High-aspect ratio fillers: Fiber-reinforced composites and their anisotropic properties

To present an overview of fiber-reinforced composites (FRCs) that are a group of non-metallic dental biomaterials used in several fields of dentistry. A range of relevant publications from the past half century are surveyed, with emphasis upon recent publications. FRCs vary according to the type of fiber fillers and orientation of fibers, the latter being responsible for several properties which can vary from isotropic to anisotropic. The length of the fibers, i.e. the aspect ratio of the filler, is another factor or variable that contributes to the properties and the development of new types of composite resins for restorative and prosthetic dentistry, as well as to reconstructive medicine. Understanding the anisotropic nature of FRCs from the perspective of dental applications has increased in recent years. This review describes some fiber orientation related anisotropic properties of FRCs which contribute to the increased use of FRCs in clinical dentistry.