MARGINAL ACCURACY AND INTERNAL FIT OF ENDOCROWN CONSTRUCTED FROM LITHIUM DISILICATE CERAMICS VERSUS POLY ETHER ETHER KETONE (PEEK) (AN IN VITRO STUDY)

Statement of the problem: The use of peek for construction of endocrown has gained popularity due to its many advantages, yet limited data is available with regard to its marginal accuracy and internal fit.Purpose: The purpose of the present study is to determine the marginal accuracy and internal fit of endocrown constructed from lithium disilicate ceramics and poly ether ether ketone (PEEK).Methodology: 16 human lower molars were endodontically treated and prepared to receive endocrown restorations with Butt joint preparation design. Prepared teeth were equally divided into two groups, Group L: Lithium disilicate ceramics and Group P: Poly ether ether ketone. All restorations were CAD/CAM milled using five axis milling machine (CORiTEC 250i Series - imes – icore). Vertical Marginal adaptation was measured using USB Digital microscope with a built-in camera (Leica microscope) at fixed magnification of 20X. Internal fit was measured by replica technique.Results: Lithium Disilicate endocrowns showed superior results, where they had statistically significant lower marginal discrepancy (28.86 ±12.69 µm) than PEEK (75.24 ± 28.89 µm) (P-value =0.002, Effect size =2.349) and statistically significant lower internal discrepancy (122.2±21.7 µm) than PEEK (163.1±25.1 µm) (P-value =0.043, Effect size =2.042). Regardless of the material of construction lingual side of endocrown showed the least marginal adaption and internal fit.Conclusions: Lithium disilicate endocrowns showed better marginal adaptation and internal fit than PEEK endocrowns. Both groups exhibited clinically acceptable marginal discrepancies and fit. Accordingly, PEEK materials could be used as an alternative to Lithium disilicate for endocrown construction.