الفهرس 
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Abstract
This study was conducted to evaluate and compare the effect of implant supported versus implant retained removable partial denture restoring Kennedy’s class I cases on the supporting structures.
Twelve patients were selected, free from any systematic disease, for each patient received implant at second molar position, and they were divided randomly in two groups (group I and II).
group I: consisted of six patients who received RPD supported by implant dome shaped abutment.
group II: consisted of six patients who received RPD retained by implant through ball and socket attachment.
Clinical and radiographic evaluations were carried out for every patient at insertion, after 3, 6 and 12 months of the functional loading.
The clinical evaluation including modified gingival index, probing depth of abutment teeth and peri-implant probing depth, the radiographic evaluation including marginal bone loss, bone density changes, around each implant from the time of insertion and through the follow up periods to one year.
Pre-operative computed tomography cone-beam (CBCT) was performed to check the quality and quantity of the available alveolar bone at the planned implant site.
All patients received new lower acrylic partial dentures constructed using the conventional method. For each patient, a customized surgical guide was fabricated using CAD/CAM technology through the data obtained from the cone-beam computed tomography (CBCT). Captured images by CBCT was imported into viewing software then sent for fabrication of the guide using CAD/CAM technology.
Fabricated surgical guides were made from clear acrylic resin and contained metal housings that accurately fit the provided removable sleeves by the manufacturer. Two lateral cylinders were provided in each guide to allow the placement of anchor pins for fixation of the guide.
For each patient, surgical exposure of the gingival covering the planned implants sites from the surrounding tissues by using surgical flap or flapless technique.
The guide was fixed using the anchor pins and the implants were placed in the planned sites then loaded after 3 months.
All patients received lower metallic partial denture with the same design consists of lingual plate, mesial rest and RPI clasp on the main abutment, and distal or cingulum rest on the adjacent teeth to the abutment.
Methods of evaluation
Clinical evaluation
1. Implant stability
Implant stability was measured after surgical procedure by using Osstel device.
2. Modified gingival index:
Gingival index around the abutment and implants was measured at insertion, 3, 6and 12 months of loading, on the four axial surfaces of each abutment and implant.
3. Probing depth.
• Probing depth around the abutment teeth was measured at insertion, 3, 6 and 12 months of loading on the four axial surfaces of each implant.
• Peri-implant probing depth:
Probing depth around the implants was measured at insertion, 3, 6 and 12 months of loading on the four axial surfaces of each implant.
Radiographic Assessment
1. Assessment of marginal bone loss
Both groups were examined radiographically using computed tomography cone-beam, at denture insertion, after 3, 6, and 12 months, to measure the amount of marginal bone loss around each implant.
2. Assessment of bone density changes:
Bone density was measured using computed tomography cone-beam, at denture insertion after 3, 6, and 12 months.
Conclusions
Within the limitation of this study, it could be concluded that:
• No difference between the two groups regarding modified gingival index around the abutment teeth and implant abutment.
• No difference between the two groups in the increase of probing depth around the abutment.
• No difference between the two groups in the increase of peri-implant probing depth around the implant abutment.
• The marginal bone loss increased in group II implant retained with ball and socket abutment than group I implant supported with dome shaped abutment after 3 and 6 months of denture insertion.
• The bone density increased in group I (implant supported) than group II (implant retained) after 6 and 12 months of denture insertion.
RECOMMENDATION
Further studies are recommended to evaluate marginal bone loss and bone density with different types of implant abutments.