Abstract: ObjectiveTo compare the clinical effect of Erbium Yttrium-Aluminum-Garnet(Er：YAG) laser and piezosurgery(PS) in removing the bone resistance of low vertically impacted mandibular third molars, and to explore the optimal method for extraction of such teeth. 
MethodsA total of 60 eligible patients were randomly divided into two groups for osteotomy: Er：YAG laser group and PS group. The duration of operation, postoperative pain, facial edema, trismus and patient satisfaction were compared between the two groups. 
ResultsThe postoperative pain at 1, 3, and 7 d after surgery，and facial edema and trismus at 3 and 7 d after surgery were slightly higher in Er：YAG laser group than in PS group, suggesting no significant difference. However, the duration of operation was significantly shorter and the patient satisfaction was higher in PS group. 
ConclusionIn the extraction of low vertically impacted mandibular third molars, the postoperative complications between Er：YAG laser and PS groups are similar, but PS is more efficient and obtains more patient satisfaction.

Key words: tooth, impacted, piezosurgery, laser