Long-Term Bone Stability Assessment Around 1,187 Immediately Placed Implants with 1-to 22-Year Follow-up

Purpose: To evaluate the retention of bone around implants placed immediately following tooth extraction and used to support dental prostheses. Materials and Methods: Patients from a previous study of implants placed immediately following tooth extraction were recalled to the original practice to obtain dental radiographs, which were then used to compare bone levels after 1 to 22 years of clinical function supporting dental prostheses. All radiographs were evaluated by measuring the bone within the implant threads. Implant bone maintenance was correlated with smoking history, type of implant surface, antibiotics used in conjunction with surgery, bisphosphonate use, presence of splinted restorations, anatomical location (mandible or maxilla and anterior or posterior), sex, and past periodontal disease status. Statistical analysis was performed using the Mann-Whitney test for statistical significance of differences in mean bone loss. Results: A total of 1,187 implants were identified, with mean bone loss of 0.52 +/- 0.79 mm. Overall bone loss was less than 1.5 mm in 90% of the implants studied. Bone loss was greater in women (0.61 +/- 0.91 mm vs 0.44 +/- 0.69 mm in men; P = .002). There was a correlation between bone loss and patient age at the time of tooth loss, with patients below the age of 50 experiencing significantly more loss (mean loss, 0.76 +/- 1.07 mm at age < 50 and 0.46 +/- 0.71 mm at age > 50; P = .008). Other significant differences were seen with implant surface (machined surface, 0.57 +/- 0.77 mm; roughened surface, 0.44 +/- 0.84 mm; P = .0049), maxilla vs mandible in molar areas (maxilla, 0.68 +/- 0.83 mm; mandible, 0.43 +/- 0.80 mm; P = .0001), and platform width (regular, 0.46 +/- 0.77; wide, 0.83 +/- 0.94 mm; P <= .0001). None of the other factors demonstrated significant differences. Conclusions: Bone loss of 1.5 mm or less was observed in 90% of the patients followed. Bone loss was correlated with age, sex, implant surface, anatomical location, and platform width. There was no statistical correlation between bone loss and any other factors evaluated.