The present invention relates to fiber-reinforced composites, particularly application-oriented composites useful in dental and medical applications/appliances, such as fiber reinforced dental composites, and to a method for the manufacture thereof. Particularly the invention concerns random glass fiber-reinforced restorative composite resins with semi-interpenetrating polymer network matrix and their use in dental applications like cavity fillings, core composites, provisional and semi-permanent crown and bridge composite, cements and adhesives.