SEALING DEPTH OF ND-YAG LASER ON HUMAN DENTINAL TUBULES

Dentin permeability and hypersensitivity are both reduced when the den tinal tubules are occluded. Previous scanning electron microscopic stu dies showed that Nd:YAG laser could cause melting of dentin and closur e of exposed dentinal tubules without dentin surface cracking. Therefo re, the aim of the present study was to evaluate the sealing depth of Nd:YAG laser on human dentinal tubules. Thirty-six dentin specimens wi th exposed dentinal tubule orifices were used in this study. Samples w ere randomly divided into three groups. Groups A and B were lased by N d:YAG laser at energy of 30 mJ with 10 pulses/s for a stroke along the dentin surface. Group C was not lased and sewed as a control. Subsequ ently, group B was frozen in liquid nitrogen and split by a sharp chis el. 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 similar to 4 mu m.