi.org/10.1016/j.dental.2014.08.154

Wear of polyetherketoneketone (PEKK) caused by different antagonists

154 Roughness of packable and flowable nanofilled composites polished with pastes D. Angerame, M. De Biasi ∗ , A. Franzò University of Trieste, Italy Purpose: To assess the effectiveness of a one-step and a two-step system with diamond pastes for polishing packable and flowable nanofilled resin composites. Methods and materials: Thirty discs per material tested, a packable (Filtek Supreme XT, 3M ESPE) and a flowable nanofilled resin composite (Filtek Supreme XT Flow, 3M ESPE), were prepared pouring the materials into silicon molds (depth 2 mm, diameter 4 mm). The top surface of the specimens was covered with a Mylar strip and light-cured with a halogen lamp at 600 mW/cm2 for 60 s. Ten specimens of each material did not undergo polishing and were used as controls. Specimens to be polished were finished with 1200P sandpaper and assigned to two polishing protocols: one-step diamond paste (Unigloss, Intensive) (n = 10) and two-step diamond paste (Diamond Polishing Mint, Ultradent Products) (n = 10). A linear rugosimetric parameter (Ra) was measured three times on randomly selected areas of the top surface of all specimens. The arithmetic mean of the readings was calculated and constituted the statistical unit. Data were subjected to statistical analysis with Kruskal–Wallis and Mann–Whitney tests with Bonferroni correction (p < 0.05). The morphology of top surfaces of representative polished specimens was assessed by scanning electron microscopy. Results: Both control and experimental groups never exceeded the 0.20-␮m Ra threshold that can inhibit bacterial adhesion. The mean surface roughness and standard deviation of polished specimens were: packable/one-step system, 0.058 ± 0.006 ␮m; packable/two-step system, 0.048 ± 0.005 ␮m; flowable/one-step system 0.044 ± 0.006 ␮m; flowable/two-step system 0.049 ± 0.006 ␮m. The surface of the packable composite polished with the one-step system was significantly rougher than its Mylar control (p < 0.01) and flowable composite polished with the same protocol (p < 0.05). Observation by scanning electron microscopy did not detect relevant surface irregularities. The surface of polished specimens appeared similarly smooth regardless of composite type or polishing system. Conclusion: Both tested systems effectively polished both the flowable and packable nanofilled composites. A two-step system appears preferable for polishing the packable composite. The resin Filtek Supreme XT Flow can be efficiently polished with the one-step system. Keywords: Surface roughness; Nanofilled composite resin; Abrasive pastes http://dx.doi.org/10.1016/j.dental.2014.08.155

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T. Kewekordes, S. Wille ∗ , M. Kern CAU Kiel, Department of Prosthodontics, Propaedeutics and Dental Materials, Kiel, Germany Purpose: Polyetherketoneketones (PEKK) is a new material in restorative dentistry. Its wear resistance is unknown. However, for the application of PEKK as restorative material its wear behavior needs to be evaluated. The purpose of this study was to evaluate the wear of a newly developed PEKK material caused by different antagonists. Methods and materials: 24 flat samples made of a PEKK material (Pekkton Ivory, Cendres + Métaux SA, Switzerland) were stressed in a chewing simulator for 1.2 million chewing cycles with a load of 49 N. These test parameters represent a lifetime of ca. 5 years in oral cavity. The specimens were randomly distributed into three groups of 8 specimens. Each group was stressed with a different antagonistic material. As antagonistic material steatite, zirconia and PEKK (Pekkton Ivory) styli were used. Before the chewing simulation and after 120,000, 240,000, 480,000, 840,000 and 1.2 million cycles precision impressions (Express 2 Ultra-Light Body Quick, 3M ESPE, Germany) were made. The impressions were investigated with a scanning laser microscope (vk-x 100, Keyence, Germany). The vertical substance loss and the volume loss were measured. The data was analyzed using two-way ANOVA followed by a Tukey test with a significance level of 0.05. Results: There was a steady increase of the volume loss of the PEKK material in all three groups. After 1.2 million cycles the volume losses were 0.228 ± 0.144 mm3 (steatite), 0.181 ± 0.066 mm3 (zirconia) and 0.087 ± 0.030 mm3 (PEKK). The vertical substance losses were 113.2 ± 42.9 ␮m (steatite), 118.0 ± 21.6 ␮m (zirconia) and 85.3 ± 22.1 ␮m (Pekkton). The two-way ANOVA test reveals that there is a statistical significant interaction between the antagonistic material and the number of chewing cycles. There is a significant difference between the PEKK and the other antagonistic materials, except for the vertical substance loss in comparison to zirconia. There was no significant difference between the groups using steatite and zirconia as antagonistic material. There was also a significant difference for the different number of chewing cycles. However, there was no steady increase of the vertical substance loss in the group with PEKK as antagonist. Conclusion: The wear resistance of PEKK against PEKK looks promising and was significantly higher than that against steatite and zirconia ceramics. This study has been supported by Cendres + Métaux SA. Keywords: Wear; Polymer; PEKK http://dx.doi.org/10.1016/j.dental.2014.08.156