Abstract
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.
Highlights
Dentin hypersensitivity (DH) is characterized by a short, sharp and pain of rapid onset arising from exposed dentin in response to thermal, osmotic, mechanical or chemical stimuli that cannot be attributed to any other form of dental disease or defect [1]-[3]
The hydrodynamic theory of DH states that when stimuli induce rapid displacement of the dentinal fluid within the tubules the fluid flow excites intradental nerves, resulting in an immediate pain response [7] [8]
As in previous studies [7] [9] [18], the smear layers produced by the diamond saw on the surfaces of the dentin specimens were removed by EDTA to avoid influencing the ef
Summary
Dentin hypersensitivity (DH) is characterized by a short, sharp and pain of rapid onset arising from exposed dentin in response to thermal, osmotic, mechanical or chemical stimuli that cannot be attributed to any other form of dental disease or defect [1]-[3]. The hydrodynamic theory of DH states that when stimuli induce rapid displacement of the dentinal fluid within the tubules the fluid flow excites intradental nerves, resulting in an immediate pain response [7] [8]. According to this theory, the key to treating DH successfully is to prevent or reduce fluid flow within the tubules [5]. Most treatments are either ineffective or only last for a short period of time [11] [12]. Because of their easy operation and more lasting DH treatment effects, several types of lasers have been used such as the Nd:YAG laser, Er:YAG laser, CO2 laser and GaAlAs laser [13] [14]
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