Benzoyl peroxide encapsulation in poly(urea‐formaldehyde) microcapsules for use in dental materials

New self‐healing resin composites with tertiary amine microcapsules enhance the mechanical performance of dental restorations. However, a higher concentration of dibenzoyl peroxide (BPO) must be added to the composite to react with the core material when the microcapsules rupture, reducing the shelf life of dental materials due to their reactivity. As a result, one approach to reducing the amount of BPO dissolved in dental resin is to microencapsulate it. Thus, this manuscript described the encapsulation of BPO in poly(urea‐formaldehyde) (PUF) microcapsules (MC) and investigated its effect on the flexural strength of BisGMA/TEGDMA composites. To synthesize hollow MC, poly(acrylic acid) (PAA) was tested as a continuous phase viscosity modifier. The MC were then infiltrated with BPO dissolved in linseed oil as core materials. PAA in continuous phase increased MC diameter due to improved air bubble stability. BPO dissolved in linseed oil was successfully infiltrated into empty PUF MC, causing the MC shell wall to expand. The dental resin had adequate adhesion to the PUF shell, which ruptured under induced stress. Thus, the MC filled with BPO as a healing agent has the potential to reduce the amount of BPO that is typically dissolved in the monomeric phase of dental materials, which can increase the shelf life of self‐healing dental materials. Highlights The reactivity of dibenzoyl peroxide (BPO) affects resin stability in dental materials. When combined with tertiary amines, BPO acts as a healing agent in self‐healing composite materials. BPO dissolved in linseed oil can be infiltrated in PUF microcapsules and increase its size. Hollow microcapsules synthesized in a more viscous continuous phase have a larger diameter. Microencapsulated BPO is released during stress stimuli in dental resin. Schematically illustration of experimental steps to produce empty and filled microcapsules of PUF filled with dissolved benzoyl peroxide.