Effect of talc, zirconium oxide, and titanium oxide addi̇ti̇ves on the physical properties of feldspathic porcelain

Dental porcelains, although resistant to heat, are brittle. Sudden changes in force and temperature can lead to fractures, reducing their strength and flexural resistance. This limitation is particularly significant for their use in posterior teeth. Therefore, enhancing the mechanical properties of porcelains is crucial for improving their clinical performance. The aim of our study is to evaluate the effect of adding talc, zirconium oxide, and titanium oxide in different proportions on the physical properties of feldspathic porcelain used in the ceramic industry, and to enhance its mechanical strength. In this study, zirconium dioxide, titanium dioxide, and talc (Kalaçlar, Ankara, Turkey) were added to feldspathic porcelain in weight proportions of 2% and 5%, and crack length, hardness value, flexural strength value, and color change were examined. A feldspathic porcelain [Ceramco 3 (Dentsply Degudent GmbH, USA)] dentin powder was used as the test material. Seven groups were formed, with eight samples in each group for the test methods. The color change measurements of the porcelain samples were performed using the VITA Easyshade spectrophotometer (Vita Zahnfabrik, Bad Sackingen, Germany). The biaxial flexural strength test was performed using the piston-on-three-balls method. The Vickers microhardness tester (High Wood, HWDM-3, Japan) was used to apply 10 N force for 10 seconds to create indentations on the surfaces, and the Vickers hardness values were found. After the tests, suitable feldspathic porcelain samples were examined using the SEM (TESCAN Mira III, Brno, Czech Republic). Statistical analyses were performed using one-way analysis of variance (ANOVA test), Tukey HSD, and Tamhane's T2 (p < 0.05). In terms of color change, all values were found to be above the clinical acceptability limit. The lowest ∆E00 value was observed in the 2% talc group. The flexural strength values increased in all groups compared to the control group, and statistically significant data were found. The 2% zirconium dioxide group was found to be statistically significant compared to the control group (p < 0.05). An increase in hardness values was observed in all groups compared to the control group, and all group increases were statistically significant compared to the control group (p < 0.05). In terms of crack lengths, a decrease was observed in the 5% talc group compared to the control group, while increases were seen in all other groups. Statistically significant differences were found. All added materials positively affected the flexural strength and hardness findings of feldspathic porcelain. More favorable results were seen in the groups where talc was added in terms of color change and crack length. Statistically significant differences were found. The only group that reduced the crack length was the 5% talc group. The ∆E00 value closest to clinical acceptability in terms of color change was seen in the 2% talc group. When SEM and EDS analyses were examined, it was found that zirconium dioxide, titanium dioxide, and talc were integrated into the structure, did not disrupt the structure, and were homogeneously distributed.