Marginal Accuracy and Fracture Resistance of Posterior Crowns Fabricated from CAD/CAM PEEK Cores Veneered with HIPC or Nanohybrid Conventional Composite

Abstract

Statement of problem: Veneered polyether ether ketone (PEEK) is a recent alternative choice for fixed dental prostheses. There is a lack of data about the effect of composite veneering techniques of CAD/CAM PEEK cores on the marginal accuracy and fracture resistance of such restorations. Purpose: To investigate the different composite veneering techniques of CAD/CAM PEEK cores influence on the marginal accuracy and fracture resistance of posterior crowns. Methods: Twenty duplicated epoxy resin dies of a prepared mandibular first molar to receive a ceramic crown were fabricated. 20 CAD/CAM PEEK cores were fabricated and divided into two groups (n=10) based on the veneering technique; group (A): HIPC veneered PEEK cores and group (B): nanohybrid crea.lign composite veneered PEEK cores (control group). Marginal gap was evaluated at 4 equidistant points on each crown by a digital microscope before and after ageing equivalent to clinical 6 months service. The fracture load was assessed after ageing. The data were statistically analyzed using one-way ANOVA, pair-wise Tukey’s post-hoc and Student’s t-tests to reveal the significance between groups (P ≤ 0.05). Results: The marginal gap was significant between before (59.638±5.91 µm and 58.587±7.74 µm) and after ageing (79.167±11.62 µm and 72.222±6.53 µm) for A and B groups respectively (p=0.0019/0.0039<0.05). ANOVA test showed a significant difference between groups before and after ageing (p= 0.0002<0.05) which was not detected by Tukey’s test (p>0.05). B group showed a significant higher fracture resistance mean value (1674±224.8 N) than A group (1294±282 N) (p=0.0164<0.05). Conclusions: The marginal gap and fracture load values recorded by posterior crowns fabricated from CAD/CAM PEEK cores veneered with HIPC or nanohybrid composite were all within the clinically acceptable range