Why can fatigue and thermal cycling cause dental resin composite restorations to fail?

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advanced structural ceramics Figure 1: Resistance to cracking in transformation-toughened zirconia. In a ceramic composed of tetragonal zirconia dispersed in a zirconia matrix, the stress field advancing ahead of a propagating crack transforms the small tetragonal particles to larger monoclinic particles. The larger particles exert a crack-closing force in the process zone behind the crack tip, effectively resisting propagation of the crack.

Dental resin composite restorations often fail because fatigue and thermal cycling compromise the integrity of the interface between the composite material and the natural tooth structure.1

In the context of materials science, these restorations consist of a resin binder and ceramic filler particles. Over time, the bond between these filler particles and the matrix can break down, leading to degradation. When subjected to the mechanical stresses of fatigue and the temperature fluctuations of thermal cycling, the connection between the composite and the tooth is weakened. This loss of interfacial integrity creates gaps that allow for the development of secondary caries, or cavities, ultimately leading to the failure of the restoration.1

While resin composites are valued for their aesthetic properties, they currently lack the long-term durability of traditional dental amalgams, particularly when used in posterior restorations.1