What substance is included in composites to facilitate the polymerization process?

Camphor quinone is a photosensitizer that plays a crucial role in the polymerization process of composite materials. When used in dental composites, it absorbs light energy, typically from a curing light, and initiates the polymerization reaction. This process transforms the composite material from a pliable state into a hardened one, allowing for superior bond strength and durability.

The other options are not involved directly in the polymerization process. Silicate, while used in some dental materials, does not facilitate polymerization. Resin modified glass ionomer is a type of material that has its own set of properties and uses but is not specifically a substance that aids in the polymerization of composites. Tetracycline is an antibiotic and has no functional role in the composite curing process. Thus, camphor quinone's specific function in initiating the polymerization makes it the appropriate choice.