Novel self-healing dental luting cements with microcapsules for indirect restorations

Dental luting cements are widely used to bond indirect restorations to teeth. Microcracks often lead to cement failures. The objectives of this study were to develop the first self-healing luting cement, and investigate dentin bond strength, mechanical properties, crack-healing, and self-healing durability in water-aging for 6 months.

Microcapsules of poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) as healing liquid were synthesized. Cement contained bisphenol A glycidyl dimethacrylate, TEGDMA, 4-methacryloyloxyethyl trimellitic and glass fillers. Microcapsules were added at 0%, 2.5%, 5%, 7.5%, 8.5%, 9.5% and 10%. Dentin shear bond strength was measured using extracted human teeth. Flexural strength and elastic modulus were measured. Single edge V-notched beams were used to measure fracture toughness (K_IC) and self-healing. Specimens were water-aged at 37°C for 6 months and then tested for self-healing durability.

Adding 7.5% microcapsules into cement achieved effective self-healing, without adverse effects on dentin bond strength and virgin mechanical properties (p>0.1). Excellent self-healing of 68%-77% recovery was obtained. Six months of water-aging did not decrease the self-healing efficiency, compared to 1 d (p>0.1), indicating that the self-healing property did not degrade in water-aging.

A self-healing dental luting cement was developed for the first time. It contained fine microcapsules and exhibited an excellent self-healing efficiency, even after being immersed in water for 6 months.

The self-healing cement is promising for cementing crowns and bridges and other adhesive cement applications, to heal cracks and increase restoration longevity.