Influence Of Low-temperature Plasma Treatment And Plasma Grafting On The Bond Strength And Mechanical Properties Of Fiber Posts

It is no wonder that the advantages in fiber posts include the elastic modulus thatis much close to dentin，good esthetic effect and stable chemical property, leading tothe widespread use for reconstrcting endodontically treated teeth. However, thefailure of post-core-retention is mostly caused by unsatisfactory interfacial bondstrength, surface pre-treatments for fiber post are employed, facilitating retentionbetween the fiber post and resin cement. The surface treatment and graftingmodification induced by low-temperature plasma could improve the chemicalretention between the fiber post and resin cement. In this study, the low-temperatureplasma technology employed for the fiber posts in order to investigate the influenceof low-temperature plasma treatment and grafting on the bonding and mechanicalproperties of fiber posts.Part1Influence of plasma treatment and plasma grafting on thebond strength of fiber posts.Objective: To study the effect of low-temperature plasma treatment and plasmagrafting on bond strength of fiber posts.Materials and methods:64glass fiber posts were divided into4groupsrandomly according to the different surface treatment: no treatment group，helium-plasma treatment group, helium-plasma postirradiation grafting modificationgroup and helium-plasma syn-irradiation grafting modification group. Each groupwas then divided into4subgroup, according to the different exposure time to air aftersurface treatment employed i.e.0h,1h,6h and12h. All the prepared bondedassemblies were used for micro-push out bonding strength test and all the de-bondedspecimens were observed under a microscope to determine the failure modes.Results: The two-Way ANOVA revealed that the micro-push bond strength wassignificantly influenced by surface treatment (P <0.05) and exposure time to air (P<0.05) and the interaction between them (P <0.05). Immediate bonding strength offiber post obtained with the two different grafting modification induced by helium- plasma was higher than the group with no treatment (P <0.05). And the improvementefficiency of the grafting modification is more longer than the group with notreatment.Conclusion: The immediate micro-push-out bond strength can be improved byhelium-plasma treatment, but the bond strength was no significant different afterexposure to air for1h or longer compared to no treatment. The improvementefficiency of the grafting modification is more longer than the group with helium-plasma treatment.Part2Influence of plasma treatment and grafting on mechanicalproperties of fiber posts.Objective: To study the effect of low-temperature plasma treatment and graftingon mechanical properties of fiber posts.Materials and methods:40glass fiber posts were divided into4groupsrandomly according to the different surface treatment and the surface treatmentmethod was the same with Part1. All the fiber posts received the test of three pointbending and flexural modulus test after the corresponding surface treatment.Results: Three point bending and flexural modulus was no significant differentbetween the group with different plasma treatment and grafting methods and notreatment (P>0.05).Conclusion: The mechanical property of the glass fiber posts was not altered byhelium-plasma treatment and grafting modification.Part3Influence of plasma treatment and grafting on morphology offiber posts.Objective: To study the effect of low-temperature plasma and grafting onmorphology of fiber posts.Materials and methods:8glass fiber posts were divided into4groupsrandomly according to the different surface treatment and the surface treatmentmethod was the same with Part1.4fiber posts received the test of SEM and the other fiber posts received the test of EDS after the corresponding surface treatment.Results: The surface morphology was not significance after helium-plasmatreatment. The fiber posts surface after plasma grafting modification was continuousand covered by epoxy resin matrix and Bis-GMA/TEGDMA. EDS analysis showedthe oxygen content of fiber post increase, and meanwhile the C/O ration wasdecrease.Conclusion: The surface morphology was not significance after helium-plasmatreatment. The fiber posts surface after plasma grafting modification was continuousand covered by epoxy resin matrix and Bis-GMA/TEGDMA.