PROBLEM TO BE SOLVED: To solve the problem in which, when free radical polymerization of vinyl monomers such as (meth)acrylic acid derivative monomers used for a dental composite resin forms and cures a polymer by cleaving a carbon-carbon double bond to form single bonds, these polymerization systems have problems of oxygen inhibition resulting in radical-scavenging (hyporeactivity), high contractility, a low reaction rate caused by rapid gelation expression in the beginning of the polymerization, and their resultant network heterogeneity and the like, that is, (meth)acrylic acid derivative monomers lose flowability by instantaneous initiation of radical polymerization via a polymerization initiator activated by applied external energy such as light irradiation, causing a majority of unpolymerized monomers to remain, which is a factor causing mechanical strength degradation of medical and dental restorations.SOLUTION: Functional composite fine particles having both covalent and hydrogen bonding properties are
