Effect Of Two Kinds Of Surface Pretreatment On Bending Strength To PEEK

Due to its excellent physical and mechanical properties,extremely stable chemical properties,reliable biological safety and potential antibacterial properties,polyetheretherketone(PEEK)and it's composites become a new type of dental material that has the most potential alternative to traditional metal and ceramic materials.However,the extremely stable chemical properties of PEEK lead to low adhesion.Surface sandblasting and sulfuric acid etching are considered by most scholars to improve the adhesive properties of PEEK effectively,however,sandblasting or acid etching whether or not to reduce the strength of the material is the important factors affecting the service life of the prosthesis.Objective:To evaluate the effect of sandblasting or acid etching on the three-point bending strength to PEEK.The length,width and thickness of each specimen were measured with vernier caliper before and after surface treatment.The influence of surface treatment on the dimension of PEEK specimens was evaluated by the change of length,width and thickness.Scanning electron microscopy(SEM)was used to observe the surface morphology of PEEK after different surface treatment,and to analyze the influence of surface treatment on the strength and dimension of the specimen.Materials and Methods:48 bars(15mmx2mmxlmm)of specimens were fabricated from PEEK(BioHPP)using a CAD/CAM technique.Ultrasonic cleaning in alcohol for 10 minutes after the PEEK surfaces were ground and polished with silicon carbide paper,oil-free air drying.The specimens were randomly divided into eight groups:no treatment(NT),sandblast for 10s at a pressure of 0.2MPa with 120?m,50?m or 250?m alumina particle(S-120,S-50 and S-250,respectively),sandblast for 10s with 120?m alumina particle at a pressure of 0.7MPa(S-0.7),etching with 98%sulfuric acid for 60s,120s or 300s(AE-60,AE-120 and AE-300,respectively).Before surface treatment,the length,width and thickness of each specimen were measured and recorded.After the treatment,one specimen was randomly selected from each experimental group for scanning electron microscopy.The remaining 5 specimens of each conditioning method were subjected to three-point bending test.The length,width and thickness of these specimens were measured and recorded before bending strength test.SPSS software was used for statistical analysis of experimental data to test whether the difference was statistically significant.Results:SEM analysis showed the different surface morphology after different surface treatment and different degrees of cracks,pits or holes appeared on the PEEK surface.Compared with the NT group,three-point bending test showed that the strength of the specimens decreased after sandblasting or sulfuric acid treatment(P<0.05).No significant differences were observed between sandblasting with different grain size at a pressure of 0.2MPa(P>0.05),sandblasting with 120?m alumina particle at a pressure of 0.7MPa can significantly reduce the bending strength in comparison to the group of S-120(P<0.05).For the 98%sulfuric acid treatment groups,there were no significant differences of the bending strength between 60s,120s or 300s after etching(P>0.05).The dimension of the specimens were measured by vernier caliper before and after treatments,and the results showed that there were no significant differences in the length of the specimens before and a:fter sandblasting or acid etching(P>0.05),the width of S-0.7 group increased after the treatment(P<0.05),the thickness of S-250 group and S-0.7 group decreased after the treatment(P<0.05),however,the thickness of AE-300 group increased after etching 300s(P<0.05).Conclusions:1.Alumina particle sandblasting or 98%sulfuric acid treatment has a significant effect on the bending strength of the PEEK specimens,and the bending strength of the treated group is significantly lower than that of the untreated group.2.For sandblasting groups,under the same conditions,the particle size has no significant effect on the bending strength of PEEK;but with the same particle size,increasing the pressure of sandblasting will result in a significant decrease in the bending strength of PEEK specimens.3.98%sulfuric acid etching can reduce the bending strength of PEEK,but the acid etching time has no significant effect on the bending strength of PEEK.4.Under certain conditions,sandblasting or acid etching will result in the change of the dimension of the PEEK specimens.For sandblasting specimens,larger particle size or greater pressure will result in a reduction in the thickness of the specimens,what is more,the greater pressure will increase the width,the effect of pressure on specimen size is more significant;if the time of sulfuric acid etching was too long,that the thickness of the specimen would be increased significantly.