Purpose: To determine the fracture strength and stress distribution of esthetic dental implant abutments.
Materials and methods: Fifty specimens were prepared. Four hybrid abutment groups with titanium bases (zirconia [Z], lithium disilicate [L], ceramic-reinforced polymer [B] and [BC]) and a custom titanium abutment control group (T) were restored with monolithic zirconia crowns except BC, which was crowned with layered composite. Ceramic abutments were cemented on Ti bases with a self-curing resin cement. Polymer abutments were cemented on Ti bases with an adhesive resin cement. All crowns for T, Z, and L were cemented with another self-adhesive resin cement, while the B and BC groups were cemented with the same adhesive resin cement for the polymer. Fatigue testing was performed by a chewing simulator (CS-4.2, SD, 50 N, 240,000 cycles) followed by fracture strength testing (0.5 mm/min, 5,000 N). Failure type analysis was made by a stereomicroscope. Statistical analyses were made (SPSS 25.0, analysis of variance [ANOVA], Tukey honestly significant difference [HSD], 95% CI). Complementary finite element analyses (FEAs) were performed (Algor Fempro).
Results: Mean ± SD fracture strengths for T, Z, L, B, and BC were 1,522.67 ± 190.77, 1,207.76 ± 89.03, 818.81 ± 109.96, 1,126.23 ± 142.23, and 899.08 ± 60.36, respectively (P < .05). Abutment screw flexure and/or cracks or crown material fractures for T, Z, L, and B occurred, while no implant and/or abutment fractures were observed for BC except for crown fracture and Ti base flexure. FEA exhibited similar stress concentrations.
Conclusion: Monolithic zirconia crowns on titanium abutments and hybrid zirconia abutments exhibited the highest fracture strengths. Lithium disilicate and BioHPP abutments had the lowest fracture strength, while no fractures were observed on the implant, abutment, or screw.
