The evolution of the diode laser

In modern dentistry applications, two different types of laser occupy dominant positions: gas lasers and solid-state lasers. The first of these categories includes the Co2 laser (10 600 nm) and the argon laser (480 + 515 nm), while examples of the solid-state laser are the Nd:YAG (1064 nm), Er:YAG (2940 nm), Er:CrYSGG (2780 nm) and the diode laser (mainly 810 and 980 nm). As the name suggests, gas lasers use gas mixtures as their active laser medium whereas solid-state lasers usually employ a crystal as their active laser medium. In classic solid-state lasers, the laser medium takes the form of an optical crystal which is excited by a flashlight (a process known as “pumping”). The laser crystal and flashlight are located in a unit known as a resonator, a chamber comprising 2 mirrors between which the laser process takes place. At a low percentage rate, one of these mirrors is permeable to laser light, enabling usable light energy to be disengaged from the process. A fundamental property of this design principle involves a certain level of laser energy being stored in the resonator which can be released in a very short pulse. The shorter the energy release time (i.e. the pulse time), the lower the thermal impact of the laser beam. In eye surgery applications, tissue can be removed by very short pulses of laser light to correct vision defects, and this can be done without damaging this tissue with heat. In the world of dentistry, manufacturers of Er:YAG lasers are committed to achieving the shortest possible pulse times. This increases the removal rate for hard tooth material while at the same time reducing the sensation of pain.