الفهرس 
Title : Evaluation of the internal fit of Pressable versus CAD/CAM PEEK post and core using scanning electron microscope: An in vitro study
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Abstract
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.