Composite Materials in Dentistry

Composite materials represent the foundation of modern aesthetic dentistry. Their composition consists of three key components: an organic matrix, inorganic fillers that provide mechanical strength, and silane as a coupling agent that bonds the organic and inorganic phases. Polymerization initiators and inhibitors are responsible for initiating and controlling the curing reaction. The classification of composites is primarily based on filler particle size into macrofilled, microfilled, and hybrid types. They are also categorized according to consistency, curing method, and clinical application. Special groups include flowable and bulk-fill composites, as well as hybrid materials such as compomers, ormocers, and giomers.

Light polymerization is a critical step for achieving optimal material properties. It requires proper technique and adequate light sources, such as LED curing lights or lasers. During polymerization, the degree of monomer-to-polymer conversion is measured, during which undesirable polymerization shrinkage occurs. Material properties include solubility, aesthetic and mechanical properties, radiopacity, and water sorption, which affects the clinical longevity of restorations. Optical properties depend on the color and translucency of enamel and dentin, requiring precise shade selection and blending to mimic the natural tooth. Adhesive systems enable the bonding of the material to the dental tissue. The process involves acid etching of the enamel and the removal or modification of the smear layer. Adhesives are classified by generations and pH values into etch-and-rinse and self-etch systems. Finally, biological properties define the biocompatibility of composites with the pulpo-dentin complex and their resistance to degradation in the oral cavity, which is a prerequisite for long-term clinical success.