Clinical evaluation of a prospective multicenter study on 1-piece implants. part 1: marginal bone level evaluation after 1 year of follow-up.

PURPOSE

The aim of the present investigation was to evaluate the marginal bone level after 1 year of follow-up of 1-piece implants after immediate provisional restoration fabrication.

MATERIALS AND METHODS

Patients received NobelDirect and NobelPerfect 1-piece implants (Nobel Biocare, G6teborg, Sweden) that were immediately restored and placed into function as part of a 3-year, multicenter investigation. Life table analysis was used for evaluation of implant cumulative survival rates. The Student t test (for dichotomous variables) and Pearson correlation (for continuous and ordered categorical variables) were used to estimate the influence of separate parameters on marginal bone.

RESULTS

Eighty-seven patients received 152 NobelDirect or NobelPerfect 1-piece implants. Of these, 81 patients returned for the 1-year follow-up and 21 for the 2-year follow-up. Three implants were lost, resulting in a cumulative survival rate of 97.9% after up to 2 years. The average marginal bone level at implant placement was 0.33 mm (SD 1.20, n = 141) superior to the reference point (lower edge of the implant collar). Marginal bone level was -0.77 mm (SD 1.33, n = 138) at 6 months and -0.98 mm (SD 1.38, n = 123) at 1 year. Average bone level at the 2-year follow-up was 0.17 mm (SD 1.20, n = 26). After 1 year of loading, bone level in the maxilla was more apical compared to that in the mandible (P = .05), and a positive correlation was found between bone level at placement and bone level at 12 months (P = .008). Shallow implant positioning resulted in less marginal bone remodeling compared to deep implant positioning.

CONCLUSION

On the basis of this prospective multicenter study, stable marginal bone level and soft tissue support the hypothesis that the 1-piece implant has the capacity to preserve both hard and soft tissue.