Sealing Depth of Q-Switched Nd:YAG 1064nm Laser in the Treatment of Patients with Hypersensitive Teeth: An In Vitro Study

Abstract

Abstract: The purpose of this work was to study the effects of the Nd:YAG laser on exposed dentinal tubules of human extracted teeth using a scanning electron microscope (SEM). Eighty 2.5mm-thick slices were cut at the cementoenamel junction from 20 extracted human teeth with an electric saw. A diamond bur was used to remove the cementum layer to expose the dentinal tubules. Each slice was sectioned into four equal quadrants and the specimens were randomly divided into four groups (A to D ). Groups B to D were lased for 2 mins using an Nd:YAG laser at 6 pulses per second at energy outputs of 80 , 100 and 120 mJ. Group A served as control. Under SEM observation, nonlased specimens showed numerous exposed dentinal tubules. SEM observation revealed that application of Nd:YAG laser at energy output of 80 mJ may cause melting of dentin and partial closure of exposed dentinal tubules without dentin surface cracking. But when the energy output raised to 100 and 120 mJ more sealing of dentinal tubules occurs. Heat generation occurred in all lased groups but the amount of temperature increase was within the permissible limits(less than 5.5⁰C). The measured sealing depths were from 3-5µm for groups B-D and the width of the created groove was 30µm in all lased groups. In conclusion lasing with nanosecond Nd:YAG with a wavelength of 1064nm at 120mJ with 6Hz for 2 minutes (group D) shows the efficient laser parameters for complete sealing of exposed dentinal tubules without temperature increase to the damaging level of the pulp tissue.