Introduction: The use of endocrown for restoring decayed endodontically treated molar is one of the most advocated treatment options. PEEK (polyether ether ketone) has excellent mechanical and chemical properties. Aim of the Study: To assess the efficacy of different types of surface treatment of PEEK endocrowns on the fracture resistance of endodontically treated teeth. Methodology: Thirty-two CAD/CAM endocrowns were fabricated and divided into 4 groups (n=8). In the first group, the endocrowns were fabricated from lithium disilicate and was treated with hydrofluoric acid. In the other three groups, the endocrowns were fabricated from PEEK and their surfaces were treated with sulfuric acid, air abrasion, and combination of air abrasion and laser. The endocrowns were cemented with self-adhesive resin cement. The fracture resistance was evaluated by using universal testing machine. The mode of failure was analyzed by using stereomicroscope. Result: There was a significant difference between different groups (p < 0.001). The highest value was found in PEEK (A&L) (3526.27±110.18), followed by PEEK (S) (2871.53±281.74), then PEEK (A) (2847.77±28.72), while the lowest value was found in Emax (HF) (2039.05±4.99).
Conclusions: PEEK endocrowns showed higher fracture resistance than E-max endocrowns. Regarding surface treatment of PEEK endocrowns, combination of Erbium YAG laser and air abrasion improved fracture resistance compared to sulfuric acid and air abrasion only. Both PEEK and lithium disilicate endocrowns can be used safely in terms of fracture resistance. Both lithium disilicate and air abraded PEEK endocrowns showed mostly unfavorable mode of failure.