Resin composites are popular materials to fill tooth cavities due to their esthetics and direct-filling capabilities. However, the materials are susceptible to micro-cracking brought on by thermal and mechanical stresses resulting from strong occlusal (chewing and clenching) forces. These micro-cracks can result in secondary caries formation and bulk fracture of the composite materials, limiting the service lifetime of dental restorations. Repair usually requires complete replacement of the resin filler material. There is therefore interest in developing self-healing materials that can extend the service life of dental restorations.