Effects Of Different Concentrations Of MgSiF₆ As Electrolyte For Micro-arc Oxidation On The Bond Strength Between Titanium And Porcelain

Objective: This study aims to investigate the effects of different concentrations of MgSiF6 as electrolyte on the bond strength between titanium and porcelain after micro-arc oxidation(MAO)treatment.Methods: Four different concentrations of MgSiF6(10g/L,20g/L,30g/L,40g/L)were chosen as MAO reaction solutions.Sand blast treatment was selected as a control.After MAO treatment in electrolyte,porcelain was fused on each specimen(25mm×3mm×0.5mm),then,titanium-porcelain bond strengths were detected by the three-point bending test according to ISO 9693.The scanning electron microscopy(SEM)and the energy-dispersive spectroscopy(EDS)were adopted to evaluate the morphologies and elemental compositions of both the MAO coatings on the titanium surfaces and the interfaces between the titanium and porcelain.Results: The changes of electrolyte concentration during MAO treatment impact the bond strength between titanium and porcelain.The morphologies and elemental compositions of MAO coatings on the specimens among the four groups show significant differences.The surface of titanium specimen in the sand blast group was sharp and rough,while specimens in both 10g/L group and 20g/L group were porous and homogeneous,however,the latter group had larger diameters of pores(approximately 1-2μm)than the former one(0.2-0.5μm).On the specimen of the 30g/L MgSiF6 group,a few cracks and numerous particulate matters could be observed.The surface of specimen from 40g/L MgSiF6 group was full of cranny structures,on which numerous cracks distributed.All the experimental groups acquired higher bond strengths than the sand blast group(p<0.05),and the bond strength of 20g/L MgSi F6 group was significantly higher than those of the other groups(p<0.05).Besides,the interfaces between titanium and porcelain were tight and compact in the 20g/L group,while different amounts of pores and cracks were visible in the other groups.Additionally,after the three-point bending test,few residual porcelains could be observed on the surfaces of specimens in the sand blast group,while obvious porcelains were shown on those of the experimental groups,and the specimen of 20g/L MgSiF6 group show the largest amount of residual porcelains among all the groups.Conclusions: With an appropriate concentration of MgSiF6,MAO treatment should be an applicable candidate for titanium-porcelain restorations,and could be applied to the clinical use.