Effect of Nd:YAG Laser Irradiation on the Number of Open Dentinal Tubules and Their Diameter with and without Smear of Graphite: An in Vitro Study

Abstract Introduction: Dentin hypersensitivity (DH) is characterized by tooth pain arising from exposure of dental roots. In this study the efficiency of neodymium yttrium-aluminum-garnet (Nd:YAG) laser in association with graphite on dentinal surface changes as the alternative to the treatment of DH was evaluated.Methods: Sixteen noncarious human third molars were collected and sectioned into ۵ parts from cementoenamel junction (CEJ) to the furcation area. The prepared samples were randomly assigned into five groups (Gs) of each ۱۶: Control (G۱), treated by Nd:YAG laser at ۰.۵ W (G۲), irradiation of Nd:YAG with a ۰.۲۵ W output power(G۳), smeared with graphite and then using Nd:YAG laser at output powers of ۰.۵ W (G۴) and ۰.۲۵ W (G۵). For all groups the parameters were ۱۵ Hz, ۶۰ s, at two stages and with a right angle irradiation. The number and diameter of dentinal tubules (DT) were compared and analyzed by SPSS software, One way ANOVA and Post hoc LSD tests.Results: The number of open dentinal tubules varied significantly between all groups except among G۱ with G۳ and G۲ with G۵. Multiple comparison tests also exhibited significant differences regarding the diameter of tubules between the groups two by two except among G۲ with G۵.Conclusion: Nd:YAG laser used at ۰.۲۵ W and ۰.۵ W with application of graphite smear was able to reduce the number and diameter of dentinal tubules. Keywords: dentin hypersensitivity Nd YAG lasers scanning electron microscopy.