Which term describes the agent that triggers polymerization when exposed to light in light-cured composites?

Which term describes the agent that triggers polymerization when exposed to light in light-cured composites?

• A. Catalyst
• B. Base
• C. Photoinitiator
• D. Filler

Answer: (C)

When a light-cured composite polymerizes, the trigger is a photoinitiator. This substance absorbs the blue light and forms reactive species (free radicals) that start the chain-growth polymerization of the resin’s methacrylate monomers. The radicals initiate cross-linking, turning the paste into a hard, solid composite. A common example is camphorquinone, which works with a co-initiator to efficiently produce these radicals. The other terms don’t fit because a catalyst is a general accelerator not specifically activated by light in this system, the base is part of the resin composition but not the initiating trigger, and the filler provides structure and radiopacity rather than initiating polymerization.

When a light-cured composite polymerizes, the trigger is a photoinitiator. This substance absorbs the blue light and forms reactive species (free radicals) that start the chain-growth polymerization of the resin’s methacrylate monomers. The radicals initiate cross-linking, turning the paste into a hard, solid composite. A common example is camphorquinone, which works with a co-initiator to efficiently produce these radicals. The other terms don’t fit because a catalyst is a general accelerator not specifically activated by light in this system, the base is part of the resin composition but not the initiating trigger, and the filler provides structure and radiopacity rather than initiating polymerization.