Abstract: This apparatus is of the type comprising a hand instrument (5) adapted to perform a sandblasting operation by projecting a powder onto the teeth, combined with a rinsing operation by projecting a liquid.According to the invention, the powder (300) is contained in a first receptacle (3) in which it is suspended in compressed air, whereas the rinsing liquid (400) is contained in a second receptacle (4), and there is provided a single compressor (1) which supplies compressed air to the two receptacles (3, 4), conduits (30, 40) transferring respectively the powder suspended in the compressed air and the liquid to the hand instrument (5), from where the two flows of treatment are projected by means of an intrabuccal cannula (51).