Microhybrid

Microhybrid is a class of resin-based dental composite used for direct tooth-colored restorations. It combines microfill particles with larger hybrid fillers to balance the aesthetic qualities of microfill materials with the strength and wear resistance of hybrids, making it suitable for a range of clinical situations.

Typical composition includes a resin matrix (commonly Bis-GMA, UDMA, and TEGDMA) and a diverse inorganic filler system comprised of microfill particles and larger filler spheres, often silica or glass. The filler loading is generally high, around 75-85 percent by weight, and the particles are silanated to improve bonding with the resin matrix. The combination of particle sizes helps achieve good polishability while maintaining adequate strength for everyday chewing forces.

Properties of microhybrids include good surface gloss and color stability, with better wear resistance than traditional microfill composites and improved strength compared with pure microfill systems. They exhibit relatively low polymerization shrinkage stresses and are typically radiopaque, aiding postoperative radiographic assessment. Handling characteristics are described as smooth and sculptable, allowing precise contouring and finishing.

Indications for microhybrids cover a wide range of direct restorations, including anterior aesthetics and posterior, moderately stressed areas. They are commonly used for Class I–III restorations and some Class IV cases where esthetics and durability are both important. Limitations may include potential staining over time if surfaces are not properly finished or maintained, and, in high-stress posterior applications, some practitioners may opt for newer nanohybrid or ormocer-based systems with enhanced properties.