| Purpose and background:Due to the rapid development of CAD/CAM technology,more and more machinable ceramics can be applied to the dental restoration market.In the past two years,a polymer infiltrated ceramic,namely Vita Enamic elastic porcelain,which combines the toughness of the composite resin and the strength of the ceramic has appeared clinically.Vita Enamic elastic porcelain consists of 14%polymer network(organic composition)and 86%feldspar ceramic(inorganic component).This also means that the polymer infiltrated ceramics may be coated with a glass matrix ceramic material when it is bonded to the dental tissue.Studies have shown that the treatment of resin matrix ceramic materials by surface treatment of glass matrix ceramic materials will have better bonding effect,but the side effects caused by such methods still need further research.Acid etching is a common method of ceramic surface treatment.Etching the ceramic surface matrix with an etchant(such as hydrofluoric acid)can form a honeycomb structure,enhance the surface energy of the ceramic,expose the crystal structure,and finally form a micro-mechanical mating force on the surface of the ceramic resin.Clinically used ceramic etchants are 4%,9.5%hydrofluoric acid,Ivoclar 4%hydrofluoric acid,Bisco 9.5%hydrofluoric acid,the manufacturer of these two products is recommended in acid etching The time for machinable ceramics is 20S-60S,but the acid etching concentration and time of hydrofluoric acid on the ceramic surface have not yet been determined.Recently,Ivoclar Vivadent has developed a all-ceramic treatment solution MonobondEtch&Prime(MBEP),which contains three different functional groups-silane coupling agent,sulfurized ester,phosphate,and the manufacturer claims that MBEP can be used for milder acid.Etching and silanization treatment,but the experiments on its performance are not sufficient,and further in vitro experiments and clinical experiments are needed to prove its effect.Most experiments studied the effect of hydrofluoric acid etching on the bond strength and surface morphology of ceramics and resins,while ignoring the effect of acid etching on the internal microstructure and glass phase loss of ceramic materials.Due to the development of minimally invasive dentistry,the thickness of ceramic restorations is gradually decreasing,sometimes even less than 0.5 mm;because tiny structural changes can affect the mechanical properties of the restoration,which leads to a very limited amount of dissolved parts of the material structure.The effect of acid etching on the internal microstructure of the ceramic and the loss of the glass phase becomes critical.When ceramic materials with different compositions are available,it is necessary to analyze the structural effects of hydrofluoric acid on each material by the change of specific c.omponents.This experiment investigated the effects of different acid etching methods on the surface morphology and internal glass phase loss of two machinable ceramic materials.Method:Processing 4 pieces of 4 mm x 4 mm x 2 mm resin infiltrated ceramic(Vita Enamic)and lithium disilicate glass ceramic(Up.CAD)specimens,respectively,using 4%HF and 9.5%HF to treat the surface of the test piece,according to hydrogen Fluoric acid concentration and surface treatment agent were randomly divided into 4 groups:14%HF,20 s;29.5%HF,20 s;3 all-ceramic treatment solution,20 s;4 blank control group,no treatment.The AFM test surface roughness and the three-dimensional contour of the scanned test piece,SEM,EDS and mapping were used to test the composition of the surface elements of each test piece,and the weight ratio(wt%)of the etched phase to the non-etched phase representative element was recorded.One-way analysis of variance and Tukey’s multiple test were performed using SPSS 21.0.Result:1.VITA Enamic material group:MBEP group and control group surface are uniformly distributed porous network structure;4%HF group can see double network structure dissolved,9.5%HF group treated surface presents a large number of irregular surface The structure is dissolved to form a fractured double network structure.Up.CAD material group:MBEP group and control group have similar surface morphology,flat surface and slightly slender scratches;4%HF group can see a small amount of glass matrix dissolution,9.5%HF group surface glass matrix dissolves a lot,resulting in Multiple bumps and depressions create an uneven surface etch pattern.2.Vita Enamic material group:The surface roughness values of 4%and 9.5%HF groups were significantly higher than the control group,and the difference values were statistically significant(P=0.00<0.05);there was no difference in surface roughness values of MBEP group.Statistical significance(P>0.05).Up.CAD material group:9.5%HF group produced the highest surface roughness value,which was statistically significant(P<0.05);MBEP group and 4%HF group had higher surface roughness than the control group,but The difference value was not statistically significant(P>0.05).3.Vita Enamic material group:The ratio of Si/C in 4%HF and 9.5%HF group was lower than that in the control group,and the difference was statistically significant(P<0.05).There was no significant difference in the ratio of Si/C in MBEP group.(P>0.05).Up.CAD material group:4%HF,9.5%HF,MBEP group Si/K element ratio and the control group were not statistically significant(P>0.05).4.Vita Enamic material group:The energy spectrum sweeping diagram shows that Si and C elements have different distribution trends,which can distinguish the position of Si and C elements,the stronger the acid etching concentration,and the breaking tendency of Si element,C element The more continuous the distribution is.Up.CAD material group:The energy spectrum scan shows that the Si and K elements have the same trend,and the morphological structure of the two elements has almost no difference in the treated surface.Conclusion:1.Acid etching affects the surface and internal microstructure of VITA Enamic and Up.CAD materials,and the degree of influence is related to the concentration of acid etching and the difference in material composition.2.MBEP treats both materials,and the results show a weak surface etching effect,which is a treatment liquid with weak acid etching ability.3.9.5%HF will dissolve the Si element on the surface of the VITA Enamic material in large quantities,which may affect the bonding between the ceramic block and the resin material.Therefore,the surface treatment of VITA Enamic requires a milder etching scheme to retain more Si elements.. |
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