Etching Quartz/Glass Fiber Posts with Hydrofluoridric Acid:SEM Investigation

Studies have showed that quartz fiber posts can be etched with hydrofluoric acid,which increases the composite-to-post adhesion.Objectives:the purpose is to evaluate the effect of surface treatment with hydrofluoric acid 9.6% on both quartz and glass fiber posts and the influence of the etching time.Methods:quartz fiber(Endolightpost,RTD)and glass fiber posts(FRC Postec,Ivoclar)have been etched for 5-10-15-30 sec.,1-2 min. and subjected to SEM observation.Results:after 5 sec. glass fibers show superficial and transverse microcracks;quartz fibers are intact.After 10 sec. glass fibers show branched and deeply penetrating microcracks;quartz fibers are intact.After 15 sec.many glass fibers are fragmented;quartz fibers show surface roughness and rare transverse microcrack.After 30 sec.many glass fibers are destroyed and detached,and a layer below of intact fibers is evident;quartz fibers show deeper and branched microcracks but are not fragmented. After 1 min. the superficial layer of glass fibers is mostly lost;in the layer below the fibers are differently impaired.Some quartz fibers are fragmented and detached,and fibers below are evident. The picture does not change after 2 min.Conclusion:etching with hydrofluoric acid 9.6% leads to immediate notching of glass fibers,which increases according to the time and reaches fibers destruction and detachment after 30 sec.Quartz fibers start to be notched after 15 sec.,deeper cracks are evident after 30 sec.More prolonged etching leads to fibers destruction and detachment.All the above suggests that glass fiber posts should not be etched with hydrofluoric acid 9.6%,which on the contrary can be used onto quartz fiber posts for 15 sec.,to increase composite-to-post adhesion.