This in vitro study evaluated the effect of thermocycling and mechanical loading (TCML) on the fracture strength of metal-ceramic and all-ceramic cantilever resin-bonded fixed dental prostheses (CRBFDPs). The fracture patterns of the restorations were also assessed. A total of 40 CRBFDPs were fabricated from either base metal alloys or glass-infiltrated zirconia-reinforced aluminum oxide ceramic. The restorations were cemented using adhesive resin cement. Half of the specimens were subjected to TCML. The failure load and type of fracture pattern were evaluated by applying a 45-degree load 3 mm from the incisal edge of the pontics. TCML had a significant influence on the failure load of the tested prostheses (P = .0001). Metal-ceramic and all-ceramic CRBFDPs demonstrated significantly different fracture patterns, with metal-ceramic restorations showing the highest values. All restorations had the potential to withstand normal occlusal forces applied in anterior regions. TCML had a negative effect on the fracture strength of the tested prostheses. The primary mode of failure in the metal-ceramic group was debonding of the cement-to-tooth adhesive, while connector fracture was predominant in the all-ceramic group. (Am J Esthet Dent 2012;2:200–209.)