Bending moments of zirconia and titanium abutments with internal and external implant-abutment connections after aging and chewing simulation

Abstract

Objectives: To test the fracture load of zirconia abutments with different types of implant-abutment connections after chewing simulation and to compare their bending moments to internally connected identical titanium abutments.

Materials and methods: Forty-eight identical customized zirconia abutments with different implant-abutment connections were fabricated for four different test groups: one-piece internal implant-abutment connection (BL; Straumann Bonelevel), two-piece internal implant-abutment connection (RS; Nobel Biocare Replace Select), external implant-abutment connection (B; Brånemark MK III), two-piece internal implant-abutment connection (SP; Straumann Standard Plus). Twelve titanium abutments with one-piece internal implant-abutment connection (T; Straumann Bonelevel) served as control group. After aging by means of thermocycling (5-50°C, 120 s) and chewing simulation (1,200,000 cycles, 49 N load, 1.67 Hz), static load was applied at a 30° angle to the palatal surface until failure. Bending moments were calculated for comparison of the groups. Data were analyzed descriptively and by performing the Kruskal-Wallis test with Bonferroni correction.

Results: The mean bending moments of the abutments were 714.1 ± 184.9 N cm (T), 331.7 ± 57.8 N cm (BL), 429.7 ± 62.8 N cm (RS), 285.8 ± 64.4 N cm (B) and 379.9 ± 59.1 N cm (SP). The bending moments of control group T were significantly higher than those of all other groups. The values of group RS were significantly higher than those of group B but within the value range of groups SP and BL.

Conclusion: The bending moments of the different tested types of zirconia abutments vary with different implant-abutment connections after chewing simulation. The use of a secondary metallic component might have a beneficial influence on the stability of zirconia abutments.