The Sealing Performance And The Influence On The Dentin Bond Strength Of SBU Protective Film

ObjectiveTo evaluate the immediate sealing performance of SBU and its effect on the bonding strength of dentin,providing a theoretical basis for the chair-side IDS operation of SBU.Methods1.Electron microscopic observation:Select sixteen healthy third molars and remove the enamel of buccal side to expose the dentin plane.Every sample was treated by 6%citric acid etching,making sure the dentin sensitive model was made.Sixteen teeth were randomly divided into two groups（n=8）.The experimental group was coated with SBU protective film on the buccal dentin surface according to IDS technique standard;The control group was not specially treated.The surface and longitudinal profiles of buccal dentin in two groups were observed under scanning electron microscope（SEM）.The immediate sealing performance of SBU on dentin tubules was qualitatively analyzed.2.Shear strength test:36 healthy third molars were selected and stored in 1%chloramine solution for 1-3 months.The same performer removed off the enamel from the buccal and lingual side of the teeth to expose two parallel dentin planes,larger than 4mm×4 mm.Buccal side was selected as the experimental group which treated with SBU,and the lingual side was the control group with no special treatment.Prepared 72 resin columns.Divided the molars randomly into A、B、C3groups,bonding pre-formed resin column respectively with Multilink Speed（group A）、OptiBond Versa+NX₃（group B）、Tetric N-Bond+Variolink Esthetic DC（group C）.The shear strength was tested and analyzed statistically.Results1.Electron microscopic observation:The control group:After 6%citric acid etching,the dentin tubules were completely exposed,the diameter of dentin was enlarged,the surface was clean,and there was no smear layer.In the longitudinal section,the dentin tubule was completely open and empty.The sensitive dentin model was well constructed.The experimental group:The surface of dentin pretreated with SBU can be seen that SBU can seal most of the canals of dentin with only a small amount of exposure.The longitudinal section shows that the resin layer of a certain thickness can be formed.2.Shear strength test:After treatment with SBU,the shear strength of dentin increased 5.57±1.06MPa in group A,3.76±1.17MPa in group B,1.41±2.01MPa in group C.All of them had statistical significance.Conclusion1.SBU has excellent immediate sealing effect,which meets the requirement of DBA selection in IDS technology.2.SBU as an immediate dentin sealant can significantly enhance the shear strength of Multilink Speed、OptiBond Versa+NX3、Tetric N-Bond+Variolink Esthetic DC,it can be used in clinic to optimize the effect of resin bonding.