There is limited dental literature evaluating the retentive capabilities of luting agents when used between metal components, such as cast metal restorations cemented onto machined metal implant abutments. This study compared the retentive strengths of 5 different classes of luting agents used to cement cast noble metal alloy crowns to 8-degree machined titanium cementable implant abutments from the Straumann ITI Implant System. Sixty prefabricated 5.5-mm solid titanium implant abutments and implants were used; 30 received the standard surface preparation and the other 30 received an anodized surface preparation. Anodized implant components were used to reflect current implant marketing. Sixty castings were fabricated and randomly paired with an abutment and implant. A total of 12 castings were cemented onto the implant abutment assemblies for each of the 5 different luting agents (zinc phosphate, resin composite, glass ionomer, resin-reinforced glass ionomer, and zinc oxide¨Cnon-eugenol). After cementation, the assemblies were stored in a humidor at room temperature prior to thermocycling for 24 hours. Each casting was pulled from its respective abutment, and the force at which ond failure occurred was recorded as retentive trength. A statistically significant difference was ound between the 5 cements at P ¡Ü .001. Of the cements used, resin composite demonstrated the highest mean retentive strength. Zinc phosphate and resin-reinforced glass-ionomer cements were the next most retentive, while glass ionomer and zinc oxide¨Cnon-eugenol cements demonstrated minimal retention. In addition, retention was not altered by the use of an anodized abutment surface. Keywords: cemented implant restorations, dental cements, dental implants