Author(s)

Xiaoyu Guo¹, Jinhua Yu¹, Roger J. Smales², Huifen Chen³, Haiyan Si³, Younong Wu^1*

¹Department of Endodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
²School of Dentistry, Faculty of Health Sciences, The University of Adelaide, Adelaide, Australia.
³Institute of Stomatology, Nanjing Medical University, Nanjing, China.

Objective: To evaluate the effect of different irradiation times on the occlusion of dentinal tubules when using Nd:YAG laser. Background data: Dentin hypersensitivity is a frequent problem that has limited treatment success despite many chemical and physical therapies. Methods: Four coronal dentin disks 2 mm thick were cut with a low-speed diamond saw from four freshly extracted intact first molars. The coronal dentin surface of each disk was divided into four regions, each approximately 2 mm × 3 mm. The dentin surfaces were treated with 27% EDTA then the four regions irradiated separately in a randomized pattern with a Nd:YAG laser (120 mJ, 5 Hz), using irradiation times of 0 s, 20 s, 40 s and 60 s, representing laser energies of 0 J/cm², 200 J/cm², 400 J/cm² and 600 J/cm², respectively. SEM photomicro-graphs were taken at 1500× and 3000× to calculate the dentinal tubule orifice occlusion rates and to measure the tubule diameters, respectively. Results: For the laser irradiation times of 0 s, 20 s, 40 s and 60 s, the corresponding dentinal tubule occlusion rates were 2.05 (SD 0.29)%, 10.01 (1.71)%, 23.58 (2.51)% and 90.23 (2.24)%, respectively; and the tubule diameters were 4.18 (0.32) μm, 3.46 (0.24) μm, 1.69 (0.32) μm and 0.12 (0.02) μm, respectively. There were significant differences among all groups for both measured variables (p ≤ 0.005). Conclusions: Within the limitations of this in Vitro study, when using a Nd:YAG laser at 120 mJ and 5 Hz, an irradiation time of 60 s achieved the best sealing of the coronal dentinal tubule orifices.

Nd:YAG Laser, Dentinal Tubule, Scanning Electron Microscope

Guo, X. , Yu, J. , Smales, R. , Chen, H. , Si, H. and Wu, Y. (2015) Effect of Different Irradiation Times on the Occlusion of Dentinal Tubules When Using a Nd:YAG Laser: An in Vitro SEM Study. Open Journal of Stomatology, 5, 72-79. doi: 10.4236/ojst.2015.53011.