Comparative study of effects on shear bond strength of dentin with two treatments

Objective Based on the dentin deproteinization,to compare the shear bong strength(SBS) of dentin with Phosphoric acid etched only or Phosphoric acid etched/Sodium Hypochlorite combined treatment before adhesion and the micromorphological observation of resin-dentin bonding interface.Methods Twenty-four healthy premolars extracted for orthodontics were selected and prepared of dentin bonging surface,then divided them into two groups(n=12):group A,specimens were treated with Phosphoric acid;group B,specimens were treated with Phosphoric acid/Sodium Hypochlorite,all specimens were coated with the dentin-bonding agent mixed with fluorescent(PrimeBond NT,PB),restored with the composite resin.After 24 h storage in artificial saliva at 37℃,the bonded teeth were sectioned into buccolingual halves through the center of the restorations and along the axis of teeth which were prepared for SBS and observed the micromorphy of bonding interface under the laser confocal scanning microscopy(LCSM) respectively,all datas were analyzed by t-test.Results The shear bond strength of groupA and B is(26.30±3.51)Mpa、(30.13±2.71)Mpa respectively;the length of resin tags is(71.27±4.55)μm、(84.95±3.60)μm;the thickness of hybrid layers is(49.38±4.37)μm、(29.62±2.58)μm,there are statistical differences in each group(P0.05).Conclusion Dentin deproteinization can remove the exposed collagen fibers effectively,increase the penetration of bonding agent into dentin bonding interface,improve the shear bong strength of PB to dentin.