Purpose: The purpose of this study was to investigate the effect of resin cement type on the retentive strength of custom zirconia abutments bonded to titanium inserts. Materials and Methods: Sixty implant (4.3 mm diameter and 11.5 mm length) and custom zirconia abutment (15 mm height and 2 mm wall thickness) pairs were used to form six groups (n = 10 each). Three different resin cements were used to bond the zirconia abutments and titanium inserts: Panavia F 2.0, Zirconite, and Multilink Hybrid Abutment. Control groups and thermomechanically aged groups were formed. Specimens were subjected to tensile test to failure, and the retention values were analyzed by two-way analysis of variance (ANOVA). Results: Two-way ANOVA showed a significant effect of the cement type and thermomechanical aging (P < .05). Regardless of the cement, control groups showed significantly (P < .05) higher retentive strength than the thermomechanically aged groups. Comparing the resin cements, the retentive strength of Zirconite, aged or not, was higher than that of Panavia F 2.0 and Multilink Hybrid Abutment; no significant differences between the latter two cements were found. In the Zirconite group, adhesive failure occurred mostly between the titanium and the resin cement. In the Panavia F 2.0 and Multilink Hybrid Abutment groups, adhesive failure between the zirconia and the resin cement was observed. Conclusion: Resin cement type had an effect on the retentive strength of custom zirconia abutments bonded to titanium inserts. Thermomechanical aging had a negative effect on the retentive strength. Zirconite adhesively bonded to the zirconia surface of the custom abutment. Differences were noted in adhesive failure types among the cements.