Effect of Er:YAG , Nd:YAG Lasers & Bur on Intrapulpal Temperature

"Objective:" to determine the intrapulpal temperature rise when using Er:YAG laser, Nd:YAG laser and conventional bur in class five cavity preparations.

"Methods:" sixty non carious premolar teeth extracted for orthodontic purposes were used in this study, these samples were equally grouped into two major groups according to cavity depth; group 1 represented temperature variance during 1 mm cavity depth while the second group represented temperature variance during 2 mm cavity depth. Each group was further subdivided into three subgroups, each subgroup composed of ten teeth and standardized class V preparation was prepared on each buccal and lingual surfaces.The teeth were prepared with Er:YAG laser operated with 10 Hz frequency , 500 mJ pulse energy and 63.69 J/cm2 energy density for the first subgroup and with Nd:YAG laser operated with 10 Hz frequency, 200 mJ pulse energy and 249 J/cm2 energy density for the second subgroup while conventional bur was used for the third subgroup. Apical preparation was made for each tooth and the contents of the pulp was extirpated then the thermocouple probe was introduced inside the pulp chamber, the highest temperature reading was recorded before, during 1 mm cavity preparation and during 2 mm cavity preparation then temperature variance was obtained for each reading and recorded.

"Results:" there was a highly significance difference among subgroups for each group, and there was a highly significance difference between group1 and group 2. The best result was obtained for subgroup A for both groups which represented by Er:YAG laser.

"Conclusion:" the Er:YAG laser cavity preparation with energy density 63.69 J/cm2 was more effective than conventional bur cavity preparation and Nd:YAG laser regarding temperature rise in class V cavity preparation. The highest temperature rise was obtained with Nd:YAG laser which cause local carbonization in the area of preparation and might threaten the dental pulp.