| OBJECTIVE:To compare the shade and translucency of ceramic veneer prepared by two different layering techniques to provide theoretical basis for the application of multi-layer dentin porcelain to achieve pleasing restoration in clinical practice.METHODS:In this study,the 3M2 shade porcelain powder of VITA VM9 was mixed with Vita VM modelling liquid according to recommended proportion to make green state in circular metal mold.According to manufacturer's recommendation vacuum sintering,grinding and polishing of 11 ENL enamel,22 base dentin and 11 Transpa dentin ceramic disks were prepared to a required size.The thickness of each ceramic disk was 0.5±0.04 mm,and the diameter of each ceramic disk was 8.3±0.36 mm.After ultrasonic cleaning,the ceramic disks were divided into control group and experimental group.Each group consisted of three layers: the control group consisted of double base dentin disks overlapped with enamel porcelain disk.The experimental group consisted of Transpa dentin disk sandwiched between base dentin and enamel porcelain disks.Glycerin was used as coupling medium.Vita Easyshade compact was used to measure the color of base dentin porcelain,transpa dentin porcelain and layered porcelain specimens respectively.The white background was used to analyse the color.Translucency parameter was measured using black and white background.The measured values include L*,a*,b*,C*,H* coordinate value in layered and intermediate porcelain disks.The mean values were obtained by measuring each sample three times consequetively.Comparison in L*,a*,b* coordinate was done between two groups in layered porcelain specimens to determine color difference.Translucency parameters(TP)of layered and intermediate porcelain disks were calculated using equation.The color difference(?E)and Translucency parameter difference(?TP)between two groups in layered porcelain disks and intermediate porcelain disks was also calculated using equation.Independent sample t test was used to compare L*,a,b* coordinate to determine color difference between intermediate base dentin and transpa dentin porcelain.Independent sample t test was performed to compare TP to determine translucency difference between intermediate base dentin and transpa dentin porcelain.The pair sample t test was performed in L*,a*,b* coordinate to determine color difference between two groups in layered porcelain disk specimens.Pair sample t test was performed to compare TP between two groups in layered porcelain disk specimens.At the same time visual shade analysis between two groups in layered porcelain disk specimens was performed by 35 volunteer participants to determine color difference and its acceptability using standard shade matching light and were asked to answer the questionnaire of this study.Chi-square test was done to analyze visual method for color difference performance of the participants and color difference acceptability by the participants.SPSS 23 statistical software was used for statistical analysis significance(P value was set to 0.05).RESULTS:Measurement result in intermediate monolayer porcelain disks:The mean and standard deviation of base dentin porcelain disks(thickness is 0.49 ±0.05)in control group were L* = 87.31±1.23,a* = 8.32±0.74,b* = 37.64±1.35,C* = 38.54±1.47,H* = 77.55±0.67,TP = 29.7±2.05.The mean and standard deviations of transpa dentin porcelain disks(thickness 0.49 ±0.03)in experimental group were L* = 94.55±0.87,a* = 2.82±0.44,b* = 28.53±1.46,C* = 28.67±1.49,H* = 84.38±0.6,TP = 33.3±2.16.Independent sample t test showed that there was significant difference(P<0.05)in L*,a*,b* and TP between intermediate base dentin and transpa dentin porcelain disks.Between the intermediate base dentin and transpa dentin porcelain disks;color difference(?E)= 12.95 units and the transparency parameter difference(?TP)= 3.6 units.Measurement results of layered porcelain disk specimens:The mean and standard deviation of CIEL*,a*,b* and C*,H* value in Control group of layered porcelain disks specimens were 81.93 ± 1.33,6.03 ± 0.25,23.85 ± 0.69 and 24.6 ± 0.71,75.82 ± 0.47 respectively.The mean and standard deviation for TP of layered porcelain disks in control group specimen was 14.85 ± 1.74.The mean and standard deviation of CIEL*,a*,b* and C*,H* value in Experimental group specimens were 84.51 ± 0.95,4.19 ± 0.17,23.15 ± 1.33 and 23.53 ± 1.33,79.71 ± 0.51 respectively.The mean and standard deviation for TP of layered porcelain disks in experimental group specimen was 18.08 ± 1.73.The pair sample t test showed that there was a significant difference(P<0.001)in L*,a* whereas,no significant difference(P>0.05)in b* color coordinates between two groups.Thus,between two groups of layered porcelain disk specimens,a color difference(?E)was 3.51 units.There was significant difference(P<0.001)in the translucency parameters between the two groups.Thus,between two groups of layered porcelain disk specimens,the translucency parameter difference(?TP)was 3.23 units.The result of chi-square test showed a significant difference(P<0.05)in visual shade analysis performance of participants and color difference acceptability by the participants.Out of 35 volunteer participants,25 participants could differentiate a color difference and 10 participants could not differentiate a color difference between two groups in layered porcelain disk specimens.Among 25 participants,18 participants could accept the color difference in prosthesis while 7 participants could not accept in prosthesis for clinical practice.CONCLUSION:Application of translucent dentin porcelain in all ceramic restoration can produce brighter,more translucent,less chromatic ceramic veneers.Color difference due to translucent dentin porcelain in layered porcelain specimens were perceivable to human eyes and were acceptable for clinical use. |
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