Dentinal tubule sealing effects of 532-nm diode-pumped solid-state laser, gallic acid/Fe³⁺ complex, and three commercial dentin desensitizers

The purpose of this study was to compare dentinal tubule sealing effects of a 532-nm diode-pumped solid-state (DPSS) laser, gallic acid/Fe³⁺ complex, and three commercially available dentin desensitizers. Human premolars (n = 44) extracted for orthodontics had standardized cervical cavities prepared, etched (37% phosphoric acid) and randomly assigned to either a control (n = 4), or one of five treatment groups (n = 8/group). Desensitizing treatments were either a 532-nm DPSS laser, gallic acid/Fe³⁺ complex, oxalate-based Super Seal™ (SS), DIO™ Enamel Coating Pen Pro Tooth (Dio), or adhesive-type Hybrid Coat™ (HC). Dentinal fluid flow (DFF) was monitored continuously in real time during the application of each desensitizing agent, by using a nanoliter-scaled fluid flow-measuring device. Following treatment, morphological changes on dentinal surfaces and within tubules were observed by scanning electron microscopy (SEM). DFF rates were significantly reduced after treatment in all experimental groups (P < 0.05), except SS (P > 0.05). The gallic acid/Fe³⁺ complex reduced DFF rates the most, and significantly (P < 0.05) more than the three commercial dentin desensitizers. There were no significant differences in DFF reduction rates between the gallic acid/Fe³⁺ complex and the DPSS laser groups (P > 0.05). There were no significant differences in DFF reduction rates among the three commercial dentin desensitizers (P > 0.05). SEM examination of treated dentin showed that the degree of occlusion of dentinal tubules correlated closely with the corresponding reduction in DFF rates. The gallic acid/Fe³⁺ complex and 532-nm DPSS laser were superior to other desensitizing methods in occluding dentinal tubules and reducing DFF rates.