Effects of water-aging on self-healing dental composite containing microcapsules

Abstract

Objectives The objectives of this study were to develop a self-healing dental composite containing poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT) as healing liquid, and to investigate the mechanical properties of the composite and its self-healing efficacy after water-aging for 6 months. Methods PUF microspheres were synthesized encapsulating a TEGDMA-DHEPT healing liquid. Composite containing 30% of a resin matrix and 70% of glass fillers by mass was incorporated with 0%, 2.5%, 5%, 7.5% and 10% of microcapsules. A flexural test was used to measure flexural strength and elastic modulus. A single edge V-notched beam method was used to measure fracture toughness (KIC) and self-healing efficacy. Specimens were water-aged at 37 °C for 1 d to 6 months and then tested for self-healing. Fractured specimens were healed while being immersed in water to examine self-healing efficacy, in comparison with that in air. Results Incorporation of up to 7.5% of microcapsules into the resin composite achieved effective self-healing, without adverse effects on the virgin mechanical properties of the composite (p > 0.1). An excellent self-healing efficacy of 64%–77% recovery was obtained (mean ± sd; n = 6). Six months of water-aging did not decrease the self-healing efficacy compared to 1 d (p > 0.1). Exposure to water did not decrease the healing efficacy, compared to that healed in air (p > 0.1). Conclusions A composite was developed with excellent self-healing efficacy even while being immersed in water. The self-healing efficacy did not decrease with increasing water-aging time for 6 months. Clinical significance The novel self-healing composite may be promising for dental applications to heal cracks, resist fracture, and increase the durability and longevity.

Dental Composite Formulation Design with Bioactivity on Protein Adsorption Combined with Crack-Healing Capability

“…Efficient self-healing has been also demonstrated in previous studies using the applied method of fabrication of microcapsules [ 29 , 31 ]. The microencapsulated healing is quite stable and durable, which broadens the process window for fabricating self-healing composites and prevents the deterioration of the healing capability of the composites during storage [ 32 ]. The successful demonstration of this healing system will open pathways for healing in dental composites.…”

“…The amount of protein adsorbed on the composite discs was determined by the micro bicinchoninic acid method [ 32 ]. Six disks were evaluated for each group.…”

Trends in restorative composites research: what is in the future?

“…Reports on the use of poly(urea formaldehyde) microcapsules (average diameter: 70 µm) filled with TEGDMA and a tertiary amine (N,N-dihydroxyethyl-p-toluidine, DHEPT) as activator in experimental composites were recently published. 60,61,62 This self-repair system uses benzoyl peroxide (BPO) added to the resin matrix as initiator to polymerize the healing liquid. In the first study, 62 these microcapsules were added to a BisGMA-TEGDMA resin.…”

“…61 Healing efficiency of composites with 7.5% of TEGDMA-DHEPT microcapsules was not affected by prolonged water storage of the specimen prior to initial K 1c test (up to six months), or when healing took place in water. 60 A self-healing dental composite (or, more precisely, a compomer) based on glass ionomer cement chemistry was recently developed. 52 Silanated silica microcapsules filled with an aqueous solution of polyacrylic acids (average diameter: 29 µm) were prepared and dispersed in an experimental composite containing a photocurable BisGMA/HEMA matrix and 70 wt% of strontium fluoroaluminasilicate glass particles.…”

Development of an Innovative Urease-Aided Self-Healing Dental Composite

“…Once cracking occurs, its propagation ruptures the shells and finally the healing materials flow as a result of capillary action to seal the crack. In this context, Wu et al [11] employed urea-formaldehyde to encapsulate N,N-Dihydroxyethyl-p-toluidine (DHEPT) and triethylene glycol dimethacrylate (TEGDMA) for developing a self-healing dental composite. It was found that the incorporation of 7.5% healing microcapsules results in only 64%-70% recovery.…”