Example of filler particle is/are:

Dispersed phase of composite resins is made up of inorganic filler material. Commonly used fillers are silicon dioxide, boron silicates and lithium aluminium silicates. In some composites, quartz is partly replaced with heavy metal particles like quartz, glass particles, zinc, aluminium, barium, strontium or zirconium.  Filler content ranges from 30% to 50% by volume and 50% to 85% by weight. Ref: Textbook of Operative Dentistry, Nisha and Amit Garg, 3rd edition, Pg no:253