| Purpose:The purpose of this experiment is(1)to study the effect of different coating time of self-etching ceramic primer on the surface morphology,roughness and bonding strength of CAD/CAM ceramic materials.(2)To explore the influence of artificial aging on the bonding strength after different surface treatments.(3)To verify whether the self-etching ceramic primer can achieve the same bonding effect as the traditional hydrofluoric acid combined with silane coupling agent in different CAD/CAM ceramic materials.Method:Two materials of Lithium disilicate glass ceramics(Up.CAD)and Vita Enamic elastic porcelain were selected and processed into test pieces of 5mmx5mmx2 mm.Each material was randomly divided into four groups according to different surface treatment methods(n=10),The Up.CAD material is divided into 4 groups.Group A:Control No treatment;group B: Hydrofluoric acid treatment;group C: using Monobond Etch and Prime(MEP)applied with scrubbing for 20 s and left to react for40s;using MEP applied with scrubbing for 60 s and left to react for 40 s.VITA Enamic elastic porcelain materials are divided into group E,group F,group G and group H according to the above procedures.Atomic force microscopy(AFM)and surface scanning electron microscopy(SEM)were used to observe and examine the surface morphology,roughness and three-dimensional profile of the specimen.At the same time,resin rods were made by molds and bonded to the specimen surface with Variolink N resin cement.The shear bond strength and fracture mode before and after the cold and hot cycles were measured.SPSS.25 software was used to analyze and compare the results.Result:1.Changes in surface roughness and three-dimensional profileIt was found that the material type and surface treatment had significant effects on the surface roughness(P < 0.05).For UP.CAD ceramic material roughness results show that group B(167.63±19.89nm)> D(44.83±9.70nm)group,group C(42.63±9.58nm)> A group(23.38±4.43nm),There was statistical significance in group B,C and D compared with group A(P < 0.05);There was statistical significance in group B compared with group C and D(P < 0.05);There was no significant difference between group C and group D(P > 0.05).Surface roughness results of Vita Enamic materials show a similar trend to the above mentioned,Group F(429.73±28.34nm)group > H(102.08±9.99nm),group G(99.9±10.04nm)group > E(73.38±8.76nm),There was statistical significance between group F and group E,G and H(P < 0.05);There was statistical significance between group G,group H and group E(P < 0.05).In terms of three-dimensional morphology,in Up.CAD,the surface of the control group was smoother;The surface of HF group presents the most obvious wavy structure of small peaks;The surface of MEP20+40s group and MEP60+40s group fluctuated somewhat,but there was no obvious difference between them.In Vita Enamic,the surface of the control group fluctuated slightly and the whole was relatively flat;HF group had the most uneven surface;MEP20+40s and MEP60+40s groups showed more irregular small peaks than the control group.2.Surface morphology observation(SEM)In Up.CAD,the surface topography of the control group was relatively flat and uniform under the magnification of 2000 and 5000 times;In HF group,the glass matrix dissolved on the surface of the specimen,forming uniform pore cracks and producing obvious etching patterns;The surface of the two MEP groups was relatively uniform with a few plaques.Seen at 50,000 times,in the control group,there was no dissolution of glass matrix,and there were many micropores of the same size on the surface;In HF group,glass matrix was dissolved,strip crystal was exposed,and deep micro-pores were abundant and dense;There are many micropores on the surface of MEP20+40s group,and some dissolved regions of glass matrix appear;For MEP60+40s group,the dissolution of glass matrix increased slightly compared with that of MEP20+40s group,and the porosity and exposed crystal also increased.In Vita Enamic,it was observed that the control group presented a smooth surface at the magnification of 2000 and 5000 times;In HF group,the surface ceramic network was partially dissolved,the polymer structure was exposed,and cracks and pits of different sizes were formed at the junction of ceramic and resin network;The two MEP groups also presented a relatively smooth network structure.At the magnification of 10000 times,the ceramic network structure of MEP60+ 40 S group was slightly dissolved and part of the polymer was exposed,which was more obvious than that of MEP20+ 40 S group.3.3.Shear bond strength test resultsThe bonding strength before aging in Up.CAD ceramic materials was compared as follows: group D(14.96±2.76MPa),group C(14.57±2.37 MPa),group B(13.04±2.80 MPa)> group A(1.93±1.25MPa).There was statistically significant difference between groups B,C and D compared with group A(P < 0.05),while there was no statistically significant difference between groups B,C and D(P > 0.05);After aging,pre-bonding failure occurred in all group A,and there was no statistically significant difference among the remaining groups(P > 0.05).The pairwise comparison of bond strength before and after aging in each group showed statistically significant difference(P < 0.05).As for the bonding strength of Vita Enamic material before aging,group F(12.53±2.21MPa)> group H(10.11±2.27MPa),group G(9.45±2.05MPa)> group E(3.42±1.12MPa),There was statistically significant difference between group F,G and H compared with group E(P < 0.05),and there was statistically significant difference between group F and group E,G and H(P < 0.05),while there was no statistically significant difference between group G and group H(P>0.05);After aging,the results showed that group F(10.45±2.14MPa)>group H(7.85±1.71MPa),group G(7.24±1.37MPa)>group E(0.88±0.47MPa),There was statistically significant difference between groups F,G and H compared with group E(P < 0.05),and there was statistically significant difference between groups F and G and H(P < 0.05),while there was no statistically significant difference between groups G and H(P >0.05).Pairwise comparison of bond strength before and after aging in each group showed statistically significant difference(P < 0.05).4.Fracture modeIn Up.CAD,the fracture mode results before and after aging showed that in the control group,all the adhesive failure occurred before aging,and the pre-bonding failure occurred after aging,and all the resin rods fell off spontaneously.In the other groups,the bonding damage generally increased and the mixing damage decreased after aging.For Vita Enamic materials,both before and after aging of the control group showed bonding failure,while before aging of HF group,mixed failure and cohesion failure were dominant.After aging,cohesion failure decreased while mixed failure and bonding failure increased.After MEP20+40s group and MEP60+40s group aging,the mixing damage decreases,but the bonding damage increases,and the bonding damage is the main one.Conclusion:1.Compared with the control group,the roughness of CAD/CAM ceramic material was significantly improved by increasing MEP coating time to 60 s,but the improvement was not significant compared with the MEP treatment group with coating time of 20 s.The changes of surface morphology and roughness of CAD/CAM ceramic materials treated by HF are more obvious than those treated by MEP.Compared with the control group,MEP treatment was milder than HF treatment,but it did not cause as much damage to the internal structure of ceramics as that after HF treatment;Compared with the control group,increasing the coating time of MEP significantly increased the bonding strength,but compared with 20 seconds of MEP coating time and the bonding strength of HF combined with silane coupling agent did not increase significantly;2.Both HF combined with silane coupling agent and surface treated with MEP showed that artificial aging significantly reduced the bonding strength of the specimens.3.For Up.CAD glass ceramics,MEP is a very effective surface treatment method,which can achieve equal or even slightly better bonding effect with HF combined with silane coupling agent,and MEP is recommended.Increasing the coating time of MEP does not significantly improve the bonding strength,so continuous coating for 20 s and then standing for 40 s is still recommended.However,for Vita Enamic composite ceramics,MEP can not achieve the same bonding strength as HF combined with silane coupling agent,so it is still recommended to use HF combined with silane coupling agent for surface treatment. |
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