Clinical and radiographic outcomes of implant-supported fixed dental prostheses with cantilever extension. A retrospective cohort study with a follow-up of at least 10 years

Aim To report the clinical and radiographic outcomes of implant-supported fixed dental prostheses with cantilever extensions (FDPCs) after a function time >= 10 years. Material and methods Patients with FDPCs in posterior areas were clinically and radiographically re-evaluated. Mesial and distal radiographic marginal bone levels (mBLs) from baseline (i.e. delivery of FDPC) to the follow-up examination were calculated and compared between implant surfaces adjacent to and distant from the cantilever extension. Implant survival rate, pocket probing depth (PPD), presence/absence of bleeding on probing (BoP) and presence/absence of mechanical/technical and biological complications were recorded. Results Twenty-six patients with 30 FDPCs supported by 60 implants were re-evaluated after a mean loading time of 13.3 +/- 2.7 years (range: 10-18.6 years). One diameter-reduced implant carrying a cantilever extension fractured, yielding a patient-based survival rate of 96.2% (95% CI: 0.95/1.0). The mean marginal bone level change was not statistically significantly different from baseline to follow-up (1.2 mm +/- 0.9 to 1.6 mm +/- 1.7; 95% CI: -0.1/0.9;p > .05). The mean PPD changed statistically significantly from 3.4 mm +/- 0.7 to 3.7 mm +/- 0.7 (95% CI: 0.04/0.6;p = .02). Loss of retention occurred >= 1x in 9 patients (34.6%, 95% CI: 0.44/0.83). At follow-up, peri-implant health was diagnosed in 12 (46.2%), peri-implant mucositis in 7 (26.9%) and peri-implantitis in 7 (26.9%) patients, respectively. Conclusion Despite a high rate of loss of retention, the use of implant-supported FDPCs in posterior areas represents a reliable long-term treatment option with a high implant survival rate and minimal peri-implant bone level changes irrespective of the location of the cantilever extension.