A 20-year split-mouth comparative study of two screw-shaped titanium implant systems.

Purpose: To prospectively assess marginal bone loss and implant survival with Astra Tech (Dentsply Sirona, Charlotte, NC, USA) (group A) and Brånemark (Nobel Biocare, Zurich, Switzerland) (group B) implants in a split-mouth study conducted over a 20-year follow-up period.

Materials and methods: A total of 95 implants (n = 50, group A and n = 45, group B) were randomly placed in the left or right side of the maxilla or mandible in 18 patients. Clinical and radiographic examinations were performed, and results were reported at 5, 10, 15 and 20 years after insertion of the prosthesis.

Results: Ten patients were followed up for 20 years (n = 26 implants, group A and n = 25 implants, group B). No implant loss or prosthetic failures were observed. After 20 years of follow-up, no significant differences in marginal bone loss were found between both implant groups (P = 0.25). The proportion of marginal bone loss ≥ 0.5 mm was not significantly different between implant types (P > 0.05), and no statistically significant relationships were found between marginal bone loss and time (P ≥ 0.05). More specifically, there was no significant difference in marginal bone level between year 20 and baseline in group A (P = 0.70), whereas a difference of 0.5 to 1.0 mm was found in group B (P = 0.15).

Conclusions: After 20 years of follow-up, marginal bone loss around screw-shaped titanium implants was clinically insignificant. Furthermore, no significant differences in survival and marginal bone loss were found between group A and B implants over the follow-up period.