Abstract
We analyzed the effects of the Er:YAG laser used with different parameters on dentinal tubule (DT) occlusion, intrapulpal temperature and pulp tissue morphology in order to determine the optimal parameters for treating dentin hypersensitivity. Dentin specimens prepared from 36 extracted human third molars were randomized into six groups according to the treatment method (n=6 each): control (A); Gluma desensitizer (B); and Er:YAG laser treatment at 0.5 W , 167 J/cm2 (50 mJ, 10 Hz) (C), 1 W , 334 J/cm2 (50 mJ, 20 Hz) (D), 2 W , 668 J/cm2 (100 mJ, 20 Hz) (E), and 4 W and 1336 J/cm2 (200 mJ, 20 Hz) (F). Treatment-induced morphological changes of the dentin surfaces were assessed using scanning electron microscopy (SEM) to find parameters showing optimal dentin tubule occluding efficacy. To further verify the safety of these parameters (0.5 W, 167 J/cm2), intrapulpal temperature changes were recorded during laser irradiation, and morphological alterations of the dental pulp tissue were observed with an upright microscope. Er:YAG laser irradiation at 0.5 W (167 J/cm2) were found to be superior in DT occlusion, with an exposure rate significantly lower than those in the other groups (P<0.05). Intrapulpal temperature changes induced by Er:YAG laser irradiation at 0.5 W (167 J/cm2) with (G) and without (H) water and air cooling were demonstrated to be below the threshold. Also, no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Therefore, 0.5 W (167 J/cm2) is a suitable parameter for Er:YAG laser to occlude DTs, and it is safe to the pulp tissue.
Highlights
Dentin hypersensitivity (DH) is one of the most frequently encountered chronic conditions characterized by transient and sharp tooth pain evoked by external stimuli, including thermal, evaporative, tactile, osmotic, and chemical stimuli
The DH mechanism remains controversial, the theory of hydrodynamics is the most accepted. It suggests that external stimulation of teeth with DH results in fluid displacement within the dentinal tubules (DTs),3 which activates the nerve endings located at the pulp–dentin interface and eventually results in pain and discomfort
We investigated the effects of laser irradiation using these parameters on intrapulpal temperature changes and the morphological alterations in odontoblasts and pulp tissue were observed to determine the safety of Er:YAG laser in the treatment of DH
Summary
Dentin hypersensitivity (DH) is one of the most frequently encountered chronic conditions characterized by transient and sharp tooth pain evoked by external stimuli, including thermal, evaporative, tactile, osmotic, and chemical stimuli. The DH mechanism remains controversial, the theory of hydrodynamics is the most accepted It suggests that external stimulation of teeth with DH results in fluid displacement within the dentinal tubules (DTs), which activates the nerve endings located at the pulp–dentin interface and eventually results in pain and discomfort. Used desensitizing agents can be classified into four categories: anti-inflammatory agents (corticosteroids), protein precipitants (formaldehyde, silver nitrate, strontium chloride hexahydrate), tubule-occluding agents (calcium hydroxide, potassium nitrate, sodium fluoride), and tubule sealants (resins and adhesives).. Used desensitizing agents can be classified into four categories: anti-inflammatory agents (corticosteroids), protein precipitants (formaldehyde, silver nitrate, strontium chloride hexahydrate), tubule-occluding agents (calcium hydroxide, potassium nitrate, sodium fluoride), and tubule sealants (resins and adhesives).4 None of these agents can produce long-lasting effects, since abrasion and erosion by internal and external acids would lead to re-exposure of DTs over time. Used desensitizing agents can be classified into four categories: anti-inflammatory agents (corticosteroids), protein precipitants (formaldehyde, silver nitrate, strontium chloride hexahydrate), tubule-occluding agents (calcium hydroxide, potassium nitrate, sodium fluoride), and tubule sealants (resins and adhesives). none of these agents can produce long-lasting effects, since abrasion and erosion by internal and external acids would lead to re-exposure of DTs over time.
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