Tekrarlanan Fırınlamaların Porselen Renk Değişikliği Üzerine Olan Etkisi

Abstract

ABSTRACT Pehlivanlar, F., The effect of repeated firing, on colour alterations of porcelain. Hacettepe University, Prosthodontics Program Specialization Thesis, Ankara, 2017. Metal reinforced porcelain restorations are still widely used. Because they have both; esthetic features of porcelains with endurance and compatibility of moulding restorations, together. İt is rather hard to restore colour matching with natural teeth, in dentistry. During the production stages of metal-reinforced porcelain restorations, the porcelain may be exposed to repeated firings. Additional firing processes may cause esthetic problems like colour mismatch. Therefore, the effects of repeated firing on colour of porcelains, are still a source of concern for physicians. The aim of this study is to compare the effect on colour alterations; by metal reinforced porcelain restorations, in various trademarks and different diameters by using spectrophotometric analysis. With this design, 120 pieces of infrastructural samples have been prepared from base alloys of Ni-Cr. These samples were divided into four groups of 30 samples in each group per dental porcelain brands selected. Each group was divided into three groups of 10 samples according to the porcelain thickness (0,5mm; 1mm and 1,5mm) to be applied in themselves. Samples were subjected to a firing process a total of nine times with start firing. For each sample, the color was measured by the spectrophotometer after the initial, 3rd, 5th, 7th, and 9th firing operations and L, a and b values were determined. The ΔE value was calculated according to the CIE Lab color system., IBM SPSS Statistics 23.0 package program was used For statistical analysis As a result, as the thickness of the porcelain and the number of firing increases, the “L” value decreases. The highest average “L” value was obtained on the Vita brand. The lowest average “L” value was determined on the Noritake brand. As the number of firing increases, “a” and “b” values are shown to be decreased. The highest average “a” value belongs to the Vita brand, while the lowest average “a” value belongs to the IPS Classic brand. While the highest average “b” value was obtained on the Noritake brand, the lowest average “b” value was obtained on the Ceramco brand. The mean ΔE value was found to be statistically significantly lower in 1 mm thickness specimens than in 0.5 and 1.5 mm thickness specimens. As the number of firing increases, the value of ΔE, which indicates the amount of color change, is increasing in metal-reinforced porcelain restorations. While the lowest average “ΔE” value is obtained on the IPS Classic brand, the highest average value is obtained on the Noritake brand. Keywords: Metal-reinforced porcelain systems, repeated firing, color stability