Sealing depth of Nd:YAG laser on human dentinal tubules.

Dentin permeability and hypersensitivity are both reduced when the dentinal tubules are occluded. Previous scanning electron microscopic studies showed that Nd:YAG laser could cause melting of dentin and closure of exposed dentinal tubules without dentin surface cracking. Therefore, the aim of the present study was to evaluate the sealing depth of Nd:YAG laser on human dentinal tubules. Thirty-six dentin specimens with exposed dentinal tubule orifices were used in this study. Samples were randomly divided into three groups. Groups A and B were lased by Nd:YAG laser at energy of 30 mJ with 10 pulses/s for a stroke along the dentin surface. Group C was not lased and served as a control. Subsequently, group B was frozen in liquid nitrogen and split by a sharp chisel. Under SEM observation, nonlased specimens showed numerous exposed dentinal tubule orifices, and lased specimens showed melting of dentin and closure of exposed dentinal tubule orifices. The sealing depth of Nd:YAG laser on human dentinal tubules was approximately 4 microns.