<p>A method of cosmetically whitening teeth in vivo comprises exposing the teeth to be whitened to a flow of non-thermal gaseous plasma or at a temperature acceptable for oral administration of the non-thermal gaseous plasma and for a time sufficient for the non-thermal gaseous plasma to have a tooth- whitening effect. Repeated treatments may be performed. The non-thermal gaseous plasma may be formed of helium or a mixture of helium and oxygen.</p>
