Sealing of Human Dentinal Tubules by Nd:YAG Laser

Abstract

Studies of extracted teeth have revealed that teeth exhibiting dentin hypersensitivity have larger numbers of widened dentinal tubules at the dentin surface than nonsensitive teeth. Various methods and materials used in the treatment of dentin hypersensitivity are thought to achieve therapeutic benefit by tubule occlusion. The purpose of this investigation was to study the effects of the Nd:YAG laser on exposed dentinal tubules of human extracted teeth using a scanning electron microscope (SEM). Thirty 3-mm-thick slices were cut at the cementoenamel junction from 30 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 inner half of the dentin thickness was removed. The specimens were randomly divided into five groups (A to E). Groups A to D were lased for 2 mins using an Nd:YAG laser at 10 pulses per second at energy outputs of 20, 30, 40, and 50 mJ. Group E 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 30 mJ may cause melting of dentin and closure of exposed dentinal tubules without dentin surface cracking. But when the energy output is raised to 40 and 50 mJ, cracking lines, rupture of molten materials, and exposure of dentinal tubules were noted.