Comparison of fracture strength of modified peek, nanohybrid ceramic, monolithic zirconium endocrowns produced with CAD/CAM system

In this in vitro study, it was aimed to compare the fracture strength of endocrones obtained from three different materials are produced with the CAD/CAM system Thirty mandibular first molar teeth with similar morphology, which were extracted due to periodontal and orthodontic planning, were randomly divided into groups (n=10). Endocrown preparations were performed after root canal treatment was applied to the samples. The groups in the study; Group 1; Monolithic zirconium endocrowns (KATANA UTML Zirconia, Kuraray Noritake INC., Okayama, Japan), Group 2; Nanohybrid ceramic endocrowns (Cerasmart, GC Corp., Tokyo, Japan), Group 3; Modified PEEK (JUVORA, Juvora Ltd. Thornton Cleveleys, Lancastershire, England) endocrowns veneered with composite. Cementation of specimens was performed with dual cure resin cement (Panavia F 2.0, Kuraray Noritake INC., Okayama, Japan). The aging process of the samples was carried out in a dual axis chewing simulator using 120,000 cycles, 1.86 Hz, 49 N parameters. For the fracture strength test, with the help of a universal test machine (Instron device 3345, Norwood, MA, USA), 1 mm/min. loading was carried out at head speed. The compressive strength value that caused the breakage was calculated and recorded in Newtons (N). The Oneway Anova test was used for the comparison of the parameters between the groups, and the Tukey HDS test was used to determine the group that caused the difference. The mean fracture strength of the Monolithic Zirconium Endocrown group (2496.5±189.1 N); Statistically significantly higher than the Modified Peek Endocrown (1728.2±139.2 N) and Nanohybrid Ceramic Endocrown (1248.8±107.6 N) groups (p1:0.000; p2:0.000; p<0.05). The average fracture strength of the modified Peek Endocrown group; It was statistically significantly higher than the Nanohybrid Ceramic Endocrown group (p:0.000; p<0.05). The average fracture strength of the modified Peek Endocrown group; It was statistically significantly higher than the Nanohybrid Ceramic Endocrown group (p:0.000; p<0.05). In our study, the fracture strength of the monolithic zirconium endocrone group produced with the CAD/CAM system was found to be significantly higher than the other groups. All three materials in the study showed a much higher fracture strength compared to the average of the maximum intraoral maximum chewing forces. It was concluded that the three materials used in the study would be suitable for molar teeth in endocrown production. Keywords: CAD/CAM, endocrown, PEEK, fracture strength