Methods: According to anatomical conditions two or four implants were inserted to intraforaminal region of 36 edentulous patients. A total of 84 implants: 38 ITI (Institut Straumann AG Waldenburg, Switzerland), 22 SwissPlus (Zimmer Dental Inc. Calsbad, USA), 24 Astra (Astratech AB, Molndal,Sweden) were inserted. Patients were recalled at 6, 12, 24, 36, 48, 60 months. During these controls implants were examined clinically and radiographically. In clinical evaluations plaque index, sulcus bleeding index, periodontal pocket depth (PD), and marginal bone level (MBL) examinations were done. The patients' own appreciation of the implant and the prosthetic therapy were also evaluated. Kruskal Wallis Test and Wilcoxon Signed Rank Test were used for statistical analysis.
Results: The cumulative implant survival rate after 60 months of loading was 100%. The peri-implant soft tissues were clinically healthy. There were significant differences in PD between 3 implant groups(p<0.05). PD of Astra group was significantly higher than ITI and Swiss group (p<0.05). Observed peri-implant bone loss was in the clinically acceptable levels. There were significant differences among the three groups for MBL scores between baseline and 5 years (P<0.05). MBL of ITI group was significantly lower than Astra and Swiss group (p<0.05). In 60 months of evaluation period most common prosthetic complication was the dislodgement of the female attachment part and fracture of the acrylic portion above the attachment.
Conclusion: For patients with a severely resorbed mandible, overdentures retained by dental implants appear to provide a satisfactory solution.