Tensile Peel Strength Versus Fracture Toughness of Luting Cements

Objectives: The purpose of this study was to explore the possible correlation between the fracture toughness of different luting cements and their tensile peel strength. Materials and methods: Six cements were investigated; two chemically adhesive resin cements (Super-Bond C&B and Panavia 21), one compomer cement (Dyract Cem), two resin-modified glass ionomer cements (Fuji Plus and RelyX Luting), and one conventional glass ionomer cement (Ketac Cem). The tensile peel strength (TPS) was investigated by bonding grit-blasted Ni/Cr alloy beams to a block of the same alloy using the different types of luting cements (n = 20 for each cement), leaving half the length of the beam suspended. Beams were pulled off the block with a peeling action by applying a tensile load to the free end of the beam and the load at failure was recorded. The values of the tensile peel strength were compared with the known fracture toughness values of these cements taken from the dental literature. Results: A direct relationship was found between the fracture toughness of the luting cements and their TPS. The linear regression analysis showed that the correlation coefficient (r) is equal to 0.94 and 0.98 when compared with 24 hours and 7days fracture toughness data respectively Conclusion: Luting cements with a higher fracture toughness has a higher tensile peel strength and thus better potential for retention of a resin bonded bridge.