The Exeprimental Study Of The Effects Of Thickness Of Veneering Resin Composite On The Color Of Polyetheretherketone-Composite Resin Restorations

Objectives:In order to meet the aesthetic requirements for clinical application when polyetheretherketone is Fixed prosthodontics.In this experiment,polyetheretherketone-Crea.lign specimens with different opaque-shade resin layers and body-shade resin layers thicknesses were prepared to test the effect of the different thickness of opaque-shade resin layers and body-shade resin layers on the color of polyetheretherketone-composite resin restorations.Methods:Experiment 1:Fabrication and color measurement of different thickness opaque-shade resin layer specimens.30 polyetheretherketone specimens with the diameter of 0.7mm and the thickness of 0.6mm are made.The specimens were divided into 6 groups,each group had 5 specimens,which were numbered:O-1,O-2,O-3,O-4,O-5,O-6.The color value of group O-1 was measured by Shadepilot,then all spcimens were sanding and coating visio.link,then using the self-made stainless steel mold,made the specimens of group O-1,O-2,O-3,O-4,O-5,O-6 into the thickness of 0.0mm,0.1mm,0.2mm,0.3mm,0.4mm and 0.5mm opaque-shade resin layers,respectily.The color value of O-2,O-3,O-4,O-5,O-6 were measured by Shadepilot.On the surface of trial surfaces,1.0mm body-shade resin layers was stacked with the self-made stainless steel mold.The groups were changed to OB-1,OB-2,OB-3,OB-4,OB-5,OB-6.The color value of groups were measured by Shadepilot.Experiment 2:Fabrication and color measurement of different thickness body-shade resin layer test pieces.5 polyetheretherketone specimens with the diameter of 0.7mm and the thickness of 0.6mm are made.The color value of groups was measured by Shadepilot,then all spcimens were sanding and coating visio.link,then 0.1mm opaque-shade resin layers and 1.5mm body-shade resin layers using was stacked with the self-made stainless steel mold.The thickness of the 5 specimens were evenly grinded into 1.4mm,1.2mm,1.0mm,0.8mm,0.6mm,0.4mm,0.2mM,0.0mm,in sequence.Then numbered groups in turn:B-8、B-7、B-6、B-5、B-4、B-3、B-2、B-1.After the end of the grinding,using Shadepilot measure the color value,every time.SPSS 17.0 software was used for statistical analysis of experimental data to test whether the difference was statistically significant.Results:1.With the constant thickness of polyetheretherketone,and the range of 0.0mm body-shade resin layer+0.1～0.3mm opaque-shade resin layer and the 1.0mm body-shade resin layer+0.1～0.3mm opaque-shade resin layer,the L*,a*,b*values all showed upward trend with the increase of the thickness of opaque-shade resin layer.No significant difference in change(P>0.05).2.With the constant thickness of polyetheretherketone and the 0.1mm opaque-shade resin layer,the range of 1.0 1.4mm body-shade resin layer,the L*,a*,b*values all showed downward trend with the increase of the thickness of body-shade resin layer.No significant difference in change,in addition to the L*value between the groups of 1.0mm and 1.4mm body-shade resin layer thickness(P>0.05).3.Compared with polyetheretherketone,the L*and b*value decreased,and a*value increased,only addition of the opaque-shade resin layer.However,the L*value decreased,the a*and b*value increased,after add body-shade resin layer.Significant difference was found between the group of opaque-shade resin layer and opaque-shade resin layer+ body-shade resin layer(P<0.05).4.With the constant thickness of polyetheretherketone and the body-shade resin layer was 0.0mm and(or)1.0mm,the color difference between each group of 0.0mm～0.5mm opaque-shade resin layer thickness wre within the clinical acceptable range(△E<1.5NBS).There are more than clinically acceptable color difference,compared with polyetheretherketone(AE>1.5NBS).5.With the constant thickness of polyetheretherketone and the opaque-shade resin layer was 0.1mm,the color difference between the adjacent groups were less than 1.5NBS,but the color difference between the non-adjacent groups were more than 1.5NBS,after the thickness of the body-shade resin layer reached 0.6mm.There are more than clinically acceptable color difference,compared with polyetheretherketone(AE>1.5NBS).Conclusions:Under the conditions of this study:1.The color of polyetheretherketone can be obviously changed by increasing the composite resin opaque-shade resin layer and(or)body-shade resin layer.2.0.1mm is the smallest thickness of opaque-shade resin layer that can cover the dentin-shade polyetheretherketone.3.Under the condition of the thickness of opaque-shade resin layer is 0.1mm,the thickness of 0.6mm body-shade resin layer is enough to be clinically acceptable for the color of the polyetheretherketone-composite resin restoration.