Objective: To evaluate crestal bone height changes and biting forces in three implant-supported mandibular overdentures retained by Poly ether ketone (PEEK) bar and chromium cobalt (Co-Cr) bar attachment.
Materials and Methods.: Twenty completely edentulous patients above 60 years were selected for this study. Three implants were placed in the interforamina region; two were placed bilaterally in the canine regions and one near the midline. In all patients, conventional maxillary full dentures were constructed against implant-supported mandibular overdentures. The patients were randomly divided into two equal groups according to the material of the bar attachments. Polyether ether ketone (PEEK) bar attachments were fabricated to hold the overdenture for patients in group A, while custom-designed chromium cobalt (Co- Cr) bar attachments were constructed for patients in group B. Crestal bone loss around implants was assessed by CBCT after denture pick up (T0) baseline, after 3 months(T3), 6 months(T6), and after 12 months (T12) from the pickup of the overdentures. Bite force was evaluated using a loadstar sensor device at baseline,1 month, and 3 months from overdenture pickup.

Results: The obtained data revealed that bone loss in the mesial, distal, and average aspects of the PEEK group was significantly higher than the chrome cobalt bar group. For the buccal and lingual aspects, the difference was not statistically significant. Results of intergroup comparisons for biting force values presented that for peak and total biting forces, the PEEK group had significantly higher values. However, the difference between groups was not statistically significant.