Preheated composite resin emerged as a response to the degradation of dual resin cement over time, seeking to reduce the percentage of indirect restorations that failed due to restoration detachment.

Sixty Z250 composite resin cylinders (3M, USA) measuring 0.8 mm in diameter and 2 mm in length were attached to 15 Z350 resin sheets (3M, USA) in three experimental groups (n=20). RelyX Ultimate Clicker dual resin cement (3M, USA) was used for the control group, Z350 A2 composite resin (3M, USA) preheated to 60°C for 15 minutes was used for the preheated resin group, and Bulk Fill Flow fluid resin (3M, USA) was used for the fluid resin group. After 24 hours, 10 samples were randomly selected from each group and tested in a universal testing machine at a speed of 0.5 mm/minute. The remaining test specimens were aged in a Vítale class CD autoclave (Cristofoli, Brazil) for 6 cycles at 135°C at 0.23 MPa, to be tested. The data were collected in an Excel spreadsheet. The data were analyzed using ANOVA and T-tests.

The dual resin cement presented the highest absolute values both before and after aging, while the flowable resin showed the lowest values. The preheated resin showed a moderate reduction in bond strength, remaining in an intermediate range between the other materials.