الفهرس 
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Abstract
Aim: The current study was conducted to evaluate the internal fit and marginal adaptation of cemented custom-made Pressable compared to CAD/CAM PEEK post and core at three levels (coronal, middle and apical).
Methodology: Twenty-eight extracted human maxillary central incisors of comparable size and form were endodontically treated and prepared for custom post and cores with a standardized technique. Acrylic resin post and cores patterns were fabricated and randomly divided into two equal groups (n=14) according to technique of fabrication: group I (CAD/CAM): The resin patterns were directly scanned and milled from modified PEEK blocks (BioHPP: High Performance Polymer) and group II (Press): Patterns were pressed with BioHPP granulate. After posts cementation, roots of all samples were sectioned horizontally, perpendicular to the long axis of the root using low speed diamond saw under water coolant to obtain three sections of 2 mm thickness representing cervical, middle and apical third of the root. The cement thickness around each specimen was measured at four standardized points and the vertical marginal discrepancy of each core was measured at twelve points (three at each surface) using scanning electron microscope (SEM). One Way-ANOVA and Tukey`s post hoc test were performed to compare between the
sections of each group; while Independent T-test was performed to compare between the two groups at different sections.
Results: Regarding CAD/CAM group, the mean cement thickness was the highest in the coronal section (85.57±17.81) followed by the middle (72.87±18.57) then the apical (45.92±18.73). While for Press group, the middle section showed the highest mean cement thickness (50.99±15.98), followed by the coronal section (39.70±18.16), the apical section (21.37±4.30). The coronal and middle sections had significantly higher internal gap than the apical section in both groups (P=0.001). Comparing between the two groups, CAD/CAM group had significantly higher internal gap in the three cross sections (P=0.0001). Among cores marginal adaptation, no significant difference in means of all surfaces was revealed between the CAD/CAM (98.83±13.90) and press (95.08±13.91) groups (P=0.54)
Conclusion: Within the limitations of this study, pressed PEEK custom-made post and cores achieved superior internal fit compared to CAD/CAM. Neither CAD/CAM nor pressing fabrication technique influenced the marginal adaptation of PEEK cores and both were within the clinical acceptance range.
Keywords: CAD/CAM, press, custom-made, post and cores, internal fit, marginal adaptation, scanning electron microscope, cement thickness.