The energy in the beams of laser light interact with target substances according to the individual wavelengths. The different wavelengths have varying degrees of relative absorption into the various components of hard and soft tissue. The body pigments of melanin and hemoglobin readily absorb the lasers in the lower end of the spectrum of laser wavelengths. From the middle of the spectrum and above, those wavelengths are readily absorbed in both water and hydroxyapatite. This results in rapidly vaporizing the high water content soft tissue and altering tooth enamel and dentin.
All wavelengths have essentially the same mechanism of tissue interaction.
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.