Synthetic substrates as alternatives to bovine enamel in restorative dental materials research — A review

The aim of this integrative review was to investigate the use of non-animal derived substrates and models as alternatives to bovine enamel in restorative dental materials research. It included studies on the use of various synthetic alternatives to animal-derived enamel in such experimental research. Excluded from the review were: 1) reviews, clinical cases, letters, chapters, conference abstracts and editorials; and 2) studies assessing datasets, alternatives to other types of tissues such as dentin or bone, biomaterials in the context of enamel repair, and laboratory studies using substrates of animal and human origin without any comparison with enamel-like synthetic materials. It was demonstrated that calcium phosphate-based ceramics, multiscale materials, 3D-printed and hydroxyapatite-based materials have the capability to emulate the mechanical and chemical properties of dental enamel. However, these materials have inherent limitations, with some needing further investigation in order to understand their responses in certain laboratory tests. Even so, some materials appear promising and have already performed well with regard to the most relevant aspects that are commonly evaluated in testing. It is thus recommended that new studies prioritise the use of such synthetic substitutes as standard in laboratory protocols whenever possible, in order to gradually abandon the use of animal-derived tissues and transition to a more ethical science without contributing to animal exploitation by acquiring bovine teeth from abattoirs.