Experimental Study The Influence Of Different Ceramics On The Curing Efficiency Of Two Resin Cements

Background: Ceramic material has the similar optical properties andtranslucency with natural teeth, so it can simulate the color and luster andshape of natural teeth, with its excellent corrosion resistance andbiocompatibility, and can be used as ideal prosthetic material for crownbridge, post, veneer and inlay. Resin cement is the best luting agent forall-ceramic restoration, because it not only can provide a good retention toprosthesis, but also enhance the flexural strength of ceramic prosthesis/tooth tissue so as to improve the success rate of all-ceramic restorations.However, adequate polymerization is crucial for resin cement to obtain theoptimal physicals and mechanical properties and to ensure strong and lastingbond strength of the bonding strength. Ceramic material is the intermediaryof the resin curing process, and the curing degree of the resin cementdepends on the different ability of light transmission through restorationlayer to the surface of the resin cement.Because the main ingredients ofall-ceramic materials, production methods are different, the physicalproperties and optical properties differ correspondingly, which will affect the utilization efficiency of curing light on resin cement.Objective: To study the effect of different all-ceramic materials oncuring efficiency of resin cement, and provide some references for clinicalall-ceramic bonding.Materials and methods: Five different commonly used all-ceramicmaterials (Cerec Blocs, IPS e.max Presss, In-Ceram Alumina, IPS e.maxZirCAD, Incoris Alumina) were prepared as core porcelain slices (6.00mmin diameter,0.70mm in thickness). The veneering ceramic was made innuclear porcelain surface and the final thickness of all-ceramic specimenwas1.20mm. Light-emitting diode (LED) curing light was used as lightsources, Variolink II, Panavia F as resin cements. According to the type ofall-ceramic materials as an intermediary in the curing process, the studyinvolved6groups: Cerec Blocs group, IPS e.max Presss group, In-CeramAlumina group, IPS e.max ZirCAD group, Incoris Alumina group andcontrol group. First, Fourier Transform the Infrared Spectroscopy (FT-IR)was used to detect Degree of conversion (DC) of polymerization before andafter the curing of the resin cements, then microhardness tester was used torecord Knoop hardness values (KHN) on the surface of the resins aftercuring in each group. Spss10.0software was used for statistical analysis.Results:The DC values of Variolink II or Pavania F resin cement showedsignificant difference among groups (P <0.01), the maximum value in the Cerec Blocs Group, followed by IPS e.max Presss group, In-Ceram Aluminagroup, the IPS e.max the ZirCAD group and Incoris Alumina group. The DCvalues in experiment groups were lower than that in control group (P <0.05).The DC value of Variolink II was significantly higher than that of Pavania Fin the same group (P <0.05).KHN values of Variolink II or Pavania F resin cement in Cerec Blocsgroup and IPS e.max Presss group presented no significant difference withblank group (P>0.05), but significant differences compared with the othergroups (P<0.05). The rank of KHN from high to low was as follows:In-Ceram Alumina group, IPS e.max ZirCAD group, Incoris Alumina group.KHN value of Variolink II was significantly higher than that of Pavania F inthe same group (P <0.05).Conclusion: In this study, the five different all-ceramic materials canaffect the DC and KHN values of two resin cements, Variolink II andPavania F. Glass-Ceramics such as Cerec Blocs group,IPS e.max Pressshave lower effect on the curing efficiency of resin cement,but Al2O3-basedceramics and ZrO2-based ceramics have an important impact on it.However,With the same ceramic material, the Degree of conversion andsurface hardness of Variolink II values are higher than those of Pavania F.