The Scanning Electron Microscope Observation Of Encircling Effect On Dentinal Tubules Played By Two Kinds Of Desensitizer

Objectives:This study aims to reveal the differences of Hybrid Coat and MS desensitizer on the treatment of dentine hypersensitivity in the surface morphology,the coating thickness and the tensile compressive capacity of the dentinal tubules from a microscopic point of view,in order to provide a reference for clinical application.Methods:36human premolars were collected which were extracted for orthodontic treatment within a month, all the teeth were prepared in accordance with the requirements of porcelain fused to metal crowns. All the teeth were randomly divided into3groups named A B C. Group A were coated with Hybrid Coat, group B with MS desensitizer and group C with nothing,then each group was randomly divided into3groups named blank group, glass ionomer cement group and zinc poly carboxylate cement group, all the teeth in addition to the blank group were restored with metal crowns and then make the crown dislocation.All samples were ultra-low temperature freeze dried, made into thin slices, coated the surfaces with gold, and then observed the surface structure of the prosthesis changes by the thermal field emission scanning electron microscope. Finally, the results were statistically analyzed using spssl3Software to analysis the difference of the two desensitizer in the pore blocking rate.Results:1) Group A:The tooth surfaces of the blank group were smooth, all dentinal tubules were blocked by the coating formed by Hybrid Coat. Besides the mixed layer formed by Hybrid Coat, the granular or flaky structure of the cement residues also existed on the tooth surfaces in the glass ionomer cement group and zinc poly carboxylate cement group, but the mixed layer did not change significantly among the3groups.2) Group B:The tooth surfaces of the blank group were uniform, all dentinal tubules were blocked, but part of the dentinal tubules blocking was collapsed on the tooth surfaces in the glass ionomer cement group and zinc poly carboxylate cement group,the surface structure was no longer complete.3) Group C:A large number of cement residue existed on the tooth surfaces of the glass ionomer cement group and zinc poly carboxylate cement group in the form of covering flaky or granular accumulation, some also existed in dentinal tubules.The dentinal tubules were blocked with varying degrees.4) The pore blocking rate of group A was higher than group B, the difference was significant.Conclusions:1) Hybrid Coat and MS desensitizer can block the dentinal tubules effectively to achieve the purpose of treatment of Dentine hypersensitivity. Cements still exist that naked eye can not see on the surface of the tooth preparation after the dislocation of the crown, we should be cautious when we get the crown cemented again.2) Part of the cement crystal sheet structure exists in the dentinal tubules after crown dislocation,This micro-mechanical chimeric structure is conducive to full crown retention.3) The appearance that crater-like structure exists on the surface of tooth preparation after crown dislocation in group using MS desensitizer,and part of the dentinal tubules blocking is collapsed.shows that the protection layer of MS desensitizer ruptures when the crown gets located,but this appearance dose not appear in the Hybrid Coat group,at the same time the statistically result shows that the pore blocking rate of Hybrid Coat group was higher than MS desensitizer group.Experiments show that the flexibility and strength of Hybrid Coat protection layer are better, it can not easily be destroyed, Hybrid Coat shows a better blocking effect.