The absorption of energy from the laser beam results in a highly localized conversion to heat, causing disruption of the target tissue. This is called a photothermal reaction. The principal functions served are a wide and significant variety of surgical procedures, curing of dental resins, caries removal and cavity preparation, dentin and enamel modification, and enhanced bleaching of the dentition. When delivered to the target tissue site, the laser beam can have four different interactions and effects. Generally, all of these interactions occur each time with each wavelength and each tissue type.
Absorption is the second and the most beneficial tissue interaction.
The treatment objective is accomplished with the photothermal effect. This is useful in photopolymerization of composite resins, but as the beam scatters, its power density eventually decreases to the point where it has no significant biologic effect. Laser energy, with one exception of wavelength, is delivered through an optical glass fiber. These fibers provide a highly flexible way of conducting the beam onto the target tissue. Fibers are available in small diameters and are sterilizable.