الفهرس 
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Abstract
This study was conducted to radiographically evaluate the effect of the different techniques of PEEK frameworks fabrication that were virtually designed using the CAD/CAM system on the supporting structures in mandibular Kennedy class I distal extension cases, by using long cone parallel technique.
Fourteen patients with mandibular Kennedy class I and opposing short Kennedy class I were chosen from the outpatient clinic of the Prosthodontic Department Faculty of Dentistry, Ain Shams University. The last standing abutment for all patients was the second premolar.
After receiving zirconia primary crowns that were digitally designed and milled, patients were randomly divided into two groups:
group I:
Seven patients were rehabilitated with digitally designed telescopic RPDs, milled from BioHpp blank.
group II:
Seven patients were rehabilitated with digitally designed telescopic RPDs, pressed from BioHpp granules.
The telescopic partial denture framework was designed using the partial-cad module, which is an add-on module in the Exocad software, as follows: model was surveyed, and undercuts were determined. All unfavourable undercuts were blocked out by the software and a modified cast was created. Denture base meshwork was then outlined. Then the outline of the lingual plate major connector was drawn. External finish line between denture base meshwork and major connector was then drawn. For both groups, the final design was sent to the CAM software to be initially milled from castable polymethyl methacrylate resin, for intra-oral inspection.
• Manufacturing the final telescopic partial denture framework from BioHpp material:
group I: The framework STL file was sent to the CAM software to prepare the milling machine order for milling the framework directly from the BioHpp blank, the milled framework was then sent for intraoral inspection. Lastly, the heat-cured acrylic resin denture base was packed and cured to the denture base meshwork as conventional, then the composite resin was added following the teeth shade on the labial aspect of the secondary crowns following the manufacturer’s bonding system protocol.
group II: the STL file of the designed framework was firstly milled from the PMMA castable resin, then the resin framework was sprued and invested following the manufacturer recommended ratios. Later, the muffle and the press plunger were placed in a preheated furnace before the BioHpp granules were filled into the muffle. The muffle with the melted BioHpp granules and the plunger were placed onto the pressing table of the device, then vacuum press process ran automatically. Next, the framework was divested, trimmed and polished for intra-oral inspection. The heat-cured acrylic resin denture base was then added to the denture base meshwork and fabricated as conventional, finally, the composite resin was added on the labial aspect of the secondary crowns as described with group I.
Patients of both groups were evaluated at the time of denture insertion then six, and twelve months later. The evaluation included bone height measurements around the natural abutments and the residual ridge of the distal extension area.
At the end of follow up period, the results showed that there was a statistically significant difference in the marginal bone height changes between the two groups. group I (milled BioHpp) showed more bone resorption around the abutments than group II, while group II (pressed BioHpp) showed more resorption at the crest of the residual ridge than group I.