[Lasers: principles, characteristics and tissue interactions].

Since their appearance in 1960, lasers have been considered useful light sources for medical applications. Laser light is monochromatic, the bundle is parallel and can be directed and focussed, as a result of which very high energy densities can be achieved. Several applications in dentistry have been investigated over the past decades. This article describes the physics behind lasers, the characteristics of the laser beam and overviews the laser wavelengths currently used in dentistry. The different interactions between the laser beam and the target are explained.