Analysis Of Shear Bond Strength Of Three Bond Systems Applied On Occlusal Veneer Made By Different Materials

Objectives: To evaluate the shear bond strength of Panavia F bonding system,Rely X Veneer bonding system and Beautifil flow plus system applied on occlusal veneer made by IPS e.max and NissonTM yttria-stabilized tetragonal zirconiapolycrystal(Y-TZP),then observed the bonding section under a stereoscopic microscope.It ultimately provided a theoretical basis for the clinical choice of occlusal veneer materials and bonding systems.Methods:36 caties-free maxillary third molars,which were freshly extracted in one month,were selected and stored in the refrigerator with-20℃.The 36 molars received a standardized nonretentive tooth preparation(simulating occlusal erosion).The surfaces of the molars were prepared into cuboid specimen with the size of 5×4×2mm~3.After that,the surfaces of the specimen were polished with water sandpapers which were 400#,600#,800# and 1000#.18 IPS e.max ceramic specimen and 18 Y-TZP specimen were made into the size of 5×4×4mm~3.IPS e.max ceramic specimen were divided into 3 groups(A1,A2,A3)with 6 in each group.Y-TZP specimen were divided into 3 groups(B1,B2,B3)with 6 in each group.The group A1 and B1 were respectively bonded to the extra teeth with Panavia F bonding system,and group A2 and B2 were respectively bonded to the extra teeth with Rely X veneer,group A3 and B3 were respectively bonded to the extra teeth with Beautifil flow plus.Then 36 specimen were inserted in a special positioning device filled with acrylic resin,embedding the root up to 1 mm below the cement-enamel junction.Each specimen was stored in distilled water at ambient temperature for 24 hours before testing.Each bonded specimen was placed in the load chamber in the same reproducible position in a universal testing machine.Load was applied in shear at a constant crosshead speed of 1mm/min until failure occurred.The maximum load(Mpa)to failure was recorded by corresponding software.The LSD test was applied to statistic analysis.The stereoscopic microscope was used to observe the type of fracture and the bond fracture mode was classified.Results:1 The shear bond strength of different groups: group A1(5.645 ±1.55Mpa),group A2(6.705±1.75Mpa),group A3(8.35±2.03Mpa),group B1(2.35±1.52Mpa),group B2(0Mpa),group B3(1.27±1.42Mpa)。2 There is no significant different group A1 and group A2(P>0.05).The shear bond strength in group A3 is higher than group A1 and A2(P<0.05),and the shear bond strength of A1,A2 and A3 are higher than B1.3 The bond fracture of A1,A2 and A3 is cohesive failure of the ceramic and mixed mode fracture.The bond fracture of B1,B2 and B3 is interface failure between resin and ceramic.Conclusions:1 For the IPS e.max ceramic,the bond strength of Beaufifil flow plus bonding system is better than Panavia F and Rely X veneer bonding system.2 For the Nisson Y-TZP,the bond strength of Panavia F bonding system is better than another two system.3 Panavia F,Rely X veneer and Beautifil flow plus all could not provide enough bond strength for the occlusal veneer made by Nisson Y-TZP.