et al.[/i]\":3e5rnm5b]In our current study, we describe a fully functioning tooth replacement achieved by transplantation of a bioengineered tooth germ into the alveolar bone of a lost tooth region in an adult mouse. We propose this as a model for future organ replacement therapy. The bioengineered tooth, which was erupted and reached occlusion in the oral environment, had the correct tooth structure, hardness of mineralized tissues for mastication, and responsiveness to experimental orthodontic treatment and noxious stimulation in cooperation with tissues in the oral and maxillofacial regions. Our results thus demonstrate the potential of bioengineered organ replacement for use in future regenerative therapies.