Effect of Particle Size and Application Pressure in Air-Borne Particle Abrasion on the Adhesion of Polyetheretherketone.

INTRODUCTION: This study aims to investigate the effect of different particle sizes and pressures on the shear bond strength (SBS) and the roughness (Ra) of polyetheretherketone. MATERIALS AND METHODS: A total of 117 polyetheretherketone specimens were fabricated and divided into a control (CN: no air-particle abrasion) and eight pre-treatment groups (air-abraded with 50- or 110-µm Al2O3 particles at 1(A), 1.5(B), 2(C), and 2.5(D) bar). The adhesive, Visio.link was used. Thermal aging was performed. Surface properties, SBS and failure mode were assessed. Data was analyzed by linear regression, Pearson correlation and Dunnett's T3 test for pairwise comparisons (p⟨0.05). RESULTS: The highest and lowest Ra were found in the 110D and CN groups respectively, and the highest SBS results were obtained from the 50B group. Pressure and particle size showed significant difference on the investigated properties (p⟨0.001). Only adhesive failure was observed in the CN, and resin cohesive failure was observed in addition to adhesive failure in the overall study groups. CONCLUSION: The air-borne particle abrasion procedures and the adhesive material combination are critical to the strength of the polyetheretherketone bond. The combination of visio.link with the pre-treatment option of 50-µm Al2O3 particles applied at 1.5-bar pressure delivered the most favorable results.

Color stability of different denture teeth materials: an in vitro study.

The aim of this in vitro study was to compare the color stability of commercially available porcelain, reinforced acrylic, and conventional acrylic denture teeth materials used in removable prostheses. Two brands of porcelain (Unilux-Enta Lactona-Holland and Vivoperl-Ivoclar-Liechtenstein), 2 brands of reinforced acrylic (Optodent-Bayer-Germany and Ivolek-Ivoclar-Liechtenstein), and 2 brands of conventional acrylic (Isodent-Güney Dis Deposu-Turkey and Samed-Turkey), were made, for a total of 6 different denture teeth groups. Denture teeth were subjected to 3 staining solutions (filtered coffee, tea, and cola) and distilled water. From each group of denture teeth, 4 sets of maxillary anterior denture teeth were immersed in each of the 4 solutions. The color values of denture teeth were measured colorimetrically with the Gardner XL 20 Tristimulus Colorimeter (Gardner Lab. Inc., Bethesda, Maryland, USA). Color changes were characterized in the CIEL*a*b* color space. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks. The color difference values were calculated and then evaluated by two-way ANOVA statistically. The filtered coffee solution was found to be more chromogenic than the other 2 staining solutions, while porcelain denture teeth materials were more color stable. Assuming the color change of deltaE* < 1.0 as a discernible limit and deltaE* = 3.3 as an acceptable value, the filtered coffee, tea, and cola had slight staining effects on all 6 groups of denture teeth.

Cytotoxicity of provisional crown and bridge restoration materials: an in vitro study.

There are numerous materials used to provide temporary coverage for teeth while permanent restorations are being fabricated. The biocompatibility of these materials is important for the protection of teeth and gingiva, but there is little information on this subject. This study aimed to examine possible time-dependent toxic effects of provisional crown and bridge restoration materials, manipulated intraorally or extraorally, on epithelia cells. A total of 20 discs, 4 sample discs from each product having dimensions of 4 mm diameter and 2 mm thickness, were prepared. After sterilization, toxicity of these discs was evaluated in the Madin Darby Bovine Kidney (MDBK) cell line. Morphological cell changes were observed microscopically at the 3rd, 6th, 12th, and 24th hours by the filter diffusion test method. After the 3rd hour, Artglass and Structur produced cytotoxic symptoms. Temdent had the least toxic effects at the end of the 12th hour. However, after the 24th hour, the toxic values were similar for all materials. The results of this study show that although the toxicity response of chemically and light curing materials had changed in different time periods, all of them had the same toxic effects at the end of the 24th hour.