Static and fatigue behavior of one- and two-piece zirconia implant abutment systems: an in vitro study

To compare static fracture behavior, fatigue survival, and fracture patterns of three one- and two-piece zirconia implant abutment systems.

Three groups comprised 48 assemblies each: (1) Astra Tech ZirDesign, one-piece zirconia; (2) Biomet 3i CAP454, two-piece zirconia with a titanium base; and (3) Straumann RC Anatomic, one-piece zirconia. Within each group, 12 assemblies underwent initial static testing and 12 each underwent fatigue at 25%, 50%, or 75% of the system-specific reference load (10 Hz, approximately 30°, five million cycles). Static outcomes underwent one-way and Welch analyses of variance; pooled run-out proportions underwent exact tests (α = 0.05).

Mean static fracture loads were 1058 ± 225 N (Astra Tech), 866 ± 189 N (Biomet 3i), and 873 ± 402 N (Straumann), without a significant difference (p = .194). Calculated tensile-side stress differed (p = .016); compressive-side findings were method-dependent. Run-out was 88.9% at 25% (32/36; 95% confidence interval, 73.9%-96.9%) and 0% at higher levels (p < .001). Residual fracture outcomes described survivors only. Fractography indicated brittle cervical failure.

Static fracture-load superiority was not demonstrated. Fatigue run-out varied with relative loading; modeled stress differences do not establish intrinsic material-strength differences.

These system-specific laboratory results cannot isolate an independent titanium-base effect or establish clinical service life.