The purpose of this study was to evaluate the effects of the various surface treatment methods on the retention of single crowns on implant abutments. The study included 50 single crowns that were cemented with adhesive resin cement onto the ITI solid abutments. The specimens were randomly divided into 5 groups, each including 10 specimens according to the following surface treatments: group C, control, abutments remained unaltered as control; group L, etching with CO(2) laser; group SB, sandblasting with 50-μm Al(2)O(3); group MS: coating with titanium nitride (TiAlN) with a radiofrequency magnetron sputtering system; and group SP, silicoating by Silano-Pen. After the surface treatment procedures were finished, the casted crowns were cemented onto the abutments, and thermocycling was applied to simulate oral environment. The uniaxial tensile force was applied to all test crowns using a universal test machine (Instron) with a crosshead speed of 0.5 mm/min. The load required to dislodge each crown was recorded in Newton. The lowest tensile bond strength values were obtained with group MS (223.26 ± 14.30 N) and significantly differ from all other groups except group C. Group SB showed highest test results (506.02 ± 18.04 N) and differs from other groups (P < .05). The test values that were obtained in group MS-group C did not show significant differences (P > .05). Sandblasting is an effective method to increase bond strength. Also, Silano-Pen and laser application is advisable for increasing the crown retention to abutments. Titanium aluminum nitride coating with magnetron sputtering technique seems to be ineffective.

This study puts forth the synergistic effect of fiber concentration and maleic anhydride-grafted polyethylene (PE-g-MA) compatibilization on the abrasive wear properties of high-density polyethylene (HDPE) composites. Composites including carbon, basalt, jute and coconut short fibers with different weight ratios were processed by melt blending and then tested by using a pin-on-disc abrasive wear tester in dry sliding conditions. The test rig was also equipped with a vacuum system, for the first time, to promote two-body abrasive wear of the composites by reducing the wear debris which may be trapped in the wear track and alter the wear properties. In addition, fiber and coupling agent concentrations and test parameters were investigated using L16 full-factorial experimental design and the relationships between these parameters and wear behaviors of the composites were analyzed on the basis of the findings. This work clearly shows that high rigidity obtained by fiber contribution was not beneficial from the abrasive wear resistance point of view, due to repeated plowing effect of the counterpart material under the test conditions. Nevertheless, basalt fiber-reinforced composites showed higher wear resistance than other composites. Except for coconut fibers, PE-g-MA exhibited good miscibility between fibers and matrix, and thus an enhancing effect on the hardness values, and also wear resistance of the samples. Briefly, the rigidity and miscibility of the composites were found in balance for optimum wear rates.

PURPOSEAlthough several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core.MATERIALS AND METHODSFifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 µm aluminum oxide particles (Al2O3), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 µm Al2O3 + Al coating and air particle abrasion with 50 µm Al2O3 + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (α=.05).RESULTSThe highest bond strengths were obtained by air abrasion with 50 µm Al2O3, the lowest bond strengths were obtained in polishing + Al coating group (P<.05).CONCLUSIONAl and AlN coatings using the reactive magnetron sputtering technique were found to be ineffective to increase the bond strength of adhesive resin cement to zirconia core.

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The aim of this study is to put forth the structural, mechanical and tribological properties of Miswak powder reinforced composites and find an inspiration about their availability for diverse applications, from mechanical to medical parts. Polypropylene (PP) matrix and a maleic anhydride-grafted PP (PP-g-MA) copolymer as coupling agent were used. Composites with different Miswak concentrations (5, 10, 20, and 30 wt%) were characterized primarily by tensile and flexural tests, dynamic mechanic analysis, X-ray diffraction, scanning electron microscopy, goniometer, water uptake and ball-on-disc test. The results show that the favorable properties of the composites are enhanced under the influence of Miswak with different concentrations. As a result, taking into consideration the required conditions for high surface energy and effective adhesion at the interface also with adequate mechanical and tribological properties, this is proved in the case of low Miswak concentrations (5 and 10%). A 5% Miswak reinforcement is also found to be effective in wet conditions without a serious surface deterioration which increases its usability in medical parts, as proposed in this study. POLYM. COMPOS., 00:000-000,