Designing Novel Dental Composite With Protein-repellent and Autonomous Crack-healing Capabilities

Objectives: Fracture and secondary caries are primary reasons for dental restoration failures. Objectives: The objectives of this study were to: (1) develop a new protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine (MPC) that also has the ability to self-heal and recover the load-bearing capability via microencapsulated triethylene glycol dimethacrylate (TEGDMA) and N, N-dihydroxy ethyl-p-toluidine (DHEPT), and (2) evaluate protein adsorption, bacteria growth, and mechanical properties including self-healing efficacy.
Methods: Methods: Microcapsules of poly(urea-formaldehyde) (PUF) were synthesized incorporating a TEGDMA–DHEPT healing liquid. The composite contained 30% of resin matrix, 70% glass fillers and 10% microcapsules, with 7.5% of MPC in resin matrix. Mechanical properties were measured in three-point flexure. A single edge V-notched beam method measured fracture toughness (K_IC) and self-healing efficiency. Protein adsorption onto the composite was determined by a micro-bicinchoninic acid method. A human saliva microcosm biofilm model was tested on the composites.
Results: Results: The two distinct advantages of strong protein-repellency and self-healing load-bearing recovery were achieved by this strategy. The new composite had a self-healing efficiency of up to 71%. The K_IC values before and after healing were 0.76±0.08 and 0.60±0.05 MPa×m^1/2 (mean±sd; n=6), respectively. Its flexural strength matched commercial control composite (p>0.1). The incorporation of 7.5% MPC imparted a strong protein-repellent capability to the new composite, achieving the lowest protein adsorption of (0.30±0.01) µg/cm², which was only 5% that without MPC (5.10±0.55) µg/cm² (p<0.05). Oral bacteria attachment was greatly reduced on the surfaces of the new composite, compared to control (p<0.05).
Conclusions: Conclusions: The novel composite with a combination of protein-repellent MPC and self-healing PUF-microcapsules for healing cracks is a promising strategy for dental restorations to overcome the two main challenges of fracture and secondary caries. The new composite with greatly reduced bacteria growth and strong crack-healing ability is promising to improve the longevity of dental restorations.