The treatment of hypersensitive dentine by laser is a safe therapy with good results. However, the effectiveness of the treatment depends on the type of laser and parameters used. Therefore, the authors conducted this study with the following objectives: to compare the dentinal tubule sealing effectiveness and tubular orifice cracking impacts of 810nm diode laser at 3 doses, 5 seconds, 10 seconds and 15 seconds in vitro. 6 rabbits are divided into 3 groups receiving different dose of laser: 5 second (5J/mm2), 10 second (10J/mm2) and 15 second (15J/mm2). After three times of laser radiations (once for 7days), the teeth are extracted, the surface was treated and scanned with SEM. Research results: the percentage of dentinal tubule sealing in 3 groups is 49.4 percent, 86.3 percent and 86.9 percent respectively. The percentage of cracked dentinal tubule is: 14 percent
16.2 percent and 38.2 percent respectively. Conclusion: Using 810 nm laser
0.5W and a 10 - constant - second dose (10J/mm2) produces a high dentinal tubule sealing effectiveness while restricting impacts on the dentinal tubule structure.