Statement of problem:Veneered polyether ether ketone (PEEK) is a recent alternative choice for fixed dental prostheses. There is lack of data about the effect of veneering techniques of CAD/CAM PEEK cores on marginal accuracy and fracture resistance of such restorations.
Purpose:To investigate the 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 prepared mandibular first molar to receive 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):nano-hybrid crea.lign composite veneered PEEK cores (control group).Marginal gap was evaluated at 4 equidistant points on each crown by 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 t tests to reveal the significance between groups (P ≤ 0.05).
Results:The marginal gap was significant between before (59.638±5.91µm and 58.587±7.74µm) and after ageing (79.167±11.62µm and 72.222±6.53µm) for A and B groups respectively (p=0.0019/0.0039<0.05). ANOVA test showed significant difference before or after ageing between groups (p= 0.0002<0.05) which was not detected by Tukey's test (p>0.05).B group showed 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 nano-hybrid composite were all within the clinically acceptable range.