THE EFFECT OF THICKNESS ON THE OPTICAL PROPERTIES OF ENAMIC HYBRID CERAMIC COMPARED TO VITA FELDSPATHIC ONE: IN VITRO STUDY

Aim of the study: The aim of the study was to evaluate the effect of thickness on the translucency parameter of Enamic hybrid ceramic compared to feldspathic ceramic (Markll) ceramic.
 
Materials   and   Methods:   Forty   ceramic   discs   were   fabricated   using   IsoMet   4000 (Buehler, USA) from CAD-CAM blocks of vita Enamic (n=20) and vita Markll ceramic material (n=20). The samples was made into two different thicknesses (0.8 mm – 1.5 mm). One standard shade according to vita 3D master shade guide (VITA Zahnfabrik, Bad Sackingen, Germany), (2M2) was used with all the samples. Finishing and polishing procedures carried out through manufacturer instruction for each ceramic material. Translucency parameter were analyzed and measured using a scanning spectrophotometer (UV- Shimadzu 3101 PC, Chiyoda-ku, Tokyo, Japan). Color measurements (L*, a* and b*) to the samples placed against an ideal white background (CIE L* = 96.68, a*=_0.18, and b*=_0.22) and against an ideal black background (CIE L* = 1.15, a*=_0.11, and b*=_0.50) relative to the standard illuminant D65. All the samples was subjected to measurements for each material type, different thicknesses, the same observer carried out the measurements. Three readings was taken and the mean values were tabulated and analyzed. Three way-ANOVA was used to study the effect of ceramic materials and thickness on Translucency Parameter (TP). Tukey’s post-hoc test was used for pair-wise comparison between the means when ANOVA test is significant. One-Way ANOVA used to compare between the interaction between variables for mean Translucency parameters.
 
Results: Vita Mark II feldspathic ceramic (18.74±3.33) showed the highest statistical significant mean translucency value compared to Vita Enamic hybrid ceramic (12.59±2.96) at p≤0.001*. Thickness of 0.8 mm (18.31±3.71) showed the highest statistical significant mean translucency value compared to 1.5 mm thickness (13.02±3.34) at p≤0.001*.
Conclusions: Vita Mark II Feldspathic ceramic are more translucent than Vita Enamic Hybrid ceramic. Increasing the thickness as well as thermocycling decrease the translucency parameter for both ceramic materials.