Cost-effectiveness of short implants (6–8.5 mm) compared to regular length implants (> 10 mm) with bone regeneration in posterior atrophic mandible: a 8-year microsimulation model

Abstract

Background: To evaluate the cost-effectiveness of short implants (6–8.5 mm) placed without guided bone regeneration (GBR) vs. regular length implants (> 10 mm) placed with vertical GBR for the rehabilitation of the posterior atrophic mandible (Seibert type II defects). Methods: A discrete-time state-transition microsimulation model was developed to compare two strategies over an 8-year horizon from a private-payer perspective. Clinical inputs were extracted from a recent meta-analysis of randomized trials, while unit costs were obtained from publicly available Chilean fee schedules and converted to 2025 USD using purchasing power parity. Outcomes included implant survival, biological and prosthetic complications, summarized as implant-years (IY) and complication-free IY (CFIY) as a stricter secondary measure. Incremental cost-effectiveness ratios (ICERs) were calculated. Uncertainty was addressed through one-way deterministic sensitivity analysis (OWSA), and probabilistic sensitivity analysis (PSA, 2,000 iterations). Results: Over an 8-year horizon, short implants were associated with lower mean costs (USD 3,662 vs. 6,030) and modestly greater effectiveness (6.77 vs. 6.49 IY; 6.71 vs. 6.27 CFIY) compared with regular-length implants with GBR, yielding incremental savings of USD 2,367 and incremental gains of 0.28 IY and 0.44 CFIY. OWSA identified initial implant costs as the most influential parameters. PSA across 2,000 iterations corroborated these findings, with the great majority of simulations falling in the south-east quadrant of the cost-effectiveness plane. Conclusions: Within the Chilean private-payer setting and over an 8-year horizon, single-tooth short implants (6–8.5 mm) placed without GBR were cost-saving and at least non-inferior in effectiveness compared with regular-length implants with vertical GBR for the posterior atrophic mandible. This cost advantage remained consistent across deterministic, probabilistic, and scenario analyses, although transferability to other settings requires re-estimation using local cost structures.