Comparison of Microtensile Bonding Strength and Microleakage of Endocrowns Restorations Prepared With Two Different Materials

Background: The aim of this study was to compare microleakage levels and microtensile bond strength (MBS) of lithium disilicate and polyetheretherketone (PEEK) endocrown restorations cemented with adhesive resin. Material and Methods: For this study, caries-free human maxillary and mandibular first molars of similar size were selected. Root canal treatment was applied to the teeth and endocrown preparation was made. The restorations were fabricated using CAD/CAM technology and divided into two groups: Group 1: Lithium disilicate (L) and Group 2: PEEK (P). All restorations were cemented using resin cement. Following cementation, the samples were stored in distilled water at 37°C for 24 hours and subjected to 5000 thermal cycles between 5°C and 55°C. For the microleakage test, the samples were immersed in a 2% methylene blue dye solution for 24 hours and then sectioned using a minitom precision cutting device. Dye penetration depth was evaluated at three levels: restoration-cement interface, within the cement, and cement-tooth interface. For the microtensile test, the samples divided into sections were placed in the micro tension tester and tension was applied until they were separated, the tensile load at which separation occurred was recorded. The microtensile bond strength value was expressed in MPa. Data were analyzed using SPSS Statistics Version 25, employing frequency analysis, Chi-Square tests, and Monte Carlo Simulation. Results: The restoration-cement (0.0077±0.0594) and within-cement (0.0172±0.0386) microleakage levels in the L group were significantly lower than those in the P group (0.8873±1.7631 and 0.0529±0.0794) (p0.05). The MBS of the P group (3.31±1.85) was significantly lower than that of the L group (7.11±2.5) (p