Long-term evaluation of implant-supported fixed dental prostheses (FDPs) with cantilever extension in posterior areas. A retrospective cohort study

DWPJZ ORAL COMMUNICATION CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY

Background: Despite the amount of evidence documenting the successful long-term use of osseointegrated dental implants to support fixed dental prostheses (FDPs), alternative implant-supported prosthetic solutions aiming at reducing patient's morbidity (i.e. FDPs with cantilever extension) have been proposed. However, some questions remain on the use of cantilever extensions in posterior areas where loading forces may jeopardize marginal bone levels or even implant survival.

Aim/Hypothesis: To report the clinical and radiographic outcomes of implant-supported fixed dental prostheses with cantilever extension (FDPCs) in posterior areas.

Materials and Methods: Partially edentulous patients comprehensively treated between November 1999 and March 2009 at the Department of Periodontology, University of Bern, Switzerland were enrolled. Patients had to to be rehabilitated with 2 osseointegrated dental implants in the canine or posterior areas of maxilla and mandible supporting a metal-ceramic FDPCs with a mesial or distal cantilever extension. After a follow-up of at least 10 years, patients underwent a complete clinical examination including radiographic evaluation of the peri-implant marginal bone levels (mBLs). Moreover, pocket probing depths (PPDs) and bleeding on probing (BoP) scores were assessed at 4 sites/implant (i.e. mesial, distal, oral, buccal). Biological and mechanical/technical complications were recorded.

Results: Twenty-six patients (12 M, 14 F) with a mean age of 72.2 ± 7.2 years rehabilitated with 60 dental implants supporting 30 metal-ceramic FDPCs, were included. Four patients (3 M, 1 F) were smokers. Seven implants (11.7%) had a diameter of 3.3 mm, 44 (73.3%) a diameter of 4.1 mm and 9 (15%) a diameter of 4.8 mm. All except one cemented FDPCs were in function for a mean of 13.3 ± 2.7 years. After 11.3 years, one patient lost one implant due to fracture yielding a patient-based implant survival rate of 96.2%. Peri-implant health was diagnosed in 12 (46%), peri-implant mucositis in 7 (27%) and peri-implantitis in 7 (27%) patients, respectively. The most frequent technical complication was loss of retention observed ≥ 1x in 9 patients (34.6%). No statistically significant change (P > 0.05) in overall mBL from 1.2 mm ± 0.9 at baseline to 1.6 mm ± 1.7 at follow-up was observed. The overall PPD changed statistically significantly from 3.4 mm ± 0.7 at baseline to 3.7 mm ± 0.7 at follow-up (P = 0.02).

Conclusions and Clinical Implications: Within the limits of the present study, 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.

Keywords: Dental implants, Bone loss, Biological complications, Cantilever extensions, Fixed dental prostheses.