Microfilled

Microfilled refers to a class of materials that incorporate micro-scale filler particles into a resin matrix. In dentistry, microfilled composite resins use very small inorganic fillers, typically colloidal silica or glass, with particle sizes around 0.04 to 0.4 micrometers. This small particle size enables a smooth, highly polishable surface and is associated with superior esthetics, particularly for the anterior dentition. Filler loading is relatively low, on the order of 35–60% by volume, which helps maintain a lower modulus of elasticity and excellent polish, but can reduce strength and wear resistance compared with higher-filled systems.

Compared with hybrid composites, microfilled resins exhibit higher resin content, greater polymerization shrinkage, increased water sorption, and lower wear resistance. As a result, they are generally less suitable for load-bearing posterior restorations but have historically been favored for cosmetic anterior restorations and veneers. The category emerged in the late 20th century and has been largely supplanted for many applications by hybrid and nanofilled composites, though microfilled formulations are still used where surface polish and esthetics are prioritized.

In addition to dental applications, the term microfilled can describe other materials that use micro-scale filler particles, emphasizing surface finish and polishability. The concept contrasts with macrofilled, hybrid, and nanofilled systems, which aim to improve strength, wear resistance, and other mechanical properties by altering filler size, loading, and distribution.