REVIEW Comparison of Er:YAG and Er,Cr:YSGG lasers used in dentistry

Erbium-doped solid-state laser systems have become an established tool in dentistry. The two most commonly used Erbium lasers in dentistry are Er:YAG and Er,Cr:YSGG, with a subtle but important difference in their respective laser wavelengths. There is also an important difference in the type of technology they utilize to energize the flashlamps. The conventional PFN (Pulse Forming Network) pulses are bell shaped and are, in most cases, of fixed duration, while VSP (Variable Square Pulse) pulses are nearly square-shaped and of variable pulse duration. When used on hard dental tissues, the Erbium laser energy heats up the water within the hard tissue and causes that water to be turned into steam. This causes a mini-explosion to occur and the hard tissue is « ablated » (removed). Ideally, the remaining dental tissue beneath should not be affected by the Erbium laser ablation, thereby allowing precise control and minimal damage to the surrounding tissue. On the other hand, there are times, particularly when treating soft tissue, when the coagulation of the remaining tissue is exactly what is needed. In this paper we analyze and compare Er:YAG and Er,Cr:YSGG dental lasers and their pulse forming technologies from the viewpoint of which laser allows the highest possible control of tissue ablation and of the effects on the underlying tissue that remains.