An Experimental Study On The Inlfuence Of Three Kinds Of Desensitizers On Dentin Bond Strength

Objectives: Apply three kinds of desensitizers to dentin and study theinfluence they impose on the bond strength of self-etch/total-etchadhesive.Methods: Newly120fresh removed non-carious human premolars or thethird molars, which were stored in1%chloramines-T at roomtemperature. Removing the root along the enamel-cemental junctionunder the water cooling condition, and dividing the remaining toothcrown along the mesial and distal direction into two parts. The enamelwas abrased using the silicon carbide burs to creat the dentin adhesivesurfaces. The prepared dentin samples were mounted into self-curingresin, after curing, we used alumina water sandpaper to polish theexposed dentin shallow surface from coarse to fine under running waterin the sequence of320#、400#、600#、800#. In the end,240specimenswere divided into self-etch(OptiBond， iBond,Xeno Ⅳ) andtotal-etch(OptiBond，iBond，Probond) adhesive groups. Due to thedifferent brands adhesive, each group is subdivided into3sub-groups;each sub-group is divided into three experimental groups and one controlgroup, each group contains10samples. In strict accordance with theInstructions of three kinds of desensitizers and self-etching/etching adhesives, Z100resin composite cylinders were bonded on the dentinsurfaces. The specimens were stored in distilled water at37℃for24hours, then the shear bond strengths were measured by using a UniversalTesting Machine at a crosshead speed of0.5mm/min. One-way ANOVAwas used to compare the differences of the values. Scanning electronicmicroscope was used to observe the surfaces of the fracture and thedentinal surface which were coated by different desensitizers.Results:1. The shear strength of ibond+Ddes+the Z100resin self-etchinggroup is lower than that of the control group, the difference wasstatistically significant (P <0.05), there were no statistical significance inthe other experimental group and the control group (P>0.05).2.The shear bond strength of Optibond+Gluma、Optibond+Ddes andibond+Ddes+the Z100total etching groups were lower than that of thecontrol group, there were significant difference（P<0.05），while therewere no significant difference between other experimental groups andcontrol group （P>0.05）.Conclusion:1.Dentin desensitizer could reduce the shear bond strength ofself-etching adhesive ibond, but has no impact on the performance ofself-etching Optibond and Xeno IV adhesive bond. 2.Dentin desensitizer decreased the shear strengths of total etchingadhesives Optibond、iBond and probond group, compared with that ofthe control group, there was a significant difference (P <0.05), sobefore the clinical selection of total-etching adhesive bond, one canchoose Gluma or uPrimeB desensitizers to perform dentindesensitization.3.Best no coating any desensitizers before Probond adhesive bondbecause this will reduce its own bond strength.