Temperature rise during Er : YAG and Nd : YAP laser ablation of dentin

This in vitro study compared temperature rises during cavity preparation wi th an Er:YAG laser, Nd: YAP laser, and a high-speed handpiece, Eighteen tee th were sectioned longitudinally and divided into six groups: group 1 was t reated with a carbide bur on a high-speed dental handpiece; group 2 was tre ated with an Er:YAG laser with an energy of 140 mJ, a pulse repetition rate of 4 Hz; and group 3 was treated with an Nd:YAP laser with an energy of 24 0 mJ, a pulse repetition rate of 10 Hz, In these groups no water cooling wa s used. Groups 4 to 6 were treated in the same way, but with water spray. T emperature increases were measured at different dentin thicknesses by a mic rothermocouple attached to the inner side of the pulp chamber. Water coolin g was essential to reduce temperature effects in all groups. Nd:YAP laser i nduced significantly higher temperature rises than Er:YAG or handpiece, Tem perature response to the Er:YAG laser and the handpiece seemed to be simila r.