Device for the reduction of microorganisms containing a radiation apparatus that has a light source (26) and a first connection body (50) as well as at least one applicator containing a light conductor (2) surrounded by a protective jacket (4) and a second connection body (6) by means of which the applicator is detachably connected to the radiation apparatus through its first connection body (50), in which case the connection bodies (50, 6) they are engaged in such a way that the light from the light source (26) can be emitted by the light conductor (2) over an area undergoing therapy, on which a light activatable substance has been applied for therapy, characterized by the ability to be used for the therapy of an area of the oral cavity such that the light conductor (2) has a numerical aperture greater than 0.5 and has a free end (18, 22) of protective jacket ( 4), in which case the ray of light coming out of the co opens well Light nductor (2), because the dimensions of the applicator are defined in such a way that it can be inserted into the oral cavity and is designed as a bagged probe with sanded conical tip or as an area probe, because the radiation apparatus has a housing tube (42) and a head part (50) disposed at its front ends, which is designed as the first connecting body, because the light source e (26) and on the front part of the casing tube (42) are arranged and an electronic device stage (84) with a key (56) that can be operated from outside, and because in the housing tube (42) batteries (70) or accumulators are also provided for the power supply of the electronic part for the source of light (26), in which case a cover (46) is connected detachably to the rear end of the housing tube (42) through a threaded connection.Dispositivo para la reducción de microorganismos que contiene un aparato de radiación que tiene una fuente de luz (26) y un primer cuerpo de conexión (50) así como al menos un aplicador que contiene un conductor de luz (2) rodeado de u
