Orthodontic thermoformed retainers: a two-arm laboratory study into post-fabrication outcomes.

Thermoformed retainers do no thin uniformly against individual teeth and have variable intra- and inter-arch post-fabrication thicknesses. There is no clear benefit in using a specific type of thermoforming machine or material for increasing post-fabrication thickness or reducing thinning rate. Blank thickness and tooth morphology influence these outcomes.