| Intraoral preparation of zirconia implant abutments creates deep surface defects making abutments susceptible to fracture during loading. Fracture strengths were tested for (1) HIP-processed zirconia bars (Astra-Tech) after preparation and/or surface repair treatments: no preparation (NP), dry-preparation (DP), wet-preparation (WP), or wet-preparation and 30d water storage (WP+30d), mitigating treatment of bonding agent (WP+B), sandblasting (WP+SB), or polishing (WP+P), and (2) abutment-assemblies (preparations of 0, 0.5, or 1 mm margin reduction).; NP established the strength for pristine zirconia bars (1634+/-95MPa). DP (1144+/-109MPa), WP (1442+/-89MPa), WP+30d (1193+/-155MPa), and WP+B (1218+/-77MPa) groups had significantly (p≤0.05) reduced strengths. WP+SB (1632+/-134MPa) or WP+P (1664+/-176MPa) repairs equally well recovered original strengths (p<0.001).; There were no statistically significant differences (p>0.05) among different abutment-assembly groups and no logical relationship of strength to increasing amount of reduction. All fractures occurred at the interface where the abutment was connected to the analog, suggesting that fracture was unrelated to the actual abutment. |
