الفهرس 
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Abstract
This study was designed to compare the internal adaptation and fracture resistance of three different types of materials which were Katana zirconi, IPS e-max and Bio-HPP, of two different designs of the inlay retained fixed partial dentures.
Sixty inlay retained fixed partial dentures were classified into two main groups according to the preparation design. group B (Box-shape design, no=30 samples) and group S (Slice shape design, no=30 samples). Then each group of them was classified into three subgroups according to material type. Subgroup Z (zirconia ceramic, no=10 samples), subgroup L (lithium di-silicate ceramic, no=30 samples), and subgroup P (Bio-HPP, no=30 samples). Then each subgroup was divided into two classes, each class consisted of 5 samples to measure internal adaptation and fracture resistance.
Two mandibular first premolars and two mandibular first molars were selected and cleaned ultrasonically and then embedded in the teeth sockets of a plastic cast in their corresponding places to later receive the standardized preparation, silicon index was taken to uniform the restorations thickness. Standardized teeth preparation of box and slice shape designs were done.
Epoxy samples were constructed to avoid the problems encountered during teeth preparation such as cracks, hypo mineralization and difficulty to found the whole number of teeth needed for the study.
All inlay retained fixed partial dentures were constructed by CAD/CAM technique. Then cemented using Rely X U200 cement according to manufacturing instructions.
All samples were subjected to thermocycling by alternate exposure of to temperature of 5° C and 55°C for 5000 cycles with a 25-seconds dwell time at each temperature for specimens which will have being tested for internal adaptation and fracture resistance tests, according to ISO standardization.
Internal adaptation measurements were taken using USB digital microscopy with built in camera at ×25 magnification, while fracture resistance test done using the universal testing machine.
For internal adaptation, results showed that regarding different tested materials, for the box-shape design, the highest mean value was recorded for the e-max IRFPDs of (360.0μm ± 34.2μm) for the mesial abutment, and (322.4 μm ± 112.9 μm) for the distal abutment, followed by zirconia IRFPDs of (291.7μm ± 92.5μm) for the mesial abutment, and (308.2 μm ± 58.8 μm) for the distal abutment, while the lowest mean value was recorded for Bio-HPP IRFPDs of (281.6μm ± 42.3μm) for the mesial abutment, and (298.0μm ± 74.5μm) for the distal abutment.
For the Slice-shape design, the highest mean value was recorded for the e-max IRFPDs of (469.9μm ± 269.1μm) for the mesial abutment, and (497.5μm ± 128.3μm) for the distal abutment, followed by zirconia IRFPDs of (338.0μm ± 94.6μm) for the mesial abutment, and (302.6 μm ± 83.8μm) for the distal abutment, while the lowest mean value was recorded for Bio-HPP IRFPDs of (153.6μm ± 40.9μm) for the mesial abutment, and (225.4μm ± 59.2μm) for the distal abutment.
While regarding different tested designs, results showed that for the e-max IRFPDs the highest mean value was recorded at the slice-shaped design for (469.9μm ± 269.1μm) for the mesial abutment and (497.5μm ± 128.3μm) for the distal abutment, while the lowest mean value was recorded for the box-shaped design for (360.0μm ± 34.2μm) for the mesial abutment and (322.4μm ± 112.9μm) for the distal abutment.
For the Bio-HPP IRFPDs the highest mean value was recorded at the box-shaped design for (281.6μm ± 42.3μm) for the mesial abutment and (298.0μm ± 74.5μm) for the distal abutment, while the lowest mean value was recorded for the slice-shaped design for (153.6μm ± 40.9μm) for the mesial abutment and (225.4μm ± 59.2μm) for the distal abutment.
For the zirconia IRFPDs, the results showed non-significant difference between tested groups, the mean values recorded for the slice-shape design were (338.0μm ± 94.6μm) for the mesial abutment and (302.6μm ± 83.8μm) for the distal abutment, while the mean values recorded for the box-shape design were (291.7μm ± 92.5μm) for the mesial abutment and (308.2μm ± 58.8μm) for the distal abutment.
For fracture resistance test, results showed that that the highest mean value was recordes for zirconia at ( 2427.8 ± 163.1 μm), followed by Bio-HPP which recorded (2067.9 ± 219.1 μm), while the lowest mean value was recorded for the e.max at ( 1239.2 ± 74.7 μm).